Re: [time-nuts] 58503a and Yixunhk
On 14 Dec 2014 02:12, Adrian rfn...@arcor.de wrote: Same here. I have a Z3805A from this vendor that works flawlessly, and I know of other people that purchased from him without any problems. To call it a cam when a HP unit comes with a remanufactured box is quite a harsh statement, IMHO. I'm glad they are putting those ugly units into a neat and practical box that is made with attention to every detail. Adrian If the boxes had Yixun Electronics or similar printed on the rear I would not have a problem with him putting the electronics in new boxes,. But clearly there is an attempt to deceive people when it says Hewlett Packard on the front rear. The attention to detail is superficial. Someone who formally worked at HP has sent me a list of about 5 things wrong with the rear panel. I am not going to disclose them all here as I realise someone from Yixenhk could read this list. All I would achieve is help them make more realistic fakes. I have also noticed that the IEC socket is placed in a location about 3 mm outside the space on the fake panel. There is a serial number sticker which previously covered up a warning. That has since fallen off. It is also printed Hewlett Packard. It is doubtful the ventilation slots are adequate - someone sent me an email saying his similar HP model had much slots for ventilation. This seller has a number of HP GPSDOs ranging in price from $180 to $799. Some are marked Samsung. I bought the $799 one believing I would get an unmodified HP unit, but instead I have an expensive fake. I would be quite happy to buy a Ferrari replica - in fact I helped a friend build one on a Voltzwagen Beatle chassis. But I would not be happy if I bought an expensive car that was sold as a Ferrari, but which I layer found out was a Voltzwagen. Dave. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 58503a and Yixunhk
On 14 Dec 2014 08:07, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: If the boxes had Yixun Electronics or similar printed on the rear I would not have a problem with him putting the electronics in new boxes,. But clearly there is an attempt to deceive people when it says Hewlett Packard on the front rear. I mean I would not have a problem if the front and rear had Yixun Electronics on them. A box not made by Hewlett Packard should not say Hewlett Packard anywhere. It is not a replica but a fake. I did not expect to pay $799 for a fake. Dave. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Set time on Solaris computer from HP 58503A
Both my computers run Solaris. * One, a Sun Ultra 27 has a Xeon processor, no serial ports, but I do have a good quality USB serial adapter for it. * The other, a Sun Blade 2000, has a SPARC processor a 25 pin serial port. I am using the Sun Blade 2000 to talk to the HP now, but I don't run that machine 24/7 due to the fact it is rather power hungry. The Xeon based machine is much more modern, much faster and uses a lot less power. I would like to be able to set the date time of the Xeon workstation from the HP 58503A. I appreciate that the USB is likely to cause some performance degradation compared to a real serial port, but I can live with that. Can anyone advise if this is possible, and if so what software is needed? Any idea what sort of accuracy would be achievable? I bought this to use as a frequency reference, not a clock, so I am not going to buy commercial software to do it, but if it can be done easily from open source software I will do so. Any suggestions? Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Ublox time/freq aiding was Re: Linear voltage regulator hints...
On 14/12/2014 04:08, d...@irtelemetrics.com wrote: Note that most high-end GNSS timing receivers go one better and simply have an external input for the clock. That way you feed your own lab clock into the receiver. If you have Rb/Cs/maser you would use that as the reference. It's what the national timing labs do, along with dual-frequency and post-processing and all the other tricks of the trade. I think it would be agreat idea also. It's a wonder that more of the 'timing' receivers don't have that external clock option! I wonder what these Ublox parts use for a clock? Is it something frequency compatible with a 10Mhz source??? (Hmm, can we pry one apart to figure it out! ;) ) Ublox modules have a 48mhz internal clock. There is the following interesting paragraph in at least the 7 8 data sheets: --- 1.8.2 Aiding The EXTINT pin can be used to supply time or frequency aiding data to the receiver. For time aiding, hardware time synchronization can be achieved by connecting an accurate time pulse to the EXTINT pin. Frequency aiding can be implemented by connecting a periodic rectangular signal with a frequency up to 500 kHz and arbitrary duty cycle (low/high phase duration must not be shorter than 50 ns) to the EXTINT pin. Provide the applied frequency value to the receiver using UBX messages. --- I haven't been able to find any information about what this actually does though. Anyone know ? Cheers Simon ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
Le 14 déc. 2014 à 10:02, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk a écrit : Both my computers run Solaris. * One, a Sun Ultra 27 has a Xeon processor, no serial ports, but I do have a good quality USB serial adapter for it. * The other, a Sun Blade 2000, has a SPARC processor a 25 pin serial port. I am using the Sun Blade 2000 to talk to the HP now, but I don't run that machine 24/7 due to the fact it is rather power hungry. The Xeon based machine is much more modern, much faster and uses a lot less power. I would like to be able to set the date time of the Xeon workstation from the HP 58503A. I appreciate that the USB is likely to cause some performance degradation compared to a real serial port, but I can live with that. If the serial driver will pass the DCD, so much the better. Can anyone advise if this is possible, and if so what software is needed? Any idea what sort of accuracy would be achievable? try ref clock driver 26 Type 26 http://www.eecis.udel.edu/%7Emills/ntp/html/drivers/driver26.html Hewlett Packard 58503A GPS Receiver (GPS_HP) I bought this to use as a frequency reference, not a clock, so I am not going to buy commercial software to do it, but if it can be done easily from open source software I will do so. Any suggestions? Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] tyco electronics A1025
Hi all, I've just found an old anti-theft system (I think) for cars . It has a tyco electronics A1205 gps module. I've been unable to find any information about this module, other than it should be a 3.3V 12 channel GPS module with serial NMEA output. Does anyone have any informations about it? Even a pinout would help. I'd like to use it as a cheap NMEA receiver for a stratum 1 ntp server. Thanks in advance. Frank IZ8DWF ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
drkir...@kirkbymicrowave.co.uk said: Can anyone advise if this is possible, and if so what software is needed? Any idea what sort of accuracy would be achievable? I'm not familiar with Solaris. I've never worked with a 58503A, but I have worked with the Z3801A and KS-24361. I'd try ntpd. There is probably a version that comes with Solaris. USB probably doesn't support PPS. I'd expect time to be within ballpark of 10s of ms, roughly what you would expect with a good network connection so use that as a sanity check. You will need to setup your ntp.conf to use the HP driver, 26. You will need to setup your 58503A to use UTC in T2 mode. :diag:gps:utc 1 (and reboot?) :ptime:tcode:format F2 You can check the GPS/UTC setting on the status page, and check the T2 setting by sending: :PTIME:TCODE? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Which First GPSDO to buy?
On Dec 13, 2014, at 9:47 PM, Chris Albertson albertson.ch...@gmail.com wrote: Actually I've added some features to it like a 2 line by 16 character LCD display and some status LEDs. And I can log data to a computer via a USB cable so it is easy to plot data and it is using my more expansive mast mounted timing antenna. Just in case any of you like reading Arduino code, for fun or functions to copy-and-paste, the code for my PCB that combines an ATMega328p with an Adafruit GPS and 16x2 LCD to display GPS info as it sends the PPS out the DB9 DCD is at GitHub. It’s not exactly, say, measuring oscillator cycles (yet... ) but it’s perhaps a good introduction for someone who’s never ever before used anything Arduino. (And now that I’ve done more PCBs with Cypress and FTDI chips, I wish I’d put that straight on my board instead of as a future daughterboard, but, feature creep.) https://github.com/ptudor/jemma-clock PT smime.p7s Description: S/MIME cryptographic signature ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
Based on my recent testing - including Solaris - you will be better off with the Internet unless your USB adapter is far better behaved than the several I have here On Sunday, December 14, 2014, Hal Murray hmur...@megapathdsl.net wrote: drkir...@kirkbymicrowave.co.uk javascript:; said: Can anyone advise if this is possible, and if so what software is needed? Any idea what sort of accuracy would be achievable? I'm not familiar with Solaris. I've never worked with a 58503A, but I have worked with the Z3801A and KS-24361. I'd try ntpd. There is probably a version that comes with Solaris. USB probably doesn't support PPS. I'd expect time to be within ballpark of 10s of ms, roughly what you would expect with a good network connection so use that as a sanity check. You will need to setup your ntp.conf to use the HP driver, 26. You will need to setup your 58503A to use UTC in T2 mode. :diag:gps:utc 1 (and reboot?) :ptime:tcode:format F2 You can check the GPS/UTC setting on the status page, and check the T2 setting by sending: :PTIME:TCODE? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com javascript:; To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
On 14 December 2014 at 11:57, Hal Murray hmur...@megapathdsl.net wrote: drkir...@kirkbymicrowave.co.uk said: Can anyone advise if this is possible, and if so what software is needed? Any idea what sort of accuracy would be achievable? I'm not familiar with Solaris. I've never worked with a 58503A, but I have worked with the Z3801A and KS-24361. I'd try ntpd. There is probably a version that comes with Solaris. I 1) Downloaded ntp-4.2.6p5 2) Configured with as ./configure --enable-HPGPS 3) Built it, without any problems. 4) Switched user to root 4) Disabled the ntpd which was already running # svcadm disable ntp 4) Installed it. I found it created a number of files in /usr/local/bin drkirkby@buzzard:~$ ls -lrt /usr/local/bin/ | grep Dec 14 -rwxr-xr-x 1 root root1394 Dec 14 12:19 ntp-wait -rwxr-xr-x 1 root root2029 Dec 14 12:19 ntptrace -rwxr-xr-x 1 root root 466252 Dec 14 12:19 sntp -rwxr-xr-x 1 root root 2253412 Dec 14 12:19 ntpd -rwxr-xr-x 1 root root 299696 Dec 14 12:19 ntpdate -rwxr-xr-x 1 root root 604280 Dec 14 12:19 ntpdc -rwxr-xr-x 1 root root 606312 Dec 14 12:19 ntpq -rwxr-xr-x 1 root root 176496 Dec 14 12:19 ntptime -rwxr-xr-x 1 root root 23288 Dec 14 12:19 tickadj -rwxr-xr-x 1 root root 460120 Dec 14 12:19 ntp-keygen and also the directory /dev/fd drkirkby@buzzard:~$ ls /dev/fd 0112 127 141 156 170 185 2213 228 242 27 41 56 70 85 1113 128 142 157 171 186 20 214 229 243 28 42 57 71 86 10 114 129 143 158 172 187 200 215 23 244 29 43 58 72 87 100 115 13 144 159 173 188 201 216 230 245 344 59 73 88 101 116 130 145 16 174 189 202 217 231 246 30 45 674 89 102 117 131 146 160 175 19 203 218 232 247 31 46 60 75 9 103 118 132 147 161 176 190 204 219 233 248 32 47 61 76 90 104 119 133 148 162 177 191 205 22 234 249 33 48 62 77 91 105 12 134 149 163 178 192 206 220 235 25 34 49 63 78 92 106 120 135 15 164 179 193 207 221 236 250 35 564 79 93 107 121 136 150 165 18 194 208 222 237 251 36 50 65 894 108 122 137 151 166 180 195 209 223 238 252 37 51 66 80 95 109 123 138 152 167 181 196 21 224 239 253 38 52 67 81 96 11 124 139 153 168 182 197 210 225 24 254 39 53 68 82 97 110 125 14 154 169 183 198 211 226 240 255 454 69 83 98 111 126 140 155 17 184 199 212 227 241 26 40 55 784 99 drkirkby@buzzard:~$ USB probably doesn't support PPS. I'd expect time to be within ballpark of 10s of ms, roughly what you would expect with a good network connection so use that as a sanity check. You will need to setup your ntp.conf to use the HP driver, 26. That I am not sure how to configure ntp.conf - a case of RTFM. You will need to setup your 58503A to use UTC in T2 mode. :diag:gps:utc 1 (and reboot?) That command works. How do you reboot - apart from of course powering the thing off? :ptime:tcode:format F2 That command works too. You can check the GPS/UTC setting on the status page, and check the T2 setting by sending: :PTIME:TCODE? E-101 :PTIME:TCODE? T220141214123441337 (remember I have not rebooted) Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
On Dec 14, 2014, at 07:42, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 11:57, Hal Murray hmur...@megapathdsl.net redacted That command works. How do you reboot - apart from of course powering the thing off? # shutdown -y -i6 -g0 Or # reboot Or # init 6 Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
On 14 December 2014 at 12:39, Neil Schroeder gign...@gmail.com wrote: Based on my recent testing - including Solaris - you will be better off with the Internet unless your USB adapter is far better behaved than the several I have here The USB - serial adapter I have is an Keyspan USA-19HS http://www.tripplite.com/high-speed-usb-to-serial-adapter-keyspan~USA19HS/ I bought that one, as it was officially supported by Sun. I also have another one somewhere - forget which model. Again that was officially supported by Sun. Both have worked for industrial control applications, whereas I gather some cheap ones are only suitable for common consumer devices. In any case, it will be more fun educational to use the GPS receiver. To be honest, I don't need great accuracy. I only bought the unit as a frequency standard - the clock functionality is not important to me, but if I can have a bit of fun playing around with it, then I will. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
On 14 December 2014 at 13:37, bownes bow...@gmail.com wrote: On Dec 14, 2014, at 07:42, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 11:57, Hal Murray hmur...@megapathdsl.net redacted That command works. How do you reboot - apart from of course powering the thing off? # shutdown -y -i6 -g0 Or # reboot Or # init 6 Bob I know those commands, although I don't recommend reboot - it is less clean than init 6. I assumed that that Hal Murry's reboot was meant to be the GPS receiver, not the Solaris computer, but maybe I mis-understood. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] KS-24361 quirk
I haven't checked the pps either. But the reason to put the 15 Mhz into standby is that they combine both signals in a resistive combiner and distribute the signals to multiple radios. If two were active it would create issues. This method avoids the gap switch of a relay. Regards Paul WB8TSL On Sun, Dec 14, 2014 at 12:23 AM, Joseph Gray jg...@zianet.com wrote: I haven't checked the PPS yet, but the 15 MHz from the standby unit is off on my setup. Joe Gray W5JG On Sat, Dec 13, 2014 at 9:55 PM, Hal Murray hmur...@megapathdsl.net wrote: Can somebody confirm that the PPS and 15 MHz on the standby unit are disabled? Does anybody understand how/why they do things that way? Is that a typical Telco interface? If anybody is poking around inside and find a simple way to turn them back on, please share. The PPS is 400 microseconds wide. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] KS-24361 quirk
Hi The cell phone base only needs one reference to keep it running. They disable the un-needed output to make it clear which one should be used. It’s a very common thing in modern systems, not just telecom setups. Bob On Dec 13, 2014, at 11:55 PM, Hal Murray hmur...@megapathdsl.net wrote: Can somebody confirm that the PPS and 15 MHz on the standby unit are disabled? Does anybody understand how/why they do things that way? Is that a typical Telco interface? If anybody is poking around inside and find a simple way to turn them back on, please share. The PPS is 400 microseconds wide. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ublox time/freq aiding was Re: Linear voltage regulator hints...
Hi There is also a little note down in the (many) notes section: Not all features are available with all firmware versions. It applies to all of the external inputs (like USB and SPI). Since the oscillator in the uBlox is a TCXO and not a VCTCXO, the aiding feature would not help in the case of biasing the unit with a hot air gun. It would still loose lock as the TCXO went nuts. The ideal outcome would be a system that reported against the external input rather than the internal TCXO. Since they digitize the external pin with the TCXO, the outcome is pretty coarse (10’s of ns). That’s not going to help us much. Bob On Dec 14, 2014, at 4:26 AM, Simon Marsh subscripti...@burble.com wrote: On 14/12/2014 04:08, d...@irtelemetrics.com wrote: Note that most high-end GNSS timing receivers go one better and simply have an external input for the clock. That way you feed your own lab clock into the receiver. If you have Rb/Cs/maser you would use that as the reference. It's what the national timing labs do, along with dual-frequency and post-processing and all the other tricks of the trade. I think it would be agreat idea also. It's a wonder that more of the 'timing' receivers don't have that external clock option! I wonder what these Ublox parts use for a clock? Is it something frequency compatible with a 10Mhz source??? (Hmm, can we pry one apart to figure it out! ;) ) Ublox modules have a 48mhz internal clock. There is the following interesting paragraph in at least the 7 8 data sheets: --- 1.8.2 Aiding The EXTINT pin can be used to supply time or frequency aiding data to the receiver. For time aiding, hardware time synchronization can be achieved by connecting an accurate time pulse to the EXTINT pin. Frequency aiding can be implemented by connecting a periodic rectangular signal with a frequency up to 500 kHz and arbitrary duty cycle (low/high phase duration must not be shorter than 50 ns) to the EXTINT pin. Provide the applied frequency value to the receiver using UBX messages. --- I haven't been able to find any information about what this actually does though. Anyone know ? Cheers Simon ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] tyco electronics A1025
Hi On Dec 14, 2014, at 6:03 AM, Francesco Messineo francesco.messi...@gmail.com wrote: Hi all, I've just found an old anti-theft system (I think) for cars . It has a tyco electronics A1205 gps module. I've been unable to find any information about this module, other than it should be a 3.3V 12 channel GPS module with serial NMEA output. Does anyone have any informations about it? Even a pinout would help. I'd like to use it as a cheap NMEA receiver for a stratum 1 ntp server. Thanks in advance. It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of it. Finding one that will do position hold is even less likely. You can get modules that will do both for $20 and have a documented interface. Bob Frank IZ8DWF ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Fake 58503
Fellow time-nuts, I have seen the long debate about the fake 58503s. Maybe we should take a step back and think a little about that. Why does someone rebuild say Z3801s into 58503s? Because somehow they are expected to have a higher value, and therefore there is a profit to be made in doing so. Why is there a higher value? Because the potential buys have made that decision, sub-consciously. There is a few differences, but to some degree they are superficial. If you want to reduce the likelihood of being fooled by fakes, then don't raise certain magic number boxes to the skies and prices with it. I could make better use of my Z3801A if I did a few mods myself, beyond the modification from RS422 to RS232. Honest mods and upgrades is one thing we might encourage rather than encourage the fakes. I too have considered the 58503, but consider the price disproportionate to what the Z3801A gives me. So, let's stop this thread of hurt feelings, while it has been interesting and enlightening, we can't get very much more right now. Let's open our boxes and try to see the modifications we can do, collect them on a webpage for everyone to enjoy and use, and be done with it. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Which First GPSDO to buy?
Hi On Dec 14, 2014, at 12:47 AM, Chris Albertson albertson.ch...@gmail.com wrote: I tried to see just how simple, low cost and self contained I could make a GPSDO. I started with the Lars Walenius design then removed everything I could from it. I replace all the software with just a small loop with about a dozen lines of code so it would be easy to understand. My goal was to make something that could be built and tested using just basic equipment. The question is of course How do you know the unit is making a 10 MHz signal if you don't already have a 10MHz reference to compare it to? Well you can assume that your 1PPS reference is accurate. Except that the GPS PPS is *not* perfect, far from it. It’s only reasonably accurate over very long time spans. Over short spans the pps moves around a lot. Then you count and make sure you see EXACTLY 10,000,000 oscillator cycles per each PPS. If you do a tight lock (“EXACTLY”) against a GPS PPS that is moving +/- 10 ns, your frequency will swing +/- 1x10^-8 every second Count both for a few days and verify the ratio remains at ten million to one, exactly. Ok, that’s looking at the long term where GPS is indeed accurate. That’s the easy part on any GPSDO design. I ran mine for about 8 weeks and it stays at the desired ratio.I know this is not a perfect test because it could have been running at zero hertz for 30 seconds and then 20MHz for 30 seconds but I assume the OCXO is better than that. The point is that once you have the GPS working you DO have a pretty good 1Hz reference. Well, not quite so fast. You just jumped over a massive amount of work that normally gets done on a GPS. A unit that *was* swinging +/- 1x10^-8 every second would pass your test. (which is not in any way to say that your design actually does that). It would make a lousy GPSDO for most uses. You very much *do* need to check the ADEV (or what ever) close in and tune your filter up to match your parts. Cost: Motorola Oncore GPS$18 magnnetic patch antenna 6 OCXO (eBay) 19 Arduino, mini 3 PLL chip 2 TTL diver chip1 Plug-in power cube0 perf-board 1 Total cost of GPSDO $50 Just a side note - A *lot* of the $19 OCXO’s I have from eBay are in very poor shape spec wise. Testing them before using them would be a very good idea. Bob Actually I do have A Thunderbolt. I place the 10MHz output of the above unit and the TB on my dual channel scope and was able to see the phase of the two 10MHz references was locked. I saw the phase drift over about an hour but then it would pull back. But I made this very simple and it could be better. Actually I've added some features to it like a 2 line by 16 character LCD display and some status LEDs. And I can log data to a computer via a USB cable so it is easy to plot data and it is using my more expansive mast mounted timing antenna. The Arduino based design is OK for controlling an OCXO but I think it is best used for controlling my Rubidium oscillator. The RB is so stable I should only update the frequency control every few hours at most. On Sat, Dec 13, 2014 at 7:21 PM, Jim Harman j99har...@gmail.com wrote: On Sat, Dec 13, 2014 at 9:36 PM, Bob Camp kb...@n1k.org wrote: The problem with “build it yourself” is that there is no way do know if you got it right unless you have something to compare your design to. You *will* make mistakes as you build one of these…. I think you will have the same problem with an off-the-shelf unit if you don't have at least one reference for comparison. However speaking from experience with Lars Walenius' Arduino-based design, I can say that it is not hard to make a working system, even without another reference. Along the way you will learn a tremendous amount about how these systems work, plus a lot about Arduino programming. Lars' design will run stand-alone, but if you want it can send very useful logging data to a PC, much more informative than a locked led on a commercial unit. Total cost including processor, Adafruit GPS shield, and $25.00 ebay OCXO is about $100.00 -- --Jim Harman ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ublox time/freq aiding was Re: Linear voltage regulator hints...
The oscillator in he m8f is a vctcxo and can be steered with feedback or controlled by the host. Also the m8f can send compliant DAC words to a TLV8515 and and MCP part via i2c for external VCXOs. It accepts their return signal on what would normally be its feedback in ports. On Sunday, December 14, 2014, Bob Camp kb...@n1k.org wrote: Hi There is also a little note down in the (many) notes section: Not all features are available with all firmware versions. It applies to all of the external inputs (like USB and SPI). Since the oscillator in the uBlox is a TCXO and not a VCTCXO, the aiding feature would not help in the case of biasing the unit with a hot air gun. It would still loose lock as the TCXO went nuts. The ideal outcome would be a system that reported against the external input rather than the internal TCXO. Since they digitize the external pin with the TCXO, the outcome is pretty coarse (10’s of ns). That’s not going to help us much. Bob On Dec 14, 2014, at 4:26 AM, Simon Marsh subscripti...@burble.com javascript:; wrote: On 14/12/2014 04:08, d...@irtelemetrics.com javascript:; wrote: Note that most high-end GNSS timing receivers go one better and simply have an external input for the clock. That way you feed your own lab clock into the receiver. If you have Rb/Cs/maser you would use that as the reference. It's what the national timing labs do, along with dual-frequency and post-processing and all the other tricks of the trade. I think it would be agreat idea also. It's a wonder that more of the 'timing' receivers don't have that external clock option! I wonder what these Ublox parts use for a clock? Is it something frequency compatible with a 10Mhz source??? (Hmm, can we pry one apart to figure it out! ;) ) Ublox modules have a 48mhz internal clock. There is the following interesting paragraph in at least the 7 8 data sheets: --- 1.8.2 Aiding The EXTINT pin can be used to supply time or frequency aiding data to the receiver. For time aiding, hardware time synchronization can be achieved by connecting an accurate time pulse to the EXTINT pin. Frequency aiding can be implemented by connecting a periodic rectangular signal with a frequency up to 500 kHz and arbitrary duty cycle (low/high phase duration must not be shorter than 50 ns) to the EXTINT pin. Provide the applied frequency value to the receiver using UBX messages. --- I haven't been able to find any information about what this actually does though. Anyone know ? Cheers Simon ___ time-nuts mailing list -- time-nuts@febo.com javascript:; To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com javascript:; To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Fake 58503
Hi On Dec 14, 2014, at 9:53 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Fellow time-nuts, I have seen the long debate about the fake 58503s. Maybe we should take a step back and think a little about that. Why does someone rebuild say Z3801s into 58503s? or convert 3805’s the same way … Because somehow they are expected to have a higher value, and therefore there is a profit to be made in doing so. Why is there a higher value? Because the potential buys have made that decision, sub-consciously. There is a few differences, but to some degree they are superficial. If you want to reduce the likelihood of being fooled by fakes, then don't raise certain magic number boxes to the skies and prices with it. I could make better use of my Z3801A if I did a few mods myself, beyond the modification from RS422 to RS232. Honest mods and upgrades is one thing we might encourage rather than encourage the fakes. I too have considered the 58503, but consider the price disproportionate to what the Z3801A gives me. Even the “real genuine original” Z38xx and 58xxx boxes differ mainly in the power supply area. The firmware and performance differences are minor. So, let's stop this thread of hurt feelings, while it has been interesting and enlightening, we can't get very much more right now. Let's open our boxes and try to see the modifications we can do, collect them on a webpage for everyone to enjoy and use, and be done with it. Or one could buy the KS boxes that are known *not* to be fakes / have the same basic performance and move on in that direction with web pages etc…. Bob Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ublox time/freq aiding was Re: Linear voltage regulator hints...
On Dec 14, 2014, at 9:46 AM, Neil Schroeder gign...@gmail.com wrote: The oscillator in he m8f is a vctcxo and can be steered with feedback or controlled by the host. Also the m8f can send compliant DAC words to a TLV8515 and and MCP part via i2c for external VCXOs. It accepts their return signal on what would normally be its feedback in ports. The oscillator in the LEA-6T is not a VCTCXO and it’s got the same notes on it. Bob On Sunday, December 14, 2014, Bob Camp kb...@n1k.org wrote: Hi There is also a little note down in the (many) notes section: Not all features are available with all firmware versions. It applies to all of the external inputs (like USB and SPI). Since the oscillator in the uBlox is a TCXO and not a VCTCXO, the aiding feature would not help in the case of biasing the unit with a hot air gun. It would still loose lock as the TCXO went nuts. The ideal outcome would be a system that reported against the external input rather than the internal TCXO. Since they digitize the external pin with the TCXO, the outcome is pretty coarse (10’s of ns). That’s not going to help us much. Bob On Dec 14, 2014, at 4:26 AM, Simon Marsh subscripti...@burble.com javascript:; wrote: On 14/12/2014 04:08, d...@irtelemetrics.com javascript:; wrote: Note that most high-end GNSS timing receivers go one better and simply have an external input for the clock. That way you feed your own lab clock into the receiver. If you have Rb/Cs/maser you would use that as the reference. It's what the national timing labs do, along with dual-frequency and post-processing and all the other tricks of the trade. I think it would be agreat idea also. It's a wonder that more of the 'timing' receivers don't have that external clock option! I wonder what these Ublox parts use for a clock? Is it something frequency compatible with a 10Mhz source??? (Hmm, can we pry one apart to figure it out! ;) ) Ublox modules have a 48mhz internal clock. There is the following interesting paragraph in at least the 7 8 data sheets: --- 1.8.2 Aiding The EXTINT pin can be used to supply time or frequency aiding data to the receiver. For time aiding, hardware time synchronization can be achieved by connecting an accurate time pulse to the EXTINT pin. Frequency aiding can be implemented by connecting a periodic rectangular signal with a frequency up to 500 kHz and arbitrary duty cycle (low/high phase duration must not be shorter than 50 ns) to the EXTINT pin. Provide the applied frequency value to the receiver using UBX messages. --- I haven't been able to find any information about what this actually does though. Anyone know ? Cheers Simon ___ time-nuts mailing list -- time-nuts@febo.com javascript:; To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com javascript:; To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
Hi On Dec 14, 2014, at 8:38 AM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 12:39, Neil Schroeder gign...@gmail.com wrote: Based on my recent testing - including Solaris - you will be better off with the Internet unless your USB adapter is far better behaved than the several I have here The USB - serial adapter I have is an Keyspan USA-19HS http://www.tripplite.com/high-speed-usb-to-serial-adapter-keyspan~USA19HS/ I bought that one, as it was officially supported by Sun. I also have another one somewhere - forget which model. Again that was officially supported by Sun. There are some long and detailed threads back in the archives about just how USB works and what this does to timing. Simple / quick summary: To do a proper / accurate time transfer, an edge from a source needs to be accurately clocked into the target machine. Any delay in this process is a bad thing. There are a lot of places delay can come from. USB is a packett / block transfer protocol. It gets it’s speed from sending a lot of stuff all at one time. When a serial USB sees a long string coming in, it formats it into a single block and transfers the whole thing in one bus transaction. That’s perfect for most things (commercial or consumer). The device gets on the bus and off the bus quickly with minimum overhead involved. Waiting on something like a pps string is a real bad idea. Your serial port is running at a rational baud rate. At 9600 baud, each character time you delay messes up the PPS timing by almost a millisecond. The PPS ID strings are many characters long. The impact on pps timing could (and often is) quite major. Even in the “best case” of sending the data one or two characters later, the pps is not very accurate. In the “worst case” it’s 10X or maybe 100X less accurate still. Some numbers: 1) PPS out of your GPSDO is likely 100 ns all the time. Most of the time (one sigma) it’s in the 10 to 30 ns range depending on which box you are running. 2) One character at 8N1 is 10 bits. At 9600 baud that’s 1.04 ms. It’s unlikely the USB sends in less than 1 character time. 3) A normal string is in the 30 to 40 characters range. A normal USB will buffer for 30X the character time ... NTP via ethernet, with well chosen servers, can get you down to 10 ms timing on you machines. It’s reliable and fairly easy to set up. The other alternative is to get the PPS edge into the machine in a more direct manner than USB. Yes I have a pile of SUN boxes, they often don’t come with all the i/o chards you might like to have…. Another alternative (and thus it’s popularity on the list) is to set up something small and light weight as a dedicated NTP server on your local LAN. That gets the timing issues of your local connection to the internet out of the NTP equation. You can get down under 10 us with a setup like that. The result may be better than your ability to time an edge on the SUN box, due to all the other overheads involved there. It’s also a nice stand alone project that is far less likely to mess up your main machine. The boards commonly used are $100 and some are much cheaper than that. Bob Both have worked for industrial control applications, whereas I gather some cheap ones are only suitable for common consumer devices. In any case, it will be more fun educational to use the GPS receiver. To be honest, I don't need great accuracy. I only bought the unit as a frequency standard - the clock functionality is not important to me, but if I can have a bit of fun playing around with it, then I will. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] raspberry pi, pps interrupts by kernel
Hi, I tested it...and could not get it to work. gpsd opens pps0 but strace does not show me the regular ppsapi syscalls and also ppstest gives a time out. e.g. I did an strace and I did not see any PPS_FETCHs passing by. I verified with lsof that gpsd does have pps0 open. With help from Hal I got it to work! I thought you could just poke the gpio pin number in that /sys virtual file. You can't. The bcm2708 code needs to know the pin number at boot time. Then, you can't get the pps via gpsd: when gpsd opens /dev/ttyAMA0 to talk to the gps, a new /dev/pps1 is created, for that AMA0 device. That pps1 is not the one you need; the serial port on the raspberry pi has no dcd pin so pps1 points to nothing. Yes it is connected to the ldisc but that has no (hardware) dcd pin connected to it. So long story short: you need to configure an atom driver in ntpd which then correctly opens /dev/pps0 and then the share memory coupling with gpsd. Yeah or connect ntpd directly to /dev/ttyAMA0 but then you'll miss the possibilities of running the nice gpsmon application. Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] tyco electronics A1025
Strongly agree with Bob. The neo 6 on ebay is a good example silly stupid cheap! Regards Paul WB8TSL On Sun, Dec 14, 2014 at 9:46 AM, Bob Camp kb...@n1k.org wrote: Hi On Dec 14, 2014, at 6:03 AM, Francesco Messineo francesco.messi...@gmail.com wrote: Hi all, I've just found an old anti-theft system (I think) for cars . It has a tyco electronics A1205 gps module. I've been unable to find any information about this module, other than it should be a 3.3V 12 channel GPS module with serial NMEA output. Does anyone have any informations about it? Even a pinout would help. I'd like to use it as a cheap NMEA receiver for a stratum 1 ntp server. Thanks in advance. It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of it. Finding one that will do position hold is even less likely. You can get modules that will do both for $20 and have a documented interface. Bob Frank IZ8DWF ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew frequency counter, need help
Hi Li Ang, On 12/12/2014 04:40 PM, Li Ang wrote: Hi Bob, The job done by linear regression is to reduce the uncertainty. This counter is designed to use continous timestamp method. My current design can measure 9000 times/second. If I only use the 1st and last one to calculate, it's the traditional recipocal + interploator method. This is what you can see on the chart named without linear regression. The uncertainty of slope(the frequency ratio of ref and signal ) is contributed by these 2 measurements. With linear regression of all 9000 data within one second, the uncertainty will reduced to smaller one. (I really can't remember the ratio. Something like sqrt(9000)). Bob's comment about filtering is correct. The lack of uncertainty is partly systematic and partly white noise. As you filter it, as with linear regression, you will weight samples with a parabolic value, called the Omega filtering, and this will act as a low-pass filter. The low-pass filter will alter the white-noise shape of the ADEV, as the bandwidth have reduced. This is strictly predictable by the processing. The produced ADEV curve is shaped by the measuring device and processing, not by the DUT, so it's not showing the real ADEV of the DUT, but it would not be doing that anyway. One such filtering mechanism exists in MDEV, but it has established formulas for how noise-shapes behave with various degrees of filtering, so therefore it is accepted as a standard. Regression filtering for frequency measures have already been done in the Pendulum counter range, but not for phase measurements. It's not as much as right or wrong as how you present the numbers and interprent them. Cheers, Magnus while(1) { double t3; //fraction part of refcnt, measured by tdc_gp22 double ref_curr; uint32_t sig_curr; static double ref_start; static uint32_t sig_start; uint32_t refcnt, sigcnt; const uint32_t gate_time = 1000; // 1000ms gate time if (i == 0) { init_regression(rv); cpld_rst(); timestamp(refcnt, sigcnt, t3); ref_start = refcnt - t3; sig_start = sigcnt; i++; continue; } timestamp(refcnt, sigcnt, t3); regression_enter_data(rv, refcnt - t3 - ref_start, sigcnt - sig_start); if (msecond gate_time) { i++; continue; } else { t = regression_slope(rv) ; // with linear regression printf(\r\nFreq=%.*f, 14, t); ref_curr = refcnt - t3; sig_curr = sigcnt; t = CalcFreq(ref_curr - ref_start, sig_curr - sig_start); // without linear regression printf( Interpolated=%.*f, 12, t); msecond = 0; i = 0; } } 2014-12-12 21:18 GMT+08:00 Bob Camp kb...@n1k.org: HI On Dec 12, 2014, at 4:04 AM, Tom Van Baak t...@leapsecond.com wrote: This large posting is from Li Ang. /tvb - Original Message - From: Li Ang To: Discussion of precise time and frequency measurement Sent: Thursday, December 11, 2014 7:37 AM Subject: Re: [time-nuts] Homebrew frequency counter, need help Hi Bob, I've sent the PCB to the factory and I am waiting for the new board. This time, it's a 4-layer borad and changed from CPLD to FPGA. This is the first time of FPGA 4-layer project. Hope everthing be OK. Very nice looking. I hope it works !!! TPS79333 as the LDO for TDC. Better PSRR and noise spec than before (XC6206). Analog and digital parts have their dedicated LDO. While I'm waiting the the new board. I did a test with PRS10 FE5650 with current board. It's strange that the 20s adev of without linear regression is better than with linear regression” Be careful pre-processing ADEV data. There are a variety of statistical “traps” you can fall into. An overly simple explanation is that ADEV looks at noise and that most pre-processing is a filter. Filters take out noise. Finding one that only takes out the “bad noise” and keeps the “good noise” can be quite difficult. What exactly are you doing in your linear regression computation? Bob .bottom_layer.GIFpower_plane.GIFtop_layer.GIFadev.gif___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] tyco electronics A1025
Should have added. You get great documentation also and everything is well established and most likely will handle some 1024 week rollovers. The old stuff is quite annoying with respect to this. Regards Paul WB8TSL On Sun, Dec 14, 2014 at 11:05 AM, paul swed paulsw...@gmail.com wrote: Strongly agree with Bob. The neo 6 on ebay is a good example silly stupid cheap! Regards Paul WB8TSL On Sun, Dec 14, 2014 at 9:46 AM, Bob Camp kb...@n1k.org wrote: Hi On Dec 14, 2014, at 6:03 AM, Francesco Messineo francesco.messi...@gmail.com wrote: Hi all, I've just found an old anti-theft system (I think) for cars . It has a tyco electronics A1205 gps module. I've been unable to find any information about this module, other than it should be a 3.3V 12 channel GPS module with serial NMEA output. Does anyone have any informations about it? Even a pinout would help. I'd like to use it as a cheap NMEA receiver for a stratum 1 ntp server. Thanks in advance. It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of it. Finding one that will do position hold is even less likely. You can get modules that will do both for $20 and have a documented interface. Bob Frank IZ8DWF ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived
Another Time-nut suggested the use of 10 baseT ethernet transformers for 10 MHz isolation that he pulls from old ethernet boards. The 20F001n. These are available from UTSource on ebay at 90 cents each NOS. Ordered 20. Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT then how could they be when they are a pretty flat transformer from 40 KHz to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some lumps and bumps in that pass band But not large maybe 1-1.3db I need to get much more accurate. But now I have a nice transformer that can work at WWVB 60 Khz as well as with frequency distribution. They come in a dip foot print and 2 X to a package. I have more to check because to good to be true almost always is. At least for me. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew frequency counter, need help
On 12/12/2014 06:15 PM, Bob Camp wrote: Hi On Dec 12, 2014, at 11:44 AM, Li Ang lll...@gmail.com wrote: Yes, you are right. 5650_5650 is sig=ref case. prs10_5650 is sig=prs10 and ref=5650 case. In the “both same (5650 / 5650) case” your linear regression filtering is faking you out a bit. The SR620 counter has exactly this same issue. That’s probably for the same reason. It’s a fine test to see if you have various problems under control. It’s not a perfect way to estimate the number of digits you will get on a real measurement. Using two independent sources is a better way to do that. When you have two identical signals, the TDC noise is the main issue. All the edges are arriving in the same relation to each other (same timing). The linear regression is (obviously) good at suppressing the sort of noise the TDC has. With two independent signals the noise is more complex. The edges arrive at various times relative to each other. More things contribute to the total noise. The linear regression is having a harder time suppressing that sort of noise. In some cases (as you observed) the linear regression is actually making things worse. If Magnus was here, he would be tossing empty beer bottles at me and saying — see Bob, sqrt(N) doesn’t always work …. Indeed, except I would not be tossing empty beer bottles at you, I might jokingly attempt do, but never actually throw it. One has to realize that the quantization noise of the TIC may seem to process as if it where white phase noise, but it isn't random noise, it is a systematic noise and if you fool around with the systematics is may work for you or against you. I do consider to pass another bottle of good beer to Bob for good behavior. :) The filtering process used does need to be adapted to the noise of the total system. It's one of the forgotten parameters, and I've even seen good Sam Stein stand up and say we used to do this wrong on the same point, you need to publish and consider the bandwidth of your processing, as it *will* affect the ADEV plot (but only MDEV and TDEV somewhat). Since I really want to reduce the noise, what is the best test set you suggest? All the frequency source I have: FE5650 Rb , PRS10 Rb , MV89a*2 OCXO, If the MV89’s are in good working condition, they are the best thing to compare.The have the best ADEV of the group you have available I would check them for output level and stability before I trusted them. There are a lot of defective parts on the market. People get some, sort them and sell the bad ones. The bad ones just keep getting re-sold again and again … My guess is that they were good parts at one time and they got damaged when pulled off boards. If you use them, keep them on power at all times. Any OCXO will do better if you run it that way. In order to test if systematics is messing badly with you, measure the ADEV of the oscillator as it is steered (and stabilized) to a number of different frequencies. For larger offsets to the counter reference, multiple beatings occurs within the regression interval. You want that number to be an even number of beats, or the beat count to be so large that the phase of the last beat does not care. Linear regression helps out, as it weighs out the outermost measures compared to the central one, making the beating at the beginning and end not care as much. These are *systematic* noise effects, and as you play around with systematics and processing, you might have the systematics works for or against you, but at the same time, the random noise you try to measure will suffer the processing filtering, and you need to recall that. If you balance these properly, you can make good and correct measurements, it's just that few do. Oh, and only use ADEV, MDEV and TDEV to estimate random noises, system noises as they show up there should be estimated separately and removed from the random noise estimates. They have *way* different behaviors. Cheers, Magnus - considering what beer will be best to start the evening with ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] tyco electronics A1025
Hi Maybe a bit more on a timing receiver: GPS is (for some reason) better known for navigation than for timing. In navigation the receiver moves around a lot. In most timing applications, the receiver is stationary. When moving, the mathematical solution to the “where am I / what time is it” question has errors in both terms. Often consumer grade GPS’s “push” the error into the time side of the solution to make the location appear more accurate. There is a lot of debate over this actually making the location more accurate or simply being a result of sloppy code. In a timing situation, with the location fixed, you can eliminate the location variability from the math. This involves a survey (often an automatic feature) of the location. Once the survey is complete, the timing data out of the receiver improves significantly. With improvements in the survey, the data may improve even more. This mode of operation is of no use in a normal non-timing situation. It only shows up in devices with firmware written for timing. Like it or not, all GPS devices are made as cheaply as possible against a design specification. The PPS out of the GPS comes from a free running TCXO on the simple modules. Since the TCXO can be anywhere relative to the PPS, there is an error in the edge that is delivered. It’s commonly referred to as sawtooth error. On a timing receiver, this error can be measured by the firmware and reported to “higher authority”. — Does all this matter in all applications? No, of course it does not. It may well be overkill. That’s well worth considering along with all the other issues. — Coming back to the original point: You can get modules for $20 with some or all of the features above. They may also have other nice attributes (documentation ….). I have no idea what the value of the A1205 is to you. It may well be free at this point. If it does have a cost, compare it to the other modules as you look at it. Another consideration is that your A1205 may be in fine shape and a random device off of eBay may have spent part of it’s life under water. There is no one single answer, only a lot of things to consider. Bob On Dec 14, 2014, at 11:07 AM, paul swed paulsw...@gmail.com wrote: Should have added. You get great documentation also and everything is well established and most likely will handle some 1024 week rollovers. The old stuff is quite annoying with respect to this. Regards Paul WB8TSL On Sun, Dec 14, 2014 at 11:05 AM, paul swed paulsw...@gmail.com wrote: Strongly agree with Bob. The neo 6 on ebay is a good example silly stupid cheap! Regards Paul WB8TSL On Sun, Dec 14, 2014 at 9:46 AM, Bob Camp kb...@n1k.org wrote: Hi On Dec 14, 2014, at 6:03 AM, Francesco Messineo francesco.messi...@gmail.com wrote: Hi all, I've just found an old anti-theft system (I think) for cars . It has a tyco electronics A1205 gps module. I've been unable to find any information about this module, other than it should be a 3.3V 12 channel GPS module with serial NMEA output. Does anyone have any informations about it? Even a pinout would help. I'd like to use it as a cheap NMEA receiver for a stratum 1 ntp server. Thanks in advance. It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of it. Finding one that will do position hold is even less likely. You can get modules that will do both for $20 and have a documented interface. Bob Frank IZ8DWF ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew frequency counter, need help
Hi On Dec 14, 2014, at 11:36 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 12/12/2014 06:15 PM, Bob Camp wrote: Hi On Dec 12, 2014, at 11:44 AM, Li Ang lll...@gmail.com wrote: Yes, you are right. 5650_5650 is sig=ref case. prs10_5650 is sig=prs10 and ref=5650 case. In the “both same (5650 / 5650) case” your linear regression filtering is faking you out a bit. The SR620 counter has exactly this same issue. That’s probably for the same reason. It’s a fine test to see if you have various problems under control. It’s not a perfect way to estimate the number of digits you will get on a real measurement. Using two independent sources is a better way to do that. When you have two identical signals, the TDC noise is the main issue. All the edges are arriving in the same relation to each other (same timing). The linear regression is (obviously) good at suppressing the sort of noise the TDC has. With two independent signals the noise is more complex. The edges arrive at various times relative to each other. More things contribute to the total noise. The linear regression is having a harder time suppressing that sort of noise. In some cases (as you observed) the linear regression is actually making things worse. If Magnus was here, he would be tossing empty beer bottles at me and saying — see Bob, sqrt(N) doesn’t always work …. Indeed, except I would not be tossing empty beer bottles at you, I might jokingly attempt do, but never actually throw it. One has to realize that the quantization noise of the TIC may seem to process as if it where white phase noise, but it isn't random noise, it is a systematic noise and if you fool around with the systematics is may work for you or against you. I do consider to pass another bottle of good beer to Bob for good behavior. :) …. as long as we don’t start tossing kegs at each other, I consider myself lucky :) The filtering process used does need to be adapted to the noise of the total system. It's one of the forgotten parameters, and I've even seen good Sam Stein stand up and say we used to do this wrong on the same point, you need to publish and consider the bandwidth of your processing, as it *will* affect the ADEV plot (but only MDEV and TDEV somewhat). Since I really want to reduce the noise, what is the best test set you suggest? All the frequency source I have: FE5650 Rb , PRS10 Rb , MV89a*2 OCXO, If the MV89’s are in good working condition, they are the best thing to compare.The have the best ADEV of the group you have available I would check them for output level and stability before I trusted them. There are a lot of defective parts on the market. People get some, sort them and sell the bad ones. The bad ones just keep getting re-sold again and again … My guess is that they were good parts at one time and they got damaged when pulled off boards. If you use them, keep them on power at all times. Any OCXO will do better if you run it that way. In order to test if systematics is messing badly with you, measure the ADEV of the oscillator as it is steered (and stabilized) to a number of different frequencies. For larger offsets to the counter reference, multiple beatings occurs within the regression interval. You want that number to be an even number of beats, or the beat count to be so large that the phase of the last beat does not care. Linear regression helps out, as it weighs out the outermost measures compared to the central one, making the beating at the beginning and end not care as much. These are *systematic* noise effects, and as you play around with systematics and processing, you might have the systematics works for or against you, but at the same time, the random noise you try to measure will suffer the processing filtering, and you need to recall that. If you balance these properly, you can make good and correct measurements, it's just that few do. Oh, and only use ADEV, MDEV and TDEV to estimate random noises, system noises as they show up there should be estimated separately and removed from the random noise estimates. They have *way* different behaviors. … and this is where it gets complicated. I would toss in the Hadamard deviation into that mix as well. If I had to only use three, I would include it with modified ADEV (MDEV) and TDEV. All three are available in TimeLab with the click of a button. If you start getting lots of data (9,000 points per second) I would toss in a frequency domain (FFT) analysis as well. FFT on phase data is not (as far as I know) a feature of TimeLab. To start with, on all of these measures, you are looking for bumps and spikes. They are telling you that something is wrong. If you flip over to the phase plot in TimeLab, spikes and abrupt steps in it also are telling you the same sort of thing. Exactly what this or that bump is telling you may not be obvious at
Re: [time-nuts] tyco electronics A1025
On Sun, Dec 14, 2014 at 3:46 PM, Bob Camp kb...@n1k.org wrote: Hi On Dec 14, 2014, at 6:03 AM, Francesco Messineo francesco.messi...@gmail.com wrote: Hi all, I've just found an old anti-theft system (I think) for cars . It has a tyco electronics A1205 gps module. I've been unable to find any information about this module, other than it should be a 3.3V 12 channel GPS module with serial NMEA output. Does anyone have any informations about it? Even a pinout would help. I'd like to use it as a cheap NMEA receiver for a stratum 1 ntp server. Thanks in advance. It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of it. Finding one that will do position hold is even less likely. You can get modules that will do both for $20 and have a documented interface. that's not meant as a time nut stratum 1. It's just a free gps module I would like to recycle as a needed stratum 1 server for a small network. Of course if I can find informations on it. I know there're better options, but in this case anything would do. Frank ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived
Hi Paul I confirm the 17MHz LPF response I didn't measure them for flatness :-)) The source I used was surplus 16way 10BaseT switches which were junked some time back but may still be lying in the back of store-room cupboards.you get a lot on one board that way. Alan G3NYK - Original Message - From: paul swed paulsw...@gmail.com To: Time-nuts time-nuts@febo.com Sent: Sunday, December 14, 2014 4:18 PM Subject: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived Another Time-nut suggested the use of 10 baseT ethernet transformers for 10 MHz isolation that he pulls from old ethernet boards. The 20F001n. These are available from UTSource on ebay at 90 cents each NOS. Ordered 20. Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT then how could they be when they are a pretty flat transformer from 40 KHz to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some lumps and bumps in that pass band But not large maybe 1-1.3db I need to get much more accurate. But now I have a nice transformer that can work at WWVB 60 Khz as well as with frequency distribution. They come in a dip foot print and 2 X to a package. I have more to check because to good to be true almost always is. At least for me. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] tyco electronics A1025
Hi On Dec 14, 2014, at 12:01 PM, Francesco Messineo francesco.messi...@gmail.com wrote: On Sun, Dec 14, 2014 at 3:46 PM, Bob Camp kb...@n1k.org wrote: Hi On Dec 14, 2014, at 6:03 AM, Francesco Messineo francesco.messi...@gmail.com wrote: Hi all, I've just found an old anti-theft system (I think) for cars . It has a tyco electronics A1205 gps module. I've been unable to find any information about this module, other than it should be a 3.3V 12 channel GPS module with serial NMEA output. Does anyone have any informations about it? Even a pinout would help. I'd like to use it as a cheap NMEA receiver for a stratum 1 ntp server. Thanks in advance. It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of it. Finding one that will do position hold is even less likely. You can get modules that will do both for $20 and have a documented interface. that's not meant as a time nut stratum 1. It's just a free gps module I would like to recycle as a needed stratum 1 server for a small network. Of course if I can find informations on it. I know there're better options, but in this case anything would do. … and NTP is not a GPSDO or a Cs replacement. My guess is that there is no PPS out of the device. It would be very unusual if there was. Finding the NEMA output pin should be possible with an oscilloscope. At that point, a simple serial connection to the server is about all you need. Bring up the NEMA driver and it is running. It is unlikely that any further optimization would be possible, even with the (maybe) 290 page data sheet on the part. I would not let the lack of a data sheet stop you in this case. Hook up the output to a PC with a terminal program and see what you get. The main problem would be if you need to find the serial input pin to change what it puts out, hopefully you do not. Bob Frank ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived
Hi If you get the whole magnetics package (and not just a transformer) it probably will have a pretty good common mode choke in it. If you go back to the days of coax ethernet, the choke was more the “magic” that let them go to twisted pair than the transformer. Why does this matter? Well … we seem to still be stuck back in the “coax ethernet” era when it comes to standard distribution. Every time somebody brings up a need to go hundreds of feet, coax becomes a second choice sort of solution. That’s even more true for a pps. Don’t toss out the rest of the magnetics when you salvage one of these old beasts … Why mention pps? There are more than one isolated pair on those connectors. You would need to modulate the pps onto something at one end and demodulate it at the other end. There are a lot of cheap ways to do that, very much so if you are generating the pps yourself in something on the transmitting end. Bob On Dec 14, 2014, at 11:59 AM, Alan Melia alan.me...@btinternet.com wrote: Hi Paul I confirm the 17MHz LPF response I didn't measure them for flatness :-)) The source I used was surplus 16way 10BaseT switches which were junked some time back but may still be lying in the back of store-room cupboards.you get a lot on one board that way. Alan G3NYK - Original Message - From: paul swed paulsw...@gmail.com To: Time-nuts time-nuts@febo.com Sent: Sunday, December 14, 2014 4:18 PM Subject: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived Another Time-nut suggested the use of 10 baseT ethernet transformers for 10 MHz isolation that he pulls from old ethernet boards. The 20F001n. These are available from UTSource on ebay at 90 cents each NOS. Ordered 20. Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT then how could they be when they are a pretty flat transformer from 40 KHz to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some lumps and bumps in that pass band But not large maybe 1-1.3db I need to get much more accurate. But now I have a nice transformer that can work at WWVB 60 Khz as well as with frequency distribution. They come in a dip foot print and 2 X to a package. I have more to check because to good to be true almost always is. At least for me. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] tyco electronics A1025
On Sun, Dec 14, 2014 at 6:12 PM, Bob Camp kb...@n1k.org wrote: It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of it. Finding one that will do position hold is even less likely. You can get modules that will do both for $20 and have a documented interface. that's not meant as a time nut stratum 1. It's just a free gps module I would like to recycle as a needed stratum 1 server for a small network. Of course if I can find informations on it. I know there're better options, but in this case anything would do. … and NTP is not a GPSDO or a Cs replacement. My guess is that there is no PPS out of the device. It would be very unusual if there was. Finding the NEMA output pin should be possible with an oscilloscope. At that point, a simple serial connection to the server is about all you need. Bring up the NEMA driver and it is running. It is unlikely that any further optimization would be possible, even with the (maybe) 290 page data sheet on the part. I would not let the lack of a data sheet stop you in this case. Hook up the output to a PC with a terminal program and see what you get. The main problem would be if you need to find the serial input pin to change what it puts out, hopefully you do not. The A1029, which is a newer model, has indeed a PPS output and I've been able to find a datasheet for it but the pinout isn't anything like the A1025. I planned to reverse engineer the pinout, but I'd like at least not to be forced to try to guess the power pins. Maybe someone still has the data for this older module. Frank ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew frequency counter, need help
Tom, On 12/12/2014 08:01 PM, Tom Van Baak wrote: Hi Li, What you're doing is the same trick the Pendulum CNT-91 uses, as well as modern Agilent frequency counters, and even my own picPET. The good news is that for frequency measurement all those many samples and the sqrt(N) advantage allow you to measure the frequency far more accurately than with traditional methods. That's why a hp 53132A can rightly advertise 12 digits/second. The bad news is that what you gain in frequency resolution you lose in temporal resolution. This is why in spite of having 1 ps/s frequency specs, the counter has 150 ps single-shot time resolution. What most time interval counters then do is average in order to gain precision. This works fine unless what you're trying to measure is not time, or even frequency, but frequency stability (modulation domain). In that case averaging may remove the very thing you are trying to measure. As for ADEV, all you need is the raw phase data, even at 9000 points per second (USB is fast enough), and let TimeLab take care of the rest. It will properly scale, decimate, and filter the data to produce correct ADEV plots, from your minimum tau0 of 0.000111 s out any tau you want. You will quickly see the noise floor of the counter this way. Some papers to read: Continuous time stamping http://www.spectracomcorp.com/Desktopmodules/Bring2Mind/DMX/Download.aspx?EntryId=450 This is a good overview. Staffan got some minor factoids wrong, but who cares? It brings out the basic idea of history. That ses of links is a good read. The HP Application note 200 series is also a good read for counters in general. Do notice Staffan's heads-up that you need to measure on stable signals, as severer frequency drift will cause values to be, well a bit interesting. The reason is that the linear regression used is for a linear model and not quadratic model. Jim Barnes did an interesting analysis, and it turns out that regression measurements can be a bad solution for drift analysis. The lesson that Staffan and Jim gives us is that just trying to apply your favorit magic without understanding side-consequences of systematic effects, may not give the effects you think. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived
Well with zero effort the spec sheet. Bob indeed there are common mode chokes in them. Jeeze a lot in 1 package along with center taps. Regards Paul WB8TSL On Sun, Dec 14, 2014 at 12:22 PM, Bob Camp kb...@n1k.org wrote: Hi If you get the whole magnetics package (and not just a transformer) it probably will have a pretty good common mode choke in it. If you go back to the days of coax ethernet, the choke was more the “magic” that let them go to twisted pair than the transformer. Why does this matter? Well … we seem to still be stuck back in the “coax ethernet” era when it comes to standard distribution. Every time somebody brings up a need to go hundreds of feet, coax becomes a second choice sort of solution. That’s even more true for a pps. Don’t toss out the rest of the magnetics when you salvage one of these old beasts … Why mention pps? There are more than one isolated pair on those connectors. You would need to modulate the pps onto something at one end and demodulate it at the other end. There are a lot of cheap ways to do that, very much so if you are generating the pps yourself in something on the transmitting end. Bob On Dec 14, 2014, at 11:59 AM, Alan Melia alan.me...@btinternet.com wrote: Hi Paul I confirm the 17MHz LPF response I didn't measure them for flatness :-)) The source I used was surplus 16way 10BaseT switches which were junked some time back but may still be lying in the back of store-room cupboards.you get a lot on one board that way. Alan G3NYK - Original Message - From: paul swed paulsw...@gmail.com To: Time-nuts time-nuts@febo.com Sent: Sunday, December 14, 2014 4:18 PM Subject: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived Another Time-nut suggested the use of 10 baseT ethernet transformers for 10 MHz isolation that he pulls from old ethernet boards. The 20F001n. These are available from UTSource on ebay at 90 cents each NOS. Ordered 20. Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT then how could they be when they are a pretty flat transformer from 40 KHz to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some lumps and bumps in that pass band But not large maybe 1-1.3db I need to get much more accurate. But now I have a nice transformer that can work at WWVB 60 Khz as well as with frequency distribution. They come in a dip foot print and 2 X to a package. I have more to check because to good to be true almost always is. At least for me. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. 20F001N.pdf Description: Adobe PDF document ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived
paulswedb at gmail.com Another Time-nut suggested the use of 10 baseT ethernet transformers for 10 MHz isolation that he pulls from old ethernet boards. The 20F001n. These are available from UTSource on ebay at 90 cents each NOS. Ordered 20. Well I have to say as a BPF or something for 10 Mhz they are lousy.. Before you pooh-pooh these transformer/filters, try feeding a 10Mhz square wave into a one of these filters and check out the fairly clean sine wave you get out. These are handy cheap units and I have used them in the past as a quick and not so dirty way to clean up a 10Mhz signal. Several companies made these and they are all basically the same unit. http://elcodis.com/parts/900719/FL1012.html#datasheet http://akizukidenshi.com/download/ds/ycl/20F001NG.pdf -Arthur ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] KS-24361 quirk
On Sat, Dec 13, 2014 at 11:55 PM, Hal Murray hmur...@megapathdsl.net wrote: Can somebody confirm that the PPS and 15 MHz on the standby unit are disabled? Yes, the PPS is held active. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
From pictures bumpers are installed in an inverted position. Reverse them Whoever put this together in CN did not have any idea of how this series of cases are assembled or did not care Content by Scott Typos by Siri On Dec 13, 2014, at 2:08 PM, HP-mini blm-ubu...@slingshot.co.nz wrote: On Sat, 2014-12-13 at 15:18 +, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: I just noticed. Since there are no feet on this, there is no way any air can get into the slots in the base The oven was running too hot for me to touch - I doubt that is normal, but perhaps others no different. Dave Pull the rear rubberized plastic bump stop off the case fit it up the other way. As long as the OCXO operates below its turning point it has thermal control. Only need to dissipate the non-heating power, that sets the max operating temperature. Some OCXOs are quieter running in high temperature ambient still air. All are degraded by changes in thermal load. Brett. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
On 14 December 2014 at 02:31, Bob Camp kb...@n1k.org wrote: Hi You see a lot of surplus HP gear with the feet pulled. That was pretty standard when gear was rack mounted. Bob There are not the usual 3 holes underneath where feet go. I would nice to be able to find a few photos of a real 58503A. Does anyone have a known genuine one? I suspect this will go back to China, so I'm not going to spend much time on it, but I have slid the the case back 25 mm or so, to get a bit more ventilation. The electronics runs much cooler. I would not want it to overheat before it gets back to China. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived
Hi They are pretty fancy little gizmos if you want to do twisted pair. Volume counts here in terms of making them cheap. Twisted pair is *good* stuff for isolation at low frequencies. It’s not so hot for microwaves. There is an item called STP (shielded twisted pair) that addresses the microwave part pretty well. Will it beat some $1K / foot quartz filled uber coax for delay dispersion .. of course not. If you have those sort of needs (and credit card) go for the fancy coax. Plugging twisted pair into the back of a HP 5334 is a bit awkward as well. If you are running 6 feet from distribution point to instrument, don’t bother with any of this stuff. Same goes if everything is already very solidly bonded to a common ground. Yes if you are in the middle of a DMTD or a phase noise tester other rules may apply. Have a GPSDO buried in a 100’ deep dry hole in the back yard, 400’ from your house, running on it’s own isolated nuclear generator? These are pretty good gizmos to think about. Bob On Dec 14, 2014, at 1:41 PM, paul swed paulsw...@gmail.com wrote: Well with zero effort the spec sheet. Bob indeed there are common mode chokes in them. Jeeze a lot in 1 package along with center taps. Regards Paul WB8TSL On Sun, Dec 14, 2014 at 12:22 PM, Bob Camp kb...@n1k.org wrote: Hi If you get the whole magnetics package (and not just a transformer) it probably will have a pretty good common mode choke in it. If you go back to the days of coax ethernet, the choke was more the “magic” that let them go to twisted pair than the transformer. Why does this matter? Well … we seem to still be stuck back in the “coax ethernet” era when it comes to standard distribution. Every time somebody brings up a need to go hundreds of feet, coax becomes a second choice sort of solution. That’s even more true for a pps. Don’t toss out the rest of the magnetics when you salvage one of these old beasts … Why mention pps? There are more than one isolated pair on those connectors. You would need to modulate the pps onto something at one end and demodulate it at the other end. There are a lot of cheap ways to do that, very much so if you are generating the pps yourself in something on the transmitting end. Bob On Dec 14, 2014, at 11:59 AM, Alan Melia alan.me...@btinternet.com wrote: Hi Paul I confirm the 17MHz LPF response I didn't measure them for flatness :-)) The source I used was surplus 16way 10BaseT switches which were junked some time back but may still be lying in the back of store-room cupboards.you get a lot on one board that way. Alan G3NYK - Original Message - From: paul swed paulsw...@gmail.com To: Time-nuts time-nuts@febo.com Sent: Sunday, December 14, 2014 4:18 PM Subject: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived Another Time-nut suggested the use of 10 baseT ethernet transformers for 10 MHz isolation that he pulls from old ethernet boards. The 20F001n. These are available from UTSource on ebay at 90 cents each NOS. Ordered 20. Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT then how could they be when they are a pretty flat transformer from 40 KHz to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some lumps and bumps in that pass band But not large maybe 1-1.3db I need to get much more accurate. But now I have a nice transformer that can work at WWVB 60 Khz as well as with frequency distribution. They come in a dip foot print and 2 X to a package. I have more to check because to good to be true almost always is. At least for me. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. 20F001N.pdf___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Hi On Dec 14, 2014, at 2:14 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 02:31, Bob Camp kb...@n1k.org wrote: Hi You see a lot of surplus HP gear with the feet pulled. That was pretty standard when gear was rack mounted. Bob There are not the usual 3 holes underneath where feet go. I understand that they are different. The problem is the same though. Pulling a box in and out of a rack with feet or bumpers on it is a pain. They often get “lost” early in the instrument’s life. Often it’s a standard process on all gear as it comes into the facility. All of the un-needed bits and pieces go into a big pile. When the feet (or whatever) are found later in life they may or may not be re-installed correctly. They might not even be the ones that came with the instrument. Bob I would nice to be able to find a few photos of a real 58503A. Does anyone have a known genuine one? I suspect this will go back to China, so I'm not going to spend much time on it, but I have slid the the case back 25 mm or so, to get a bit more ventilation. The electronics runs much cooler. I would not want it to overheat before it gets back to China. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Meaning of SS on status screen from 58503A
Hi, I'm trying to make sense of the output from the status screen of this GPSDO E-113 :SYSTEM:STATUS? --- Receiver Status --- SYNCHRONIZATION . [ Outputs Valid ] SmartClock Mode ___ Reference Outputs ___ Locked to GPS TFOM 3 FFOM 0 Recovery 1PPS TI +48.6 ns relative to GPS Holdover HOLD THR 1.000 us Power-up Holdover Uncertainty Predict 8.5 us/initial 24 hrs ACQUISITION [ GPS 1PPS Valid ] Tracking: 6 Not Tracking: 1 Time PRN El Az SS PRN El AzUTC 19:12:37 14 Dec 2014 5 43 191 7121 13 307GPS 1PPS Synchronized to UTC 13 67 96 59 ANT DLY 0 ns 15 36 290 52 Position 26 81 307 50 MODE Hold 28 50 108 53 30 39 62 45 LAT N 51:39:04.122 LON E 0:46:36.379 ELEV MASK 10 deg HGT +44.16 m (MSL) HEALTH MONITOR . [ OK ] Self Test: OKInt Pwr: OK Oven Pwr: OK OCXO: OK EFC: OK GPS Rcv: OK E-113 What does the SS mean? According to the 58503A / 59551A *Symmetricom* manual http://www.leapsecond.com/museum/hp59551a/097-59551-02-iss-1.pdf there should be a C/N there, not a SS. The manual says 50 is the maximum value for C/N, and 35 is the minimum for stable tracking. The fact I have four satellites showing an SS of over 50 indicates that I can't just assume SS=C/N. The manual for the 58503B, http://www.leapsecond.com/museum/hp58503a/097-58503-13-iss-1.pdf which I assume is a later model than the 58503A, says again C/N is used on the 58503B, but it does say SS is used on the 59551A, which is a quite a different beast - it does not have a 10 MHz output. For that it says SS ranges from 0 to 255, and that 20-30 is weak. *IF* I can assume the SS in the 58503A works the same was as SS in the 59551A, then it looks like I have 6 satellites which are not weak. But that is a big IF Does anyone have an HP manual for the 58503A? Dr. David Kirkby Ph.D CEng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK. Registered in England and Wales, company number 08914892. http://www.kirkbymicrowave.co.uk/ Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
On 14 December 2014 at 19:32, Bob Camp kb...@n1k.org wrote: There are not the usual 3 holes underneath where feet go. I understand that they are different. The problem is the same though. Pulling a box in and out of a rack with feet or bumpers on it is a pain. They often get “lost” early in the instrument’s life. Often it’s a standard process on all gear as it comes into the facility. All of the un-needed bits and pieces go into a big pile. When the feet (or whatever) are found later in life they may or may not be re-installed correctly. They might not even be the ones that came with the instrument. Bob I am not sure if you are following me. On most (all??) HP kit I have seen, there are 3 holes at each corner of the bottom, where is possible to fit feet if one is going to use it on a desktop, rather than a rack. This unit does not have those holes, so it would be impossible to fit the usual HP feet on it. Looking around, I have 15 bits of HP kit, all of which have holes in the corner for feet. But this 58503A, with the Chinese box, does not have the holes. I don't know whether the 85053A is supposed to have them, or whether this is just a flaw in the design of the counterfeit. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived
Am 14.12.2014 um 18:46 schrieb Arthur Dent: Before you pooh-pooh these transformer/filters, try feeding a 10Mhz square wave into a one of these filters and check out the fairly clean sine wave you get out. These are handy cheap units and I have used them in the past as a quick and not so dirty way to clean up a 10Mhz signal. From a time nut pov this is probably less cleaning and more like infecting with phase errors that drift along at the mercy of the temp. behaviour of some unknown piece of ferrite. regards, Gerhard (who is just winding the Amidon cores for the 5 and 15 MHz traps of his 5-10MHz doubler for the new Lucent. 1812 chokes have failed big time.) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Meaning of SS on status screen from 58503A
Hi SS is signal strength. There is a setting somewhere buried deep in the SCPI to switch the display units. Bob On Dec 14, 2014, at 2:40 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: Hi, I'm trying to make sense of the output from the status screen of this GPSDO E-113 :SYSTEM:STATUS? --- Receiver Status --- SYNCHRONIZATION . [ Outputs Valid ] SmartClock Mode ___ Reference Outputs ___ Locked to GPS TFOM 3 FFOM 0 Recovery 1PPS TI +48.6 ns relative to GPS Holdover HOLD THR 1.000 us Power-up Holdover Uncertainty Predict 8.5 us/initial 24 hrs ACQUISITION [ GPS 1PPS Valid ] Tracking: 6 Not Tracking: 1 Time PRN El Az SS PRN El AzUTC 19:12:37 14 Dec 2014 5 43 191 7121 13 307GPS 1PPS Synchronized to UTC 13 67 96 59 ANT DLY 0 ns 15 36 290 52 Position 26 81 307 50 MODE Hold 28 50 108 53 30 39 62 45 LAT N 51:39:04.122 LON E 0:46:36.379 ELEV MASK 10 deg HGT +44.16 m (MSL) HEALTH MONITOR . [ OK ] Self Test: OKInt Pwr: OK Oven Pwr: OK OCXO: OK EFC: OK GPS Rcv: OK E-113 What does the SS mean? According to the 58503A / 59551A *Symmetricom* manual http://www.leapsecond.com/museum/hp59551a/097-59551-02-iss-1.pdf there should be a C/N there, not a SS. The manual says 50 is the maximum value for C/N, and 35 is the minimum for stable tracking. The fact I have four satellites showing an SS of over 50 indicates that I can't just assume SS=C/N. The manual for the 58503B, http://www.leapsecond.com/museum/hp58503a/097-58503-13-iss-1.pdf which I assume is a later model than the 58503A, says again C/N is used on the 58503B, but it does say SS is used on the 59551A, which is a quite a different beast - it does not have a 10 MHz output. For that it says SS ranges from 0 to 255, and that 20-30 is weak. *IF* I can assume the SS in the 58503A works the same was as SS in the 59551A, then it looks like I have 6 satellites which are not weak. But that is a big IF Does anyone have an HP manual for the 58503A? Dr. David Kirkby Ph.D CEng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK. Registered in England and Wales, company number 08914892. http://www.kirkbymicrowave.co.uk/ Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Meaning of SS on status screen from 58503A
On 14 December 2014 at 19:52, Bob Camp kb...@n1k.org wrote: Hi SS is signal strength. There is a setting somewhere buried deep in the SCPI to switch the display units. Bob I guessed SS probably was signal strength, but what values are good and bad? There's nothing in any manual I can find that mentions SS on the 58503A. I can't find any SCPI command that is supposed to switch the display units. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Beaglebone NTP server
On my rpi the jitter is between 2 and 10us iirc but it is a while since I tested it. A quick peak shows me currently 3us jitter. Not bad for a userspace solution imho. Really? The PPS to GPIO interface is handles in user space? It is not interrupt driven? Yes it is. But, until today, I used a software solution which interfaces the interrupt to ntp. I did that because I hate recompiling kernels and the pps code for rpi+gpio was not in the main distrio. Folkert van Heusden -- Ever wonder what is out there? Any alien races? Then please support the seti@home project: setiathome.ssl.berkeley.edu -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
The 58503A in the picture on leapsecond.com looks very similar to my older 34401A DVM which doesn't have separate feet. The molded plastic pieces on both ends have those crenelations that serve the same function. Alan On Sun, Dec 14, 2014 at 12:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 19:32, Bob Camp kb...@n1k.org wrote: There are not the usual 3 holes underneath where feet go. I understand that they are different. The problem is the same though. Pulling a box in and out of a rack with feet or bumpers on it is a pain. They often get “lost” early in the instrument’s life. Often it’s a standard process on all gear as it comes into the facility. All of the un-needed bits and pieces go into a big pile. When the feet (or whatever) are found later in life they may or may not be re-installed correctly. They might not even be the ones that came with the instrument. Bob I am not sure if you are following me. On most (all??) HP kit I have seen, there are 3 holes at each corner of the bottom, where is possible to fit feet if one is going to use it on a desktop, rather than a rack. This unit does not have those holes, so it would be impossible to fit the usual HP feet on it. Looking around, I have 15 bits of HP kit, all of which have holes in the corner for feet. But this 58503A, with the Chinese box, does not have the holes. I don't know whether the 85053A is supposed to have them, or whether this is just a flaw in the design of the counterfeit. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Hi The desktop version (with handle) used the rubber “bumper” wrap around for feet. The bumpers got pulled when they were rack mounted. The ones that got put back on may or may not be identical to the originals. That’s a very normal part of the surplus process. The 100% correct HP original case on the box as HP built it did not use the clip on feet. The reason for this is pretty simple. The Z3801 / Z3805 came before the “instrument” versions of the same products. The internal case structure is same/ same. The instrument simply gets a gray sheet metal jacket that fits around the Z38xx box. That’s the way HP designed it. Since its just a jacket, it gets feet as part of the bumpers. Most of these (likely 99%) got rack mounted and the feet / bumpers were tossed. I have a *lot* of very legit surplus HP gear that did not come with feet or bumpers. Bob On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 19:32, Bob Camp kb...@n1k.org wrote: There are not the usual 3 holes underneath where feet go. I understand that they are different. The problem is the same though. Pulling a box in and out of a rack with feet or bumpers on it is a pain. They often get “lost” early in the instrument’s life. Often it’s a standard process on all gear as it comes into the facility. All of the un-needed bits and pieces go into a big pile. When the feet (or whatever) are found later in life they may or may not be re-installed correctly. They might not even be the ones that came with the instrument. Bob I am not sure if you are following me. On most (all??) HP kit I have seen, there are 3 holes at each corner of the bottom, where is possible to fit feet if one is going to use it on a desktop, rather than a rack. This unit does not have those holes, so it would be impossible to fit the usual HP feet on it. Looking around, I have 15 bits of HP kit, all of which have holes in the corner for feet. But this 58503A, with the Chinese box, does not have the holes. I don't know whether the 85053A is supposed to have them, or whether this is just a flaw in the design of the counterfeit. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Which First GPSDO to buy?
It's not worth making a PCB, not when you can buy the whole thing already assembled for $3 with free shipping. I use these just as if they where a single chip and put them in a socket. See eBay 141505833625 as an example. Those holes are in 0.1 inch centers so you can figure out the size. (I get 1.3 inches long.) direct link http://www.ebay.com/itm/ARDUINO-PRO-MINI-Nano-Pro-Mini-atmega328-Compatible-Nano-5V-16M-/141505833625?pt=LH_DefaultDomain_0hash=item20f267aa99 I'll write up what I built. It would be good to see the range of these. I tried to make mine as simple an low cost as possible without regard to anything else. Just to find the bottom line. I doubt I would have met that gaol by using a bare AVR chip. That is NOT simple because it requires so much more skill from the builder and with an entire working Arduino selling for $3 how much could you save? Actually the chips on that $3 board cost more than $3. (I don't even see how shipping from China can be that cheap.) On Sat, Dec 13, 2014 at 10:56 PM, Patrick Tudor ptu...@ptudor.net wrote: On Dec 13, 2014, at 9:47 PM, Chris Albertson albertson.ch...@gmail.com wrote: Actually I've added some features to it like a 2 line by 16 character LCD display and some status LEDs. And I can log data to a computer via a USB cable so it is easy to plot data and it is using my more expansive mast mounted timing antenna. Just in case any of you like reading Arduino code, for fun or functions to copy-and-paste, the code for my PCB that combines an ATMega328p with an Adafruit GPS and 16x2 LCD to display GPS info as it sends the PPS out the DB9 DCD is at GitHub. It’s not exactly, say, measuring oscillator cycles (yet... ) but it’s perhaps a good introduction for someone who’s never ever before used anything Arduino. (And now that I’ve done more PCBs with Cypress and FTDI chips, I wish I’d put that straight on my board instead of as a future daughterboard, but, feature creep.) https://github.com/ptudor/jemma-clock PT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
I would still like to experiment with it. As I wrote earlier I bought this for a frequency reference, not a clock, but I would not object to a bit of fun messing around with it. If the goal is just getting good enough time onto the Solaris machine then use NTP and some pool servers on the Internet. You get about 10 millisecond level accuracy and the cost is zero. If you have solaris running you might even have this all setup and running. If not do this as the first step and verify it works. If 10ms is unacceptable, next step is to connect the PPS signal. Doing this will move you from milli to micro second level accuracy. It is easy if the Solaris machine has a real serial port. If you have to go through a USB dongle you loose about an order of magnitude accuracy but this is still very good. There is zero point in buying a special computer to run NTP. Just use any computer you own that is already running 24x7. Of course if you don't have a computer that runs 24x7 then you would look for one that uses very little power. Don't worry to much if the USB connection skews the time on the NTP server by some tens of microseconds, your server can't transfer time to your other computers on the LAN any better than millisecond level so a few tenths of an millisecond hardly mater. My opinion of computer time is that for normal use being a few milliseconds off is OK because the typical monitor is refreshed no faster than 100Hz so you have lag cause by screen refresh times even if the internal clock is dead-on perfect. Same for disk time stamps, these is lag in the IO system too -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Which First GPSDO to buy?
Well, thanks, everyone, for the information. I appreciate the help. First, I am presently not up to adding another project to my long list of projects. I get whiplash every time I walk into the lab. Building a GPSDO sound like fun. Perhaps down the line. I figured I should add some information about myself: I am an electrical engineer (currently employed) with a lot of digital/Verilog experience and a fair bit of analog experience (but less than my digital experience) and quite a bit of software experience, all of this from working for about thirty-eight years on various embedded systems. Currently, I shy away from writing code just because I don't enjoy it much and have done too much professionally. But I know that eventually I will need to write code in my lab. Presently, I am in the process of restoring some older ham radio gear, but I became sidetracked from that by the necessity to repair a bunch of vintage test equipment which effort has somehow taken on a life of it's own. What I need right now is a frequency standard that is accurate enough to use as a reference for things like calibrating test gear. I also want to play with one before I build one. Just going through all of the educational material is a daunting task. I figured I'd combine an interest with GPSDOs in general with a need for an accurate enough standard (I use the term loosely here) to get some instruments calibrated. Thanks again for all the information! Cheers, DaveD I had forgotten about the LTE-lite; I should add that to the list of choices. I'm tending towards either a 10 MHz version of that or the Lucent boxes. On 12/14/2014 8:00 AM, Bob Camp wrote: Hi On Dec 14, 2014, at 12:47 AM, Chris Albertson albertson.ch...@gmail.com wrote: I tried to see just how simple, low cost and self contained I could make a GPSDO. I started with the Lars Walenius design then removed everything I could from it. I replace all the software with just a small loop with about a dozen lines of code so it would be easy to understand. My goal was to make something that could be built and tested using just basic equipment. The question is of course How do you know the unit is making a 10 MHz signal if you don't already have a 10MHz reference to compare it to? Well you can assume that your 1PPS reference is accurate. Except that the GPS PPS is *not* perfect, far from it. It’s only reasonably accurate over very long time spans. Over short spans the pps moves around a lot. Then you count and make sure you see EXACTLY 10,000,000 oscillator cycles per each PPS. If you do a tight lock (“EXACTLY”) against a GPS PPS that is moving +/- 10 ns, your frequency will swing +/- 1x10^-8 every second Count both for a few days and verify the ratio remains at ten million to one, exactly. Ok, that’s looking at the long term where GPS is indeed accurate. That’s the easy part on any GPSDO design. I ran mine for about 8 weeks and it stays at the desired ratio.I know this is not a perfect test because it could have been running at zero hertz for 30 seconds and then 20MHz for 30 seconds but I assume the OCXO is better than that. The point is that once you have the GPS working you DO have a pretty good 1Hz reference. Well, not quite so fast. You just jumped over a massive amount of work that normally gets done on a GPS. A unit that *was* swinging +/- 1x10^-8 every second would pass your test. (which is not in any way to say that your design actually does that). It would make a lousy GPSDO for most uses. You very much *do* need to check the ADEV (or what ever) close in and tune your filter up to match your parts. Cost: Motorola Oncore GPS$18 magnnetic patch antenna 6 OCXO (eBay) 19 Arduino, mini 3 PLL chip 2 TTL diver chip1 Plug-in power cube0 perf-board 1 Total cost of GPSDO $50 Just a side note - A *lot* of the $19 OCXO’s I have from eBay are in very poor shape spec wise. Testing them before using them would be a very good idea. Bob Actually I do have A Thunderbolt. I place the 10MHz output of the above unit and the TB on my dual channel scope and was able to see the phase of the two 10MHz references was locked. I saw the phase drift over about an hour but then it would pull back. But I made this very simple and it could be better. Actually I've added some features to it like a 2 line by 16 character LCD display and some status LEDs. And I can log data to a computer via a USB cable so it is easy to plot data and it is using my more expansive mast mounted timing antenna. The Arduino based design is OK for controlling an OCXO but I think it is best used for controlling my Rubidium oscillator. The RB is so stable I should only update the frequency control every few hours at most. On Sat, Dec 13, 2014 at 7:21 PM, Jim Harman j99har...@gmail.com wrote: On Sat, Dec 13,
Re: [time-nuts] Meaning of SS on status screen from 58503A
Hi http://www.cnssys.com/files/M12+UsersGuide.pdf On page 46 there is a pretty good chart for signal strength to c/n. The chart for the Motoroal GPS module in yours should be quite similar. If there is no SCPI then it’s a “feature enhancement” in a later version of the firmware. Are you looking at the data with a terminal program or via Z38xx? If it’s through Z38xx the program is probably converting things for you. From the screen shot it looks like your are running a terminal. Sending: *CLS will clear the error message at the top of your screen ... Bob On Dec 14, 2014, at 2:57 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 19:52, Bob Camp kb...@n1k.org wrote: Hi SS is signal strength. There is a setting somewhere buried deep in the SCPI to switch the display units. Bob I guessed SS probably was signal strength, but what values are good and bad? There's nothing in any manual I can find that mentions SS on the 58503A. I can't find any SCPI command that is supposed to switch the display units. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Linear voltage regulator hints...
Yeah, I guess it's all relative. :) I do agree it is a HUGE change compared to what the GPS should see in normal operation. The same blast of air can be pointed at the GPSDO board for 20 seconds and see no change. On high at the oscillator for 60+ seconds with no change is apparent. The GPS is what responds. Does this mean anthing? It's well beyond what the GPS should see, so I doubt it. Is the GPS the most sensitive part in the system right now? Maybe. But, Bob could be correct that the OCXO is the sensitive part. The PWM DAC used to respond like the GPS to temp changes. Using 'heat and watch' found it. Addressing it has cut overall temp sensitivity down by more than a factor of 10. I consider that a measurable change. Any temp sensitivity left is really small, and wonder if it can be addressed with the hardware and tools at hand. My gut feeling is you are right about the GPS time base being sensitive. It would be fun to hack into this and try clocking it off the OCXO, but I'm not there yet! :) I might try some good old 'overkill' and put the GPS in it's own heavy aluminum box. It's been a thought for a while, and should address the thermal integration and time constants you referred to. For this system, it's doubtful that an underground bomb proof bunker is needed. ;) I'd like to learn more about what testing could be done and would be more than happy to discuss this off line, if anyone is interested. This thread has probably out lived it's useful life. Thanks, Dan LOL. A couple of seconds of warm air at 15C above ambient is a HUGE temperature transient for any sensitive electronics, especially anything with an oscillator. I would venture a guess that the lion's share of the drift you see is the GPS time base shooting off-frequency, but there are probably other effects, too (voltage regulators, to name just one). To me, a little change in this context might be blowing one warm breath toward the GPS unit from 18 away and seeing what happens over the next minute or two. But the GPS temperature sensitivity shouldn't be a big factor in actual use. The GPS should be thermally isolated from anything that changes temperature rapidly, and enclosed such that external temperature changes are integrated over at least tens of minutes. Then, the inside of the enclosure will reach its own thermal equilibrium and any external changes will be slowed enough to be tracked out by the GPS discipline. My recommendation would be to put it in a cast aluminum box (search the archives for cast aluminum box), but there are others who think you need to build a two foot cube out of cinderblocks and fire brick against a wall in the deepest external corner of your basement. OR, if my suspicion is correct that the temperature sensitivity is mostly the GPS time base, figure out a way to kludge the GPS to accept the disciplined OCXO as its time base. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived
I investigated those 10b-t isolation modules a while back, and have saved every module from every network card and router/hub/switch that I have junked out. The very old 10b-t stuff is the best for getting LPFs and individual per-channel (port) type parts. When they started making 10/100 Mb/sec, the 17 MHz filters were eliminated, and the parts got integrated to ever-higher levels, with multiple channels in each module. You have to be able to find the data sheets to be sure of what's in them - some are transformers only, and some also have LPFs and common-mode chokes in various combinations. The filter sections can also be cascaded for even sharper cutoff, but there's quite a bit of crosstalk, so a lot of higher frequency stuff gets through, especially above 100 MHz, so it's mostly effective from around 20-100 MHz. It has been mentioned before that very sharp filters will tend to have more phase noise (phase shift with temperature/component variations), but the negative effects depend on the application - I only care about frequency reference distribution to SAs and synthesizers, for example, so I don't worry about exact phase and timing between equipment. There is a nice variety of magnetic parts from all types of network devices, including DSL an ISDN. Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Meaning of SS on status screen from 58503A
On 14 December 2014 at 20:25, Bob Camp kb...@n1k.org wrote: Hi http://www.cnssys.com/files/M12+UsersGuide.pdf Thank you. On page 46 there is a pretty good chart for signal strength to c/n. The chart for the Motoroal GPS module in yours should be quite similar. If there is no SCPI then it’s a “feature enhancement” in a later version of the firmware. OK Are you looking at the data with a terminal program or via Z38xx? If it’s through Z38xx the program is probably converting things for you. From the screen shot it looks like your are running a terminal. A terminal program on my unix box (Sun Blade 2000 running Solaris 10). I have also just started to open the port using the open command and send it data via the write command. Next step is to read it of course. Then I can collect data over time, and log it. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Which First GPSDO to buy?
Hi Ok so down to two choices: LTE Lite: 1) Comes up nice and fast (it’s a TCXO) 2) Modern GPS receiver 3) Good documentation 4) Very low power 5) Nice small size 6) Needs a box 7) You know where to find Jackson Labs if there is a problem 8) Getting a couple more in a couple years may be possible Lucent: 1) More accurate if you keep it on (it’s an OCXO) 2) Spare parts set (= the second box) when you buy the pair 3) Comes with a (clunky) enclosure 4) Outputs are already isolated / buffered 5) Needs an antenna ($30 or so for a good one, $3 for a simple one) 6) Needs a power supply ($20 maybe less) 7) Hook it up and check it out fast, there’s a 30 day warranty (which the guy does honor) 8) Once this guy sells out, there may not be many more. Both: 1) You still need to mount the antenna somewhere 2) You need to distribute the 10 MHz or 1 pps to your gear 3) With only one you will always be wondering “what if it’s wrong?”. Having two only confuses this situation …. 4) Neither one lets you play much with the loop (filtering), both are pretty much optimum for the hardware as received 5) Price wise not a lot of difference. Both will be $200-ish once you get them delivered and set up without the distribution stuff. What to do - get some of each :) Bob On Dec 14, 2014, at 12:49 PM, Dave Daniel kc0...@gmail.com wrote: Well, thanks, everyone, for the information. I appreciate the help. First, I am presently not up to adding another project to my long list of projects. I get whiplash every time I walk into the lab. Building a GPSDO sound like fun. Perhaps down the line. I figured I should add some information about myself: I am an electrical engineer (currently employed) with a lot of digital/Verilog experience and a fair bit of analog experience (but less than my digital experience) and quite a bit of software experience, all of this from working for about thirty-eight years on various embedded systems. Currently, I shy away from writing code just because I don't enjoy it much and have done too much professionally. But I know that eventually I will need to write code in my lab. Presently, I am in the process of restoring some older ham radio gear, but I became sidetracked from that by the necessity to repair a bunch of vintage test equipment which effort has somehow taken on a life of it's own. What I need right now is a frequency standard that is accurate enough to use as a reference for things like calibrating test gear. I also want to play with one before I build one. Just going through all of the educational material is a daunting task. I figured I'd combine an interest with GPSDOs in general with a need for an accurate enough standard (I use the term loosely here) to get some instruments calibrated. Thanks again for all the information! Cheers, DaveD I had forgotten about the LTE-lite; I should add that to the list of choices. I'm tending towards either a 10 MHz version of that or the Lucent boxes. On 12/14/2014 8:00 AM, Bob Camp wrote: Hi On Dec 14, 2014, at 12:47 AM, Chris Albertson albertson.ch...@gmail.com wrote: I tried to see just how simple, low cost and self contained I could make a GPSDO. I started with the Lars Walenius design then removed everything I could from it. I replace all the software with just a small loop with about a dozen lines of code so it would be easy to understand. My goal was to make something that could be built and tested using just basic equipment. The question is of course How do you know the unit is making a 10 MHz signal if you don't already have a 10MHz reference to compare it to? Well you can assume that your 1PPS reference is accurate. Except that the GPS PPS is *not* perfect, far from it. It’s only reasonably accurate over very long time spans. Over short spans the pps moves around a lot. Then you count and make sure you see EXACTLY 10,000,000 oscillator cycles per each PPS. If you do a tight lock (“EXACTLY”) against a GPS PPS that is moving +/- 10 ns, your frequency will swing +/- 1x10^-8 every second Count both for a few days and verify the ratio remains at ten million to one, exactly. Ok, that’s looking at the long term where GPS is indeed accurate. That’s the easy part on any GPSDO design. I ran mine for about 8 weeks and it stays at the desired ratio.I know this is not a perfect test because it could have been running at zero hertz for 30 seconds and then 20MHz for 30 seconds but I assume the OCXO is better than that. The point is that once you have the GPS working you DO have a pretty good 1Hz reference. Well, not quite so fast. You just jumped over a massive amount of work that normally gets done on a GPS. A unit that *was* swinging +/- 1x10^-8 every second would pass your test. (which is not in any way to say that your design actually does that). It would make a lousy GPSDO for most uses. You very
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Much of the Malaysian Agilent gear uses this style of case with a wraparound bumper in place of the system II feet and feet are removed when gear is rack mounted. One of my best surplus buys ever was a huge crate of mixed mounting hardware feet / rack flanges etc I've been using that box o stuff for 10 years Content by Scott Typos by Siri On Dec 14, 2014, at 3:09 PM, Bob Camp kb...@n1k.org wrote: Hi The desktop version (with handle) used the rubber “bumper” wrap around for feet. The bumpers got pulled when they were rack mounted. The ones that got put back on may or may not be identical to the originals. That’s a very normal part of the surplus process. The 100% correct HP original case on the box as HP built it did not use the clip on feet. The reason for this is pretty simple. The Z3801 / Z3805 came before the “instrument” versions of the same products. The internal case structure is same/ same. The instrument simply gets a gray sheet metal jacket that fits around the Z38xx box. That’s the way HP designed it. Since its just a jacket, it gets feet as part of the bumpers. Most of these (likely 99%) got rack mounted and the feet / bumpers were tossed. I have a *lot* of very legit surplus HP gear that did not come with feet or bumpers. Bob On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 19:32, Bob Camp kb...@n1k.org wrote: There are not the usual 3 holes underneath where feet go. I understand that they are different. The problem is the same though. Pulling a box in and out of a rack with feet or bumpers on it is a pain. They often get “lost” early in the instrument’s life. Often it’s a standard process on all gear as it comes into the facility. All of the un-needed bits and pieces go into a big pile. When the feet (or whatever) are found later in life they may or may not be re-installed correctly. They might not even be the ones that came with the instrument. Bob I am not sure if you are following me. On most (all??) HP kit I have seen, there are 3 holes at each corner of the bottom, where is possible to fit feet if one is going to use it on a desktop, rather than a rack. This unit does not have those holes, so it would be impossible to fit the usual HP feet on it. Looking around, I have 15 bits of HP kit, all of which have holes in the corner for feet. But this 58503A, with the Chinese box, does not have the holes. I don't know whether the 85053A is supposed to have them, or whether this is just a flaw in the design of the counterfeit. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Meaning of SS on status screen from 58503A
On 12/14/2014 08:57 PM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: On 14 December 2014 at 19:52, Bob Camp kb...@n1k.org wrote: Hi SS is signal strength. There is a setting somewhere buried deep in the SCPI to switch the display units. Bob I guessed SS probably was signal strength, but what values are good and bad? There's nothing in any manual I can find that mentions SS on the 58503A. I can't find any SCPI command that is supposed to switch the display units. The 58503 manual gives this detail: C/N (58503B) indicates the carrier-to-noise ratio of the received the signal, from a range of 26 to 55. A ratio below 35 is a weak signal that may not be acquired by the Receiver. SS (59551A) indicates the strength of the signal, from a range of 0 to 255. A signal strength of 20 to 30 is a weak signal that may not be acquired by the Receiver. I suspect that the SS was upgraded to C/N in the development. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Linear voltage regulator hints...
Hi What you actually have tested (in this case) is temperature rate of change. The parts involved are designed for a rate change in the 0.1 to 1C / minute range. Taking them way outside that range leads to unpredictable results. In the case of the GPS, it goes into some sort of failure mode. It’s no different that taking an IC that’s rated to 125C and seeing what happens at 300C. That’s outside it’s design range and odd things will happen. Bob On Dec 14, 2014, at 3:38 PM, d...@irtelemetrics.com wrote: Yeah, I guess it's all relative. :) I do agree it is a HUGE change compared to what the GPS should see in normal operation. The same blast of air can be pointed at the GPSDO board for 20 seconds and see no change. On high at the oscillator for 60+ seconds with no change is apparent. The GPS is what responds. Does this mean anthing? It's well beyond what the GPS should see, so I doubt it. Is the GPS the most sensitive part in the system right now? Maybe. But, Bob could be correct that the OCXO is the sensitive part. The PWM DAC used to respond like the GPS to temp changes. Using 'heat and watch' found it. Addressing it has cut overall temp sensitivity down by more than a factor of 10. I consider that a measurable change. Any temp sensitivity left is really small, and wonder if it can be addressed with the hardware and tools at hand. My gut feeling is you are right about the GPS time base being sensitive. It would be fun to hack into this and try clocking it off the OCXO, but I'm not there yet! :) I might try some good old 'overkill' and put the GPS in it's own heavy aluminum box. It's been a thought for a while, and should address the thermal integration and time constants you referred to. For this system, it's doubtful that an underground bomb proof bunker is needed. ;) I'd like to learn more about what testing could be done and would be more than happy to discuss this off line, if anyone is interested. This thread has probably out lived it's useful life. Thanks, Dan LOL. A couple of seconds of warm air at 15C above ambient is a HUGE temperature transient for any sensitive electronics, especially anything with an oscillator. I would venture a guess that the lion's share of the drift you see is the GPS time base shooting off-frequency, but there are probably other effects, too (voltage regulators, to name just one). To me, a little change in this context might be blowing one warm breath toward the GPS unit from 18 away and seeing what happens over the next minute or two. But the GPS temperature sensitivity shouldn't be a big factor in actual use. The GPS should be thermally isolated from anything that changes temperature rapidly, and enclosed such that external temperature changes are integrated over at least tens of minutes. Then, the inside of the enclosure will reach its own thermal equilibrium and any external changes will be slowed enough to be tracked out by the GPS discipline. My recommendation would be to put it in a cast aluminum box (search the archives for cast aluminum box), but there are others who think you need to build a two foot cube out of cinderblocks and fire brick against a wall in the deepest external corner of your basement. OR, if my suspicion is correct that the temperature sensitivity is mostly the GPS time base, figure out a way to kludge the GPS to accept the disciplined OCXO as its time base. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Hi On Dec 14, 2014, at 3:50 PM, Scott McGrath scmcgr...@gmail.com wrote: Much of the Malaysian Agilent gear uses this style of case with a wraparound bumper in place of the system II feet and feet are removed when gear is rack mounted. One of my best surplus buys ever was a huge crate of mixed mounting hardware feet / rack flanges etc I've been using that box o stuff for 10 years Somewhere there’s a building full of gear all of which is missing it’s feet and bumpers … You are lucky to have found that box. In most cases they get tossed out with the trash. The same is true of many of the fancy i/o cables, they get put into the copper recycle pile and are gone… Bob Content by Scott Typos by Siri On Dec 14, 2014, at 3:09 PM, Bob Camp kb...@n1k.org wrote: Hi The desktop version (with handle) used the rubber “bumper” wrap around for feet. The bumpers got pulled when they were rack mounted. The ones that got put back on may or may not be identical to the originals. That’s a very normal part of the surplus process. The 100% correct HP original case on the box as HP built it did not use the clip on feet. The reason for this is pretty simple. The Z3801 / Z3805 came before the “instrument” versions of the same products. The internal case structure is same/ same. The instrument simply gets a gray sheet metal jacket that fits around the Z38xx box. That’s the way HP designed it. Since its just a jacket, it gets feet as part of the bumpers. Most of these (likely 99%) got rack mounted and the feet / bumpers were tossed. I have a *lot* of very legit surplus HP gear that did not come with feet or bumpers. Bob On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 19:32, Bob Camp kb...@n1k.org wrote: There are not the usual 3 holes underneath where feet go. I understand that they are different. The problem is the same though. Pulling a box in and out of a rack with feet or bumpers on it is a pain. They often get “lost” early in the instrument’s life. Often it’s a standard process on all gear as it comes into the facility. All of the un-needed bits and pieces go into a big pile. When the feet (or whatever) are found later in life they may or may not be re-installed correctly. They might not even be the ones that came with the instrument. Bob I am not sure if you are following me. On most (all??) HP kit I have seen, there are 3 holes at each corner of the bottom, where is possible to fit feet if one is going to use it on a desktop, rather than a rack. This unit does not have those holes, so it would be impossible to fit the usual HP feet on it. Looking around, I have 15 bits of HP kit, all of which have holes in the corner for feet. But this 58503A, with the Chinese box, does not have the holes. I don't know whether the 85053A is supposed to have them, or whether this is just a flaw in the design of the counterfeit. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew frequency counter, need help
Hi Bob, On 12/14/2014 06:00 PM, Bob Camp wrote: Hi On Dec 14, 2014, at 11:36 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 12/12/2014 06:15 PM, Bob Camp wrote: Hi On Dec 12, 2014, at 11:44 AM, Li Ang lll...@gmail.com wrote: Yes, you are right. 5650_5650 is sig=ref case. prs10_5650 is sig=prs10 and ref=5650 case. In the “both same (5650 / 5650) case” your linear regression filtering is faking you out a bit. The SR620 counter has exactly this same issue. That’s probably for the same reason. It’s a fine test to see if you have various problems under control. It’s not a perfect way to estimate the number of digits you will get on a real measurement. Using two independent sources is a better way to do that. When you have two identical signals, the TDC noise is the main issue. All the edges are arriving in the same relation to each other (same timing). The linear regression is (obviously) good at suppressing the sort of noise the TDC has. With two independent signals the noise is more complex. The edges arrive at various times relative to each other. More things contribute to the total noise. The linear regression is having a harder time suppressing that sort of noise. In some cases (as you observed) the linear regression is actually making things worse. If Magnus was here, he would be tossing empty beer bottles at me and saying — see Bob, sqrt(N) doesn’t always work …. Indeed, except I would not be tossing empty beer bottles at you, I might jokingly attempt do, but never actually throw it. One has to realize that the quantization noise of the TIC may seem to process as if it where white phase noise, but it isn't random noise, it is a systematic noise and if you fool around with the systematics is may work for you or against you. I do consider to pass another bottle of good beer to Bob for good behavior. :) …. as long as we don’t start tossing kegs at each other, I consider myself lucky :) Maybe empty, the beer will be so hard to tap if you throw full kegs, even if full kegs have better impact to get the point through. :) The filtering process used does need to be adapted to the noise of the total system. It's one of the forgotten parameters, and I've even seen good Sam Stein stand up and say we used to do this wrong on the same point, you need to publish and consider the bandwidth of your processing, as it *will* affect the ADEV plot (but only MDEV and TDEV somewhat). Since I really want to reduce the noise, what is the best test set you suggest? All the frequency source I have: FE5650 Rb , PRS10 Rb , MV89a*2 OCXO, If the MV89’s are in good working condition, they are the best thing to compare.The have the best ADEV of the group you have available I would check them for output level and stability before I trusted them. There are a lot of defective parts on the market. People get some, sort them and sell the bad ones. The bad ones just keep getting re-sold again and again … My guess is that they were good parts at one time and they got damaged when pulled off boards. If you use them, keep them on power at all times. Any OCXO will do better if you run it that way. In order to test if systematics is messing badly with you, measure the ADEV of the oscillator as it is steered (and stabilized) to a number of different frequencies. For larger offsets to the counter reference, multiple beatings occurs within the regression interval. You want that number to be an even number of beats, or the beat count to be so large that the phase of the last beat does not care. Linear regression helps out, as it weighs out the outermost measures compared to the central one, making the beating at the beginning and end not care as much. These are *systematic* noise effects, and as you play around with systematics and processing, you might have the systematics works for or against you, but at the same time, the random noise you try to measure will suffer the processing filtering, and you need to recall that. If you balance these properly, you can make good and correct measurements, it's just that few do. Oh, and only use ADEV, MDEV and TDEV to estimate random noises, system noises as they show up there should be estimated separately and removed from the random noise estimates. They have *way* different behaviors. … and this is where it gets complicated. I would toss in the Hadamard deviation into that mix as well. The Hadamard deviation is a great tool as it is not sensitive to linear frequency drift as Allan deviation is. This would help to remove the systematic effect, just as a quadratic curve-fitting of the raw-data and ADEV of the residual. Modified Hadamard deviation (MHDEV) is a good replacement for MDEV, with the same properties for drift. Similarly will Time Hadarmard Deviation (THDEV) replace TDEV. However, for longer taus you want better processing, so therefore you want to consider the TOTAL set of deviations, such
Re: [time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived
The Pulse Engineering PE-68025 module from Electronic Goldmine (http://www.goldmine-elec-products.com/prodinfo.asp?number=G17078) has common mode chokes and LPFs on both Tx and Rx lines. On clearance for $1.00 each. Datasheet is at http://www.datasheetarchive.com/dlmain/Datasheets-9/DSA-179465.pdf Cheers, Dave M ed breya wrote: I investigated those 10b-t isolation modules a while back, and have saved every module from every network card and router/hub/switch that I have junked out. The very old 10b-t stuff is the best for getting LPFs and individual per-channel (port) type parts. When they started making 10/100 Mb/sec, the 17 MHz filters were eliminated, and the parts got integrated to ever-higher levels, with multiple channels in each module. You have to be able to find the data sheets to be sure of what's in them - some are transformers only, and some also have LPFs and common-mode chokes in various combinations. The filter sections can also be cascaded for even sharper cutoff, but there's quite a bit of crosstalk, so a lot of higher frequency stuff gets through, especially above 100 MHz, so it's mostly effective from around 20-100 MHz. It has been mentioned before that very sharp filters will tend to have more phase noise (phase shift with temperature/component variations), but the negative effects depend on the application - I only care about frequency reference distribution to SAs and synthesizers, for example, so I don't worry about exact phase and timing between equipment. There is a nice variety of magnetic parts from all types of network devices, including DSL an ISDN. Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Dr. David Kirkby Ph.D CEng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK. Registered in England and Wales, company number 08914892. http://www.kirkbymicrowave.co.uk/ Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please) On 14 December 2014 at 20:07, Alan Hochhalter alanh...@gmail.com wrote: The 58503A in the picture on leapsecond.com looks very similar to my older 34401A DVM which doesn't have separate feet. Where can I find the 58503A on leapsecond.com ? I don't see any GPS receivers in Tom's museum of HP clocks http://leapsecond.com/hpclocks/ I'd like to find a picture of a *genuine* 58503A. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Hi If you type 58503A into Google, it will come up with a whole raft of pictures of various angles on the device. Since none of them are from HP / Symmetricom, any / all *could* be fakes. Logic suggests that at least 90% of them are the real thing. Bob On Dec 14, 2014, at 4:08 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: Dr. David Kirkby Ph.D CEng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK. Registered in England and Wales, company number 08914892. http://www.kirkbymicrowave.co.uk/ Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please) On 14 December 2014 at 20:07, Alan Hochhalter alanh...@gmail.com wrote: The 58503A in the picture on leapsecond.com looks very similar to my older 34401A DVM which doesn't have separate feet. Where can I find the 58503A on leapsecond.com ? I don't see any GPS receivers in Tom's museum of HP clocks http://leapsecond.com/hpclocks/ I'd like to find a picture of a *genuine* 58503A. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What sort of oscillator is this?
On 9/28/14, 7:55 AM, Richard Karlquist wrote: I find it odd that an instrument that probably cost $50,000 when new did not have a TCXO as standard, and perhaps an oven as an option. But I think HP did this sort of thing a lot. Something that would have cost very little to add, became an expensive option. In some cases these expensive options are nothing more than enabling a bit of software, although the RD cost of the software is probably a lot more than the hardware cost of adding a better oscillator. There's also a difference between the kind of oscillator in the instrument.. Rick can probably tell us for sure, but I've heard it rumored that counters typically got an oscillator optimized for accuracy and low aging, but not necessarily so hot for phase noise, while synthesizers and spectrum analyzers would get a good phase noise oscillator, but maybe with more aging, figuring that the cal lab at the customer's facility would reset the frequency every year anyway. I'm sure there's also some aspects of whether customers were more likely to have a house standard or leave the equipment powered on vs connected to power (so that a standby mode could keep the oscillator powered on). And that in turn was somewhat determined by whether the equipment was portable (has a handle, like a 8563 spectrum analyzer) or rack/bench (like a 8663 signal generator). The portable units aren't going to be powered on all the time, so you want something that is ready to go within a short time after plugging it in. I worked for the HP Santa Clara Division for 19 years. The reason why a customer would NOT want a precision oscillator in a high end instrument would be that he was going to use a house standard. We of course made OCXO's at SCD and sold them to other HP divisions. It would not be impossible for a division to use a TCXO, but it would be out of character given that we transferred 10811's at cost, which was then about $400. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived
On 12/14/14, 10:41 AM, paul swed wrote: Well with zero effort the spec sheet. Bob indeed there are common mode chokes in them. Jeeze a lot in 1 package along with center taps. Regards Paul WB8TSL I've seen a lot of MiniCircuits BNC 10.7 MHz BPFs used in equipment racks over the years as a sort of get rid of trash filter (at least I'm sure that's what the person who bought them thought). Not so hot in terms of phase vs temperature (elliptic filter, 2 MHz wide, centered at 10.7), but probably pretty good at knocking down harmonics and such. BBP-10.7+ ... $41 each. http://www.minicircuits.com/pdfs/BBP-10.7+.pdf Interestingly, only 26 dB rejection at 20 MHz. Must be in the middle of the first bounce of the response.. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] tyco electronics A1025
kb...@n1k.org said: My guess is that there is no PPS out of the device. It would be very unusual if there was. Finding the NEMA output pin should be possible with an oscilloscope. At that point, a simple serial connection to the server is about all you need. Bring up the NEMA driver and it is running. You may need an inverter in the serial path. I'd expect there to be a PPS signal coming out of a GPS module. It is often left unconnected, or connected to a LED. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What sort of oscillator is this?
Hi On Dec 14, 2014, at 4:14 PM, Jim Lux jim...@earthlink.net wrote: On 9/28/14, 7:55 AM, Richard Karlquist wrote: I find it odd that an instrument that probably cost $50,000 when new did not have a TCXO as standard, and perhaps an oven as an option. A *lot* of places that had this stuff ran it out of a frequency standard distribution system 100% of the time. If you saw “TCXO” in the specs, the first thing to do was call the HP sales guy and ask if you could get a discount on one that had a crystal instead….. But I think HP did this sort of thing a lot. Something that would have cost very little to add, became an expensive option. In some cases these expensive options are nothing more than enabling a bit of software, although the RD cost of the software is probably a lot more than the hardware cost of adding a better oscillator. There's also a difference between the kind of oscillator in the instrument.. Rick can probably tell us for sure, but I've heard it rumored that counters typically got an oscillator optimized for accuracy and low aging, but not necessarily so hot for phase noise, while synthesizers and spectrum analyzers would get a good phase noise oscillator, but maybe with more aging, figuring that the cal lab at the customer's facility would reset the frequency every year anyway. HP bought a *lot* of oscillators on the open market from a wide range of suppliers. They very much customized the spec’s on these oscillators to match what they felt were the needs of the target market for this or that piece of gear. I'm sure there's also some aspects of whether customers were more likely to have a house standard or leave the equipment powered on vs connected to power (so that a standby mode could keep the oscillator powered on). Back in the 80’s the federal government / DOD in the US issues an edict that gear could not be on overnight . Oddly enough they were a pretty large customer for this sort of gear. That did indeed impact the specs on the oscillators. In some cases the practice flowed down to contractor sites. That just increased the size of the market with on/off cycles. And that in turn was somewhat determined by whether the equipment was portable (has a handle, like a 8563 spectrum analyzer) or rack/bench (like a 8663 signal generator). The portable units aren't going to be powered on all the time, so you want something that is ready to go within a short time after plugging it in. Some of that gear got low powered OCXO’s Back in the days when manuals with schematics were common it was pretty easy to spot this sort of thing. Bob I worked for the HP Santa Clara Division for 19 years. The reason why a customer would NOT want a precision oscillator in a high end instrument would be that he was going to use a house standard. We of course made OCXO's at SCD and sold them to other HP divisions. It would not be impossible for a division to use a TCXO, but it would be out of character given that we transferred 10811's at cost, which was then about $400. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
gign...@gmail.com said: Based on my recent testing - including Solaris - you will be better off with the Internet unless your USB adapter is far better behaved than the several I have here That depends, (TM) How good/bad is your network connection? Mine gets over 3 seconds of queuing delays. I challenge anybody to find a USB device that bad. There are only 2 or 3 significant vendors of USB-serial chips. I think they are reasonably well supported by all major OSes. USB is polled, so interrupt latency turns into polling latency. I think the polling cycle is 1 ms for slow things like serial ports. Maybe 1/4 ms for faster things like disks. At the system level, faster polling means more overhead and slower polling means bigger buffers. Many of the low cost GPS units use the SiRF chips. They have a wander of ~100 ms. I said wander rather than jitter because it's very slow as in hours. You can't filter it out with a 10 or 100 second sample. The old Garmin GPS-18-USB (not 18x) units had pretty good timing. No wander. Unfortunately, they weren't very sensitive. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived
Eds Right I did see it used to turn square waves into sine waves. I will have to try that. But I am very happy with it even as a simple transformer. Thats what surprised me something that goes nicely all the way down below 60 KHz. I have to tell you I have been using lots of things that I have found for 60 and 100 Khz. This offers me some consistency with actual documentation. Its hard to find LF things these days. Beats un-soldering from a board also. Bob granted these can be used for twisted pair. Unshielded also. What about radiation at 5 or 10 Mhz. Granted there is shielded twisted pairs. Regards Paul WB8TSL On Sun, Dec 14, 2014 at 4:20 PM, Jim Lux jim...@earthlink.net wrote: On 12/14/14, 10:41 AM, paul swed wrote: Well with zero effort the spec sheet. Bob indeed there are common mode chokes in them. Jeeze a lot in 1 package along with center taps. Regards Paul WB8TSL I've seen a lot of MiniCircuits BNC 10.7 MHz BPFs used in equipment racks over the years as a sort of get rid of trash filter (at least I'm sure that's what the person who bought them thought). Not so hot in terms of phase vs temperature (elliptic filter, 2 MHz wide, centered at 10.7), but probably pretty good at knocking down harmonics and such. BBP-10.7+ ... $41 each. http://www.minicircuits.com/pdfs/BBP-10.7+.pdf Interestingly, only 26 dB rejection at 20 MHz. Must be in the middle of the first bounce of the response.. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
Hi On Dec 14, 2014, at 4:26 PM, Hal Murray hmur...@megapathdsl.net wrote: gign...@gmail.com said: Based on my recent testing - including Solaris - you will be better off with the Internet unless your USB adapter is far better behaved than the several I have here That depends, (TM) How good/bad is your network connection? Mine gets over 3 seconds of queuing delays. I challenge anybody to find a USB device that bad. There are only 2 or 3 significant vendors of USB-serial chips. I think they are reasonably well supported by all major OSes. USB is polled, so interrupt latency turns into polling latency. I think the polling cycle is 1 ms for slow things like serial ports. On at least some (= the ones I’ve seen) of the serial devices, they will continue to buffer if they have a character coming in. Put another way, a string sent at 19.2 Kbaud will likely transfer as a block rather than a character at a time. Is this at the bus or the driver level? - who knows. The result (in Linux / Win-dooze / or OS-X) is that data comes in in bursts. Maybe 1/4 ms for faster things like disks. At the system level, faster polling means more overhead and slower polling means bigger buffers. Many of the low cost GPS units use the SiRF chips. They have a wander of ~100 ms. I said wander rather than jitter because it's very slow as in hours. You can't filter it out with a 10 or 100 second sample. .. as in a pps output is not necessarily a *useful* pps output. Only useful outputs count. We’ve been over the why and the how of chips that put out pps’s way late a number of times. Simple answer - it didn’t matter in the firmware design spec. Bob The old Garmin GPS-18-USB (not 18x) units had pretty good timing. No wander. Unfortunately, they weren't very sensitive. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Set time on Solaris computer from HP 58503A
1) Downloaded ntp-4.2.6p5 If you are going to compile it (rather than use whatever comes with your system), please use the Release Candidate version from: http://support.ntp.org/bin/view/Main/SoftwareDownloads [Anybody else willing to help... This is your chance. If you find bugs, submit a bug report and/or poke me off list.] and also the directory /dev/fd That's something else. I don't know what they are. My guess would be something associated with the file system. That I am not sure how to configure ntp.conf - a case of RTFM. It's probably as simple as adding server 127.127.26.0 but read the driver26.html page You also need something like: ln -s /dev/ttyS0 /dev/hpgps0 How do you reboot - apart from of course powering the thing off? Yes. Power cycle. E-101 :PTIME:TCODE? T220141214123441337 You can sanity check the UTC/GPS by eyeball. They are 16 seconds apart. You can clear the E-101 (and get back to scpi) by sending: *CLS I know those commands, although I don't recommend reboot - it is less clean than init 6. I assumed that that Hal Murry's reboot was meant to be the GPS receiver, not the Solaris computer, but maybe I mis-understood. Yes. Power cycle the GPSDO. At least on the Z3801A, it's stored in flash. You only have to do it once. I think there is a software command to reboot. I don't have it handy. Mostly, I work from the Z3801A manual. A few things don't work on the KS-24361. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
What Bob suggested is just what I did. The leapsecond photos happened to be the very first ones. I was careless when typing and didn't think about gmail creating a link out of it. Alan On Sun, Dec 14, 2014 at 2:13 PM, Bob Camp kb...@n1k.org wrote: Hi If you type 58503A into Google, it will come up with a whole raft of pictures of various angles on the device. Since none of them are from HP / Symmetricom, any / all *could* be fakes. Logic suggests that at least 90% of them are the real thing. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Hi Every one that I found showing enough detail had the bumper with feet rather than the feet that clip into the case. A couple of power options are illustrated (DC and AC) with various option numbers attached. Bob On Dec 14, 2014, at 5:25 PM, Alan Hochhalter alanh...@gmail.com wrote: What Bob suggested is just what I did. The leapsecond photos happened to be the very first ones. I was careless when typing and didn't think about gmail creating a link out of it. Alan On Sun, Dec 14, 2014 at 2:13 PM, Bob Camp kb...@n1k.org wrote: Hi If you type 58503A into Google, it will come up with a whole raft of pictures of various angles on the device. Since none of them are from HP / Symmetricom, any / all *could* be fakes. Logic suggests that at least 90% of them are the real thing. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Which First GPSDO to buy?
Thanks. See below: On 12/14/2014 1:48 PM, Bob Camp wrote: Hi Ok so down to two choices: LTE Lite: 1) Comes up nice and fast (it’s a TCXO) 2) Modern GPS receiver 3) Good documentation 4) Very low power 5) Nice small size Good so far. 6) Needs a box Boxes I have. 7) You know where to find Jackson Labs if there is a problem 8) Getting a couple more in a couple years may be possible Also good. Lucent: 1) More accurate if you keep it on (it’s an OCXO) 2) Spare parts set (= the second box) when you buy the pair 3) Comes with a (clunky) enclosure 4) Outputs are already isolated / buffered All good. 5) Needs an antenna ($30 or so for a good one, $3 for a simple one) OK, doesn't sound too expensive. 6) Needs a power supply ($20 maybe less) I have a bunch of DC power supplies sitting in the storage closet. Or I can build one. It's pretty simple. 7) Hook it up and check it out fast, there’s a 30 day warranty (which the guy does honor) 8) Once this guy sells out, there may not be many more. Yes, I have been thinking about that. Maybe get one of these just to do it before they are gone. Both: 1) You still need to mount the antenna somewhere The lab is one the second floor; It shouldn't be a problem to add it to the breakout box going outside the room to the exterior. 2) You need to distribute the 10 MHz or 1 pps to your gear Yes, I haven't figured that out yet. But it will be fun. 3) With only one you will always be wondering “what if it’s wrong?”. Having two only confuses this situation …. One really needs three at a minimum. But acquiring three starts with acquiring one. 4) Neither one lets you play much with the loop (filtering), both are pretty much optimum for the hardware as received I think this where building one oneself comes in. Or buying the Thunderbolt. 5) Price wise not a lot of difference. Both will be $200-ish once you get them delivered and set up without the distribution stuff. Yes, and that is affordable while I am still working. What to do - get some of each :) Precisely my conclusion. I need to buy one of each. This is precisely how I ended up with thirteen Tektronix oscilloscopes. It's the same process. And right in the middle of Christmas gift-buying season. A very useful summary. Thanks! DaveD Bob On Dec 14, 2014, at 12:49 PM, Dave Daniel kc0...@gmail.com wrote: Well, thanks, everyone, for the information. I appreciate the help. First, I am presently not up to adding another project to my long list of projects. I get whiplash every time I walk into the lab. Building a GPSDO sound like fun. Perhaps down the line. I figured I should add some information about myself: I am an electrical engineer (currently employed) with a lot of digital/Verilog experience and a fair bit of analog experience (but less than my digital experience) and quite a bit of software experience, all of this from working for about thirty-eight years on various embedded systems. Currently, I shy away from writing code just because I don't enjoy it much and have done too much professionally. But I know that eventually I will need to write code in my lab. Presently, I am in the process of restoring some older ham radio gear, but I became sidetracked from that by the necessity to repair a bunch of vintage test equipment which effort has somehow taken on a life of it's own. What I need right now is a frequency standard that is accurate enough to use as a reference for things like calibrating test gear. I also want to play with one before I build one. Just going through all of the educational material is a daunting task. I figured I'd combine an interest with GPSDOs in general with a need for an accurate enough standard (I use the term loosely here) to get some instruments calibrated. Thanks again for all the information! Cheers, DaveD I had forgotten about the LTE-lite; I should add that to the list of choices. I'm tending towards either a 10 MHz version of that or the Lucent boxes. On 12/14/2014 8:00 AM, Bob Camp wrote: Hi On Dec 14, 2014, at 12:47 AM, Chris Albertson albertson.ch...@gmail.com wrote: I tried to see just how simple, low cost and self contained I could make a GPSDO. I started with the Lars Walenius design then removed everything I could from it. I replace all the software with just a small loop with about a dozen lines of code so it would be easy to understand. My goal was to make something that could be built and tested using just basic equipment. The question is of course How do you know the unit is making a 10 MHz signal if you don't already have a 10MHz reference to compare it to? Well you can assume that your 1PPS reference is accurate. Except that the GPS PPS is *not* perfect, far from it. It’s only reasonably accurate over very long time spans. Over short spans the pps moves around a lot. Then you count and make sure you see EXACTLY 10,000,000 oscillator cycles per each PPS. If you do a tight lock (“EXACTLY”)
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
On Sun, Dec 14, 2014 at 4:08 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: I'd like to find a picture of a *genuine* 58503A. The instance pictured has the 16-char display option so it doesn't look like many of the images you find of the 58503A. http://www.leapsecond.com/museum/58503a-01/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Which First GPSDO to buy?
Hi On Dec 14, 2014, at 4:20 PM, Dave Daniel kc0...@gmail.com wrote: Thanks. See below: On 12/14/2014 1:48 PM, Bob Camp wrote: Hi Ok so down to two choices: LTE Lite: 1) Comes up nice and fast (it’s a TCXO) 2) Modern GPS receiver 3) Good documentation 4) Very low power 5) Nice small size Good so far. 6) Needs a box Boxes I have. There’s also odd things like power connectors, again likely junk box items. 7) You know where to find Jackson Labs if there is a problem 8) Getting a couple more in a couple years may be possible Also good. Lucent: 1) More accurate if you keep it on (it’s an OCXO) 2) Spare parts set (= the second box) when you buy the pair 3) Comes with a (clunky) enclosure 4) Outputs are already isolated / buffered All good. 5) Needs an antenna ($30 or so for a good one, $3 for a simple one) OK, doesn't sound too expensive. The same $30 antenna will last a bit longer and mount a bit easier when used with most GPSDO’s. The exception are ones that put out 3.3V rather than 5V. There are a range of antennas out there to pick from. There are also antennas in the = $100 range that you might consider for some applications. 6) Needs a power supply ($20 maybe less) I have a bunch of DC power supplies sitting in the storage closet. Or I can build one. It's pretty simple. The unit needs 18 to 36(?) V. That’s a lot of room for choices. The target supply was likely a “24V” battery bank. Take all the normal 12V numbers (charge / discharge / dead battery/ smoke from the battery fast charge) and just double them. I would not target 22 V or 30V out of the supply. The internal brick is a regulated switcher, there is no need to hyper regulate the external supply. 7) Hook it up and check it out fast, there’s a 30 day warranty (which the guy does honor) 8) Once this guy sells out, there may not be many more. Yes, I have been thinking about that. Maybe get one of these just to do it before they are gone. That’s why I keep harping on them Both: 1) You still need to mount the antenna somewhere The lab is one the second floor; It shouldn't be a problem to add it to the breakout box going outside the room to the exterior. You are after a clear view of the southern sky and at least due east / due west. A full sky view (360 degrees) would be nice. 2) You need to distribute the 10 MHz or 1 pps to your gear Yes, I haven't figured that out yet. But it will be fun. You can do it for $1 per channel. 3) With only one you will always be wondering “what if it’s wrong?”. Having two only confuses this situation …. One really needs three at a minimum. But acquiring three starts with acquiring one. Right, but consider that you are indeed buying the first of several. These things pop up and then go away. The Lucent is in that category. I have no idea of Jackson Lab’s plans for the LTE on eBay. That also *could* be a limited time deal. 4) Neither one lets you play much with the loop (filtering), both are pretty much optimum for the hardware as received I think this where building one oneself comes in. Or buying the Thunderbolt. The T Bolt’s are pretty expensive these days. They also have a limited ability to modify things (but better than the other boxes). A home-brew is the only way to have full control. There’s no need to run out and get a TBolt at the prices they sell for these days. 5) Price wise not a lot of difference. Both will be $200-ish once you get them delivered and set up without the distribution stuff. Yes, and that is affordable while I am still working. I suspect that one this guy sells out of the Lucent’s you will see them creep up in price. All the other Z38xx’s have done the same thing. Z3801’s once sold for what these are now selling for. TBolt’s sold for less. I would not count on Jackson labs having a fire sale. The LTE is a very good deal on a new commercial unit at the price it’s at. Unless the market changes a lot, you should be able to sell any of the surplus boxes in the future for more than what you paid for it (if it still works). If the LTE is a limited time deal, they will likely follow the same sort of price trajectory. What to do - get some of each :) Precisely my conclusion. I need to buy one of each. This is precisely how I ended up with thirteen Tektronix oscilloscopes. It's the same process. And right in the middle of Christmas gift-buying season. Which could flush out the inventory of the Lucent boxes faster than one might think. They also could be around next June at the same price. I suppose there could be a massive inventory of them in China (water damage risk and all) and they could be $60 next June. A very useful summary. Thanks! No problem. Bob DaveD Bob On Dec 14, 2014, at 12:49 PM, Dave Daniel kc0...@gmail.com wrote: Well, thanks, everyone, for the information. I appreciate the help. First, I am
Re: [time-nuts] Which First GPSDO to buy?
I don't mean to one up Chris, but if you are looking for inexpensive, I have bought the same Pro Mini from this seller for $2.58. Like Chris says, you can't buy the parts this for this. And if you need the 3.3 VDC version: http://www.ebay.com/itm/191182699659 I bought six of the Pro Mini's from this seller and every one tested OK. I have also bought other items from this seller. I have no complaints. One thing to be aware of when looking for the Pro Mini boards. There are at least three slightly different versions. At least one of them has the serial programming pins on one end reversed. The board that Chris and I have linked to are the exact same thing that SparkFun sells. I believe it is the version 2.0 board. You can recognize it not only by the serial programming pinout, but it also has the two pairs of extra holes next to the chip. Those are A4/A5 and A6/A7. Just as an aside, although it is often true that many of these Chinese vendors sell ripoff copies of things, in this case, the Pro Mini design is open source hardware, so it is legitimate for the Chinese or anyone else to make and sell them. Joe Gray W5JG On Sun, Dec 14, 2014 at 8:56 AM, Chris Albertson albertson.ch...@gmail.com wrote: It's not worth making a PCB, not when you can buy the whole thing already assembled for $3 with free shipping. I use these just as if they where a single chip and put them in a socket. See eBay 141505833625 as an example. Those holes are in 0.1 inch centers so you can figure out the size. (I get 1.3 inches long.) direct link http://www.ebay.com/itm/ARDUINO-PRO-MINI-Nano-Pro-Mini-atmega328-Compatible-Nano-5V-16M-/141505833625?pt=LH_DefaultDomain_0hash=item20f267aa99 I'll write up what I built. It would be good to see the range of these. I tried to make mine as simple an low cost as possible without regard to anything else. Just to find the bottom line. I doubt I would have met that gaol by using a bare AVR chip. That is NOT simple because it requires so much more skill from the builder and with an entire working Arduino selling for $3 how much could you save? Actually the chips on that $3 board cost more than $3. (I don't even see how shipping from China can be that cheap.) On Sat, Dec 13, 2014 at 10:56 PM, Patrick Tudor ptu...@ptudor.net wrote: On Dec 13, 2014, at 9:47 PM, Chris Albertson albertson.ch...@gmail.com wrote: Actually I've added some features to it like a 2 line by 16 character LCD display and some status LEDs. And I can log data to a computer via a USB cable so it is easy to plot data and it is using my more expansive mast mounted timing antenna. Just in case any of you like reading Arduino code, for fun or functions to copy-and-paste, the code for my PCB that combines an ATMega328p with an Adafruit GPS and 16x2 LCD to display GPS info as it sends the PPS out the DB9 DCD is at GitHub. It's not exactly, say, measuring oscillator cycles (yet... ) but it's perhaps a good introduction for someone who's never ever before used anything Arduino. (And now that I've done more PCBs with Cypress and FTDI chips, I wish I'd put that straight on my board instead of as a future daughterboard, but, feature creep.) https://github.com/ptudor/jemma-clock PT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Which First GPSDO to buy?
I have to watch what I'm typing a little closer. I meant to say You can't buy the parts this cheap. Joe Gray W5JG On Sun, Dec 14, 2014 at 8:56 AM, Chris Albertson albertson.ch...@gmail.com wrote: It's not worth making a PCB, not when you can buy the whole thing already assembled for $3 with free shipping. I use these just as if they where a single chip and put them in a socket. See eBay 141505833625 as an example. Those holes are in 0.1 inch centers so you can figure out the size. (I get 1.3 inches long.) direct link http://www.ebay.com/itm/ARDUINO-PRO-MINI-Nano-Pro-Mini-atmega328-Compatible-Nano-5V-16M-/141505833625?pt=LH_DefaultDomain_0hash=item20f267aa99 I'll write up what I built. It would be good to see the range of these. I tried to make mine as simple an low cost as possible without regard to anything else. Just to find the bottom line. I doubt I would have met that gaol by using a bare AVR chip. That is NOT simple because it requires so much more skill from the builder and with an entire working Arduino selling for $3 how much could you save? Actually the chips on that $3 board cost more than $3. (I don't even see how shipping from China can be that cheap.) On Sat, Dec 13, 2014 at 10:56 PM, Patrick Tudor ptu...@ptudor.net wrote: On Dec 13, 2014, at 9:47 PM, Chris Albertson albertson.ch...@gmail.com wrote: Actually I've added some features to it like a 2 line by 16 character LCD display and some status LEDs. And I can log data to a computer via a USB cable so it is easy to plot data and it is using my more expansive mast mounted timing antenna. Just in case any of you like reading Arduino code, for fun or functions to copy-and-paste, the code for my PCB that combines an ATMega328p with an Adafruit GPS and 16x2 LCD to display GPS info as it sends the PPS out the DB9 DCD is at GitHub. It's not exactly, say, measuring oscillator cycles (yet... ) but it's perhaps a good introduction for someone who's never ever before used anything Arduino. (And now that I've done more PCBs with Cypress and FTDI chips, I wish I'd put that straight on my board instead of as a future daughterboard, but, feature creep.) https://github.com/ptudor/jemma-clock PT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Hi That display is a pretty hard part to fake. It’s not custom enough to be impossible to find, but I doubt it’s a stock part at your local market. Bob On Dec 14, 2014, at 6:37 PM, Paul tic-...@bodosom.net wrote: On Sun, Dec 14, 2014 at 4:08 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: I'd like to find a picture of a *genuine* 58503A. The instance pictured has the 16-char display option so it doesn't look like many of the images you find of the 58503A. http://www.leapsecond.com/museum/58503a-01/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
If any of you want me to post more photos let me know. I have several of every kind of HP/Agilent GPSDO product. And they are all genuine because I bought them a decade before the China/eBay/GPSDO business. Right, I probably should have included some of HP's GPSDO products in the hpclocks photo shoot. /tvb Where can I find the 58503A on leapsecond.com ? I don't see any GPS receivers in Tom's museum of HP clocks http://leapsecond.com/hpclocks/ I'd like to find a picture of a *genuine* 58503A. What Bob suggested is just what I did. The leapsecond photos happened to be the very first ones. I was careless when typing and didn't think about gmail creating a link out of it. The instance pictured has the 16-char display option so it doesn't look like many of the images you find of the 58503A. http://www.leapsecond.com/museum/58503a-01/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
And 'scope probes :-) On Dec 14, 2014 12:59 PM, Bob Camp kb...@n1k.org wrote: Hi On Dec 14, 2014, at 3:50 PM, Scott McGrath scmcgr...@gmail.com wrote: Much of the Malaysian Agilent gear uses this style of case with a wraparound bumper in place of the system II feet and feet are removed when gear is rack mounted. One of my best surplus buys ever was a huge crate of mixed mounting hardware feet / rack flanges etc I've been using that box o stuff for 10 years Somewhere there’s a building full of gear all of which is missing it’s feet and bumpers … You are lucky to have found that box. In most cases they get tossed out with the trash. The same is true of many of the fancy i/o cables, they get put into the copper recycle pile and are gone… Bob Content by Scott Typos by Siri On Dec 14, 2014, at 3:09 PM, Bob Camp kb...@n1k.org wrote: Hi The desktop version (with handle) used the rubber “bumper” wrap around for feet. The bumpers got pulled when they were rack mounted. The ones that got put back on may or may not be identical to the originals. That’s a very normal part of the surplus process. The 100% correct HP original case on the box as HP built it did not use the clip on feet. The reason for this is pretty simple. The Z3801 / Z3805 came before the “instrument” versions of the same products. The internal case structure is same/ same. The instrument simply gets a gray sheet metal jacket that fits around the Z38xx box. That’s the way HP designed it. Since its just a jacket, it gets feet as part of the bumpers. Most of these (likely 99%) got rack mounted and the feet / bumpers were tossed. I have a *lot* of very legit surplus HP gear that did not come with feet or bumpers. Bob On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 19:32, Bob Camp kb...@n1k.org wrote: There are not the usual 3 holes underneath where feet go. I understand that they are different. The problem is the same though. Pulling a box in and out of a rack with feet or bumpers on it is a pain. They often get “lost” early in the instrument’s life. Often it’s a standard process on all gear as it comes into the facility. All of the un-needed bits and pieces go into a big pile. When the feet (or whatever) are found later in life they may or may not be re-installed correctly. They might not even be the ones that came with the instrument. Bob I am not sure if you are following me. On most (all??) HP kit I have seen, there are 3 holes at each corner of the bottom, where is possible to fit feet if one is going to use it on a desktop, rather than a rack. This unit does not have those holes, so it would be impossible to fit the usual HP feet on it. Looking around, I have 15 bits of HP kit, all of which have holes in the corner for feet. But this 58503A, with the Chinese box, does not have the holes. I don't know whether the 85053A is supposed to have them, or whether this is just a flaw in the design of the counterfeit. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Fwd: Homebrew frequency counter, need help
Hi (yes, this is a bit confusing … it’s my replies to a forward from Magnus who got a bounce on submittal) Begin forwarded message: Date: December 14, 2014 at 7:57:39 PM EST From: Magnus Danielson mag...@rubidium.se To: Bob Camp kb...@n1k.org Cc: mag...@rubidium.se Subject: Re: [time-nuts] Homebrew frequency counter, need help Hi Bob, Repost my email as I accidentally posted it with wrong from address. On 12/14/2014 08:26 PM, Bob Camp wrote: Since I really want to reduce the noise, what is the best test set you suggest? All the frequency source I have: FE5650 Rb , PRS10 Rb , MV89a*2 OCXO, If the MV89’s are in good working condition, they are the best thing to compare.The have the best ADEV of the group you have available I would check them for output level and stability before I trusted them. There are a lot of defective parts on the market. People get some, sort them and sell the bad ones. The bad ones just keep getting re-sold again and again … My guess is that they were good parts at one time and they got damaged when pulled off boards. If you use them, keep them on power at all times. Any OCXO will do better if you run it that way. In order to test if systematics is messing badly with you, measure the ADEV of the oscillator as it is steered (and stabilized) to a number of different frequencies. For larger offsets to the counter reference, multiple beatings occurs within the regression interval. You want that number to be an even number of beats, or the beat count to be so large that the phase of the last beat does not care. Linear regression helps out, as it weighs out the outermost measures compared to the central one, making the beating at the beginning and end not care as much. These are *systematic* noise effects, and as you play around with systematics and processing, you might have the systematics works for or against you, but at the same time, the random noise you try to measure will suffer the processing filtering, and you need to recall that. If you balance these properly, you can make good and correct measurements, it's just that few do. Oh, and only use ADEV, MDEV and TDEV to estimate random noises, system noises as they show up there should be estimated separately and removed from the random noise estimates. They have *way* different behaviors. … and this is where it gets complicated. I would toss in the Hadamard deviation into that mix as well. The Hadamard deviation is a great tool as it is not sensitive to linear frequency drift as Allan deviation is. This would help to remove the systematic effect, just as a quadratic curve-fitting of the raw-data and ADEV of the residual. I like the Hadamard because it’s a bit better for mapping to the frequency domain. It’s what HP used to get phase noise from phase error data. I find that it gives a bit better detail on some types of problems. I use if regularly, but TimeLab unfortunatly does not have the MHDEV. The whole process of getting *correct* versions of things into a program is (unfortunately) much harder than simply tossing it in there. I’m glad that the stuff in TimeLab works correctly. Modified Hadamard deviation (MHDEV) is a good replacement for MDEV, with the same properties for drift. Similarly will Time Hadarmard Deviation (THDEV) replace TDEV. However, for longer taus you want better processing, so therefore you want to consider the TOTAL set of deviations, such that confidence intervals is better. If I had to only use three, I would include it with modified ADEV (MDEV) and TDEV. All three are available in TimeLab with the click of a button. If you start getting lots of data (9,000 points per second) I would toss in a frequency domain (FFT) analysis as well. FFT on phase data is not (as far as I know) a feature of TimeLab. FFT on phase-data is only available in TimeLab when doing phase-noise measurements. FFT is the way to analyse systematic noise rather than random noise where ADEV and friends is being used. You need to separate them, and the ADEV plot is not good for both. There is a set of FFT based ADEV-style measures, which uses FFT, filtering of the various ADEV styles. There is a nice set of articles covering that approach, and actually the only style of ADEV processing that I haven't yet implemented, even if I have done most others. Stable-32 will take phase data and convert it to the frequency domain. Depending on what processing you are going to do, phase or frequency may be optimum. Phase is better for normal deviations. Frequency is better for modified deviations. Stable 32 is nice in that it will convert one to the other with the click of a button. To start with, on all of these measures, you are looking for bumps and spikes. They are telling you that something is wrong. If you flip over to the phase plot in TimeLab, spikes and abrupt steps in it also
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Hi On Dec 14, 2014, at 8:05 PM, Pete Lancashire p...@petelancashire.com wrote: And 'scope probes :-) Ok, that’s just plain not fair. I could accept the motherland of bumpers and handles. Tossing in scope probes … you are not to expect the usual fruit basket from me at Christmas :) Bob On Dec 14, 2014 12:59 PM, Bob Camp kb...@n1k.org wrote: Hi On Dec 14, 2014, at 3:50 PM, Scott McGrath scmcgr...@gmail.com wrote: Much of the Malaysian Agilent gear uses this style of case with a wraparound bumper in place of the system II feet and feet are removed when gear is rack mounted. One of my best surplus buys ever was a huge crate of mixed mounting hardware feet / rack flanges etc I've been using that box o stuff for 10 years Somewhere there’s a building full of gear all of which is missing it’s feet and bumpers … You are lucky to have found that box. In most cases they get tossed out with the trash. The same is true of many of the fancy i/o cables, they get put into the copper recycle pile and are gone… Bob Content by Scott Typos by Siri On Dec 14, 2014, at 3:09 PM, Bob Camp kb...@n1k.org wrote: Hi The desktop version (with handle) used the rubber “bumper” wrap around for feet. The bumpers got pulled when they were rack mounted. The ones that got put back on may or may not be identical to the originals. That’s a very normal part of the surplus process. The 100% correct HP original case on the box as HP built it did not use the clip on feet. The reason for this is pretty simple. The Z3801 / Z3805 came before the “instrument” versions of the same products. The internal case structure is same/ same. The instrument simply gets a gray sheet metal jacket that fits around the Z38xx box. That’s the way HP designed it. Since its just a jacket, it gets feet as part of the bumpers. Most of these (likely 99%) got rack mounted and the feet / bumpers were tossed. I have a *lot* of very legit surplus HP gear that did not come with feet or bumpers. Bob On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 14 December 2014 at 19:32, Bob Camp kb...@n1k.org wrote: There are not the usual 3 holes underneath where feet go. I understand that they are different. The problem is the same though. Pulling a box in and out of a rack with feet or bumpers on it is a pain. They often get “lost” early in the instrument’s life. Often it’s a standard process on all gear as it comes into the facility. All of the un-needed bits and pieces go into a big pile. When the feet (or whatever) are found later in life they may or may not be re-installed correctly. They might not even be the ones that came with the instrument. Bob I am not sure if you are following me. On most (all??) HP kit I have seen, there are 3 holes at each corner of the bottom, where is possible to fit feet if one is going to use it on a desktop, rather than a rack. This unit does not have those holes, so it would be impossible to fit the usual HP feet on it. Looking around, I have 15 bits of HP kit, all of which have holes in the corner for feet. But this 58503A, with the Chinese box, does not have the holes. I don't know whether the 85053A is supposed to have them, or whether this is just a flaw in the design of the counterfeit. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The Trapezoidal Clocking
Bob, On 12/14/2014 02:10 AM, Robert Darby wrote: This is an paper that may be of some interest to those interested in clock distribution. The author, Jinyuan Wu has done considerable work on FPGA TIC's with Fermi Lab. http://www-ppd.fnal.gov/EEDOffice-w/Projects/ckm/comadc/TrapezCLK1b.pdf How incredibly cunning! Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The Trapezoidal Clocking
Hi …. but … Low edge speeds = poor signal to noise = high jitter. The result is a clock that aligns, but has high(er) jitter compared to a conventional square wave clock. Most of the “lower phase noise / lower jitter” progress in CMOS logic has gone hand in hand with faster edge rates. Bob On Dec 14, 2014, at 8:27 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, On 12/14/2014 02:10 AM, Robert Darby wrote: This is an paper that may be of some interest to those interested in clock distribution. The author, Jinyuan Wu has done considerable work on FPGA TIC's with Fermi Lab. http://www-ppd.fnal.gov/EEDOffice-w/Projects/ckm/comadc/TrapezCLK1b.pdf How incredibly cunning! Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew frequency counter, need help
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Re: [time-nuts] Fwd: Homebrew frequency counter, need help
Hi Bob, On 12/15/2014 02:22 AM, Bob Camp wrote: Hi (yes, this is a bit confusing … it’s my replies to a forward from Magnus who got a bounce on submittal) Whe're confusing Bob, I think they got that part now. Begin forwarded message: Date: December 14, 2014 at 7:57:39 PM EST From: Magnus Danielson mag...@rubidium.se To: Bob Camp kb...@n1k.org Cc: mag...@rubidium.se Subject: Re: [time-nuts] Homebrew frequency counter, need help Hi Bob, Repost my email as I accidentally posted it with wrong from address. On 12/14/2014 08:26 PM, Bob Camp wrote: … and this is where it gets complicated. I would toss in the Hadamard deviation into that mix as well. The Hadamard deviation is a great tool as it is not sensitive to linear frequency drift as Allan deviation is. This would help to remove the systematic effect, just as a quadratic curve-fitting of the raw-data and ADEV of the residual. I like the Hadamard because it’s a bit better for mapping to the frequency domain. It’s what HP used to get phase noise from phase error data. I find that it gives a bit better detail on some types of problems. I use if regularly, but TimeLab unfortunatly does not have the MHDEV. The whole process of getting *correct* versions of things into a program is (unfortunately) much harder than simply tossing it in there. I’m glad that the stuff in TimeLab works correctly. I do know that, and it's not the only culprit, John naturally wants one that works correctly in update form, and not batch form. He also does not want too many of these running in parallel. Modified Hadamard deviation (MHDEV) is a good replacement for MDEV, with the same properties for drift. Similarly will Time Hadarmard Deviation (THDEV) replace TDEV. However, for longer taus you want better processing, so therefore you want to consider the TOTAL set of deviations, such that confidence intervals is better. If I had to only use three, I would include it with modified ADEV (MDEV) and TDEV. All three are available in TimeLab with the click of a button. If you start getting lots of data (9,000 points per second) I would toss in a frequency domain (FFT) analysis as well. FFT on phase data is not (as far as I know) a feature of TimeLab. FFT on phase-data is only available in TimeLab when doing phase-noise measurements. FFT is the way to analyse systematic noise rather than random noise where ADEV and friends is being used. You need to separate them, and the ADEV plot is not good for both. There is a set of FFT based ADEV-style measures, which uses FFT, filtering of the various ADEV styles. There is a nice set of articles covering that approach, and actually the only style of ADEV processing that I haven't yet implemented, even if I have done most others. Stable-32 will take phase data and convert it to the frequency domain. Depending on what processing you are going to do, phase or frequency may be optimum. Phase is better for normal deviations. Frequency is better for modified deviations. Stable 32 is nice in that it will convert one to the other with the click of a button. I'm sure it is fine, but it does not fit my needs in one way, it doesn't run on Linux. My milage with Wine on different applications vary. TimeLab works, but is free. For an application I pay for and not knowing it works would be strange. Besides, I try to minimize my dependence on Windows apps, as they tend to bite me. Stable 32 thus does not fit my needs very well, even if I'm sure it is a fine application. To start with, on all of these measures, you are looking for bumps and spikes. They are telling you that something is wrong. If you flip over to the phase plot in TimeLab, spikes and abrupt steps in it also are telling you the same sort of thing. Exactly what this or that bump is telling you may not be obvious at first. Posting plots to the list is a great way to get things sorted out. Bumps, spikes and slopes... ADEV isn't the only tool one should be using, FFT might be much better for systematic noises. Right, so when you see them, alarm bells should go off. Something is indeed wrong and further investigation is required. Maybe, ADEV is good at smoothing out things, so spikes in spectrum-analysis might not be as easy to spot in the ADEV form. A good reason to look at multiple data sets and analysis approaches Which is what I am say, do not rely on ADEV alone, and move your analysis of systematics out of the ADEV plot and remove those effects fro the ADEV plot so it becomes better at modeling the random noises. In the end of the day, there is an overbeleife in ADEV both as a scale as well as a processing tool, to analyze deviations, without considering the separation of various systmeatic effect and systematic noises, while ADEV and friends is there to analyze random noise types, it does not handle systematics good. Seems like we have to kill ADEV as the universal measure. Ah well. It’s been
Re: [time-nuts] The Trapezoidal Clocking
Hi, Agree. It's not ideal. In it's simplicity it achieves first degree delay compensation, but it is not the best of signals you get. You need to treat the signal as being essentially a sine, and overcome the slew-rate. It may be a useful technique besides it's limits. Cheers, Magnus On 12/15/2014 03:45 AM, Bob Camp wrote: Hi …. but … Low edge speeds = poor signal to noise = high jitter. The result is a clock that aligns, but has high(er) jitter compared to a conventional square wave clock. Most of the “lower phase noise / lower jitter” progress in CMOS logic has gone hand in hand with faster edge rates. Bob On Dec 14, 2014, at 8:27 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, On 12/14/2014 02:10 AM, Robert Darby wrote: This is an paper that may be of some interest to those interested in clock distribution. The author, Jinyuan Wu has done considerable work on FPGA TIC's with Fermi Lab. http://www-ppd.fnal.gov/EEDOffice-w/Projects/ckm/comadc/TrapezCLK1b.pdf How incredibly cunning! Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Ebay is your friend when you need footsies for your old HP equipment... just search for HP FEET and you should be able to find what you need. As usual, you will find sellers with reasonable prices and those that think they are made of 25k gold. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
On 15 Dec 2014 00:52, Tom Van Baak t...@leapsecond.com wrote: If any of you want me to post more photos let me know. I have several of every kind of HP/Agilent GPSDO product. And they are all genuine because I bought them a decade before the China/eBay/GPSDO business. Hi Tom, I would appreciate some pictures of a 85053B that is * mains powered * Does not have the keypad/display if you have one. I appreciate given the options on this instrument, you might not have one with the exact same configuration as mine. Ideally pictures of the front, back, sides bottom. I was intending dropping Symmetricon an email in the hope that they could help. If they had an HP one it would be really useful. I am weary of believing any photo I currently see on the web to be honest. Someone said 90% are likely to be genuine, but I am not so sure that is true. I rather suspect a lot of dealers have fakes, but are unaware of it. I notice that the keypad display were available as an upgrade, suggesting that the case would not need extra ventilation, so the case should be the same, but eBay may be less convinced. Likewise I doubt a different case would be used for AC and DC models, but eBay might be less convinced. Dave. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver
Hi Dave, There are several variations of 58503A, 58503B, 59551A, etc. Not to mention all the Z38 variations of the basic HP SmartClock technology. Please do not bother HP, Agilent, Symmetricom, or Microsemi. At this point I have more vintage gear and way more historical and forensic interest in the past than they do. I will take this up with you off-list, as this thread/topic is now getting rather off-topic. List -- if something useful comes from all of this, David or I will surely post a single, informative follow-up note in the coming days or weeks. Meanwhile, let's close this thread. Thanks, /tvb - Original Message - From: Dr. David Kirkby (Kirkby Microwave Ltd) To: Discussion of precise time and frequency measurement ; Tom Van Baak Sent: Sunday, December 14, 2014 10:38 PM Subject: Re: [time-nuts] Ventilation of HP 58503A GPS time frequency reference receiver On 15 Dec 2014 00:52, Tom Van Baak t...@leapsecond.com wrote: If any of you want me to post more photos let me know. I have several of every kind of HP/Agilent GPSDO product. And they are all genuine because I bought them a decade before the China/eBay/GPSDO business. Hi Tom, I would appreciate some pictures of a 85053B that is * mains powered * Does not have the keypad/display if you have one. I appreciate given the options on this instrument, you might not have one with the exact same configuration as mine. Ideally pictures of the front, back, sides bottom. I was intending dropping Symmetricon an email in the hope that they could help. If they had an HP one it would be really useful. I am weary of believing any photo I currently see on the web to be honest. Someone said 90% are likely to be genuine, but I am not so sure that is true. I rather suspect a lot of dealers have fakes, but are unaware of it. I notice that the keypad display were available as an upgrade, suggesting that the case would not need extra ventilation, so the case should be the same, but eBay may be less convinced. Likewise I doubt a different case would be used for AC and DC models, but eBay might be less convinced. Dave. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Did a member of time-nuts buy this?
Hi On Dec 10, 2014, at 11:12 PM, Mike Monett timen...@binsamp.e4ward.com wrote: [...] Can you tell me some of the ones that do? I have yet to see one for under $2K that does it correctly. I don't have the cash to buy ones at those sort of prices. Some have reported that the old Motorola UT's will do it. The samples I have tried have not done very well. I may have not had them running right who knows. OK, that pretty much eliminates the NIST data. or means that more research is needed on single sat boards. There are a *lot* of them out there. What is a single sat board and can you give some examples? 5) Feed that into your control loop equation. There's another term I need to research! It's not a simple control process, but it's not all that terrible either. It just takes a bit of work to optimize. Figure a few months to a few years for the optimization depending on what you have for issues along the way. OK, so I figure out how to do this. How do I tell if this is making the gpsdo more accurate? In other words, how do I get the ADEV without having an H-Maser? You get a Cs (or other atomic standard) or you compare several different GPSDO's against each other. The preference would be for groups of three so you can rule out ones that are not doing what they should. The ideal would be 3 TBolts, 3 same model Rb's, 3 same model OCXO's and more than three groups overall. Each has their own ADEV curve. Comparing devices with vastly different ADEV is not the best way to go. Yes, that makes good sense. [...] There are many new dacs, op amps, and bipolar microwave devices that offer much lower noise than current designs use. I think the performance can be improved in some areas with new components and design techniques, and I have equipment and time to explore. There are only two points that system noise really comes into the GPSDO design: 1) The TDC must have enough resolution 2) The DAC on the EFC must have noise below the OCXO I was more thinking of the Rubidium physics package. Most of the Rubidiums on eBay are pretty old. The lamp must have constant intensity. The null detector has to identify a very shallow drop. The microwave signal needs to have excellent phase noise. These all need low noise, low flicker components, and significant advances have been made in recent years. The surrounding circuitry could probably benefit from a redesign to take better advantage of low noise components. For example, SRD's are much noisier than NLTL's. Probably little can be done to improve the Rubidium cell, but it should be the limiting factor and not the electronics. The TDC is limited by the basic resolution of the GPS system. It's easy to build one that has far more resolution than needed / useful. Some people have little faith:) The DAC issue is normally solved with a $4 part. Unless you have an OCXO with a very wide EFC range, it's noise is unlikely to be an issue. DAC resolution can be addressed to any desired level with two DAC's (fine and coarse). (Once you get going, you only use the fine DAC). The real fun and games revolves around the software used to implement the filtering / control loop between the GPS and the OCXO (or Rb, or TCXO, or MEMS, or VCXO, or Cs or âŠ) Focus on the software. Bob I have a few Rubidiums and OCXOs I'd like to get running for a month or so to stabilize. During this time, I'd like to monitor the performance to discover any bad units and see which are the best ones. For example, TVB shows a 100:1 variation in ADEV in FE-405B Rubidiums. The section is titled Variation in FE-405B in http://leapsecond.com/pages/fe405/ Clearly, it would be futile to try to use a bad unit in setting up a gpsdo. I need some means of measuring the performance of these units while they are running. A dozen HP5370's would be out of the question. I did some research to find the different methods available and decide which has the lowest per-channel cost and best performance. Here are some of the references I found. I discarded most of the poor ones and tried to keep only the ones that talk about measurements in the picosecond or femtosecond range. I did not include DMTD since the concept is so simple. The Reviews help to get oriented, but sometimes it takes reading the papers and the patents to see the timing diagrams and understand what the author is trying to do. There are many different variations on the FPGA approach. I would be concerned about the development time, the large DNL, and the problems with crosstalk on multi-channel units. The TI THS788 looks good on paper, but it is single-source, not well stocked, and there is lttle information on crosstalk between channels. It is also quite expensive per channel. There are no application notes and little or no information on usage on the web. The Thesis generally have excellent reviews worth reading. Articles Simple PICTIC 250ps time interval counter