[time-nuts] Solar Storms - GPS World Article
Interesting article in GPS World... http://www.gpsworld.com/gnss-system/augmentation-assistance/news/work-begin s-strengthening-egnos-against-solar-storms-12772?utm_source=GPSutm_medium=e mailutm_campaign=navigate_03_20_2012utm_content=work-begins-strengthening- egnos-against-solar-storms-12772 Rob Kimberley ___ 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] Antenna Position
All, There have been numerous discussions on antennae position in the group, so I thought the following might be interesting to both old and new to TF. I've recently had a small extension to the house built which is now my office/workshop. Living in a conservation area in the Peak District in the UK, and having 4 GPS antennae on the roof of the extension was going to be a big problem (BIG!). The extension is bordered by a dry stone wall approx. 5ft high. I'm currently running an Odetics CommSync as my house standard. This is a dual redundant GPS/OCXO unit with 16 x 10 MHz outputs and 2x 1PPS. Also running are two Zyfer NTPSync XL (badged Meinberg LanTime) network time servers. As I couldn't mount the antennae on the roof, I had to get creative. I tried various positions on the ground before settling on their current resting place. All antennae are now mounted on short poles with the poles and cables buried in the ground in front of the wall which faces South West. All antennae are approx. 1ft. above ground level and about 1ft. apart, and from the road it just looks like I'm growing some rather exotic mushrooms!! All GPS units track at least 5 SVs all the time. I know that the position is not perfect by any means, but it is a case of needs must. The CommSync is sitting showing about 1E-13 at present so I'm happy with the way it all works. (If anyone wants a photograph of the set up please contact me off list. Thanks) Rob Kimberley ___ 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] IOTECH 488 EPROM
Do not forget that BlackBox sold Converters and Controllers that are identical internally to the IOTech boxes. The EPROMs can also be swapped between these two. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: J. L. Trantham jlt...@att.net Sender: time-nuts-boun...@febo.com Date: Tue, 20 Mar 2012 20:38:19 To: 'Discussion of precise time and frequency measurement'time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] IOTECH 488 EPROM Gary, I have a CT-A and a CV-A. They come apart by removing all the mounting nuts of the 232 and GPIB sockets. The 'upgrade' was focused on the IOTECH 488 boxes to convert all to a controller. The conversation 'morphed' into 'NI boxes' by the thought that they share a common firmware. I don't think they do, for many reasons, including the fact that they have different packages and sizes of their firmware PROM's, comparing the IOTECH and NI boxes. The CT-A and CV-A both have a socket for their PLCC 32 OTPROM. I tried reading the two, moving the firmware from one to the other using an EEPROM and saw no benefit. I guess there is the possibility that the CT-A version I have is somehow damaged but I was able to get the CV-A to work quite well with a Solartron 7081 and an HP 3458A using HyperTerminal on my XP computer. An educational but not particularly helpful experiment. Hope this helps. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of gary Sent: Tuesday, March 20, 2012 8:12 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] IOTECH 488 EPROM So if you have the GPIB-232CT-A, in my case 181930G-01 Rev 001, there is no advantage to the ROM upgrade? How does this unit come apart? I'm assuming one or both of the nuts holding the 232 or GPIB socket have to be removed. And I never did get a reply as to what this upgrade does. I got two of these. Actually I sold one. The first cost a whole dollar. That pissed off a friend who wanted one. I swore he would get the next one I find, and he was good for $50. That one cost $3. The last time I played with it, there was something odd with CRLF on data. My friend gave up and just bought the USB dongle from NI. Life is short. NI was still doing the trade in program, where basically any NI controller would get you half off. That may still be true. Basically they didn't want customers going to Prologix and other vendors. On 3/19/2012 4:52 PM, paul swed wrote: A couple of answers. The difference between the pass through and full controllers is significant in the ease of use for my 2 cents. Well worth the effort. Joe I have never seen a NI controller as you describe. What I have seen is that NI seems to garner rabid interest even at flea markets. I believe the cntrollers I have been finding are simply black boxes that look like the old rs232 so no one thinks twice. Even if they did not work the cases are very nice for projects. Regards Paul. On Mon, Mar 19, 2012 at 7:33 PM, Joseph Grayjg...@zianet.com wrote: Paul, Thanks for that info. I'll keep an eye out for those models (cheap). I guess my NI unit is too different to use that EPROM. Joe Gray W5JG On Mon, Mar 19, 2012 at 12:42 PM, paul swedpaulsw...@gmail.com wrote: Hello to the group Joe here are the exact model numbers that I have and do indeed work. IOmega488a IOtech Micro 488a IOtech 488ex IOtech serial 488a Black Box 232 to 488a If I would run across other units at $5 as I have in the past I would indeed try the mod. I think the key to the discussion is the MPU board needs to actually have a eprom socket. Regards Paul. On Sun, Mar 18, 2012 at 1:56 PM, paul swedpaulsw...@gmail.com wrote: Joe Its been a while since I posted those eproms and info. I need to do 2 things. Look specifically at my models tested and listed and see what that means in the context of your question. Perhaps later today. Regards Paul. WB8TSL On Sun, Mar 18, 2012 at 11:38 AM, J. L. Tranthamjlt...@att.net wrote: Paul, Have you tried this in an NI GPIB-232CV-A or a GPIB-232CT-A? I have tried to swap the data between a 232CT-A and a 232CV-A with no joy. The two units are fundamentally different. That's why I have the chips. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Sunday, March 18, 2012 9:38 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] IOTECH 488 EPROM Hello to the group. Indeed the prom changes the behavior to a full controller and the ones I listed were changed and worked. Because those were the units I had found over the years. No idea about this particular prom and such. Regards Paul WB8TSL On Sun, Mar 18, 2012 at 10:12 AM, J. L.
[time-nuts] Experience with THS788 from TI?
Hi all, I just discovered that TI makes a TDC chip called THS788, see http://www.ti.com/product/ths788 for more info. Interesting specs, but rather expensive. Has anyone from the list had a chance to experiment with this device? Cheers Stefan ___ 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] Experience with THS788 from TI?
13ps resolution at 200Msps sampling rate and real 15.8Msps output data throughput? not too many around :) Regards, Javier El 21/03/2012 15:44, David escribió: I am surprised it is not more accurate and precise. Even old discrete designs can get down to 10ps or better. I wonder what market it is for where space is at that much of a premium. On Wed, 21 Mar 2012 14:47:28 +0100, Heinzmann, Stefan (ALC NetworX GmbH)stefan.heinzm...@alcnetworx.de wrote: I just discovered that TI makes a TDC chip called THS788, see http://www.ti.com/product/ths788 for more info. Interesting specs, but rather expensive. Has anyone from the list had a chance to experiment with this device? ___ 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] Antenna Position
In message 003e01cd0751$ded32f60$9c798e20$@btinternet.com, Rob Kimberley wr ites: As I couldn't mount the antennae on the roof, I had to get creative. What kind of roofing do you have ? You can get pretty good results under the roof as long as it is not metalic or to thick ceramics. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] DTV tuner chip usable for GPS front end?
I suppose there is limited interest in homebrew GPS receivers given how cheap the fully integrated chipsets are. However, just noticed the below tuner chip intended for DTV, actually lists GPS L1 as an applicable frequency. A TV Tuner USB stick using this chip is available for $20, and some SDR type software is apparently working with it: http://sdr.osmocom.org/trac/wiki/rtl-sdr Has anyone here played with this device? from http://www.elonics.com/product.do?id=1 The E4000 is a highly integrated multi band RF tuner IC implemented in CMOS, ideal for low power digital terrestrial TV and radio broadcast receiver solutions. The E4000 contains a single input LNA with RF filter, whose centre frequency can be programmed over the complete frequency range from 64MHz to 1700MHz. Broadcast Standards DVB-T (174-240MHz, 470-854MHz) ISDB-T (470-862MHz) DVB-H (470-854MHz, 1672-1678MHz) CMMB (470-862MHz) D-TMB (470-862MHz) T-DMB (174-240MHz, 1452-1492MHz) DAB (174-240MHz, 1452-1492MHz) MediaFLO (470-862, 1452-1492MHz) GPS L1 band (1575MHz) [...] ___ 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] LORAN-C Reception on Cape Cod
Hi Unless they picked it up and moved it, Dana is in Indiana not Illinois :)... Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Stan, W1LE Sent: Tuesday, March 20, 2012 10:45 AM To: Discussion of precise time and frequency measurement Subject: [time-nuts] LORAN-C Reception on Cape Cod Hello The Net: (especially the LORAN-C listeners) Right now my SRS FS700 Loran-C receiver is locked onto a signal. GRI 89700 microseconds station: AUTO (M) location: DANA, IL USA Receiver locked Tracking Loran-C signal Receiver gain: 77dB Noise margin: 39 dB Loran Freq offset: -1.1E-10 Phase: -17.9 deg Stations found: (ident: Amp in dB) M59* X56 Time since lock: 0:21:40 ( had lock overnight, but with an error so I did a new search) Length last unlock: 0:10:42 Signal status: a r b n o I am using the standard SRS active whip antenna about 7' above ground in the back yard. Receiver firmware is 1.19 As time permits I will compare the Loran-C to the T'Bolt GPS/DO, with the Tracor 527E. It is nice to have Loran-C signal to play with. The Nantucket Loran-C station was a bout 40 miles away. Almost a Cs reference in my shack. Stan, W1LE Cape CodFN41sr XXXx ___ 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] Experience with THS788 from TI?
On Wed, 21 Mar 2012 09:44:14 -0500, David davidwh...@gmail.com wrote: I am surprised it is not more accurate and precise. Even old discrete designs can get down to 10ps or better. I wonder what market it is for where space is at that much of a premium. Out of curiosity, would you happen to have an example of discrete TDC design? Recently I've been exploring the TDC design space as these devices are a critical part of our experiments (I do spectroscopy of biological molecules). I'm currently (slowly) working on a FPGA TDC design (based on the PandaDAQ[1] and CERN's Spartan 6 TDC design) but it seems it will be non-trivial to get down to the 12 ns the commercial offerings provide (although at great cost). What would a discrete TDC design look like? Are there any designs in the open? Cheers, - Ben [1] http://www.keteu.org/~haunma/proj/pandadaq/ [2] http://www.ohwr.org/projects/tdc-core/wiki ___ 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] WWVB BPSK Receiver Project?
Looks like this bounced as I sent from the wrong address. Better late than never. On Wed, 14 Mar 2012 15:46:48 -0700, Chuck Forsberg WA7KGX N2469R c...@omen.com wrote: Asus has a $30 Xonar PCI soundcard that should do the job. I have two of the the more expensive pci-e versions. Some motherboards can do a/d at 192 but not as well as the Xonar. Even better: a USB DVB card [1]. For $30 you have a few million 8-bit I/Q samples per second and an interface to Gnu Radio. The possibilities are nearly endless. Cheers, - Ben [1] http://sdr.osmocom.org/trac/wiki/rtl-sdr ___ 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] Antenna Position
And in any case, with four receivers, wouldn't a single aerial and a splitter be more economical and save on feeder costs? Mind you, having an eight way splitter as I do does tend to encourage gps proliferation :^) Dan ___ 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] Experience with THS788 from TI?
Hi Are you after 12 ns or 12 ps? Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ben Gamari Sent: Wednesday, March 21, 2012 12:18 PM To: David; Discussion of precise time and frequency measurement Subject: [time-nuts] Experience with THS788 from TI? On Wed, 21 Mar 2012 09:44:14 -0500, David davidwh...@gmail.com wrote: I am surprised it is not more accurate and precise. Even old discrete designs can get down to 10ps or better. I wonder what market it is for where space is at that much of a premium. Out of curiosity, would you happen to have an example of discrete TDC design? Recently I've been exploring the TDC design space as these devices are a critical part of our experiments (I do spectroscopy of biological molecules). I'm currently (slowly) working on a FPGA TDC design (based on the PandaDAQ[1] and CERN's Spartan 6 TDC design) but it seems it will be non-trivial to get down to the 12 ns the commercial offerings provide (although at great cost). What would a discrete TDC design look like? Are there any designs in the open? Cheers, - Ben [1] http://www.keteu.org/~haunma/proj/pandadaq/ [2] http://www.ohwr.org/projects/tdc-core/wiki ___ 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] Experience with THS788 from TI?
On Wed, 21 Mar 2012 11:51:53 -0400, Ben Gamari bgam...@gmail.com wrote: On Wed, 21 Mar 2012 09:44:14 -0500, David davidwh...@gmail.com wrote: I am surprised it is not more accurate and precise. Even old discrete designs can get down to 10ps or better. I wonder what market it is for where space is at that much of a premium. Out of curiosity, would you happen to have an example of discrete TDC design? Recently I've been exploring the TDC design space as these devices are a critical part of our experiments (I do spectroscopy of biological molecules). I'm currently (slowly) working on a FPGA TDC design (based on the PandaDAQ[1] and CERN's Spartan 6 TDC design) but it seems it will be non-trivial to get down to the 12 ns the commercial offerings provide (although at great cost). What would a discrete TDC design look like? Are there any designs in the open? I read through the THS788 datasheet. TI DLL multiplies the 200 external clock to 1.2GHz for the 833ps basic cycle. That is further divided into 64 13ps time intervals which are latched to generate the 6 least significant bits of the time stamp. I suspect the time intervals are implemented as a locally generated 64 phase 1.2GHz clock. Check out the design for the Tektronix 7T11/7T11A sampling sweep unit or their earlier sampling sweep plug-ins. The service manuals with theory and schematics are available online. You might also want to look at the clock delay timer design in the Tektronix 2230/2232 and the 2440 oscilloscopes which is used to align equivalent time acquisitions with the waveform record. An all digital design like the THS788 does have a much higher throughput but the analog designs I mention above did not have throughput as a requirement. ___ 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] DTV tuner chip usable for GPS front end?
I suppose there is limited interest in homebrew GPS receivers given how cheap the fully integrated chipsets are. However, just noticed the below tuner chip intended for DTV, actually lists GPS L1 as an applicable frequency. A TV Tuner USB stick using this chip is available for $20, and some SDR type software is apparently working with it: http://sdr.osmocom.org/trac/wiki/rtl-sdr Has anyone here played with this device? from http://www.elonics.com/product.do?id=1 The E4000 is a highly integrated multi band RF tuner IC implemented in CMOS, ideal for low power digital terrestrial TV and radio broadcast receiver solutions. The E4000 contains a single input LNA with RF filter, whose centre frequency can be programmed over the complete frequency range from 64MHz to 1700MHz. Broadcast Standards DVB-T (174-240MHz, 470-854MHz) ISDB-T (470-862MHz) DVB-H (470-854MHz, 1672-1678MHz) CMMB (470-862MHz) D-TMB (470-862MHz) T-DMB (174-240MHz, 1452-1492MHz) DAB (174-240MHz, 1452-1492MHz) MediaFLO (470-862, 1452-1492MHz) GPS L1 band (1575MHz) [...] .. and available ready built here: http://www.funcubedongle.com/ but perhaps not fast enough for you. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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] DTV tuner chip usable for GPS front end?
On Wed, 21 Mar 2012 16:40:27 -, David J Taylor david-tay...@blueyonder.co.uk wrote: I suppose there is limited interest in homebrew GPS receivers given how cheap the fully integrated chipsets are. However, just noticed the below tuner chip intended for DTV, actually lists GPS L1 as an applicable frequency. A TV Tuner USB stick using this chip is available for $20, and some SDR type software is apparently working with it: http://sdr.osmocom.org/trac/wiki/rtl-sdr Has anyone here played with this device? from http://www.elonics.com/product.do?id=1 The E4000 is a highly integrated multi band RF tuner IC implemented in CMOS, ideal for low power digital terrestrial TV and radio broadcast receiver solutions. The E4000 contains a single input LNA with RF filter, whose centre frequency can be programmed over the complete frequency range from 64MHz to 1700MHz. Broadcast Standards DVB-T (174-240MHz, 470-854MHz) ISDB-T (470-862MHz) DVB-H (470-854MHz, 1672-1678MHz) CMMB (470-862MHz) D-TMB (470-862MHz) T-DMB (174-240MHz, 1452-1492MHz) DAB (174-240MHz, 1452-1492MHz) MediaFLO (470-862, 1452-1492MHz) GPS L1 band (1575MHz) [...] .. and available ready built here: http://www.funcubedongle.com/ but perhaps not fast enough for you. Or not wide enough in this case. The FunCube technical FAQ says the bandwidth is about 80 KHz as it is designed for narrow band reception only and accessed as a standard USB sound device. I do not quite understand how 96 Ksamples/sec yields 80 KHz though: Q. What is the bandwidth? A. 96kHz is the quadrature sampling rate. Once the ADCs decimation filter skirts have been taken into account, you have about 80kHz. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Antenna Position
I tried inside as a first pass, but no good. The roof is tiled, but has a metal clad foam insulation layer on all walls and ceiling. Rob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Poul-Henning Kamp Sent: 21 March 2012 15:59 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Antenna Position In message 003e01cd0751$ded32f60$9c798e20$@btinternet.com, Rob Kimberley wr ites: As I couldn't mount the antennae on the roof, I had to get creative. What kind of roofing do you have ? You can get pretty good results under the roof as long as it is not metalic or to thick ceramics. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Antenna Position
The NTP servers use the Meinberg down-converter antennae and therefore not compatible with the Odetics unit. I had the antennae, but don't have any splitter/combiners so that was the only solution. Rob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Rae Sent: 21 March 2012 16:33 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Antenna Position And in any case, with four receivers, wouldn't a single aerial and a splitter be more economical and save on feeder costs? Mind you, having an eight way splitter as I do does tend to encourage gps proliferation :^) Dan ___ 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] DTV tuner chip usable for GPS front end?
http://www.funcubedongle.com/ but perhaps not fast enough for you. Or not wide enough in this case. The FunCube technical FAQ says the bandwidth is about 80 KHz as it is designed for narrow band reception only and accessed as a standard USB sound device. I do not quite understand how 96 Ksamples/sec yields 80 KHz though: Q. What is the bandwidth? A. 96kHz is the quadrature sampling rate. Once the ADC's decimation filter skirts have been taken into account, you have about 80kHz. .. because they are quadrature samples, so it's +/- 40 KHz. In fact some of the software driver the device at 192 KHz, yielding almost enough bandwidth for FM stereo (but not quite). +/- 80 KHz RF, about 80 KHz baseband. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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] Wednesday AM Update: LORAN-C Reception on Cape Cod
Don, you are absolutely correct, Dana is in Indiana and not Illinois. Austron offered a model 2084 LF Multicoupler, with 1 antenna input and 4 outputs. Could be AC or DC powered, with peak and spherics indicator lamps, and 8 each tunable notch filters from 70 thru 130 KHz that can be individually switched inline or out. I should be able to take the FS700 Loran-C (RF) front panel output, feed the multicoupler, then feed a Austron 2100F and the 2100 to monitor other GRIs. Just have to find my notes on how to set up the older RXs. I had lock onto 89700 microsecond GRI overnight and using the internal FS700 phase meter I got as low as 3E-13 for delta frequency between the Loran-C and the T'Bolt GPS/DO. I am locked onto the Seneca, NY station. Stan, W1LECape Cod FN41sr If I am not mistaken Dana is not in Illinois it is in Indiana. Still receiving at 2200 hrs local. Don _ ___ 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] Wednesday AM Update: LORAN-C Reception on Cape Cod
Stan if you are talking about the austrons I know how to set them. Could call you if thats easier On Wed, Mar 21, 2012 at 10:10 AM, Stan, W1LE stanw...@verizon.net wrote: Don, you are absolutely correct, Dana is in Indiana and not Illinois. Austron offered a model 2084 LF Multicoupler, with 1 antenna input and 4 outputs. Could be AC or DC powered, with peak and spherics indicator lamps, and 8 each tunable notch filters from 70 thru 130 KHz that can be individually switched inline or out. I should be able to take the FS700 Loran-C (RF) front panel output, feed the multicoupler, then feed a Austron 2100F and the 2100 to monitor other GRIs. Just have to find my notes on how to set up the older RXs. I had lock onto 89700 microsecond GRI overnight and using the internal FS700 phase meter I got as low as 3E-13 for delta frequency between the Loran-C and the T'Bolt GPS/DO. I am locked onto the Seneca, NY station. Stan, W1LECape Cod FN41sr If I am not mistaken Dana is not in Illinois it is in Indiana. Still receiving at 2200 hrs local. Don _ __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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] IOTECH 488 EPROM
Prologix would be happy to host your samples, or link to them, from our website. Our customers will benefit much from your work. Abdul www.prologix.biz supp...@prologix.biz -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Monday, March 19, 2012 9:27 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] IOTECH 488 EPROM jlt...@att.net said: I have a friend who is helping me with the effort. He has written some programs to work with a 3458A and the ProLogix USB/GPIB adapter. I plan to dissect the programs and modify them to suit my needs. Hopefully, it will be a learning experience. We should collect and/or publish/advertise more examples. I know roughly nothing about Windows or NI, but here is my sample of ProLogix on Linux. http://www.megapathdsl.net/~hmurray/hacks/probe.c It's c rather than anything higher level. I might translate it to python (when I run out of other things on my list). Would that help anybody other than me? -- These are my opinions, not necessarily my employer's. 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] Experience with THS788 from TI?
Bob Camp li...@rtty.us writes: Hi Are you after 12 ns or 12 ps? Bah, yes, my bad: picoseconds is the relevant timescale here. Cheers, - Ben ___ 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] broadband MPX signal stereo
Am Thu, 15 Mar 2012 22:08:12 +0100 schrieb Azelio Boriani azelio.bori...@screen.it: Yes, there is people who have what in the past was expensive test equipment and now can be bought by 1/10 of the original price. The problem is that you need someone who can record 2 seconds of a signal that is slightly beyond the actual sound card sampling capability. A signal that you can have by simply tuning your radio and hooking directly to the FM discriminator output. This signal is available virtually all over the world. AFAIK there was in the past no expensive test equipment that can sample and record a file. Now there are: the RS SMBV100 can sample and play any signal upto 3GHz with the full options fitted and the companion recorder/player for 200K euros, the file produced are not PC compatible, of course. I wouldn't go as far as stating that the files are not PC compatible. Of course, you'll probably need some special hardware that does the A/D and D/A conversion, respectively, but i'm pretty sure most of what the RS SMBV100 does apart from data conversion is just software running on an embedded PC. Plain x86 type hardware, for that matter, as it's running either MS Windows or Linux (can't tell directly from the RS website picture, but the more recent the hardware, the higher the probability of Linux instead of Windows for RS stuff)... It still is very much $$$ though :-( Best regards, Florian ___ 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] Experience with THS788 from TI?
Hi Ok, for a legit 12 ps with 0.1 ps drift and 200 mega samples per second - not to many alternatives. The FPGA stuff will get you to 50 to 100 ps on the same basis this gets you to 12 ps. They will get you to 20 to 40 ps on a good day - sort of the way this chip gets 8 ps. The FPGA will do it at a much lower data rate. If you average over many samples, all of these will get you a better estimate. How much better depends on a bunch of things. The TI part *could* do very well if you have a 200 MHz signal to look at. Bob -Original Message- From: Ben Gamari [mailto:bgam...@gmail.com] Sent: Wednesday, March 21, 2012 3:30 PM To: Bob Camp; 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Experience with THS788 from TI? Bob Camp li...@rtty.us writes: Hi Are you after 12 ns or 12 ps? Bah, yes, my bad: picoseconds is the relevant timescale here. Cheers, - Ben ___ 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] broadband MPX signal stereo
We had the SMBV100 (full options loaded) on a demo for very few days and I used it as a GPS simulator. The menus I have used didn't let me figure out what kind of operating system was underneath... On Wed, Mar 21, 2012 at 9:49 PM, Florian Teply use...@teply.info wrote: Am Thu, 15 Mar 2012 22:08:12 +0100 schrieb Azelio Boriani azelio.bori...@screen.it: Yes, there is people who have what in the past was expensive test equipment and now can be bought by 1/10 of the original price. The problem is that you need someone who can record 2 seconds of a signal that is slightly beyond the actual sound card sampling capability. A signal that you can have by simply tuning your radio and hooking directly to the FM discriminator output. This signal is available virtually all over the world. AFAIK there was in the past no expensive test equipment that can sample and record a file. Now there are: the RS SMBV100 can sample and play any signal upto 3GHz with the full options fitted and the companion recorder/player for 200K euros, the file produced are not PC compatible, of course. I wouldn't go as far as stating that the files are not PC compatible. Of course, you'll probably need some special hardware that does the A/D and D/A conversion, respectively, but i'm pretty sure most of what the RS SMBV100 does apart from data conversion is just software running on an embedded PC. Plain x86 type hardware, for that matter, as it's running either MS Windows or Linux (can't tell directly from the RS website picture, but the more recent the hardware, the higher the probability of Linux instead of Windows for RS stuff)... It still is very much $$$ though :-( Best regards, Florian ___ 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] Experience with THS788 from TI?
Jim Williams wrote an appnote on how to do this with ~100ps resolution with a small number of parts. I think it was mentioned before and should be in the time nuts archives.. His circuit can be modified without much effort for higher resolution. bye, Said In a message dated 3/21/2012 14:03:38 Pacific Daylight Time, li...@rtty.us writes: Hi Ok, for a legit 12 ps with 0.1 ps drift and 200 mega samples per second - not to many alternatives. The FPGA stuff will get you to 50 to 100 ps on the same basis this gets you to 12 ps. They will get you to 20 to 40 ps on a good day - sort of the way this chip gets 8 ps. The FPGA will do it at a much lower data rate. If you average over many samples, all of these will get you a better estimate. How much better depends on a bunch of things. The TI part *could* do very well if you have a 200 MHz signal to look at. Bob -Original Message- From: Ben Gamari [mailto:bgam...@gmail.com] Sent: Wednesday, March 21, 2012 3:30 PM To: Bob Camp; 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Experience with THS788 from TI? Bob Camp li...@rtty.us writes: Hi Are you after 12 ns or 12 ps? Bah, yes, my bad: picoseconds is the relevant timescale here. Cheers, - Ben ___ 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] Experience with THS788 from TI?
Bob Camp li...@rtty.us writes: Hi Ok, for a legit 12 ps with 0.1 ps drift and 200 mega samples per second - not to many alternatives. The FPGA stuff will get you to 50 to 100 ps on the same basis this gets you to 12 ps. They will get you to 20 to 40 ps on a good day - sort of the way this chip gets 8 ps. The FPGA will do it at a much lower data rate. In our experiments, we are typically observing very low count rates (100kHz at absolute most). I've occassionally stumbled upon a paper which claims to get 10ps on a standard FPGA, but naturally they never show the code. Given that I'm a relative novice at high-speed electronics and FPGAing in general, I'll consider myself lucky if I get the 50ps advertised by the CERN core. In particular, one issue I've been struggling with is the discriminator. Our fast detectors produce a NIM negative-current pulse which will ultimately need to become suitable input for the FPGA. Of course, the most precise time measurement in the world is useless if the discriminator front-end has a nanosecond jitter. Unfortunately, I have yet to find any open, high precision discriminator designs. In principle a constant fraction discriminator doesn't seem to difficult to implement, but when it comes to preserving the high-speed signal integrity, it seems like it could get pretty hairy. Comments? If you average over many samples, all of these will get you a better estimate. How much better depends on a bunch of things. The TI part *could* do very well if you have a 200 MHz signal to look at. For time-correlated single photon counting (our primary use for precision timing), having high temporal resolution is quite important. That being said, all of those arrival times all get combined into a correlation function so shot-per-shot jitter will be in large part averaged out. Cheers, - Ben ___ 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] Experience with THS788 from TI?
Hi, The NIM Negative pulse is indeed problematic when trying to interface to FPGA logic! The solution I have used in the past is a board based around a Maxim MAX9601[1] acting as a comparator on the incoming NIIM pulse, and configuring the output for connection to the FPGA. Judging by the results that I have seen from this chip, the timing uncertainty is certainly not single figure picoseconds, but in the range of 30ps - not great, but still better then nanoseconds. If the input to this signal is a NIM timing pulse, there are minimal issues with timing walk as the pulse height is always the same. It's certainly a lot easier then building a CFD! Tristan [1]http://www.maxim-ic.com/datasheet/index.mvp/id/3400 On 22 March 2012 08:58, Ben Gamari bgam...@physics.umass.edu wrote: Bob Camp li...@rtty.us writes: Hi Ok, for a legit 12 ps with 0.1 ps drift and 200 mega samples per second - not to many alternatives. The FPGA stuff will get you to 50 to 100 ps on the same basis this gets you to 12 ps. They will get you to 20 to 40 ps on a good day - sort of the way this chip gets 8 ps. The FPGA will do it at a much lower data rate. In our experiments, we are typically observing very low count rates (100kHz at absolute most). I've occassionally stumbled upon a paper which claims to get 10ps on a standard FPGA, but naturally they never show the code. Given that I'm a relative novice at high-speed electronics and FPGAing in general, I'll consider myself lucky if I get the 50ps advertised by the CERN core. In particular, one issue I've been struggling with is the discriminator. Our fast detectors produce a NIM negative-current pulse which will ultimately need to become suitable input for the FPGA. Of course, the most precise time measurement in the world is useless if the discriminator front-end has a nanosecond jitter. Unfortunately, I have yet to find any open, high precision discriminator designs. In principle a constant fraction discriminator doesn't seem to difficult to implement, but when it comes to preserving the high-speed signal integrity, it seems like it could get pretty hairy. Comments? If you average over many samples, all of these will get you a better estimate. How much better depends on a bunch of things. The TI part *could* do very well if you have a 200 MHz signal to look at. For time-correlated single photon counting (our primary use for precision timing), having high temporal resolution is quite important. That being said, all of those arrival times all get combined into a correlation function so shot-per-shot jitter will be in large part averaged out. Cheers, - Ben ___ 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] OT: calibration
Their prices seems to be in the same ball park as the Austin lab (TesCom) that we use at work. Does anyone know anyone that offers 'hobbyist' rates? I could easily spend $1000 getting my equipment cal'd, but certainly can't justify the budget. Mike On 3/20/2012 11:52 PM, Joseph Gray wrote: Has anyone used these guys? I have this model DMM and need it calibrated. I can't afford to spend a fortune, as this is only for hobby use. http://www.teknetelectronics.com/Search.asp?p_ID=115pDo=DETAILHP%20-%20Agilent_3478A Joe Gray W5JG ___ 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] Experience with THS788 from TI?
Two suggestions: How about using an off-the-shelf Wavecrest counter? These have a 0.8ps resolution, and typically have a noise floor of around 3ps when averaging. They certainly can do 10ps single shot. There is a DTS-2050 on Ebay now for $700: item number 120647180882 You can't get much lower than that for the resolution and accuracy that system provides in a working off-the-shelf solution. Alternatively, if you want to design your own, you could use a time-expander. It only requires a small micro with counter/timer, and a little bit of external circuitry for charging/discharging a precision cap. You charge fast gated by the signal to measure, then you discharge slowly (expanded time) and measure the amount of charge deposited on the cap. The Linear Appnote I mentioned earlier already has most of the capacitor charge pump circuitry in it that you would need for this. The idea is to design the cap discharge and charge cycles at different time scales, say 1000x to 1, so that the capture time get's expanded out to intervals that the micro can measure. If the micro has say 60MHz counter resolution (16.66ns) then a 1000x to 1 expansion would allow a 0.016ns (16ps) resolution. Using say 2000x expansion and a 100MHz counter in the micro would get you to 5ps resolution. This setup works very well without having to buy a $170 TI chip and designing with an FPGA, and only requires a little bit of software in the micro, and a small number of analog components. I think the operating principle and circuitry is explained in great detail in the service manuals for the HP 5334A counters, and the PRS-10 rubidium service manual as well. bye, Said In a message dated 3/21/2012 14:58:57 Pacific Daylight Time, bgam...@physics.umass.edu writes: Bob Camp li...@rtty.us writes: Hi Ok, for a legit 12 ps with 0.1 ps drift and 200 mega samples per second - not to many alternatives. The FPGA stuff will get you to 50 to 100 ps on the same basis this gets you to 12 ps. They will get you to 20 to 40 ps on a good day - sort of the way this chip gets 8 ps. The FPGA will do it at a much lower data rate. In our experiments, we are typically observing very low count rates (100kHz at absolute most). I've occassionally stumbled upon a paper which claims to get 10ps on a standard FPGA, but naturally they never show the code. Given that I'm a relative novice at high-speed electronics and FPGAing in general, I'll consider myself lucky if I get the 50ps advertised by the CERN core. In particular, one issue I've been struggling with is the discriminator. Our fast detectors produce a NIM negative-current pulse which will ultimately need to become suitable input for the FPGA. Of course, the most precise time measurement in the world is useless if the discriminator front-end has a nanosecond jitter. Unfortunately, I have yet to find any open, high precision discriminator designs. In principle a constant fraction discriminator doesn't seem to difficult to implement, but when it comes to preserving the high-speed signal integrity, it seems like it could get pretty hairy. Comments? If you average over many samples, all of these will get you a better estimate. How much better depends on a bunch of things. The TI part *could* do very well if you have a 200 MHz signal to look at. For time-correlated single photon counting (our primary use for precision timing), having high temporal resolution is quite important. That being said, all of those arrival times all get combined into a correlation function so shot-per-shot jitter will be in large part averaged out. Cheers, - Ben ___ 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 Counter Errors
I have a question for the collective group. I have a HP 5372A and a HP 5328A frequency counters. Both counters use the same PRS-10 Rubidium frequency standard driving a 6 channel reference distribution amplifier to each counters reference input port. The problem is this; When I measure the same frequency on both counters, (done one at a time) the frequency is generally off by about 300 Hz or so between the counters. Now I would expect an error of +/- 1 digit, but 300Hz seems a bit strange to me. I can not find the problem and the difference exists even if I use the internal timebases of each counter, give or take the timebase errors. The frequency is always at least 200 to 300Hz off between the two counters and I don't know which one to believe. You know the man with 2 clocks problem. Anyone have any idea what may be causing this? Thanks Jerry ___ 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 Counter Errors
First, try counting the Rd reference frequency output. If one reads right you are halfway to solving the problem. John WA4WDL -- From: Jerry Mulchin jmulc...@cox.net Sent: Wednesday, March 21, 2012 8:05 PM To: time-nuts@febo.com Subject: [time-nuts] Frequency Counter Errors I have a question for the collective group. I have a HP 5372A and a HP 5328A frequency counters. Both counters use the same PRS-10 Rubidium frequency standard driving a 6 channel reference distribution amplifier to each counters reference input port. The problem is this; When I measure the same frequency on both counters, (done one at a time) the frequency is generally off by about 300 Hz or so between the counters. Now I would expect an error of +/- 1 digit, but 300Hz seems a bit strange to me. I can not find the problem and the difference exists even if I use the internal timebases of each counter, give or take the timebase errors. The frequency is always at least 200 to 300Hz off between the two counters and I don't know which one to believe. You know the man with 2 clocks problem. Anyone have any idea what may be causing this? Thanks Jerry ___ 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 Counter Errors
What happens if you feed the 10MHz external clock to the input. If you measure the reference frequency you should get 10MHz dead-on exact even if the reference is not exactly 10MHz. If you don't get this, the counter has a problem. I have seem my two counters disagree when I tried to measure the frequency of an old Heatkit RF signal generator. Turns out the problem was because the RF sine wave was grossly not clean with much distortion on the signal. The two counters had their triggers set to different levels. Test for triggering related problem by putting the signal into one counter and then the marker output from the first counter in the the second counter. This way only one trigger s used for both couters On Wed, Mar 21, 2012 at 5:05 PM, Jerry Mulchin jmulc...@cox.net wrote: I have a question for the collective group. I have a HP 5372A and a HP 5328A frequency counters. Both counters use the same PRS-10 Rubidium frequency standard driving a 6 channel reference distribution amplifier to each counters reference input port. The problem is this; When I measure the same frequency on both counters, (done one at a time) the frequency is generally off by about 300 Hz or so between the counters. Now I would expect an error of +/- 1 digit, but 300Hz seems a bit strange to me. I can not find the problem and the difference exists even if I use the internal timebases of each counter, give or take the timebase errors. The frequency is always at least 200 to 300Hz off between the two counters and I don't know which one to believe. You know the man with 2 clocks problem. Anyone have any idea what may be causing this? Thanks Jerry ___ 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] Frequency Counter Errors
Yes, first try the Rb with their internal timebases. Got the PRS10? Nice Rb reference: I had one (brand new) last month for only one week... On Thu, Mar 22, 2012 at 1:11 AM, jmfranke jmfra...@cox.net wrote: First, try counting the Rd reference frequency output. If one reads right you are halfway to solving the problem. John WA4WDL -- From: Jerry Mulchin jmulc...@cox.net Sent: Wednesday, March 21, 2012 8:05 PM To: time-nuts@febo.com Subject: [time-nuts] Frequency Counter Errors I have a question for the collective group. I have a HP 5372A and a HP 5328A frequency counters. Both counters use the same PRS-10 Rubidium frequency standard driving a 6 channel reference distribution amplifier to each counters reference input port. The problem is this; When I measure the same frequency on both counters, (done one at a time) the frequency is generally off by about 300 Hz or so between the counters. Now I would expect an error of +/- 1 digit, but 300Hz seems a bit strange to me. I can not find the problem and the difference exists even if I use the internal timebases of each counter, give or take the timebase errors. The frequency is always at least 200 to 300Hz off between the two counters and I don't know which one to believe. You know the man with 2 clocks problem. Anyone have any idea what may be causing this? Thanks Jerry ___ 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] Frequency Counter Errors
Jerry, My guess is that the amplitude of the reference signal may be on the ragged edge of what the counters require- either just barely adequate, or much too hot and being distorted. Also, check to see if the source and load impedances are matched. I once corrected a similar problem by inserting a 2 dB attenuator in line with the reference signal. And check to be sure that the reference signal is not riding on a DC level. 73, Eric Lemmon WB6FLY -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jerry Mulchin Sent: Wednesday, March 21, 2012 5:06 PM To: time-nuts@febo.com Subject: [time-nuts] Frequency Counter Errors I have a question for the collective group. I have a HP 5372A and a HP 5328A frequency counters. Both counters use the same PRS-10 Rubidium frequency standard driving a 6 channel reference distribution amplifier to each counters reference input port. The problem is this; When I measure the same frequency on both counters, (done one at a time) the frequency is generally off by about 300 Hz or so between the counters. Now I would expect an error of +/- 1 digit, but 300Hz seems a bit strange to me. I can not find the problem and the difference exists even if I use the internal timebases of each counter, give or take the timebase errors. The frequency is always at least 200 to 300Hz off between the two counters and I don't know which one to believe. You know the man with 2 clocks problem. Anyone have any idea what may be causing this? Thanks Jerry ___ 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] DTV tuner chip usable for GPS front end?
On 3/21/12 9:17 AM, beale wrote: I suppose there is limited interest in homebrew GPS receivers given how cheap the fully integrated chipsets are. However, just noticed the below tuner chip intended for DTV, actually lists GPS L1 as an applicable frequency. A TV Tuner USB stick using this chip is available for $20, and some SDR type software is apparently working with it: http://sdr.osmocom.org/trac/wiki/rtl-sdr Has anyone here played with this device? from http://www.elonics.com/product.do?id=1 The E4000 is a highly integrated multi band RF tuner IC implemented in CMOS, ideal for low power digital terrestrial TV and radio broadcast receiver solutions. The E4000 contains a single input LNA with RF filter, whose centre frequency can be programmed over the complete frequency range from 64MHz to 1700MHz. Isn't that what they're using in the FunCubeDongle? ___ 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 Counter Errors
The frequency is always at least 200 to 300Hz off between the two counters and I don't know which one to believe. You know the man with 2 clocks problem. Anyone have any idea what may be causing this? What are you measuring? Are both of the counters' inputs set to 50 ohms, and if so, are both of the terminations OK (meaning not burned out)? Most oscillators will exhibit load pulling to some extent, where their frequency changes noticeably depending on the load they're connected to. -- john ___ 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 Counter Errors
It must be that one counter has not switched to ext ref. It has been a while with both these counters, does the 5328A auto switch to ext ref? The 5372A does have an auto ref switch and will acept 1,2,5,and 10MHz+/-1% at 1-5VPP . A quick way to check that ext ref is seen by the 5372A is during a measurement remove the ext ref. Measurements will stop. You will need to press the restart key to resume and alternate time base selected press restart will appear. Then perhaps if the 5372A is ok then use the 10MHz output from the 5372A (Which is phase locked to the ext ref in) to the ext ref in on the 5328A. That should narrow things down. Best Wishes; Thomas Knox Date: Wed, 21 Mar 2012 17:05:44 -0700 To: time-nuts@febo.com From: jmulc...@cox.net Subject: [time-nuts] Frequency Counter Errors I have a question for the collective group. I have a HP 5372A and a HP 5328A frequency counters. Both counters use the same PRS-10 Rubidium frequency standard driving a 6 channel reference distribution amplifier to each counters reference input port. The problem is this; When I measure the same frequency on both counters, (done one at a time) the frequency is generally off by about 300 Hz or so between the counters. Now I would expect an error of +/- 1 digit, but 300Hz seems a bit strange to me. I can not find the problem and the difference exists even if I use the internal timebases of each counter, give or take the timebase errors. The frequency is always at least 200 to 300Hz off between the two counters and I don't know which one to believe. You know the man with 2 clocks problem. Anyone have any idea what may be causing this? Thanks Jerry ___ 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 Counter Errors
The 5328A is manually switched. 30kHz to 10 MHz 1V RMS min, 5VP-P max into 1kohm. Mike On 3/21/2012 7:39 PM, Tom Knox wrote: It must be that one counter has not switched to ext ref. It has been a while with both these counters, does the 5328A auto switch to ext ref? The 5372A does have an auto ref switch and will acept 1,2,5,and 10MHz+/-1% at 1-5VPP . A quick way to check that ext ref is seen by the 5372A is during a measurement remove the ext ref. Measurements will stop. You will need to press the restart key to resume and alternate time base selected press restart will appear. Then perhaps if the 5372A is ok then use the 10MHz output from the 5372A (Which is phase locked to the ext ref in) to the ext ref in on the 5328A. That should narrow things down. Best Wishes; Thomas Knox Date: Wed, 21 Mar 2012 17:05:44 -0700 To: time-nuts@febo.com From: jmulc...@cox.net Subject: [time-nuts] Frequency Counter Errors I have a question for the collective group. I have a HP 5372A and a HP 5328A frequency counters. Both counters use the same PRS-10 Rubidium frequency standard driving a 6 channel reference distribution amplifier to each counters reference input port. The problem is this; When I measure the same frequency on both counters, (done one at a time) the frequency is generally off by about 300 Hz or so between the counters. Now I would expect an error of +/- 1 digit, but 300Hz seems a bit strange to me. I can not find the problem and the difference exists even if I use the internal timebases of each counter, give or take the timebase errors. The frequency is always at least200 to 300Hz off between the two counters and I don't know which one to believe. You know the man with 2 clocks problem. Anyone have any idea what may be causing this? Thanks Jerry ___ 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] WWVB phase plots
Okay. A little 3586B hacking was required, but here are some wide-band results: http://www.jks.com/wwvb/wwvb.html#wideband Thanks very much. This data shows the full-bandwidth WWVB signal very well. Attached are some plots and an octave script. The first plot shows the demodulated WWVB waveform over one second, averaged across the full 300-second recording, so it's the sum of 300 successive one-second periods. The sharp drop in power at about 45 milliseconds is the main on-the-second marker. Also visible is the mixture of carrier-power increases at 200 ms, 500 ms, and 800 ms after the on-the-second marker. The second plot is a closeup of the on-second marker. The falling edge is quite fast, with a time constant of about 350 microseconds, corresponding to a 3 dB one-sided bandwidth of about 450 Hz. I would guess that this edge might be estimated to within 5% of the time constant, or 20 microseconds (about one carrier cycle), which would be well below other sources of systematic error from propagation. The SNR is just huge, and this is for only five minutes of averaging---an hour, or a day, would be even better. Granted, though, these are good reception conditions. I should pick up one of those wideband USB audio sticks and try it from here in California. I wonder whether the WWVB receiver chips could save power by sampling only near these fast edges (narrow correlator in GPS-speak), going to sleep for the remaining 99% of the time. Unless the local clock is disastrously bad, one would think the device would only need to read the full time code once per month, say, and in between just do occasional trims using the WWVB edges. They seem to be having some difficulty holding the carrier power steady during the low-power intervals. Is that 10-Hz tremolo at the start of the second a power-supply thing? some limitation of the PA? There's some undershoot and overshoot too. I've found a few documents describing the WWVB antenna bandwidth: Page 136 of NIST Special Publication 250-67, showing a scope photo of the waveform: http://tf.nist.gov/general/pdf/1969.pdf Page 5 of this technical report: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA299080 and another scope photo on page 2 of this magazine article: http://tf.nist.gov/general/pdf/2429.pdf Cheers, Peter attachment: wwvb-averaged-second.pngattachment: wwvb-transient.png# # plot WWVB's transient response # # # convert from .au to 16-bit .wav: # sox ant.wide.5min.15.625.kHz.44.1k.24b.au -b 16 ant.wide.5min.15.625.kHz.44.1k.24b.wav # [y,fs,bps] = wavread(ant.wide.5min.15.625.kHz.44.1k.24b.wav); n = length(y); t = 0:(n-1); freq0 = (15625-0.455)/fs; c = exp(2*pi*i*t*freq0)'; d = y .* c; d = filter([1 1 1],[1],d); # residual carrier phase, one per second (in lieu of a proper PLL) pp = zeros(1,300); for r=0:299, w = d(r*fs+1:(r+1)*fs+1); pp(r+1) = sum(w); endfor ppc = unwrap(arg(pp)); # coherently sum over 300 seconds p = 8*5512.662; a = zeros(1,fs)'; for k=0:299, s = round(8*5100+p*k); a = a + real(d(s+1:s+fs)*exp(-i*ppc(k+1))); endfor # normalize ampl = 15.9; a = a / ampl; # plot plot((1:fs)/fs,a); grid on; pause; r=1900;s=2200;plot((0:(s-r))/fs,a(r:s)); grid on; ___ 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 Counter Errors
Thanks to all that replied. The problem is my 5328A reference input amplitude, and possibly the input module. I lowered the reference amplitude to 4.9v p-p and the accuracy got better, but not the same as the 5372A. So I suspect that the input front end may have something wrong with it. I have a spare 041 module so I will replace the current one at a later date. I did confirm that the 5372A is good by comparing the reference frequency as an input signal to the counter. It is dead on at 10.0MHz, and I also confirmed it against my 5370B counter as well. The same thing there. So my 5328A is suspect. Thanks again. Jerry At 05:05 PM 3/21/2012, you wrote: I have a question for the collective group. I have a HP 5372A and a HP 5328A frequency counters. Both counters use the same PRS-10 Rubidium frequency standard driving a 6 channel reference distribution amplifier to each counters reference input port. The problem is this; When I measure the same frequency on both counters, (done one at a time) the frequency is generally off by about 300 Hz or so between the counters. Now I would expect an error of +/- 1 digit, but 300Hz seems a bit strange to me. I can not find the problem and the difference exists even if I use the internal timebases of each counter, give or take the timebase errors. The frequency is always at least 200 to 300Hz off between the two counters and I don't know which one to believe. You know the man with 2 clocks problem. Anyone have any idea what may be causing this? Thanks Jerry ___ 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. Jerry Mulchin ___ 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] HP 3586B GPSDO
List, I saw a picture somewhere where someone added a GPSDO to the back of a HP3586 but it didn’t give any details. My question: I have the Ovenaire model 42-16 high stability oscillator but it has only four wires to the base. Can one apply EFC to it or does one need another oscillator? My online research showed nothing for that model and it appears that Wenzel now owns them. I’d like to do the Miller version as anything with a processor and requiring programming is beyond my abilities. I’d like to put everything inside the box if practical. Regards, Perrier ___ 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] HP 3586B Power Supply Failures
List, The other day I had my second HP 3586B power supply board smoked. It burned both the PC board traces and the connector on the motherboard so badly it will have to be replaced. Also an inch or so of one trace on the mother board but it looks like it will be repairable. Fortunately I have a donor board for the connector but it will probably be an all-day project to do the repair properly. An observation. There AFAIK a fold-back current limiting circuit but it didn’t help and the correct value of primary fuse did not blow. This made me an extremely unhappy camper. I’m also going to try and figure out how to add additional fuses. So I went through the entire instrument and came up with a list of all the Sprague TVA electrolytics that I am going to replace as they are dated coded 1983. So two questions. One, can I safely double the capacitance of the filter capacitors? (I plan on using the 105C 10K hour high reliability Nichicon or Panasonic units.) Secondly, the tantalum filter caps seem OK but can they be replaced with the same high quality aluminum electrolytics perhaps of a higher value of capacitance? Additionally, I plan on doing the same to all my vintage HP test equipment. A smoked 5370B would really, really, really, ruin my week. Opinions and solutions sought. Regards, Perrier ___ 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] HP 3586B Power Supply Failures
So I went through the entire instrument and came up with a list of all the Sprague TVA electrolytics that I am going to replace as they are dated coded 1983. So two questions. One, can I safely double the capacitance of the filter capacitors? (I plan on using the 105C 10K hour high reliability Nichicon or Panasonic units.) Secondly, the tantalum filter caps seem OK but can they be replaced with the same high quality aluminum electrolytics perhaps of a higher value of capacitance? Additionally, I plan on doing the same to all my vintage HP test equipment. A smoked 5370B would really, really, really, ruin my week. Replacing known good filter capacitors is a zero-sum exercise at best. New aluminum electrolytics are relatively expensive, and you'll be replacing parts that are probably near the bottom of their bathtub-shaped reliability curves with parts that are definitely on the left side of theirs. I did this for a while, but I eventually realized that new computer grade electrolytic capacitors no longer have the same quality levels that they must have had in the 1970s and 1980s. Back then, orders of magnitude more of them would have been used in production than are used today, and the manufacturers would have paid more attention to what they were doing. After my first few encounters with high-ESR parts out of the retail box, I stopped replacing good ones. I have no actual statistics to offer in support of either side of the question, but in my own case, it certainly hasn't cost me anything to leave good electrolytics alone. -- john ___ 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.
