Re: [time-nuts] My HP 5370B reads 6 nS out!
Hi On Jun 15, 2015, at 9:51 PM, Peter Reilley pe...@reilley.com wrote: Frank; Thanks for your long and detailed explanation. I was able to get the internal OCXO to that precision but it was probably luck to get the trimmer that close. I worked at it for a while. I am using T.I. mode with the averaging mode. I assumed that it took 10K readings and averaged the results. Is that not correct? Is something mode complicated going on? I will have to set up the GPIB and give that a try. I did get TimeLab. This will be new territory to me. I did try measuring it's own 10 MHz frequency with 1 sec gate time. It bounces around by about +- 4 in the 10th decimal place. Is my calibration with the rubidium oscillator valid? Could it be that far off? An “old style” analog tune Rb could tune a max of 1x10^-8. It’s rare to see them more than 3x10^-9 off. Most are running under 5x10^-10 when received from the salvage yard. The “new style” digital tuned Rb’s have a range limited by their VCXO (if it’s limited at all). They *should* be 3x10^-9 as received from salvage. They could be much further off. Since all of these are tunable devices. The only way to be sure of their accuracy is to calibrate them against something good. Bob I will have to ponder this some more. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Frank Stellmach Sent: Monday, June 15, 2015 5:01 PM To: time-nuts@febo.com Subject: [time-nuts] My HP 5370B reads 6 nS out! Pete, you do not specify, whether you use FREQ or T.I. when you use the averaging function. First of all, its OCXO can be adjusted to a few parts in 1e-9 only, as the trimmer is too unprecise. If the OCXO is running for several weeks already (idle state), its drift may be as low as a few parts in 1e-10 or better. If you put the instrument to FREQ mode, you may measure and the 10MHz of the GPSDO standard to about 2e-11 resolution, if you use 1sec time base on the 5370B. That should work also, if you directly measure 1pps, but you have to properly adjust the trigger level. Important: Don't use the 10k statistics, set the 5370A also to 1sec time base! Due to this low frequency, jitter should be higher, see specifications. You better do statistics by means of a PC, over GPIB. That will show the 30ps jitter of the 5370B, and the jitter of the GPSDO, on the order of 1e-10. You may also calibrate the OCXO of the 5370B this way, instead of that oscilloscope method. I strongly recommend Timelab from John Miles to do these measurements properly. http://www.ke5fx.com/timelab/readme.htm If you use the internal 10k statistics 10k, pay attention!! In this instance, the 5370B will do the frequency measurement in a different manner.. Not 100% sure, it will be a sort of a T.I. measurement, calculated to frequency. And that may produce a constant offset, if the internal T.I. calibration is not done properly. Look into the specs, its absolute T.I. uncertainty is 1ns only, although it resolves 20ps. You may check that behaviour, if you apply its own 10Mhz OCXO ouput to the FREQ input, and measure this frequency first on FREQ, 1sec. That should give nearly exactly 10MHz, 1e-10 jitter or deviation. Mine reads 9.999 999 999 85 MHz, for example. If you now switch to AVERAGE, SAMPLE SIZE 1, 100, 1k, 10K, you will see, that you will get big deviations as big as 0.1%, although it should measure its own OCXO to precisely 10.0MHZ. Mine reads 9,989 294 5 MHz, for example. That's due to the different measurement method, and should explain 6..7ns deviation on the 1pps signal also. This averaging should only be used with T.I.! 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. ___ 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] Trimble L1/L2 GPS Antenna PN: 27947-00
Hi I’ve played with one of those ... Ok, that’s the antenna that turned into the “micro centered” version. The antenna came out in the same era as the 4000 series survey GPS units. With the ground plane it’s quite large. It does pretty well with the ground plane, but good luck finding a place to mount it. Like many of the Trimble survey antennas, that one has about a 50 db amplifier in it. That amp will overdrive most GPSDO’s. It also needs a supply up around +12 rather than the more normal (on timing gear) +5V. Bob On Jun 16, 2015, at 1:11 AM, M. George m.matthew.geo...@gmail.com wrote: Hello, I snagged a Trimble GPS 27947-00 on the usual auction site awhile back... I hope I didn't snag it from other time-nuts that were bidding... Anyway, it showed up today and it cleaned up really nice. I couldn't help 'not' opening it up to take a peek... see the pictures here: Trimble L1/L2 GPS Antenna 27947-00 http://www.nc7j.com/downloads/NG7M/Time-Nuts/Trimble%2027947-00%20GPS%20L1%20L2%20Antenna/ I can't find hardly anything at all on this part number... I looked at KO4BB's manual pages trying to find something and gave it my best Google shot. Is there a common model number that I'm missing? What convinced me to go after a better antenna were comments from Bob and others and I think I got a good deal on this. Was it a good find... and are time-nuts using these with the Trimble ground plane in permanent installs with the ground plane attached. (sorry for my ignorance here, but I'm not finding too much based on my searching around and I'm a newbie time-nut) I don't have anything that would use the L2 frequencies yet... or maybe ever, but it's amazing how well this thing is built. I'm interested to see the difference it will show compared to my $30 bullet. Any insight would be helpful... mount suggestions... etc... over kill? Max NG7M -- M. George ___ 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] HP5065A upgrade kit H10
Hi all, I have developed an upgrade kit for the HP5065A. This add one or two 10MHz outputs and can be installed in all the units have the HP10811 as OCXO. The main features of this amplifier-separator are: Very low residual phase noise, typical -150dB @ 1Hz High reverse isolation typical 110 dB High input impedance do not load the HP10811 output High output power handling on 50 Ohm settled to +15dBm (as the others HP5065A outputs) Output GND isolated to avoid the low frequency current loop The Option H10-1 have one single 10MHz output The Option H10-2 have two separated 10MHz outputs The option is assembled ready to install and is complete of all the connectors, cables and others components are needed. You can find the installation manual with pictures here: http://www.timeok.it/files/hp5065AoptH10v101.pdf Visit also my HP5065A corner here: http://www.timeok.it/HP5065_corner.html If you are interested, please email me: tim...@timeok.it Best regards, Luciano ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts [1] and follow the instructions there. Message sent via Atmail Open - http://atmail.org/ ___ 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] Using CPLD/FPGA or similar for frequency
Hoi Bruce, On Tue, 16 Jun 2015 12:24:34 +1200 Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Using an ADC to sample a triggered damped sinewave easily achieves 5ps resolution (eg Keysight Acquiris). With a better optimised waveform model and least squares fitting routine greater resolution is feasible. The accuracy is dependent on the ADC sampling clock stability. An optical frequency standard derived clock may be required to maintain ps accuracy for long time intervals. Do you mean the technique that Panek et al. [1] are using? IIRC he got that down to 0.5ps RMS now. And yes, the major source of error is the oscillator, according to [2]. Ripamonti et al. showed in [3] that using an LC tank instead of an SAW filter will result in something in the order of 2-10ps RMS (after temperature compensation). So this system is in the same region as an well designed time-to-amplitude converter based system. I really wonder which one would be easier to build. Attila Kinali [1] Time interval measurement device based on surface acoustic wave filter excitation, providing 1ps precision and stability, by Panek andProchazka, 2007 http://dx.doi.org/10.1063/1.2779217 [2] Random Errors in Time Interval Measurement Based on SAW Filter Excitation, by Panek, 2008 http://dx.doi.org/10.1109/TIM.2007.915465 [3] High frequency, high time resolution time-to-digital converter employing passive resonating circuits, by Ripamonti, Abba, Geraci, 2010 http://dx.doi.org/10.1063/1.3432002 -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ 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] Using CPLD/FPGA or similar for frequency
Hi On Jun 15, 2015, at 11:26 PM, Hal Murray hmur...@megapathdsl.net wrote: kb...@n1k.org said: Since the internal PLL’s have jitter in the 20 to 30 ps RMS range, that limits a lot of the data you get. I haven't looked recently, but I doubt if much has changed. Xilinx uses DLLs rather than PLLs. The jitter on both clock sources looks pretty gaussian. They have a long chain of buffers and a giant multiplexor to select the right tap. Does anybody have data on what the jitter actually looks like? I'd expect several blurry peaks, with the spacing between peaks being the step size of the delay/mux chain and the blur being wider if there is more random logic. The calibration output is a mess … Bob -- 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] Raspberry Pi tweaks and custom kernel, was RE: PPS for NTP Server - How Close Is Good Enough?
Hi On Jun 15, 2015, at 9:38 PM, Chris Caudle ch...@chriscaudle.org wrote: On Mon, June 15, 2015 8:01 pm, Bob Camp wrote: Unless you have fancy switches on your LAN (1588 stamping), PTP performance will be dependent on load and the goodness of the switches you do have. These are pretty much the same (external) things that impact NTP. Yes, but proper differentiated services setup with multiple queues can help mitigate that to a large extent. I'm still trying to get my PTP setup going, so I don't have any measurements of my own yet, but there are lots of examples of large commercial systems in use without transparent clock support which can maintain sub-microsecond synchronization. Using PTP transparent switches should get down into the couple hundred nanosecond range or better, but even without 800 or so nanoseconds has been shown to be consistently possible. I have no idea what level of synchronization you could keep using just NTP with diffserv. I believe that you can do exactly that. Once you take the stamping switches out of the mix there isn’t a lot of difference between the two protocols. You would indeed need to tweak NTP a bit, but that part of the fun. Bob That might be an interesting experiment to try for those who only want NTP and aren't interested in setting up PTP. -- Chris Caudle ___ 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] Using CPLD/FPGA or similar for frequency
On Mon, 15 Jun 2015 20:26:09 -0700 Hal Murray hmur...@megapathdsl.net wrote: Does anybody have data on what the jitter actually looks like? I'd expect several blurry peaks, with the spacing between peaks being the step size of the delay/mux chain and the blur being wider if there is more random logic. Quick googling revieled these two papers: [1] Jitter issues in clock conditioning with FPGAs, by Aloisio, Giordano, Izzo, 2010 http://dx.doi.org/10.1109/RTC.2010.5750386 [2] Phase Noise Issues With FPGA-Embedded DLLs and PLLs in HEP Applications, by Aloisio, Giordano, Izzo, 2011 http://dx.doi.org/10.1109/TNS.2011.2143727 Both contain phase noise plots for different configurations of DLLs of Virtex 5. I haven't read them yet, so I cannot say anything about their content. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ 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] My HP 5370B reads 6 nS out!
Bob; It seems reasonable to calibrate my 5370B using the 1 PPS signal from my Resolution T and assume that my rubidium oscillator is 6 X 10^-9 off. There is no reason to believe that the GPS 1 PPS signal is wrong. The FEI FE-5680A devices seem to be hard to determine what options they actually have. Perhaps it just needs calibration. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Tuesday, June 16, 2015 7:02 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] My HP 5370B reads 6 nS out! Hi On Jun 15, 2015, at 9:51 PM, Peter Reilley pe...@reilley.com wrote: Frank; Thanks for your long and detailed explanation. I was able to get the internal OCXO to that precision but it was probably luck to get the trimmer that close. I worked at it for a while. I am using T.I. mode with the averaging mode. I assumed that it took 10K readings and averaged the results. Is that not correct? Is something mode complicated going on? I will have to set up the GPIB and give that a try. I did get TimeLab. This will be new territory to me. I did try measuring it's own 10 MHz frequency with 1 sec gate time. It bounces around by about +- 4 in the 10th decimal place. Is my calibration with the rubidium oscillator valid? Could it be that far off? An old style analog tune Rb could tune a max of 1x10^-8. It's rare to see them more than 3x10^-9 off. Most are running under 5x10^-10 when received from the salvage yard. The new style digital tuned Rb's have a range limited by their VCXO (if it's limited at all). They *should* be 3x10^-9 as received from salvage. They could be much further off. Since all of these are tunable devices. The only way to be sure of their accuracy is to calibrate them against something good. Bob I will have to ponder this some more. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Frank Stellmach Sent: Monday, June 15, 2015 5:01 PM To: time-nuts@febo.com Subject: [time-nuts] My HP 5370B reads 6 nS out! Pete, you do not specify, whether you use FREQ or T.I. when you use the averaging function. First of all, its OCXO can be adjusted to a few parts in 1e-9 only, as the trimmer is too unprecise. If the OCXO is running for several weeks already (idle state), its drift may be as low as a few parts in 1e-10 or better. If you put the instrument to FREQ mode, you may measure and the 10MHz of the GPSDO standard to about 2e-11 resolution, if you use 1sec time base on the 5370B. That should work also, if you directly measure 1pps, but you have to properly adjust the trigger level. Important: Don't use the 10k statistics, set the 5370A also to 1sec time base! Due to this low frequency, jitter should be higher, see specifications. You better do statistics by means of a PC, over GPIB. That will show the 30ps jitter of the 5370B, and the jitter of the GPSDO, on the order of 1e-10. You may also calibrate the OCXO of the 5370B this way, instead of that oscilloscope method. I strongly recommend Timelab from John Miles to do these measurements properly. http://www.ke5fx.com/timelab/readme.htm If you use the internal 10k statistics 10k, pay attention!! In this instance, the 5370B will do the frequency measurement in a different manner.. Not 100% sure, it will be a sort of a T.I. measurement, calculated to frequency. And that may produce a constant offset, if the internal T.I. calibration is not done properly. Look into the specs, its absolute T.I. uncertainty is 1ns only, although it resolves 20ps. You may check that behaviour, if you apply its own 10Mhz OCXO ouput to the FREQ input, and measure this frequency first on FREQ, 1sec. That should give nearly exactly 10MHz, 1e-10 jitter or deviation. Mine reads 9.999 999 999 85 MHz, for example. If you now switch to AVERAGE, SAMPLE SIZE 1, 100, 1k, 10K, you will see, that you will get big deviations as big as 0.1%, although it should measure its own OCXO to precisely 10.0MHZ. Mine reads 9,989 294 5 MHz, for example. That's due to the different measurement method, and should explain 6..7ns deviation on the 1pps signal also. This averaging should only be used with T.I.! 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. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
[time-nuts] Modulation Domain Analysis
I stumbled onto the time nuts list from a posting on modulation domain analysis a couple of weeks ago. I am enjoying the discussion. I want to comment on modulation domain analysis, or phase digitizing. This is a technique that uses a period mode frequency counter, or two such counters back to back, to recover the modulation history of a frequency modulated waveform. This technique was first used in the HP9540 automated transceiver test system. This system was described in the August 1973 HP Journal. The HP9540 used a single HP5326 period mode counter with a 10 MHz clock. At that time, no counter was available with a higher clock frequency. A breadboard system was assembled as part of the HP9540 development effort which used two HP5326 counters back to back. To insure that alternate periods were measured, the second HP5326 ran off the gate output of the first. However, it was realized that the characteristics of the HP9540 and its specific application were such that two counters were not required. Please refer to my HP Journal article for details. The HP9540 was developed at HP's Automatic Measurement Division. This division was disbanded in 1974. Modulation Domain Analysis and Phase Digitizing were terms that came into use with the later development of specialized stand alone instruments that combined computational capability, back to back period mode counters, higher clock frequencies, interpolation and algorithms for various measurements. All of these were worthwhile improvements on the basic technique first used in the HP9540. I would be happy to answer questions. Thank you for allowing me to post this information. Robert Gilchrist Huenemann, M.S.E.E. 120 Harbern Way Hollister, CA 95023-9708 831-635-0786 bo...@razzolink.com https://sites.google.com/site/bobhuenemann/ Extra Class Amateur Radio License W6RFW IEEE Life Member 01189471 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ___ 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] low budget UT+ newbie time-nut project: Frequency Reference
UT+ $10.95 A couple parts from the usual auction site: USB interface item #13117576 $3.56 MCX Connector, 2 for $4 and a wire from the junk box that already had a TNC plug on it. Downloaded software: WinCore12 Under $18 and a fantastic learning opportunity. The most difficult thing was configuring a USB port on my computer to make everything happy at the same time. Overall, a very easy and pleasant experiment. I am getting enough signal indoors at the top of my bench for a good fix. WinCore12 works and is free. Apparently I was fortunate to receive the timing version from Bob Stewart. Wincore12 allows selection of the 100PPS in the timing mode window. http://www.synergy-gps.com/index.php?option=com_contenttask=viewid=185Itemid=196 near the bottom of the page. I have been able to screwdriver discipline the OCXO in an '80s vintage lab grade frequency counter well beyond my needs. It is a cheap ebay Fluke 1953A with option 20. I got lucky. Down to waiting 28 hours to see the results of each adjustment. Averaging 1PPS over 10e5 periods and measuring pico seconds of error. The old OCXO is much more stable than I expected. Bob Fleming N5TX ___ 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] Modulation Domain Analysis
That's interesting. I worked for the HP Santa Clara Division from 1979 until just before it was closed in 1998. I forget who invented MDA at SCD, but it was hyped like it was some new concept and I never heard anything about the HP9540. Many times someone would come to me and ask me about some new bright idea they had, and I would tell them Yes, I can confirm that your idea is excellent, because I read the original paper on it that was published in 19XX. It is interesting that people would often get mad at me, as if it is my fault they reinvented the wheel. If only I known about your HP Journal article, I could have throw it up to the innovators at SCD. Before I worked for HP, an HP Journal article came out about fractional-N synthesizers, and everyone at Zeta Labs was anxious to use the technology in the Zeta Labs designs. Except one guy, who pointed out that he had invented frac-N 11 years previously, and he called it digiphase. I've never heard anyone at HP ever acknowledge that guy. Rick (now retired from HP/Agilent/Keysight) On 6/16/2015 12:54 PM, Robert Gilchrist Huenemann wrote: I stumbled onto the time nuts list from a posting on modulation domain analysis a couple of weeks ago. I am enjoying the discussion. I want to comment on modulation domain analysis, or phase digitizing. This is a technique that uses a period mode frequency counter, or two such counters back to back, to recover the modulation history of a frequency modulated waveform. This technique was first used in the HP9540 automated transceiver test system. This system was described in the August 1973 HP Journal. The HP9540 used a single HP5326 period mode counter with a 10 MHz clock. At that time, no counter was available with a higher clock frequency. A breadboard system was assembled as part of the HP9540 development effort which used two HP5326 counters back to back. To insure that alternate periods were measured, the second HP5326 ran off the gate output of the first. However, it was realized that the characteristics of the HP9540 and its specific application were such that two counters were not required. Please refer to my HP Journal article for details. The HP9540 was developed at HP's Automatic Measurement Division. This division was disbanded in 1974. Modulation Domain Analysis and Phase Digitizing were terms that came into use with the later development of specialized stand alone instruments that combined computational capability, back to back period mode counters, higher clock frequencies, interpolation and algorithms for various measurements. All of these were worthwhile improvements on the basic technique first used in the HP9540. I would be happy to answer questions. Thank you for allowing me to post this information. Robert Gilchrist Huenemann, M.S.E.E. 120 Harbern Way Hollister, CA 95023-9708 831-635-0786 bo...@razzolink.com https://sites.google.com/site/bobhuenemann/ Extra Class Amateur Radio License W6RFW IEEE Life Member 01189471 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ___ 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] Using CPLD/FPGA or similar for frequency
On Tuesday, June 16, 2015 10:01:09 AM Attila Kinali wrote: Hoi Bruce, On Tue, 16 Jun 2015 12:24:34 +1200 Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Using an ADC to sample a triggered damped sinewave easily achieves 5ps resolution (eg Keysight Acquiris). With a better optimised waveform model and least squares fitting routine greater resolution is feasible. The accuracy is dependent on the ADC sampling clock stability. An optical frequency standard derived clock may be required to maintain ps accuracy for long time intervals. Do you mean the technique that Panek et al. [1] are using? Not quite he used an impulse to excite a saw filter rather than switching off the dc current feed to an inductor or the equivalent. IIRC he got that down to 0.5ps RMS now. And yes, the major source of error is the oscillator, according to [2]. Ripamonti et al. showed in [3] that using an LC tank instead of an SAW filter will result in something in the order of 2-10ps RMS (after temperature compensation). So this system is in the same region as an well designed time-to-amplitude converter based system. The curve fitting algorithm they used is somewhat deficient as is the switching method employed one can do much better provided one has sufficient time or computing resources available. My crude testing using a somewhat simplified diode switched current source powered by the signal itself achieved a fitting noise of around 5ps with a 14 bit ADC. A better driver and higher resolution ADC with a lower noise input amplifier than the input amplifier of the oscilloscope I used should improve the results somewhat as would a better model for the damped sine signal. I really wonder which one would be easier to build. Keysight as far as I can tell used a discrete LC circuit to produce a damped sine wave rather than the conventional TAC approach used in the lower resolution Acquiris models. Bruce Attila Kinali [1] Time interval measurement device based on surface acoustic wave filter excitation, providing 1ps precision and stability, by Panek andProchazka, 2007 http://dx.doi.org/10.1063/1.2779217 [2] Random Errors in Time Interval Measurement Based on SAW Filter Excitation, by Panek, 2008 http://dx.doi.org/10.1109/TIM.2007.915465 [3] High frequency, high time resolution time-to-digital converter employing passive resonating circuits, by Ripamonti, Abba, Geraci, 2010 http://dx.doi.org/10.1063/1.3432002 ___ 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] HP53132A For Sale
Greetings all, I wish to sell my HP53132A with Option 10, High Stability time base. Included are manuals on a CD. Price is $650 plus shipping. I will ship to a US mail address through USPS. I prefer a paypal payment. Pictures available on request. If interested send an email to ivanjcous...@gmail.com Ivan Cousins ___ 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] NTGS50AA 1 PPS mod
Hi, I has been making some tests with the 1 PPS output and here are the results: Lady Heather cable delay commands works with both polarities, i.e. it can advance or retard both 1/2 and 1 PPS signals, I used as reference and external 1 PPS signal from a Rb oscillator. The first impression is that the 1 PPS edge leads the 1/2 PPS about 550 ns and this difference is consistent after some cable delay commands and antenna disconnections, it is maintained during holdover. Then I tried several power cycling and warm resets and this make an annoying thing to appear: during the acquisition and phase locking the difference jumped between 540 and 140 ns in 100 ns steps. This is due to the 1/2 PPS synchronization with the SYS_CLOCK signal, so when the internal 1/2 PPS moved back and forth until the system phase lock is obtained, the output jumps between successive cycles of the SYS_CLOCK. The annoying thing is that its final state is not always the same, the final difference can be any of the mentioned steps, from 120ns to 550 ns and there is not guarantee which one is obtained while in my board the 540 ns difference is the most common. I don't know yet it the 1 PPS is closer to the epoch second or it is the 1/2 PPS, I have to hook up a GPS timing module and an antenna splitter and see what happens. Anyway since Nortel specifies a tolerance of +/- 1 us of the 1/2 PPS with respect to GPS even second, any of the seen values are within specs but it is not very convenient for Time Nuts. Regards, Ignacio El 14/06/2015 a las 20:35, EB4APL wrote: Even if I get a cell site I would not use it for a private network, here all cell phones are GSM not CDMA. The only use for the 9.8304 MHz is as a master for deriving serial comm clocks (i.e. 9600 is 9.8304 / 1024) but I don't plan to became a Serial Comm Time Nut yet. ;-) Ignacio El 14/06/2015 a las 1:48, Bob Camp escribió: Hi Of course tomorrow you will stumble into a “great deal” on a complete cell site that needs a 9.8304 MHz clock :) One thing to watch: The pps you now have may or may not be deterministic in its relation to the every other second output. It also may or may not be in a fixed relation to GPS. I would bet money that it *is* in a fixed relation and that it’s actually better than the other signal. Just because I believe it to be true does not make it true. It needs to be checked against something else. Bob On Jun 13, 2015, at 1:56 PM, EB4APL eb4...@gmail.com wrote: Hi, I just finish the mod. It was easy, I cut the trace between TP14 and U405-6 and soldered a wire between TP14 and TP33. Now I have a pretty 1 PPS on J5, the old 9.8304 MHz output. The signal has 0-5 V levels, normally high with a 10 us pulse going down. In my unit this pulse leads the even second pulse by 539 ns. I will check if the Lady Heather command for compensating the cable length can be used to move this if somebody needs a more accurate epoch second. I have to use the 1PPS from my FE5680A as a reference but now it is disconnected. I have made a picture of the mod and I'll include it with my partial schematic (I made some advances there) and the list of the TP signals that I'm preparing for upload. I have checked that now I have also 4 additional 1 PPS outputs in the 110 pin connector J2. They are in the pins previously used by the SYS_CLK signal. They are differential LVDS as most of the signals on this interface. Regards, Ignacio El 13/06/2015 a las 1:14, Ed Armstrong escribió: Ignacio, I would very much appreciate a copy of whatever schematics you have, even if it is not guaranteed to be 100% accurate I agree with you that the 9.9804 Mhz is basically useless, while the even second pulse is merely almost useless. However, as you have apparently looked the board over more carefully than me, you probably already understand why I did it the way I did. The location of the two output circuits were very easy to find, the path from the connector to them is quite distinctive. I just needed to find out where the signal got into the output circuit from, and when I flipped the board over, the trace bringing in the even second pulse was extremely obvious. There was no obvious trace for the 9.9804, and I didn't feel like probing all over the place and looking up a lot of chip numbers to try to figure out where it came from, as I have a very unsteady hand which makes poking around in these closely spaced components an invitation to disaster. So I just went with the obvious. I found it interesting that the output circuit inverts the signal a few times. I actually would have preferred to invert it, so that the polarity was correct for a raspberry pie or a serial port under Windows, but it appeared some of the traces to do so were hidden in the layers of the board, and again the more I fool around the better my chance of shorting something out and becoming very unhappy. I will be anxious to hear how your
Re: [time-nuts] Modulation Domain Analysis
On a related subject: Tektronix TVC501 Time-Interval to Voltage Converter (cousin of the modulation domain analyzer) I have worked as an Application Engineer at Tektronix for over 25 years. In the early 1990's we developed the TVC501, which was a time interval to voltage converter. I'm doing this from memory (since it's hard to find references on the Internet) but I believe it had a time interval counter with about 50 ns resolution. The counter output was subtracted from a user-settable reference time, then multiplied by a user-settable gain before driving an 8-bit D/A. The analog voltage output was updated at each measured interval, up to about 2 million updates/sec. This architecture allowed the user to see small changes in large time intervals on either an analog or digital oscilloscope or other instrument. So you could see changes in the period of the power line frequency with around 100 ns resolution, and use the oscilloscope voltage level trigger features to capture timing aberrations. The TVC501 was a single-wide TM500 plug-in unit. The TVC501 had two BNC inputs, and could sense the width or period of signals on one input, or the time interval between edges on the two inputs. It was a rather specialized product, and I don't think we sold many of them. In 1995 we discontinued nearly the entire TM500/TM5000 line. Some of these products were sold by Tegam for a few years. -- Bill Byrom N5BB On Tue, Jun 16, 2015, at 05:17 PM, Richard (Rick) Karlquist wrote: That's interesting. I worked for the HP Santa Clara Division from 1979 until just before it was closed in 1998. I forget who invented MDA at SCD, but it was hyped like it was some new concept and I never heard anything about the HP9540. Many times someone would come to me and ask me about some new bright idea they had, and I would tell them Yes, I can confirm that your idea is excellent, because I read the original paper on it that was published in 19XX. It is interesting that people would often get mad at me, as if it is my fault they reinvented the wheel. If only I known about your HP Journal article, I could have throw it up to the innovators at SCD. Before I worked for HP, an HP Journal article came out about fractional-N synthesizers, and everyone at Zeta Labs was anxious to use the technology in the Zeta Labs designs. Except one guy, who pointed out that he had invented frac-N 11 years previously, and he called it digiphase. I've never heard anyone at HP ever acknowledge that guy. Rick (now retired from HP/Agilent/Keysight) On 6/16/2015 12:54 PM, Robert Gilchrist Huenemann wrote: I stumbled onto the time nuts list from a posting on modulation domain analysis a couple of weeks ago. I am enjoying the discussion. I want to comment on modulation domain analysis, or phase digitizing. This is a technique that uses a period mode frequency counter, or two such counters back to back, to recover the modulation history of a frequency modulated waveform. This technique was first used in the HP9540 automated transceiver test system. This system was described in the August 1973 HP Journal. The HP9540 used a single HP5326 period mode counter with a 10 MHz clock. At that time, no counter was available with a higher clock frequency. A breadboard system was assembled as part of the HP9540 development effort which used two HP5326 counters back to back. To insure that alternate periods were measured, the second HP5326 ran off the gate output of the first. However, it was realized that the characteristics of the HP9540 and its specific application were such that two counters were not required. Please refer to my HP Journal article for details. The HP9540 was developed at HP's Automatic Measurement Division. This division was disbanded in 1974. Modulation Domain Analysis and Phase Digitizing were terms that came into use with the later development of specialized stand alone instruments that combined computational capability, back to back period mode counters, higher clock frequencies, interpolation and algorithms for various measurements. All of these were worthwhile improvements on the basic technique first used in the HP9540. I would be happy to answer questions. Thank you for allowing me to post this information. Robert Gilchrist Huenemann, M.S.E.E. 120 Harbern Way Hollister, CA 95023-9708 831-635-0786 bo...@razzolink.com https://sites.google.com/site/bobhuenemann/ Extra Class Amateur Radio License W6RFW IEEE Life Member 01189471 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ 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] Trimble L1/L2 GPS Antenna PN: 27947-00
Hello, I snagged a Trimble GPS 27947-00 on the usual auction site awhile back... I hope I didn't snag it from other time-nuts that were bidding... Anyway, it showed up today and it cleaned up really nice. I couldn't help 'not' opening it up to take a peek... see the pictures here: Trimble L1/L2 GPS Antenna 27947-00 http://www.nc7j.com/downloads/NG7M/Time-Nuts/Trimble%2027947-00%20GPS%20L1%20L2%20Antenna/ I can't find hardly anything at all on this part number... I looked at KO4BB's manual pages trying to find something and gave it my best Google shot. Is there a common model number that I'm missing? What convinced me to go after a better antenna were comments from Bob and others and I think I got a good deal on this. Was it a good find... and are time-nuts using these with the Trimble ground plane in permanent installs with the ground plane attached. (sorry for my ignorance here, but I'm not finding too much based on my searching around and I'm a newbie time-nut) I don't have anything that would use the L2 frequencies yet... or maybe ever, but it's amazing how well this thing is built. I'm interested to see the difference it will show compared to my $30 bullet. Any insight would be helpful... mount suggestions... etc... over kill? Max NG7M -- M. George ___ 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.
