Re: [time-nuts] GPS W/10KHz
You're looking for the older Rockwell/Conexant/Navman Jupiter-T ones. Some default in Motorola binary compatibility mode, with only 8 channels visible. Due to scarcity they are getting way to pricey... You might be better off with the newer uBlox NEO/LEA-6T, with configurable output(s). On 2/8/2014 6:10 AM, Perry Sandeen wrote: List, Wrote: where is a good source of GPS receiver modules I need one which has 10kHz output to phase lock a quartz oscillator. Fluke.1 Motorola ONCORE M12+T timing gps receiver 1pps 100hz eBay item number:290656401551 Also RDR There is another china seller that has them(10KHz) with leads for $90 but is almost impossible to find. Last time I searched it took me a hour. But he has a wide assortment. I forgot to bookmark his site. 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 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] GPS W/10KHz
Perry, you don't need 10kHz to build a GPS disciplined oscillator. GPSDOs are build with control loop response times in the range of some hours, so the loop will be absolutely happy with a 1PPS input. To keep the frequency stable at short times, you need a very stable quartz oscillator instead, something like a TCXO. There are many aviable on the surplus market, for example http://www.ebay.de/itm/Vanguard-TCXO-0-1ppm-25-000MHz-Ultra-precision-Golden-Oscillator-/131020893918?pt=LH_DefaultDomain_0hash=item1e81742ede or http://www.ebay.de/itm/HP-10811-60111-10-MHz-Quartz-Crystal-Oscillator-/321311911853?pt=LH_DefaultDomain_0hash=item4acfaeafad Volker Am 08.02.2014 05:10, schrieb Perry Sandeen: List, Wrote: where is a good source of GPS receiver modules I need one which has 10kHz output to phase lock a quartz oscillator. Fluke.1 Motorola ONCORE M12+T timing gps receiver 1pps 100hz eBay item number:290656401551 Also RDR There is another china seller that has them(10KHz) with leads for $90 but is almost impossible to find. Last time I searched it took me a hour. But he has a wide assortment. I forgot to bookmark his site. 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 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] Rb as source for ADEV?
Somewhat like Bob (Stewart) I've spent my life in IT with a little background in Ham Radio. Now, infected with the Time Bug, I'm slogging through tf.nist.gov, wenzel, and leapsecond to try and level up. I'd like to ask Bob (Camp) if he has a readily available link for a suitably quite homebrew mixer, similar to the one whose parts list he was discussing? Thanks to Magnus for his links (later in this thread), to which I'd like to add the following for those on the list, like me, who are neophytes. Fundamentals of Time and Frequency: http://tf.nist.gov/general/pdf/1498.pdf Using a Time Interval Counter to Measure Frequency Stability: http://ipnpr.jpl.nasa.gov/progress_report/42-90/90S.PDF The later link, while a little dated, still does a good job of covering concepts. Thanks again, Jimmy... N5SPE On Feb 6, 2014, at 8:57 PM, Bob Stewart b...@evoria.net wrote: I think I see the problem. I was wondering about using the 1PPS output from my Rb in a test. Cobbling all that together would be a quick bit of work for you, but I spent my life in IT. I'm good with a soldering iron, but I readily admit my shortcomings at hardware tinkering. Bob From: Bob Camp li...@rtty.us To: Tom Van Baak t...@leapsecond.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, February 6, 2014 7:43 PM Subject: Re: [time-nuts] Rb as source for ADEV? Hi My intent was certainly not to stop anybody from doing anything with what they have. My concern is that this is a lot of work for modest return. A simple single mixer setup for $20 would dramatically change things…. $3 mini circuits double balanced mixer $3 op amps x 2 +/- 15 V supply you already have (hopefully). $5 for a piece of perf board $3 for 3 BNC connectors. $3 left over for resistors and capacitors. snip ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Fwd: [ntp:hackers] NTP Development Snapshot 4.2.7p419 Released
Fellow time-nuts, I think this can be of interest to you, as this is now in the NTP development snapshot. It's a fix to unloop the wrapped time of GPS receivers producing NMEA into the NTPD NMEA driver. This is to address the 1024 week issue that can occur with GPS receivers. Cheers, Magnus Original Message Subject: [ntp:hackers] NTP Development Snapshot 4.2.7p419 Released Date: Sat, 08 Feb 2014 12:32:07 + From: NTP Public Services Project webmas...@ntp.org Reply-To: hack...@lists.ntp.org To: hack...@lists.ntp.org NTP Development Snapshot 4.2.7p419 is now available for download. Bug Fixes: * [Bug 2466] Wrap NMEA timestamps in 1024 week cycles http://bugs.ntp.org/2466 Tarball: http://archive.ntp.org/ntp4/ntp-dev/ntp-dev-4.2.7p419.tar.gz MD5 sum: http://archive.ntp.org/ntp4/ntp-dev/ntp-dev-4.2.7p419.tar.gz.md5 Complete ChangeLog: http://archive.ntp.org/ntp4/ChangeLog-dev Please report any bugs, issues, or desired enhancements at http://bugs.ntp.org/. ___ hackers mailing list hack...@lists.ntp.org http://lists.ntp.org/listinfo/hackers ___ 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] Rb as source for ADEV?
Hi I pretty much wire them up on a piece of perf board when I need them. I’ve never bothered to do a real pc board. The OP-27 and OP-37 op amps are getting a bit old / expensive. If I was going to do one, I’d probably do some digging on the op amps first. There may be new(er) parts that are cheaper. Like anything else, done one up there’s a lot more pain involved doing one than doing a batch. PC boards make things easier. ——— The real benefit comes from a couple things: 1) Mixing down to a lower frequency. The counter gives you 9 digits a second no matter what the ( 1Hz) input. Lower frequencies give you more digits. Any reasonably quiet mixer will do this for you. That includes the DBM’s with connectors on them. 2) Amplifying the beat note as much as you can ahead of the limiter. Slew rate matters. Any *quiet* audio amp will do this for you, provided it’s got the frequency response and is very quiet at the low end. 3) Limiting with a circuit that has good noise performance at low frequencies. The poor guy who did the counter could not just focus on the low end. We can. There’s lots of ways to do each of those things. You can easily improve any of the three “chunks” over the very simple circuit I outlined. You can easily get caught up in the optimization process and turn this into a very complex project. For one second ADEV at the 1.0 x 10^-12 level (1x10^-13 at 10, 1x10^-14 at 100, 1x10^-15 at 1000) a very simple circuit will do the job. — The other alternative is to get something brand new with warranty and support like a TimePod. Symmetricom will happily sell you one. They work amazingly well and there’s no muss no fuss comparing a pair of devices. They are just a bit over the $10 to $15 budget (like by three zeros). Accuracy wise it will crush my little circuit, and mine doesn’t come with a cool GUI that reports power levels and the like. Am I trying to sell you one of these - no of course not. The point is that there’s a massive step cost wise going to new gear. Even at ten cents on the dollar there’s still a massive step. (and yes in this case you *can* take that as a “anybody want to sell a TimePod for 10 cents on the dollar?” question, I’m in a shopping mood … contact off list of course). I’m not holding my berth for the inbox filling up with offers. Finding this kind of gear used in good condition at a good price is not easy. — One other approach would be group builds. There are a number of these going on off list and aimed at selling the result. Because of the off list nature of this, it’s often tough to know what people are doing and how well they are doing. They tend to turn into limited production run builds and then vanish. Short runs make it tough for newcomers to stock up on stuff. There simply isn’t enough need for these things to keep a steady supply readily available. That’s not at all unique to this area. A *lot* of hobby electronics (and mechanics and ..) has exactly the same issue. I could fill several pages with examples. — Long rambling reply to a simple question - sorry about that …. Bob On Feb 8, 2014, at 6:02 AM, Jimmy Burrell jimmydb...@gmail.com wrote: Somewhat like Bob (Stewart) I've spent my life in IT with a little background in Ham Radio. Now, infected with the Time Bug, I'm slogging through tf.nist.gov, wenzel, and leapsecond to try and level up. I'd like to ask Bob (Camp) if he has a readily available link for a suitably quite homebrew mixer, similar to the one whose parts list he was discussing? Thanks to Magnus for his links (later in this thread), to which I'd like to add the following for those on the list, like me, who are neophytes. Fundamentals of Time and Frequency: http://tf.nist.gov/general/pdf/1498.pdf Using a Time Interval Counter to Measure Frequency Stability: http://ipnpr.jpl.nasa.gov/progress_report/42-90/90S.PDF The later link, while a little dated, still does a good job of covering concepts. Thanks again, Jimmy... N5SPE On Feb 6, 2014, at 8:57 PM, Bob Stewart b...@evoria.net wrote: I think I see the problem. I was wondering about using the 1PPS output from my Rb in a test. Cobbling all that together would be a quick bit of work for you, but I spent my life in IT. I'm good with a soldering iron, but I readily admit my shortcomings at hardware tinkering. Bob From: Bob Camp li...@rtty.us To: Tom Van Baak t...@leapsecond.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, February 6, 2014 7:43 PM Subject: Re: [time-nuts] Rb as source for ADEV? Hi My intent was certainly not to stop anybody from doing anything with what they have. My concern is that this is a lot of work for modest return. A simple single mixer setup for $20 would dramatically change things…. $3 mini circuits double balanced mixer $3 op amps x 2 +/-
Re: [time-nuts] BC637PCI and OCXO
On 07/02/14 09:09, Robert Watzlavick wrote: Magnus, What kind of problems did you have with it? I have a couple of BC635PCI boards that I've been using for a while with my own LabVIEW-based register driver. I've noticed some interesting behavior after board reset (loses lock for 8 sec to 3.5 min), and after changing the mode (disrupts lock/phase bits for ~5 sec and freq bit between 4-60 min). Rev H of the user's guide has the schematics if anybody needs them. I did not see the full board. I was unable to use the off the shelf software, so I wrote my own but was not able to get full access to the board, it behaved as if the CPU side did not work or something. I can't recall seeing schematics, and if worse comes to worse I might need a copy of the EPROM. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] BC637PCI and OCXO
On 07/02/14 18:45, d0ct0r wrote: Great ! Super ! Thanks a LOT ! Also, Symmetricom shared the resource for the latest version of that driver [BCPCI-V830 build 120]. http://www.symmetricom.com/bus-level-timing-sdk-and-driver-downloads/ I tried that on Ubuntu 12.04.3 LTS x86_64, kernel 3.2.0-58-generic. And its works for me. To whom it may interested, previously I tried to use WinDriver I take directly from Xilinx site [basically Jungo's WinDriver v11.5.0] and Legacy version of BC635PCI driver [BCPCI-V700 build 111], and it was working perfectly fine too. On the same 64bit Linux machine. Thanks! I did not know there where modern drivers available! Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS W/10KHz
Thank you very much, 73 KJ6UHN Alex On 2/7/2014 8:10 PM, Perry Sandeen wrote: List, Wrote: where is a good source of GPS receiver modules I need one which has 10kHz output to phase lock a quartz oscillator. Fluke.1 Motorola ONCORE M12+T timing gps receiver 1pps 100hz eBay item number:290656401551 Also RDR There is another china seller that has them(10KHz) with leads for $90 but is almost impossible to find. Last time I searched it took me a hour. But he has a wide assortment. I forgot to bookmark his site. 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 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] GPS W/10KHz
Hi The 10 KHz that these modules put out is not very “clean” in terms of driving a synthesizer. If you are looking at taking it straight to RF (as in driving a VHF radio), you likely will be less than happy with the result. Bob On Feb 8, 2014, at 8:02 AM, Alex Pummer a...@pcscons.com wrote: Thank you very much, 73 KJ6UHN Alex On 2/7/2014 8:10 PM, Perry Sandeen wrote: List, Wrote: where is a good source of GPS receiver modules I need one which has 10kHz output to phase lock a quartz oscillator. Fluke.1 Motorola ONCORE M12+T timing gps receiver 1pps 100hz eBay item number:290656401551 Also RDR There is another china seller that has them(10KHz) with leads for $90 but is almost impossible to find. Last time I searched it took me a hour. But he has a wide assortment. I forgot to bookmark his site. 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 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] How I got my FE-5680A to lock in Sydney, Australia
On 07/02/14 20:40, beale wrote: The entry in the FE5680 FAQ on this subject may be helpful, if you haven't tried it already. http://ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq#what_if_my_5680a_output_does_not_lock_up_after_several_minutes I have 3 of those units; one did not lock until I adjusted the trim-cap C217 to bring the free-running frequency of the oscillator into range. If you have a reasonably accurate counter you can check if this is the problem or not by seeing if the output frequency (which ramps up and down prior to lock) crosses through 10.00 MHz or not. Mine did not. This is why an oscillator trim is required. The oscillators offset is outside the lock-in range, DDS offset trim can possibly, for the DDS feedback version, cause lock-up, but the output won't be 10 MHz. This can naturally be used as a feature to have neat beat-frequencies in a DMTD setup, but otherwise not really recommended. Good that you have tried it and could point to the C217 trim-cap. Hopefully Jim can use that. Jim, do you have a GPSDO around? If so, use a counter and try to see what the top and bottom values in the sweeps are, adjust C217 so that the sweep range covers the 10 MHz line. Make sure you trim it with some margin to the edge of the sweep-range. Now, you should also be able to monitor how it locks up. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia
Hi Jim, On 07/02/14 05:19, Jamieson (Jim) Rowe wrote: Hi Magnus, Thanks for those suggestions also. So if I understand you right, I'd be better off trying to tweak the oscillator tuning -- using the trimcap? Or did you mean via the RS-232C 'offset adjustment' command? I covered this in another message I just sent, but for completeness: You want the C217 trim-cap adjusted such that the lock-in sweep will sweep over 10 MHz, because that's where the synthesized magic locks up and you get 10 MHz out. If you use the offset adjustment, you could possibly get it to lock up, but not producing the 10 MHz you expect. Once you got the trick, it's actually quite fun to trim and get the warm fuzzy feeling of fixing it as it locks up. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS W/10KHz
Thank you very much for the advice 73 KJ6UHN Alex On 2/8/2014 12:32 AM, MailLists wrote: You're looking for the older Rockwell/Conexant/Navman Jupiter-T ones. Some default in Motorola binary compatibility mode, with only 8 channels visible. Due to scarcity they are getting way to pricey... You might be better off with the newer uBlox NEO/LEA-6T, with configurable output(s). On 2/8/2014 6:10 AM, Perry Sandeen wrote: List, Wrote: where is a good source of GPS receiver modules I need one which has 10kHz output to phase lock a quartz oscillator. Fluke.1 Motorola ONCORE M12+T timing gps receiver 1pps 100hz eBay item number:290656401551 Also RDR There is another china seller that has them(10KHz) with leads for $90 but is almost impossible to find. Last time I searched it took me a hour. But he has a wide assortment. I forgot to bookmark his site. 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 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] GPS W/10KHz
Hi Bob, thank you very much, I know about it, the DoD makes it jittery, that is not a problem until the average frequency is correct, if you you lock a low noise [phase-noise] crystal oscillator to it with a proper loop filter you will have a very good reference. 73 KJ6UHN Alex On 2/8/2014 8:22 AM, Bob Camp wrote: Hi The 10 KHz that these modules put out is not very “clean” in terms of driving a synthesizer. If you are looking at taking it straight to RF (as in driving a VHF radio), you likely will be less than happy with the result. Bob On Feb 8, 2014, at 8:02 AM, Alex Pummer a...@pcscons.com wrote: Thank you very much, 73 KJ6UHN Alex On 2/7/2014 8:10 PM, Perry Sandeen wrote: List, Wrote: where is a good source of GPS receiver modules I need one which has 10kHz output to phase lock a quartz oscillator. Fluke.1 Motorola ONCORE M12+T timing gps receiver 1pps 100hz eBay item number:290656401551 Also RDR There is another china seller that has them(10KHz) with leads for $90 but is almost impossible to find. Last time I searched it took me a hour. But he has a wide assortment. I forgot to bookmark his site. 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 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] GPS W/10KHz
On Sat, Feb 8, 2014 at 3:44 AM, Volker Esper ail...@t-online.de wrote: you don't need 10kHz to build a GPS disciplined oscillator. GPSDOs are build with control loop response times in the range of some hours, so the loop will be absolutely happy with a 1PPS input. Of course you are correct. Most GPSDOs are driven with a 1Hz pulse. But I think maybe the OP is not building just any GPSDO but maybe he is looking to repair a specific GPSDO that is designed to use the old (and now rare) Rockwell GPS. If that is the case he needs the old Rockwell or needs to redesign his system. If you are starting from scratch to build a new GPSDO it's easier now. All you need is some kind of a phase detector (74HC4046 ?) and a small uP that has a good built-in DAC. The uP checks the phase once per second and adjusts it'sDAC accordingly. -- 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] GPS W/10KHz
Alex, On 08/02/14 17:34, Alex Pummer wrote: Hi Bob, thank you very much, I know about it, the DoD makes it jittery, that is not a problem until the average frequency is correct, if you you lock a low noise [phase-noise] crystal oscillator to it with a proper loop filter you will have a very good reference. As of 2000, DoD does not add jitter. Bob is alluding to the fact that the receiver isn't really doing a job of producing that 10 kHz, just as with the PPS signal. As the regular adjustments occurs, the PLL is pulled here and there and this scales up and well... becomes quite large when you hit 10 GHz. Had similar issues with a PLL designed that had a dead-band, which caused unacceptable performance onces scaled to about 2,5 GHz. Someone tried to use the 4046 current-pump phase-detector. Replacing it with a SR phase-detector proved a good solution. Comparator frequency of 8 kHz in that case. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS W/10KHz
Thanks, Chris, I didn't gather that from his posting. It'd be up to Perrier to illuminate that point. Volker Am 08.02.2014 18:33, schrieb Chris Albertson: On Sat, Feb 8, 2014 at 3:44 AM, Volker Esper ail...@t-online.de wrote: you don't need 10kHz to build a GPS disciplined oscillator. GPSDOs are build with control loop response times in the range of some hours, so the loop will be absolutely happy with a 1PPS input. Of course you are correct. Most GPSDOs are driven with a 1Hz pulse. But I think maybe the OP is not building just any GPSDO but maybe he is looking to repair a specific GPSDO that is designed to use the old (and now rare) Rockwell GPS. If that is the case he needs the old Rockwell or needs to redesign his system. If you are starting from scratch to build a new GPSDO it's easier now. All you need is some kind of a phase detector (74HC4046 ?) and a small uP that has a good built-in DAC. The uP checks the phase once per second and adjusts it'sDAC accordingly. ___ 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] GPS W/10KHz
On Sat, Feb 8, 2014 at 9:47 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob is alluding to the fact that the receiver isn't really doing a job of producing that 10 kHz, just as with the PPS signal. As the regular adjustments occurs, the PLL is pulled here and there and this scales up and well... becomes quite large when you hit 10 GHz. The OP wants to use the 10KHz signal to discipline a OCXO, not to run a microwave transmitters (at least no directly.) The (minutes long) time constant on the GPSDO will even out any phase anise on the 10KHZ signal. So using 10KHz or 1Hz makes lithe difference if you avargage over a handful of minutes. The final output depends mostly on the quality of the OCXO. For a long time people stopped building GPSDOs because the Thunderbolt sold for $100. The price has gone up and so maybe it's time to think about how to build a good GPSDO but with target price under $100 and simple enough that a PCB is not required. -- 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] GPS W/10KHz
ail...@t-online.de said: you don't need 10kHz to build a GPS disciplined oscillator. GPSDOs are build with control loop response times in the range of some hours, so the loop will be absolutely happy with a 1PPS input. Right. But it's not simple to build an analog low pass filter with a cutoff frequency of 1/100 seconds. The modern approach is to use a small processor and a DAC. The hard part is getting enough effective bits out of the DAC. The archives are full of suggestions about which chip to use. For a home brew setup, you can trade bits for tuning range if you are willing to fiddle an analog pot occasionally when your crystal drifts out of tuning range as it ages. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS W/10KHz
you don't need 10kHz to build a GPS disciplined oscillator. GPSDOs are build with control loop response times in the range of some hours, so the loop will be absolutely happy with a 1PPS input. This is quite true, but there are practical issues that cause many people to much prefer 10 kHz instead of 1 PPS. Cheap surplus Jupiter 10 kHz GPS boards are still very attractive for a homebrew GPSDO. GPSDO designs based on 1 PPS typically use a digital time interval counter. The beauty of using 10 kHz is that one can use analog phase comparisons and thus *avoid* the complexity of microprocessors, software, algorithms, voltage references, and DAC. The classic example of this is James Miller's ultra simple GPSDO: http://www.jrmiller.demon.co.uk/projects/ministd/frqstd0.htm You can see it performs extremely well: http://leapsecond.com/pages/gpsdo/ There are dozens of DIY GPSDO projects on the web using the same minimalist design. Use google image search to see them: https://www.google.com/search?q=GPSDO+Jupiter+10kHztbm=isch Alex -- if you need a concise list of URL's let us know. But I think those images will give you an excellent idea what others have built. /tvb Hi where is a good source of GPS receiver modules I need one which has 10kHz output to phase lock a quartz oscillator Thank you in advance Alex ___ 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] GPS W/10KHz
The problem with the PLL analog version is the same as with any digital GPSDO. The saw tooth is present at 10 KHz just like 1 Hz. To the best of my knowledge there is no GPS receivers out there for less than $ 1000 with out saw tooth. Timing receivers output the correction value and you can either with software or a variable delay do correction. I encourage you to pursue your idea since for more than ten years I had the privilege to communicate with some of the sharpest minds on that subject and obviously the missed something. That also applies for the three of us that have been working intensely on developing and testing the next generation of GPSDO's that we hope to introduce to time nuts soon. In the meantime with the ever increasing price of Tbolts, Shera is worth a second look. When we worked on the last code release of Shrea using a Morion we got consistently better than 1 E-11. Yes some of the IC's are hard to find and that is why I used more readily available parts and did a new board layout. Also did one using a $ 1.20 Altera gate array. Bert Kehren In a message dated 2/8/2014 12:33:48 P.M. Eastern Standard Time, albertson.ch...@gmail.com writes: On Sat, Feb 8, 2014 at 3:44 AM, Volker Esper ail...@t-online.de wrote: you don't need 10kHz to build a GPS disciplined oscillator. GPSDOs are build with control loop response times in the range of some hours, so the loop will be absolutely happy with a 1PPS input. Of course you are correct. Most GPSDOs are driven with a 1Hz pulse. But I think maybe the OP is not building just any GPSDO but maybe he is looking to repair a specific GPSDO that is designed to use the old (and now rare) Rockwell GPS. If that is the case he needs the old Rockwell or needs to redesign his system. If you are starting from scratch to build a new GPSDO it's easier now. All you need is some kind of a phase detector (74HC4046 ?) and a small uP that has a good built-in DAC. The uP checks the phase once per second and adjusts it'sDAC accordingly. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] BC637PCI and OCXO
Following my earlier post with download links for the Symmetricom software and documentation CD TVB was kind enough to send me this Symmetricom link.. http://www.symmetricom.com/bus-level-timing-sdk-and-driver-downloads/ I've verified that the two Windows archives there for the BC635/637 match what's in the CD ISO and have no reason to assume the rest won't match either, so this might be a more straightforward link to individual files. I've had a BC637PCI running continuously since yesterday and can confirm that both modules here seem to have a week 1024 rollover problem, via the Datum/Symmetricom demo software both are happily reporting dates in June 1994. I'm not sure yet whether the board takes the date from the GPS module or just the week number, so I'm not sure either if this is an issue with the Datum boards or with the Trimble Ace3 GPS modules, but I do have an earlier comment from Trimble that they were happy the Ace3 wouldn't have a problem after 1999 and I don't recall seeing this anyway when I last ran a BC637 a few years ago, nor with some more recent tests on other Ace3 modules. I'll run up an Ace3 standalone tomorrow but was just wondering if anyone else has seen this behaviour with the BC637? Regards Nigel GM8PZR In a message dated 07/02/2014 17:13:35 GMT Standard Time, gandal...@aol.com writes: Whilst sorting through my BC637PCI files earlier I realised for the first time that an ISO file I'd downloaded in 2010, described by Symmetricom as BC635/637 driver, is actually a full software and documentation CD, presumably what was then being supplied with new hardware. Ether that or I had been aware and it's something else that's slipped through the sieve:-) As well as the Windows SDK and more recent versions of the BC635 and BC637 demo software this file also contains later versions of the legacy demo software than I'd used previously, perhaps making most, if not all, of the earlier software obsolete, although the pre Symmetricom manuals, especially the one with the schematics, are certainly worth having. Now it's quite possible I'm the only one who wasn't aware of this, but in case it's not just me, and as I can't locate the original again to quote a URL, I've uploaded a file that contains this ISO, the extracted files from the same, plus my original collection of earlier software and documentation. This is quite a large file, approx 235MB, so for anyone who might only be interested in the earlier files I've also uploaded those as a smaller file of approx 52MB. BC637PCI_Full.rar 234.5 MB https://mega.co.nz/#!6dgVzBQI!A8y-qffQo4X5OYViTz97ZyiFn05zaPPfxCwoGLDu0Kg BC637PCI_Reduced.rar 50.2 MB https://mega.co.nz/#!iUQiwK7R!wyRPeBnkS4o1iADZGp7c-ZS6hHNbNqEEb8p1KKbr-ZU Any problems with the downloads or files please let me know and, as always, please feel free to upload elsewhere. Regards Nigel GM8PZR In a message dated 07/02/2014 03:36:46 GMT Standard Time, t...@patoka.org writes: Hello, Does anybody seen any links to the information how to implement external OCXO to Symmetricom PCI TFP BC635/BC637 ? -- WBW, V.P. ___ 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] How I got my FE-5680A to lock in Sydney, Australia
Hi Magnus, Thanks again for those further suggestions. I do have a GPSDO, and I had been able to use it with a counter to check that the FE-5680A was swinging either side of 10MHz. But I didn't make sure that it was swinging evenly each side of 10MHz . According to my notes it was swinging between 9.999770 and 10.36MHz -- i.e., about 230Hz low and about 36Hz high. But it was spending more of the time below 10MHz than above -- does this suggest to you that I should tweak C217 until it swings by about the same amount either way? Cheers, Jim -Original Message- From: Magnus Danielson Sent: Sunday, February 09, 2014 3:36 AM To: time-nuts@febo.com Subject: Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia Hi Jim, On 07/02/14 05:19, Jamieson (Jim) Rowe wrote: Hi Magnus, Thanks for those suggestions also. So if I understand you right, I'd be better off trying to tweak the oscillator tuning -- using the trimcap? Or did you mean via the RS-232C 'offset adjustment' command? I covered this in another message I just sent, but for completeness: You want the C217 trim-cap adjusted such that the lock-in sweep will sweep over 10 MHz, because that's where the synthesized magic locks up and you get 10 MHz out. If you use the offset adjustment, you could possibly get it to lock up, but not producing the 10 MHz you expect. Once you got the trick, it's actually quite fun to trim and get the warm fuzzy feeling of fixing it as it locks up. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia
Hi Beale, Thanks for those suggestions. I had looked at that FAQ already, and when I checked the unit (before I inverted it) with a counter coupled to the 1pps signal from my GPSDO for its timebase, it was swinging through 10MHz (from -230Hz to +36Hz). But not evenly on either side, and it was spending somewhat longer below 10MHz than above. However I will try returning it to the 'right way up' position, then opening it up and running adjusting trim cap C217 to see if I can get it to swing equally either side of 10MHz. Hopefully I should then be able to get a reliable lock even 'right way up' -- right? Cheers, Jim Rowe -Original Message- From: beale Sent: Saturday, February 08, 2014 6:40 AM To: time-nuts@febo.com Subject: Re: [time-nuts]How I got my FE-5680A to lock in Sydney, Australia The entry in the FE5680 FAQ on this subject may be helpful, if you haven't tried it already. http://ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq#what_if_my_5680a_output_does_not_lock_up_after_several_minutes I have 3 of those units; one did not lock until I adjusted the trim-cap C217 to bring the free-running frequency of the oscillator into range. If you have a reasonably accurate counter you can check if this is the problem or not by seeing if the output frequency (which ramps up and down prior to lock) crosses through 10.00 MHz or not. Mine did not. ___ 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] How I got my FE-5680A to lock in Sydney, Australia
Hi Ignacio, Thanks for your comments also. I will open up the unit and see if I can find any dry or poorly soldered joints, etc. Best regards, Jim Rowe -Original Message- From: EB4APL Sent: Saturday, February 08, 2014 12:21 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia Hi, I second the idea about a mechanical issue. When I opened my FRS-C I found that one of the connector pins had never been soldered, it only made mechanical contact with the PBC. Perhaps it showed an intermittent failure and was retired with low hours. Ignacio EB4APL On 07/02/2014 3:54, Ed Palmer wrote: Hi Jim, On 2/6/2014 3:32 PM, Jamieson (Jim) Rowe wrote: Hi again folks, You may (or may not) recall that a month or so ago, I asked for any information that might be available regarding how to fix a ‘used’ FE-5680A rubidium module from China (via ebay) which was tested by the supplier in China as working OK, but would not seem to lock up to rubidium here in Sydney. There wasn’t a great deal of info available, it seems, so I kept on checking ideas myself – mostly with no luck. The module would never lock, but kept cycling back and forth between about 9.999770MHz and 10.36MHz – ‘searching’ for a lock, but never finding it. Anyway, a couple of days ago I was reading more about the operation of rubidium vapour oscillators, and noticed that the ‘filter cell’ is very sensitive to magnetic fields – hence the mu-metal shielding case, and also for the ‘C-tuning’ coil. And I wondered if the main reason why the FE-5680A had apparently worked in China, but wouldn’t lock up in Sydney (Australia) might be caused by the fact that Quangzhou (China) is in the northern hemisphere while I’m ‘down under’ in the southern hemisphere – where the earth’s field is presumably somewhat different, in terms of both strength and direction. So I decided to test this in a crude way, by inverting the FE-5680A and seeing what happened. And – lo and behold – it locked up within 2.5 minutes, and stayed locked until I turned off the power and let it go cold again. The next morning I applied power again, and within 3 minutes it locked up again with no problems. And it’s been locked up now for over 48 hours... My first thought was to make a typical 'down-under' joke and suggest you run the 5680A upside down, but you beat me to it! :) So it seems that the different magnetic field here may have been the problem – either that, or it may have received a ‘jolt’ in transit, which prevented in from locking unless it was inverted. But how do I tell which of these explanations is right, without ‘opening her up’ again and looking for some kind of subtle physical fault? Another idea: perhaps the mu-metal shield case had acquired a small dose of magnetisation in transit (via a physical shock, or from a strong field metal detector). I guess in this case that I would have to remove the two halves of the case, and bake them in a furnace to demagnetise them again. My very limited knowledge regarding mu-metal is that it is so magnetically 'soft' that it can't be magnetized. If it was somehow magnetized, inverting the unit wouldn't make any difference, would it? Or should I just run the FE-5680A upside down permanently – the simple but ‘crude’ answer? I don't believe for a second (pun intended) that the earth's magnetic field has any effect on the locking of your 5680A. It's just not strong enough. The same applies to the C-field which can only nudge the frequency one way or another by a small amount. Since flipping the unit DID make a difference, my money would be on a trivial, boring mechanical issue inside the unit. Could be a bad solder joint, broken wire, floating piece of debris, or something like that. Worst case might be a broken glue joint somewhere in the physics package. That could be ugly. I would definitely open it up and see if anything falls out. I’m not sure if this FE-5680A has the ‘C-tuning’ gizmo fitted, or wired up. Am I right in thinking that another approach might be to try varying the tuning via the RS-232C serial port? Does this work via the C-tuning coil anyway, or by tweaking the DDS? The RS-232 commands affect the DDS - assuming your unit does have one. It will have no effect on the locking, only on the output frequency. A few years ago I bought a dead Datum SLCR Rb standard. It's a cousin to the LPRO. I thought I'd learn some things by trying to fix it. The problem was intermittent. I tore it apart and found that one of the legs of the crystal had never been soldered! Never overlook the obvious. I hope a much more experienced time nut can provide a few answers, please. Maybe the blind leading the blind is a closer description. Ed Jim Rowe ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia
Thanks for that suggestion too, Mr Kehren. I'll check for dry joints, etc in that region also... Cheers, Jim Rowe -Original Message- From: ewkehren Sent: Saturday, February 08, 2014 12:39 PM To: time-nuts@febo.com Subject: Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia Could be the C coil Sent from Samsung tabletEB4APL eb4...@cembreros.jazztel.es wrote:Hi, I second the idea about a mechanical issue. When I opened my FRS-C I found that one of the connector pins had never been soldered, it only made mechanical contact with the PBC. Perhaps it showed an intermittent failure and was retired with low hours. Ignacio EB4APL On 07/02/2014 3:54, Ed Palmer wrote: Hi Jim, On 2/6/2014 3:32 PM, Jamieson (Jim) Rowe wrote: Hi again folks, You may (or may not) recall that a month or so ago, I asked for any information that might be available regarding how to fix a ‘used’ FE-5680A rubidium module from China (via ebay) which was tested by the supplier in China as working OK, but would not seem to lock up to rubidium here in Sydney. There wasn’t a great deal of info available, it seems, so I kept on checking ideas myself – mostly with no luck. The module would never lock, but kept cycling back and forth between about 9.999770MHz and 10.36MHz – ‘searching’ for a lock, but never finding it. Anyway, a couple of days ago I was reading more about the operation of rubidium vapour oscillators, and noticed that the ‘filter cell’ is very sensitive to magnetic fields – hence the mu-metal shielding case, and also for the ‘C-tuning’ coil. And I wondered if the main reason why the FE-5680A had apparently worked in China, but wouldn’t lock up in Sydney (Australia) might be caused by the fact that Quangzhou (China) is in the northern hemisphere while I’m ‘down under’ in the southern hemisphere – where the earth’s field is presumably somewhat different, in terms of both strength and direction. So I decided to test this in a crude way, by inverting the FE-5680A and seeing what happened. And – lo and behold – it locked up within 2.5 minutes, and stayed locked until I turned off the power and let it go cold again. The next morning I applied power again, and within 3 minutes it locked up again with no problems. And it’s been locked up now for over 48 hours... My first thought was to make a typical 'down-under' joke and suggest you run the 5680A upside down, but you beat me to it! :) So it seems that the different magnetic field here may have been the problem – either that, or it may have received a ‘jolt’ in transit, which prevented in from locking unless it was inverted. But how do I tell which of these explanations is right, without ‘opening her up’ again and looking for some kind of subtle physical fault? Another idea: perhaps the mu-metal shield case had acquired a small dose of magnetisation in transit (via a physical shock, or from a strong field metal detector). I guess in this case that I would have to remove the two halves of the case, and bake them in a furnace to demagnetise them again. My very limited knowledge regarding mu-metal is that it is so magnetically 'soft' that it can't be magnetized. If it was somehow magnetized, inverting the unit wouldn't make any difference, would it? Or should I just run the FE-5680A upside down permanently – the simple but ‘crude’ answer? I don't believe for a second (pun intended) that the earth's magnetic field has any effect on the locking of your 5680A. It's just not strong enough. The same applies to the C-field which can only nudge the frequency one way or another by a small amount. Since flipping the unit DID make a difference, my money would be on a trivial, boring mechanical issue inside the unit. Could be a bad solder joint, broken wire, floating piece of debris, or something like that. Worst case might be a broken glue joint somewhere in the physics package. That could be ugly. I would definitely open it up and see if anything falls out. I’m not sure if this FE-5680A has the ‘C-tuning’ gizmo fitted, or wired up. Am I right in thinking that another approach might be to try varying the tuning via the RS-232C serial port? Does this work via the C-tuning coil anyway, or by tweaking the DDS? The RS-232 commands affect the DDS - assuming your unit does have one. It will have no effect on the locking, only on the output frequency. A few years ago I bought a dead Datum SLCR Rb standard. It's a cousin to the LPRO. I thought I'd learn some things by trying to fix it. The problem was intermittent. I tore it apart and found that one of the legs of the crystal had never been soldered! Never overlook the obvious. I hope a much more experienced time nut can provide a few answers, please. Maybe the blind leading the blind is a closer description. Ed Jim Rowe ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia
Jim, According to my log, my first unit sweeps from 9.999766 to 10.56 and locks in less than 3 min. My second unit sweeps from 9.9997414 to10.493 and also locks in less than 3 min. Probably your unit needs to go a little bit higher. The time spent at the limits probably is not relevant, I also noticed it and that they lock when reaching 10.0 MHz in the same ramp, I don't remember if going up or down. But now that you are able to measure, what are the figures with the unit turned up and down? Regards, Ignacio EB4APL On 09/02/2014 2:57, Jamieson (Jim) Rowe wrote: Hi Magnus, Thanks again for those further suggestions. I do have a GPSDO, and I had been able to use it with a counter to check that the FE-5680A was swinging either side of 10MHz. But I didn't make sure that it was swinging evenly each side of 10MHz . According to my notes it was swinging between 9.999770 and 10.36MHz -- i.e., about 230Hz low and about 36Hz high. But it was spending more of the time below 10MHz than above -- does this suggest to you that I should tweak C217 until it swings by about the same amount either way? Cheers, Jim -Original Message- From: Magnus Danielson Sent: Sunday, February 09, 2014 3:36 AM To: time-nuts@febo.com Subject: Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia Hi Jim, On 07/02/14 05:19, Jamieson (Jim) Rowe wrote: Hi Magnus, Thanks for those suggestions also. So if I understand you right, I'd be better off trying to tweak the oscillator tuning -- using the trimcap? Or did you mean via the RS-232C 'offset adjustment' command? I covered this in another message I just sent, but for completeness: You want the C217 trim-cap adjusted such that the lock-in sweep will sweep over 10 MHz, because that's where the synthesized magic locks up and you get 10 MHz out. If you use the offset adjustment, you could possibly get it to lock up, but not producing the 10 MHz you expect. Once you got the trick, it's actually quite fun to trim and get the warm fuzzy feeling of fixing it as it locks up. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rb as source for ADEV?
b...@evoria.net said: Would I learn anything useful by hooking my Rb standard up to my 5335A and comparing that to the OCXO? What kind of time-nut question is that? :) Try it and see. Maybe you will find something interesting where you/we didn't expect it. If you assume the Rb is stable, you should be able to watch the long term drift of the OCXO. How many low digits can you get out of the 5335A? Do you have an GPSDO to add to the mix? That would let you calibrate the Rb. -- 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] How I got my FE-5680A to lock in Sydney, Australia
What was the timebase for your counter? I suspect that it is off freq and the Rb is not actually making it above 10 MHz. Inverting the Rb is causing a 2G shift in gravity to the Rb crystal probably shifting its freq enough to cause lock. ___ 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.
