Re: [time-nuts] Intro and Driver Request
I used one of the BC620AT cards many years ago with a DOS system. All we needed was time within a second so we used with a Bancomm-supplied DOS driver (I think) that replaced the system clock with IRIG-B based time instead of the PC clock. It may have come with a regular driver but I can't remember. You can get much newer PCI versions for around $100 on eBay unless you're dead set on the ISA bus. The BC635 is the IRIG version and the BC637 is the GPS version. -Bob On 05/12/2016 07:26 PM, Jason T wrote: Hello Time-Nuts - I've ended up here by way of the ham radio, electronics and classic computing hobbies, which I'd bet is a common trail to follow for time-standard collectors. I don't have any exotic equipment at the moment but I've run across GPS and rubidium-based test equipment online and at hamfests without knowing much about them, other than they looked cool and technical :) Recently I came upon a Datum ISA card, the BC620at, along with the 627at kit, which is a Trimble "smart antenna" that attaches to the card: http://www.gigatest.net/datum/bc620at.pdf Not that I need any more projects, but I may as well try to make it do its thing; however I am lacking the necessary drivers for the ISA card. I found (and imaged) the one disk that came with it but that turned out to be the Windows (98, NT, 2000) SDK. I believe there should be an MS-DOS driver as well. Does anyone have or has anyone used one of these cards? Any advice, in addition to tips on the driver/software, is much appreciated. Thanks much -j ___ time-nuts mailing 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] Symmetricom ET-6000 TCXO receivers
Erik, I upgraded my ET-6000 TCXO receiver to an OCXO. I was able to get Symmetricom to send me all three ROM images (TCXO, OCXO, Rubidium) so I uploaded them to the KO4BB website: http://www.ko4bb.com/getsimple/index.php?id=manuals=01_ROM_Images_and_Drivers Get the file called DatumET-6000TS-2100.zip You'll need the DT102E (OCXO) firmware. See my posts on 8/25/2012 and 8/26/2012 for more details. I would have liked to use an MV-89 that I had but it was too big so I used a small Raltron OCXO I had available at the time. It dramatically improved the output stability. For the OCXO, you can power it from either 5V or 12V (both are available on board) but the EFC range is 0-5V (I think the range of the DAC is 0.5 to 4.5V). -Bob On 04/17/2016 03:04 PM, Erik Thomassen via time-nuts wrote: Good evening group ! I am in the fortunate situation to have "inherited" two Symmetricom ET6000-TCXO receivers. Seemingly fine receivers but i do not like the way they "drift" plus /minus. They never seem to settle, even free-running OCXO's seems to be far better over short time. Yes, I know that this is the rule - but when compared with a new Meinberg GPSDO unit (replacing the ET6000) the -6000 "never" settles. I am in the firm beleif that a change from a cheap TCXO to a "reasonable" OCXO of any make will at least stabilize the 10MHz output by a decade or more. I do have the user manual but: I do not feel confortable exhanging the original TCXO with a OCXO of any higher accuracy/stability, non original component just like that... Any suggestions for making a reasonably good receiver even better by simple and cheap means? Any service manual/info deeper than the user manual? Kind regards from NorwayErik ___ time-nuts mailing 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] LAST CALL for Symmetricom 58532A antennas
Has anybody had trouble getting their antennas? I exchanged emails with David and sent him $40 for one but I never received it. I've emailed him twice now with no response. Before I try to get my money back from PayPal, I thought I'd check to see if anybody else had this issue. -Bob On 01/15/2016 12:41 PM, Gregory Beat wrote: David Zoldan contacted me this morning to inform me that their inventory of Symmetricom 58532A antennas is quickly disappearing. He thanked the time-nuts group for their previous purchases in 2015. IF you Contact David, at Launch3, and he said that Launch3 will sell remaining inventory to time-nuts members for $25 each + shipping -- while their supplies last. Thank you = CONTACT INFO (Phone numbers for Orders) BELOW: David Zoldan Launch3Telecom.com Launch3Services.com P: 646.536.3699 | C: 917.374.7482 | F: 646.536.3866 | E: da...@launch3.net 27 Daniel Rd. | Fairfield, New Jersey | 07004 Globally connected, individually personalized. ___ time-nuts mailing 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] TymServe 2100 OCXO (MTI 240-0530-D)
See the thread titled Upgrading TS2100 from TCXO to OCXO around 3/30/2011. I used a different OCXO but one that had a compatible EFC range. It's funny, a few weeks ago before the TS2100s started acting up, I would have picked up one of those OCXOs in a heartbeat. I've had an eBay watch set up for years waiting for that part. But now I'm not so sure I want it anymore. -Bob On 06/02/2015 08:32 AM, Gerhard Wittreich wrote: I just discovered that a correct model MTI OCXO (MTI 240-0530-D) for the TS-2100 is currently available on eBay. In the past MTI 240's of different versions have been available but unsuitable for the TS-2100. Price is $45.99 + shipping. I have one on the way. NEW Symmertricom BC11736-1000 MRI 240-0530-D 010285-0530-D Crystal Oscillator http://www.ebay.com/itm/NEW-Symmertricom-BC11736-1000-MRI-240-0530-D-010285-0530-D-Crystal-Oscillator-/131510917585?pt=LH_DefaultDomain_0hash=item1e9ea959d1 Now, has anyone replaced a stock oscillator with the correct MTI 240 in a TS-2100? Glad to take this off-line of the topic is not of general interest. Gerhard R. Wittreich, P.E. ___ time-nuts mailing 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] Tymserve 2100 thinks it's 1995?
You probably need the firmware update: Boot Code - Tymserve_2100 Rev 1.1 12/20/1996 13:07:21 Main Code - TymServe_2100 Rev 4.1 12/01/2005 14:45:23 http://www.ko4bb.com/getsimple/index.php?id=downloadfile=01_ROM_Images_and_Drivers/DatumET-6000TS-2100.zip -Bob On 05/04/2015 05:43 AM, Chris Mottram wrote: Hi Bob, I've just this minute joined this list, because I Tymserve 2100 unit we have at work has just started doing the same thing, at just gone 1am UT on May 3rd. I've also tried restarting and power cycling (this is somewhat convoluted as the unit is ~3000 miles away from me) but it's firmly stuck in 1995 Ours is currently running Rev 3.1 : 5 ? version Boot Code - Tymserve_2100 Rev 1.1 12/20/1996 13:07:21 Main Code - TymServe_2100 Rev 3.1 08/22/2002 12:15:37 After a power cycle, our unit comes up as follows: 3 ? time JAN 01 1995 00:01:53.687252 After the GPS has locked this changes to: 5 ? time SEP 17 1995 20:14:35.479915 Where 20:14 was the correct UT time. cheers Chris On 05/04/2015 12:31 AM, Bob Martin wrote: My Tymserve 2100 gps unit (Rev 4.1) thinks it's 1995 -- September 17, 1995. But a restart (connect via telnet and give the commands util restart) brings it back to the correct time and date -- for a while? I haven't caught it dropping back, so i don't know if it's doing this on the hour, after an hour, or what, but I noticed it last night, and I've restarted it a few times today. Any clues? I know about the off-by-a-second issue with the pending leap second. This one is more interesting! So far I've just been issuing software restarts. The next time I'll power cycle the sucker and see if that does any good. GPS signal isn't the issue; the 2100 shares an external GPS antenna with my Thunderbolts through a Symmetricom 58536A GPS splitter, and the Thunderbolts are as happy as a Thunderbolt can be. cheers bob k6rtm ___ time-nuts mailing 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] Tymserve 2100 thinks it's 1995?
Mine was fine until I power cycled it :( I can confirm that even with the v4.1 firmware, power cycling it causes the date to revert back to 1995. A software restart as listed below seems to restore the correct date for awhile but it eventually reverts back to the wrong year. Maybe some smart guy can reverse engineer the binary and patch it. It must have already been patched once by the vendor since it seems unlikely the GPS firmware would have been updated. Luckily I have an ET-6000 so I can always feed IRIG-B from it into the TS-2100 until it too exhibits the rollover bug. After that runs out, I can use the 1 PPS input. -Bob On 05/04/2015 01:23 PM, Mark Strovink wrote: Bob Martink6rtm@... writes: Additional information -- Power cycling (leaving it off for about 5 minutes) didn't do any good. Once at the correct time/date, it bounces back to 1995 at about 30 seconds after the hour (now to Sep 18, 1995). My Tymserve 2100 gps unit (Rev 4.1) thinks it's 1995 -- September 17, 1995. But a restart (connect via telnet and give the commands util restart) brings it back to the correct time and date -- for a while? I haven't caught it dropping back, so i don't know if it's doing this on the hour, after an hour, or what, but I noticed it last night, and I've restarted it a few times today. Any clues? I know about the off-by-a-second issue with the pending leap second. This one is more interesting! So far I've just been issuing software restarts. The next time I'll power cycle the sucker and see if that does any good. GPS signal isn't the issue; the 2100 shares an external GPS antenna with my Thunderbolts through a Symmetricom 58536A GPS splitter, and the Thunderbolts are as happy as a Thunderbolt can be. cheers bob k6rtm What a great way to start a Monday: phone call that the entire domain was back in 1995. The good news: Tymserve units will keep the correct date in Free mode. GPS handling, not the GPS signail, is the problem. The GPS unit is rolling the date over to its initial date once the date is past May 2 or 3, 2015. The bad news: Tech support said the company will not be providing a fix for a product 5 years past end of support. ___ time-nuts mailing list --time-nuts@febo.com To unsubscribe, go tohttps://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] Need advice for multilateration setup
Attila, From reading at the abstract, it looks interesting - bird tracking! But essentially the same problem I'm trying to solve. I was looking for a copy of the paper on the web as I'm not sure I want to purchase it. Thanks, -Bob On 04/18/2015 04:02 PM, Attila Kinali wrote: Moin, On Mon, 06 Apr 2015 07:37:53 -0500 Robert Watzlavick roc...@watzlavick.com wrote: Thank you very much for the references. I had come across [4] when searching on Kalman filters for GPS aiding of INS measurements. I didn't pay much attention to the GPS chapter at the time but I'll look at it again. I just downloaded [3] and it appears to have a good mix of practical vs. theoretical aspects. I appreciate the help! While looking for something completely different[tm] I stumbled over the paper below. It is definitly not the best paper I have seen, but it might give you some ideas. A reverse GPS architecture for tracking and location of small objects, by Andrade, Alves, Cuipdo, Santos, 2011 http://dx.doi.org/10.1109/ICL-GNSS.2011.5955273 Attila Kinali ___ time-nuts mailing 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] Need advice for multilateration setup
Attila, Thank you very much for the references. I had come across [4] when searching on Kalman filters for GPS aiding of INS measurements. I didn't pay much attention to the GPS chapter at the time but I'll look at it again. I just downloaded [3] and it appears to have a good mix of practical vs. theoretical aspects. I appreciate the help! -Bob On 04/06/2015 04:14 AM, Attila Kinali wrote: The basic system is that of an DSSS modulator/demodulator. The best text on spread spectrum systems I have found sofar is [1]. I explains modulation and demodulation in a hands on fashion. But, due to the age of the book, it does not contain any of the advanced stuff done today. But I think you don't need anything more fancy than an early-prompt-late correlator architecture for tracking. For the way how GPS works and how correlation and everything is done, I would suggest [2,3,4]. [2] is a good overview of how GPS is done and contains 99% of everything you need to know (special thanks to Magnus for mentioning it). It lacks some details on how to actually implement the system though. There [3] helps a lot, as it's a book specifically on building a GPS/Galileo receiver. I only skimmed trough a digital copy of [4] yet, so I cannot say too much about it, but that it's probably the most complete book on radio and inertial navigation I have seen sofar. The level of detail seems to vary from topic to topic quite a bit, but it is a treasure trove of references for everything the book covers (which is a damn lot!) If you are tight on time I would probably recommend to start with [3] and have a look at [1] and [2] when things don't make sense. Attila Kinali [1] Spread Spectrum Systems with Commercial Applications, 3rd edition, by Robert C. Dixon, 1994 [2] Global positioning system signals, measurements, and performance, 2nd edition, by Partap Misra and Per Enge, 2012. [3] A Software-Defined GPS and Galileo Receiver, by Bore, Akos, Bertelsen, Rinder, Jensen, 2007 [4] Principles of GNSS, Inertial, and Multisensor Integrated Navigation Systems, 2nd edition, by Paul D. Groves, 2013 ___ time-nuts mailing 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] Need advice for multilateration setup
I have an amateur radio license (mostly CW/HF and some VHF/UHF experience) and I've written some driver software for an IQ demodulation board but I have to admit, I would have no idea how to begin setting up that system as initially described by Attila and expanded by you and others. I have a rudimentary understanding of the modulation schemes involved but I don't fully understand how the various codes mentioned fit in. I've poked around a bit at some articles on PN codes and I can see how data would be transmitted but I think I'm missing something key that allows you to extract positions, velocities, etc. out of the various links. I think I have some more reading to do :) Thanks, -Bob On 04/03/2015 06:08 AM, Magnus Danielson wrote: I think this is a good idea, and it is relatively straight-forward to do. You can observe both code and carrier phase this way, given that the transmitting radio is coherent with the code generation clock. Doppler also pops out of the tracking station. A good coding-gain reduces the need for a strong transmitter. The issue might be the allowed width of the signal being transmitted, forcing the chipping rate down. 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] Need advice for multilateration setup
To head off a bunch of replies - I think I stumbled upon what is being suggested. To extract the pseudorange, you have to figure out the offset of the locally generated PN code against the one that is received. In this reverse GPS case, I assume each ground station would have to start their local PN codes at the same time? Then you would be able to get the pseudoranges at each ground station and use those values for the multilateration equations. You still would have an uncertainty of one clock cycle since the phases of the local clocks at the stations wouldn't be aligned but several folks have suggested ways around that. -Bob On 04/03/2015 10:12 PM, Robert Watzlavick wrote: I have an amateur radio license (mostly CW/HF and some VHF/UHF experience) and I've written some driver software for an IQ demodulation board but I have to admit, I would have no idea how to begin setting up that system as initially described by Attila and expanded by you and others. I have a rudimentary understanding of the modulation schemes involved but I don't fully understand how the various codes mentioned fit in. I've poked around a bit at some articles on PN codes and I can see how data would be transmitted but I think I'm missing something key that allows you to extract positions, velocities, etc. out of the various links. I think I have some more reading to do :) Thanks, -Bob On 04/03/2015 06:08 AM, Magnus Danielson wrote: I think this is a good idea, and it is relatively straight-forward to do. You can observe both code and carrier phase this way, given that the transmitting radio is coherent with the code generation clock. Doppler also pops out of the tracking station. A good coding-gain reduces the need for a strong transmitter. The issue might be the allowed width of the signal being transmitted, forcing the chipping rate down. 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] Need advice for multilateration setup
I want to thank everybody for their help on this. Thanks to the list, I have plenty of ideas that I can prototype so I'll keep you posted what I end up trying and how well it works eventually. -Bob On 03/25/2015 09:27 PM, Robert Watzlavick wrote: I want to develop a tracking system for an amateur rocket that can allow me to track the rocket even if onboard GPS is lost (as is typical during ascent and sometimes during descent) or if telemetry is lost. ___ time-nuts mailing 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] Need advice for multilateration setup
On 03/26/2015 02:25 PM, Hal Murray wrote: I want to develop a tracking system for an amateur rocket ... Do you need the position in real time, or just after the rocket returns so you can find it? Near real-time would be nice but I guess not an absolute requirement. 40 ns is 25 MHz. It shouldn't be hard to find a uP with counter/timer that runs faster than that. I think you can get away without fancy oscillators. I'm assuming you can use GPS to get the the initial position of the rocket and the receiving stations. I'm also assuming that the rocket can start transmitting a few seconds/minutes before launch to calibrate things. Suppose the receiver puts out a pulse. Feed that to a uP with a counter/timer module that gives you a time stamp. Feed all the time-stamps to a central PC that will sort things out. If the pulses are far enough apart it will be easy to figure out which time-stamps go together. [1] The clocks used to make the time stamps don't need to agree on a base time. You can sort that out at the PC with data from before the rocket leaves the ground. Good idea - I hadn't thought about that. As long as they don't drift too far, I can calibrate out the initial drift. If a flight lasts 100 seconds (handy number for back of napkin calculations) and the calibration/drift is off by 1E9, that's 100 ns. So you will need an oscillator that is stable to better than 1E10 over 100 seconds. Ballpark/handwave. Powered flight will be less than 30 seconds. Depending on when the chute deploys, it may take a few minutes or tens minutes to make it all the way down. If the chute doesn't open (a common occurrence), then it will come down much faster :) You can also calibrate the receiver oscillators again after the rocket lands. Does the transmitter survive the landing? Does the antenna survive well enough? If I get the rocket back in a small number of pieces, it will be an achievement. The recovery success rate with large amateur liquids isn't that grea Is Z interesting? I'm assuming you are firing rockets in flat desert terrain. All the receivers will be in the same plane. I'll bet the math has troubles if you try to calculate the Z when the rocket is near the plane of the receivers. Have you looked into a different set of algorithms that assume the rocket is on the ground? Altitude (z) is not too important for finding it but will be useful in confirming the performance. From the multilateration simulations I've done so far, there are some bad areas and yes, near the ground isn't too good if all them are in the same plane. Maybe I can put one or more of the ground stations on a big hill or something. Good point though - if they're nearly in the same plane, the equations may be a bit simpler. -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Need advice for multilateration setup
I've already integrated an onboard IMU (Analog Devices ADIS16xxx) but they have a lot of drift, especially in a high-g environment. I plan to record the raw IMU data to a flash card and assuming I can recover the card intact, I'll use it to tune a Kalman filter algorithm for the future version that will have active control. I understand your point - it is a complicated solution but that's some of the fun of the project, trying out new ideas and learning new concepts. -Bob On 03/26/2015 01:10 PM, Mike Cook wrote: Sounds over complicated. Why not use an onboard triple-axis accelerometer? A few mm of real-estate, milliamp consumption, up to 16g, 600+ samples a sec. The code is probably already available. Le 26 mars 2015 à 03:27, Robert Watzlavick roc...@watzlavick.com a écrit : I'm working on a project that I could use some advice on and also might be of interest to the list. If it's not appropriate for the list, my apologies. I want to develop a tracking system for an amateur rocket that can allow me to track the rocket even if onboard GPS is lost (as is typical during ascent and sometimes during descent) or if telemetry is lost. The idea is to use a transmitter in the rocket and have 4 or more ground stations about a mile apart each receive the signal. Multilateration based on TDOA (time difference of arrival) measurements would then be used to determine x, y, z, and t. With at least 4 ground stations, you don't need to know the time the pulse was transmitted. The main problem I'm running into is that most of the algorithms I've come across are very sensitive to the expected uncertainty in the time measurements. I had thought 100 ns of timing accuracy in the received signals would be good enough but I think I need to get down less than 40 ns to keep the algorithms from blowing up. My desired position accuracy is around 100 ft up to a range of 100k ft. There were two different methods I thought of. The first method would transmit a pulse from the rocket and then use a counter or TDC on the ground to measure the time difference between a GPS PPS and the pulse arrival. This is the most straightforward method but I'm worried about the timing accuracy of the pulse measurement. I should be able to find a timing GPS that has a PPS output with about +/- 30-40 ns of jitter (2 sigma) so that portion is in the ballpark. There also seem to be TDCs that have accuracy and resolution in the tens of picosecond range but they also have a maximum interval in the millisecond range. I'm not sure I can ensure the pulse sent from the rocket will be within a few miilliseconds of the 1 PPS value on the ground. I will have onboard GPS before launch so in theory I could initialize a counter to align the transmit pulse within a millisecond or so to the onboard PPS. But, once GPS is lost on ascent, unless I put an OCXO onboard that pulse may drift t oo far away (due to temperature, acceleration, etc.) for the TDC on the ground to pick it up. Plus an OCXO will add weight and require extra power for the heater. Another idea would be to send pulses at a very fast rate, say 1 kHz to stay within the TDC window. But then I need to worry about what happens if the pulses get too close to the edge of the TDC window. One other variable is the delay through the RF chain on the receive end but I figure I could calibrate that out. The other idea, and I'm not sure exactly how to implement it, would be to transmit a continuous tone (1 kHz for example) and perform some kind of phase measurement at each ground station against a reference. I could use a GPSDO to divide down the 10 MHz to 1 kHz to compare with the received signal but how can I assure the divided down 1 kHz clocks are synchronized between ground stations? Are the 10 MHz outputs from GPSDOs necessarily aligned to each other? I let two Thunderbolts sit for a couple of hours and the 10 MHz outputs seemed to stabilize with an offset of about 1/4 of a cycle, too much for this application. Another related idea would be to use the 10 MHz output to clock an ADC and then sample several thousand points using curve fitting, interpolation, and averaging to get a more accurate zero crossing than you could get based on the sample rate alone. Adding a TDC would allow the use of RIS (random interleaved sampling) for repetitive signals which could generate an effective sample rate of 1 GS/s. Does anybody have advice or practical experience on which method would work better? Thanks, -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Ceux qui sont prêts à abandonner une liberté essentielle pour obtenir une petite et provisoire sécurité, ne méritent ni liberté ni sécurité. Benjimin Franklin ___ time-nuts mailing list
Re: [time-nuts] Need advice for multilateration setup
On 03/26/2015 01:56 PM, Jim Lux wrote: The key is that you don't need *real time* position.. a few seconds or minutes delay is probably ok, right? Seconds are probably ok, minutes might be a little long. PCs are pretty fast though these days for signal processing I would think. To compensate for the receiver variability, simultaneously transmit a signal with a different PN code, at the same frequency (roughly) as the rocket's transmitter.. The receiver will receive both, but the signal from your ground reference transmitter isn't moving, so you can use the non-rocket signal as a calibration reference. Now I didn't think of that - so you're saying to send another signal from a central ground station to all the receivers and then have them use that as a relative reference? Since I'll know where each ground station is, I should be able to subtract off the TOF so each station has a common reference point. That's a pretty cool idea. What's your budget? I was thinking in the $1k range so that would be about $200 per ground station. A couple of controllers I was considering for the ground stations include the Netburner MOD54415 (same one I'm using for the flight computer) or the BeagleBone Black. Both of those are under $100 and have counter/timers onboard although I have to see what the max clock rate is. As long as the channel-to-channel delay wan't too bad, I think using a 12-bit ADC to digitize the two signals would work because you can interpolate to get a higher-resolution zero crossing. -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Need advice for multilateration setup
I'm working on a project that I could use some advice on and also might be of interest to the list. If it's not appropriate for the list, my apologies. I want to develop a tracking system for an amateur rocket that can allow me to track the rocket even if onboard GPS is lost (as is typical during ascent and sometimes during descent) or if telemetry is lost. The idea is to use a transmitter in the rocket and have 4 or more ground stations about a mile apart each receive the signal. Multilateration based on TDOA (time difference of arrival) measurements would then be used to determine x, y, z, and t. With at least 4 ground stations, you don't need to know the time the pulse was transmitted. The main problem I'm running into is that most of the algorithms I've come across are very sensitive to the expected uncertainty in the time measurements. I had thought 100 ns of timing accuracy in the received signals would be good enough but I think I need to get down less than 40 ns to keep the algorithms from blowing up. My desired position accuracy is around 100 ft up to a range of 100k ft. There were two different methods I thought of. The first method would transmit a pulse from the rocket and then use a counter or TDC on the ground to measure the time difference between a GPS PPS and the pulse arrival. This is the most straightforward method but I'm worried about the timing accuracy of the pulse measurement. I should be able to find a timing GPS that has a PPS output with about +/- 30-40 ns of jitter (2 sigma) so that portion is in the ballpark. There also seem to be TDCs that have accuracy and resolution in the tens of picosecond range but they also have a maximum interval in the millisecond range. I'm not sure I can ensure the pulse sent from the rocket will be within a few miilliseconds of the 1 PPS value on the ground. I will have onboard GPS before launch so in theory I could initialize a counter to align the transmit pulse within a millisecond or so to the onboard PPS. But, once GPS is lost on ascent, unless I put an OCXO onboard that pulse may drift too far away (due to temperature, acceleration, etc.) for the TDC on the ground to pick it up. Plus an OCXO will add weight and require extra power for the heater. Another idea would be to send pulses at a very fast rate, say 1 kHz to stay within the TDC window. But then I need to worry about what happens if the pulses get too close to the edge of the TDC window. One other variable is the delay through the RF chain on the receive end but I figure I could calibrate that out. The other idea, and I'm not sure exactly how to implement it, would be to transmit a continuous tone (1 kHz for example) and perform some kind of phase measurement at each ground station against a reference. I could use a GPSDO to divide down the 10 MHz to 1 kHz to compare with the received signal but how can I assure the divided down 1 kHz clocks are synchronized between ground stations? Are the 10 MHz outputs from GPSDOs necessarily aligned to each other? I let two Thunderbolts sit for a couple of hours and the 10 MHz outputs seemed to stabilize with an offset of about 1/4 of a cycle, too much for this application. Another related idea would be to use the 10 MHz output to clock an ADC and then sample several thousand points using curve fitting, interpolation, and averaging to get a more accurate zero crossing than you could get based on the sample rate alone. Adding a TDC would allow the use of RIS (random interleaved sampling) for repetitive signals which could generate an effective sample rate of 1 GS/s. Does anybody have advice or practical experience on which method would work better? Thanks, -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Need advice for multilateration setup
Thanks for the suggestion. Does the DSSS make it easier to correlate between ground stations? I'm not sure how to handle the phase offset on the 10 MHz ref clocks. -Bob On Mar 26, 2015, at 07:25, Attila Kinali att...@kinali.ch wrote: On Wed, 25 Mar 2015 21:27:35 -0500 Robert Watzlavick roc...@watzlavick.com wrote: I'm working on a project that I could use some advice on and also might be of interest to the list. If it's not appropriate for the list, my apologies. The gods have apporved of your request. You may speak now. ;-) I want to develop a tracking system for an amateur rocket that can allow me to track the rocket even if onboard GPS is lost (as is typical during ascent and sometimes during descent) or if telemetry is lost. Given you can synchronize the clocks of the ground stations well enough, then the rest is easy. Then you can get away with having a simple signal generator that only needs an XO. Or you can go for a TCXO to make your signal processing life easier. What you need to do, is actually the same as GPS does: Create a direct spread spectrum signal and track it on all ground stations. The DSSS has the advantage over the single pulse, that it's more resilient against noise and interference. The disadvantage is, that you have to have more complicated hardware. One viable way would be, that you have precisly synchronized sampling systems (e.g. SDR's like the bladeRF which can take an external clock) and then feed the data to a PC where you do the heavy lifting. Then you don't need to build custom hardware at least. Also, if the precision by the DSSS signal is not good enough, you can apply various tricks from the GPS world, like carrier phase tracking, etc. HTH Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] Need advice for multilateration setup
Budget is a concern but not an overriding concern. I'd like to keep the whole system around $1k. I was planning on making it as portable as possible with each ground station being self contained and sending their data to the launch site over a serial RF modem at 9600 baud. I agree though - fiber connections would make it a lot easier. -Bob On Mar 26, 2015, at 08:41, Anders Wallin anders.e.e.wal...@gmail.com wrote: What's your budget? Put a white-rabbit switch (3.5keur) in the middle, and install a mile of single-mode fiber to each rx-station. Then use TDC or FDEL SPEC-cards (1.5keur each) at the RX-stations to time-stamp the incoming pulse. 1 ns systematic and 50 ps RMS random error should be doable. The systematic constant error in time-stamp for each rx-station can maybe be calibrated out in the TDOA-algorithm? The FDEL-card can time-stamp up to 100 kEdges/s (that results in a ca 4 Mb/s datastream). Anders On Thu, Mar 26, 2015 at 4:27 AM, Robert Watzlavick roc...@watzlavick.com wrote: I'm working on a project that I could use some advice on and also might be of interest to the list. If it's not appropriate for the list, my apologies. I want to develop a tracking system for an amateur rocket that can allow me to track the rocket even if onboard GPS is lost (as is typical during ascent and sometimes during descent) or if telemetry is lost. The idea is to use a transmitter in the rocket and have 4 or more ground stations about a mile apart each receive the signal. Multilateration based on TDOA (time difference of arrival) measurements would then be used to determine x, y, z, and t. With at least 4 ground stations, you don't need to know the time the pulse was transmitted. The main problem I'm running into is that most of the algorithms I've come across are very sensitive to the expected uncertainty in the time measurements. I had thought 100 ns of timing accuracy in the received signals would be good enough but I think I need to get down less than 40 ns to keep the algorithms from blowing up. My desired position accuracy is around 100 ft up to a range of 100k ft. There were two different methods I thought of. The first method would transmit a pulse from the rocket and then use a counter or TDC on the ground to measure the time difference between a GPS PPS and the pulse arrival. This is the most straightforward method but I'm worried about the timing accuracy of the pulse measurement. I should be able to find a timing GPS that has a PPS output with about +/- 30-40 ns of jitter (2 sigma) so that portion is in the ballpark. There also seem to be TDCs that have accuracy and resolution in the tens of picosecond range but they also have a maximum interval in the millisecond range. I'm not sure I can ensure the pulse sent from the rocket will be within a few miilliseconds of the 1 PPS value on the ground. I will have onboard GPS before launch so in theory I could initialize a counter to align the transmit pulse within a millisecond or so to the onboard PPS. But, once GPS is lost on ascent, unless I put an OCXO onboard that pulse may drift too far away (due to temperature, acceleration, etc.) for the TDC on the ground to pick it up. Plus an OCXO will add weight and require extra power for the heater. Another idea would be to send pulses at a very fast rate, say 1 kHz to stay within the TDC window. But then I need to worry about what happens if the pulses get too close to the edge of the TDC window. One other variable is the delay through the RF chain on the receive end but I figure I could calibrate that out. The other idea, and I'm not sure exactly how to implement it, would be to transmit a continuous tone (1 kHz for example) and perform some kind of phase measurement at each ground station against a reference. I could use a GPSDO to divide down the 10 MHz to 1 kHz to compare with the received signal but how can I assure the divided down 1 kHz clocks are synchronized between ground stations? Are the 10 MHz outputs from GPSDOs necessarily aligned to each other? I let two Thunderbolts sit for a couple of hours and the 10 MHz outputs seemed to stabilize with an offset of about 1/4 of a cycle, too much for this application. Another related idea would be to use the 10 MHz output to clock an ADC and then sample several thousand points using curve fitting, interpolation, and averaging to get a more accurate zero crossing than you could get based on the sample rate alone. Adding a TDC would allow the use of RIS (random interleaved sampling) for repetitive signals which could generate an effective sample rate of 1 GS/s. Does anybody have advice or practical experience on which method would work better? Thanks, -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow
Re: [time-nuts] Symmetricom TymServe 2100-GPS currently fails with GPS offset
I'm seeing the same thing with my TS-2100 - it is one second behind WWV based on the front panel display. My ET-6000 appears to be in sync. What's interesting though is that I have a little applet on my iPhone (NetTime) that connects to nist.time.gov and it is also a second behind. -Bob On 01/23/2015 03:36 PM, Esa Heikkinen wrote: Hi! It seems that there's serious bug in Symmetricom Tymserve 2100 most recent firmware (V4.1). When leap second pending flag was added to GPS transmission (according to data shown by Lady Heather) the Tymserve's time started to be exactly 1 second late from UTC! Currently it claims that current UTC offset is 17 seconds, while Lady Heather shows 16 seconds. Also if I compare the NTP time with another NTP servers it is really 1 seconds late. Playing with telnet: ? utcoffset GPS -- UTC Offset = 17 (And of course there's no way to set this manually) However in the utcinfo data the dTLs value received from GPS is correct (16) but it seems that Tymserver firmware uses wrong value dTLsf, which is the future value of UTC offset after leap second event: ? utcinfo A0:0.000 A1:0.000 dTLs:16 ToT:61440.000 WNt:1829 WNLsf:1851 DN:3 dTLsf:17 It seems that there's no way to fix this. There's also leap second command available, having no efffect on this. Everyone who owns this device please check what's going on with it... To me this is somehow suprising, assumed this to be professional grade, reliable and trouble free instrument, but obviously it's not. No wonder why these are sold so cheap on Ebay (where I got mine). Maybe only way is to run this with 1PPS from Thunderbolt until the leap second period is over. ___ time-nuts mailing 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] Looking for WWVB digital wall clock with digital 24 hour UTC display
Definitely avoid BRG clocks. They are reasonably priced and look really nice on the outside but look like a high school science project inside. Plus, with both versions I purchased (while at 2 different companies), the IRIG-B option just didn't work reliably. It worked some of the time, just enough to make you think it was working. Finally, the menu system is confusing at best. Just say no... -Bob On 02/19/2014 05:52 PM, Richard (Rick) Karlquist wrote: Can anyone recommend a atomic wall clock that displays in digital 24 hour UTC? Looking for largest possible digits and LED preferred over LCD, under $100. Any brands to avoid? Rick ___ time-nuts mailing 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
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. -Bob On 02/06/2014 11:03 PM, Magnus Danielson wrote: The BC637PCI already have a VCXO onboard, but you add a OCXO on the outside to get much better results. It was the original poster that needed help. My problems with the BC637PCI was that one of my boards didn't respond completely as documented. 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] recovering firmware on TS2100
Glad to hear it worked out for you! That's also good to know about the TFTP client compatibility with the TS2100. -Bob On 12/29/2013 09:09 AM, Anton Kapela wrote: Rob, On Sat, Dec 28, 2013 at 11:00 PM, Robert Watzlavick roc...@watzlavick.com wrote: Are you talking about the archive named DatumET-6000TS-2100.zip and the file named Tymserve.bin? Indeed, that's the file. If so, I uploaded that file last year. It's a direct ROM image from a flash reader/programmer. Makes perfect sense. That's why I included the device type (AMD 29F040B-120JC) in the readme.txt. You should be able to restore your image using a flash programmer. Another list user had directed me to a SREC format of the same data; TFTP transfer (using an IOS router as a host...fbsd/linux/osx tftpd's weren't compatible w/ TS2100 v1.x tftp client) and update worked out cleanly. I'll convert the binary to SREC for grins, see if it matches ;) Thanks for the clarification, -Tk ___ time-nuts mailing 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] recovering firmware on TS2100
Are you talking about the archive named DatumET-6000TS-2100.zip and the file named Tymserve.bin? If so, I uploaded that file last year. It's a direct ROM image from a flash reader/programmer. That's why I included the device type (AMD 29F040B-120JC) in the readme.txt. You should be able to restore your image using a flash programmer. -Bob On 12/26/2013 02:07 PM, Anton Kapela wrote: Fellow nuts, I've got a TS2100 that failed to install/write a flash image of v 4.1 (using firmware from http://ko4bb.com/). Looking at the tcpdump of the packets in flight, I get the sense that the TS2100 isn't liking what I've got to offer it (I'm assuming it's checking for SREC format, not finding it, and aborts the transfer). After several failed attempts to copy the image over (tried atftpd on linux, tftpd on fbsd and osx...), I lost power and the unit is now setting on console port only, using the v1.x recovery rom image. So, access is there, network stack is up, etc. I tried again from the recovery image to copy over v 4.1 to flash -- to avail. Of course, after this failed to work, I noticed that ko4bb's archive of v 4.1 isn't SREC format (and I see many ref'x to the .HEX files as having been provided in SREC format). It looks like what I've got is an actual raw binary image of the executable code, not the SREC equivalent. So, does a guy have to covert this binary to SREC himself, or is there something I can nab right-quick online? ...better yet: can anyone confirm the zip archive on kobb.com is legit, and not corrupt? Best, -Tk ___ time-nuts mailing 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] TS2100 Firmware
See the following link for an image of the v4.1 firmware: http://ko4bb.com/Manuals/04)_ROM_Images_and_Drivers/DatumET-6000TS-2100.zip -Bob On 10/09/2013 02:49 PM, Gerhard Wittreich wrote: I have just purchased (eBay) a TS2100-IRIG with firmware v3.1. I believe v4.1 is the latest. I requested access to the Symmetricon software download but have not yet been approved. Not sure what criteria they use for approval or if the TS2100 firmware is still on their site. Does anyone have access to the latest firmware file and is willing to send it to me? BTW...Inspired by this mailing list I am hoping to use a Trimble Resolution T to convert this to a GPS unit. -- Gerhard ___ time-nuts mailing 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] 10 MHz output level from DATUM 9390...
I believe you can adjust the level of the 10 MHz output. The schematic shows a pot at R60 or R50 (the scan isn't clear) connected to U18 which drives the 10 MHz sine signal. -Bob On 12/15/2012 05:37 PM, Ziggy wrote: Burt - On the scope I see 950mv RMS with 50 ohm termination, 1.5V RMS with 1M. This is on a 9390-6000 OCXO with the default timing output configuration, 10MHz on J7. Hope this helps. Paul - K9MR On Dec 15, 2012, at 4:21 PM, Burt I. Weiner wrote: Gang, Does anyone have a DATUM 9390 series GPS receiver that can tell me what the (50 Ohm) terminated output level of the 10 MHz spigot is. One of mine started spurring and the other one is clean, but seems way to high in output level. Thanks, Burt, K6OQK Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ time-nuts mailing 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] re ET-6000 firmware
The manual I have isn't too clear on the differences between the units but the drawing shows an LPRO tucked into the left front of the unit with 2 coax cables going to the PC board (EFC, OSC), and one going to an additional power supply in the right rear. The ET-6000 DAC is 0-5V (actually 0.5-4.5 I think) so the LPRO will probably work without any adjustments other than the new firmware which contains the appropriate gain and filter constants. I believe all you need to do is: Remove the TCXO (or cut the trace from the output) Connect the 10 MHz from the LPRO to J3 (OSC in) Install a suitable resistor at position R96 (it shows 51 1 - 51 ohm, 1 watt?) Connect J2 (DAC out) to the LPRO Install an appropriate power supply for the LPRO Somebody mentioned a while back that the units with the LPRO in them ran very hot. -Bob On 08/26/2012 02:05 PM, Joe Leikhim wrote: Bob; I have a TCXO version and wonder apart from the ROM change, what recommended hardware is required to install a rubidium osc? Is there a parts list somewhere? I would prefer not to cobble up if I can help it. I finally got a flash programmer so I uploaded all three ROM images (TCXO, OCXO, Rub) for the Datum ET-6000 / 9390-6000 to the KO4BB website. Last year I sent them 3 chips and asked for all the variants so I could play with converting my TCXO unit to an OCXO unit (and potentially a Rubidium some day). I think the images are in the upload folder awaiting their final home. This latest firmware addresses the GPS date problem. DT101E = TCXO DT102E = OCXO DT103E = Rubidium Some guy is selling DT101E chips on eBay for $50 (sorry if you're on the list...) -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] ET-6000 firmware
I finally got a flash programmer so I uploaded all three ROM images (TCXO, OCXO, Rub) for the Datum ET-6000 / 9390-6000 to the KO4BB website. Last year I sent them 3 chips and asked for all the variants so I could play with converting my TCXO unit to an OCXO unit (and potentially a Rubidium some day). I think the images are in the upload folder awaiting their final home. This latest firmware addresses the GPS date problem. DT101E = TCXO DT102E = OCXO DT103E = Rubidium Some guy is selling DT101E chips on eBay for $50 (sorry if you're on the list...) -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt GPS rollover
Sorry to resurrect an old thread but I also have a question about using the Thunderbolt in the future. I'm considering using 4 of them in a multilateration setup to track an amateur rocket with an onboard beacon. I'm a few years away from the flight so I don't want to invest in hardware that may not work. It doesn't matter if the date (or even the absolute time) is wrong as I'll just be measuring the delta time between reception of the beacon and each unit's 1 PPS output. However, accurate position data would be required. I would also need the 10 MHz to be usable to drive the counter measuring the delta time. Will the unit still work but just put out the wrong date? Or will it effectively turn into a brick? Thanks, -Bob On 10/19/2011 08:06 PM, Thomas S. Knutsen wrote: I do assume this is because of the 1024 week cycle? if so would it be possible to tell the GPS what cycle it should be? Would the 10MHz out still be accurate? BR. Thomas. 2011/10/20 Mark Simshol...@hotmail.com: On July 30, 2017 all our Thunderbolts turn into back-dated pumpkins... ___ time-nuts mailing 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] 2 (Spoofing)
I used to get tons (100-300 a day) of backscatter emails - emails that were supposedly sent by me but bounced back because the recipient didn't really exist. I use a web hosting company for my website and email so I had them enable SPF (Sender Policy Framework) on my domain and all that stopped within a few days. I'm not an expert on it but the way I understand it, any email received by a compliant system is supposed to check if SPF is enabled and if so, verify the email is from a legitimate source. Here are more details: http://www.openspf.org/Introduction -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] locate 6 digit digital clock
I would avoid BRG clocks. I've used them in two different companies now and they're pretty much junk in my opinion. Both of the clocks I used had IRIG inputs and they only sort of work. They seem to randomly lose IRIG lock every few days and will easily get 1/2 second off, even when locked. The user interface is incomprehensible and takes me 20 minutes to figure out every time I have to adjust the UTC offset to display local time. Finally the instruction manuals are too complicated to be useful. It seems like they just keep tacking on features to firmware written 20 years ago, even with the new features don't fit the UI model. When IRIG time wouldn't sync up on one of the units, I took it apart and found the clock to be constructed of a metal picture frame with the circuit boards loosely laying inside some green crafting foam and wires running all over the place. Even my electronics projects when I was a kid looked more professional than these clocks. When I reassembled it, the IRIG feature mysteriously started working again, sort of. The prices look very appealing but trust me, stay away - they just don't work. -Bob On 06/08/2011 03:46 PM, Bob Camp wrote: Hi Found the GSA price list at: http://www.brgprecision.com/pdffiles/brg_gsa_contract.pdf Looks like you can get the basic no frills model for about $400 and they go up from there. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Wednesday, June 08, 2011 4:35 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] locate 6 digit digital clock Hi I suspect that something like: http://www.brgprecision.com/products/synchronized_clocks/poe6mega.php would do the trick. No idea what they cost. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of William H. Fite Sent: Wednesday, June 08, 2011 4:07 PM To: j...@quik.com; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] locate 6 digit digital clock I think he wants a clock that will actually tell time, rather than one that merely blinks *12:00...12:00...12:00...* [?][?] On Wed, Jun 8, 2011 at 3:10 PM, J. Forsterj...@quik.com wrote: Why not just buy or scrounge a small microwave oven or VCR? -John == Please add my me-too to this discussion. I would like to see a clock that simply tells time, reminiscent of the ones I put together in the 1970s, but with LED displays large enough to read from across a darkened room. I would prefer 24-hour format and I want a 6-digit display with seconds. For accuracy, I would want an internal TCXO, with the option of using a 10 MHz or 1 PPS external signal when available, but I want the clock to automatically switch to the internal timebase if the external signal is disconnected or lost With a PIC I would like to see a switch for PDT/PST, so I don't have to reset the clock twice a year. I would also like to see an option for having the clock be self-setting or self-synchronizing by adding an inexpensive GPS module. I don't need date and I don't need DOW or DOY as I already have other clocks and watches that give me that information. It might be useful to have a smaller second line that would show me those, and show me the time in UTC to keep track of what time it is back in the old country when I want to listen to Radio Denmark on the Internet, but this would add to the complexity and the number of solder points. And I would like all this to fit in a spare HP 2U half-width rack-mount case that I have saved for that purpose. This would be a companion to my Thunderbolt GPSDO which is housed in an identical case. One option would be to mount the clock in the same case as the Thunderbird, and have the second line display your choice of GPS signal. -- Flemming Larsen, KB6ADS/OZ6OI Fra:Brooke Clarkebro...@pacific.net Til:Discussion of precise time and frequency measurement time-nuts@febo.com Sendt:7:12 onsdag den 8. juni 2011 Emne:Re: [time-nuts] locate 6 digit digital clock By using a PIC you can do much more than just tell time, for example display the Day of the Week and because the calendar is good back to 1800 something you can set the clock back that far and know the DOW. The next step was going to be to install a table of leap seconds so that you could replay any of those events in history. See: http://en.wikipedia.org/wiki/Zeller%27s_congruence Have Fun, Brooke Clarke http://www.PRC68.comhttp://www.prc68.com/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] 58536A splitter and 9390-6000 GPS
On 05/19/2011 10:35 PM, WB6BNQ wrote: Robert, Two questions. First, what is the voltage at the 9390 antenna connector with nothing attached besides your DVM ? It shows 5V open circuit. Second, what happens if you just attach the antenna straight to the 9390 ? By this i mean if voltage is on the antenna connector and while you are observing it and then attach the antenna what happens ? I found something interesting here - with it connected straight to the antenna, I measured 4.6V. I connected and disconnected it several times and didn't see any drops. But, after the 5th connection or so, I finally got the 9390 to show the same behavior as with the splitter and shut off its antenna supply. So it seems it's not exclusive to the splitter but just that it occurs more often. The antenna is connected directly to the little GPS daughterboard module and I don't have schematics for it. This isn't a showstopper, just interesting behavior. One of the things I like about the 58536A is that it will continue to power the antenna if you remove other receivers from the ports (for troubleshooting etc.) I guess with this particular receiver, it is a little more sensitive to antenna disconnects while it is powered on. I suspect there is some protection process with the 9390 and the load or reverse voltage present from the splitter is causing it to activate. However, I am not familiar with that unit. Just asking general troubleshooting questions. BillWB6BNQ Agree - thanks. -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] 58536A splitter and 9390-6000 GPS
I received my Symmetricom 58536A GPS antenna splitter today (new from eBay) and did some testing with my Datum 9390-6000, Datum TS2100, and Thunderbolt. The Thunderbolt and TS2100 work fine with the splitter but the 9390 has some interesting behavior with the splitter. If the 9390 is connected by itself to the splitter, it doesn't report any satellites. However, if I then connect either of the other two receivers (Thunderbolt or TS2100) to the splitter, the 9390 will start picking up satellites. Then, if I disconnect the other receivers and leave the 9390 connected by itself, it continues to work. I tested this several times and it seems to be repeatable behavior. So as long as a different receiver has been connected to the splitter at least once, the 9390 works with it. I'm thinking the initial surge of connecting the 9390 to the splitter is causing a momentary overcurrent which shuts down the antenna supply. In the failure case, the voltage measured (with a T) at the splitter from the 9390 is 0V. In the working after a different receiver has been connected case, I measure 4.3V. The other two receivers output 5V with no load and about 4.6V under load connected to the splitter. Has anybody seen this before? The antenna is a Symmetricom AT575 type antenna. -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lady Heather Question
I think the graph is not using peak detect for the plotting. I leave mine set at a 12-hour window and all the points are moving around every second. When plotting more data than will fit in the available resolution, it is best to bin the points that correspond to each plot bin/pixel. Then you can plot a bar (min/max) or a single point (mean) for that bin. -Bob On 05/02/2011 01:14 AM, Ed Palmer wrote: I've been running Lady Heather for some months now. I've always been puzzled by one characteristic of the graphs. If I use a view setting of anything other than 1 sec. per division, the oscillator graph in particular, 'runs wild'. Spikes appear and disappear. From second to second the sdv value can swing up and down by 10 or 20 ppt or more. The ADEV values reported by Lady Heather are stable at 1.x e-8 @ 1 sec. and 1.x e-12 @ 10K sec. through this. My ability to measure ADEV at low Tau values is not great, but I'm getting numbers in the e-12 range for Tau = 1-10 seconds which suggests that the Osc isn't all that bad. Lady Heather Version 3.0; Jan. 15 - 2011. Autoscaling of the graphs is disabled. Time Constant, Damping, Gain are at default Satellite constellation is stable. Right now it happens to be 5 satellites. What's going on? Thanks, Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] Upgrading TS2100 from TCXO to OCXO
That's good to know. I've been running the TS2100 for a few days with a Morian MV89A (too big to fit into the case though) and it seems to work well, definitely more stable than the TCXO. A test that I haven't run yet is to pull the GPS antenna and see how long the NTP server reports Stratum 1 performance and what the dispersion values are. You're correct about the d/a setting - it seems all you have to is set it and it stores it in NVRAM. -Bob On 03/28/2011 07:28 PM, Greg Dowd wrote: I think a couple of those bits do correspond to the oscillator type installed but I think you can ignore them. If I remember right, those oscillator bits were only used to calculate the dispersion update for ntp packets when flywheeling through a loss of signal. As far as I recall, you just need to change gain and filter. And the setting for the current d/a value should have been accessible in root tim utils as d2a. As someone pointed out, the default ovenized for those boxes was the MTI 240 low profile. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Robert Watzlavick Sent: Sunday, March 27, 2011 3:54 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Upgrading TS2100 from TCXO to OCXO If anybody has a TS2100 that came from the factory with an OCXO, can you telnet into the unit and run the following command? root eng ee info This appears to be some sort of factory-configured personality of the board. My TS2100-GPS unit with a TCXO has an info value of 0024. A TS2100-IRIG unit (no GPS) with a TCXO has a value of . I'm curious whether any of those bits correspond to the oscillator type or if all that needs to be changed is the gain. Thanks, -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] Upgrading TS2100 from TCXO to OCXO
If anybody has a TS2100 that came from the factory with an OCXO, can you telnet into the unit and run the following command? root eng ee info This appears to be some sort of factory-configured personality of the board. My TS2100-GPS unit with a TCXO has an info value of 0024. A TS2100-IRIG unit (no GPS) with a TCXO has a value of . I'm curious whether any of those bits correspond to the oscillator type or if all that needs to be changed is the gain. Thanks, -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Upgrading TS2100 from TCXO to OCXO
Ok, thanks. I was so focused on the IRIG and 10 MHz parts I didn't think about the NTP function (which is what the unit is for after all). BTW - I had some misinformation in my original post. The Abracon AOCJY1A is probably pin compatible with the TS2100 but it's not voltage compatible. The OCXO supply voltage on PC board pads is 12 not 5 volts. So unless I can get the same MTI 240 OCXO, then I'm looking at just putting one in the case somewhere and running wires to it. I'd prefer not to cut traces. Anybody know of an inexpensive OCXO that meets the following criteria? 10 MHz sine output 12V or 5V supply voltage (either will work since it will be installed off board) 5V EFC (TS2100 DAC is 0.5-4.5V) Small enough to fit in a 1U rack enclosure (the Morion MV89A is too tall) I'm not striving for perfection, just some that is significantly better than the stock TCXO. -Bob On 03/25/2011 02:11 AM, Hal Murray wrote: Not sure what the precision setting is for (it's currently -19). That's probably for NTP. Roughly, it's how many useful bits of data you get when you read the clock. I can probably find a description if anybody is curious. -19 is 2 microseconds which is a reasonable ballpark for an embedded system. ___ time-nuts mailing 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] Upgrading TS2100 from TCXO to OCXO
I've been able to successfully upgrade my Datum TS2100 to an OCXO from the stock TCXO. I didn't see it in the archives so I thought I'd post my findings. I noticed that the same firmware was used regardless of oscillator configuration so there must either be jumpers or a hidden set of commands. The newer versions of the ET6000 have jumpers to select the oscillator but I couldn't find anything similar on the TS2100. However, in the back of the manual, 8500-0033 Rev K, Appendix I describes how to reconfigure the unit to output GPS instead of UTC for NTP. I'm not interested in that but there are some hints about a hidden menu structure (root eng ee) which allows you to change EEPROM settings. Here's the hidden menu items: root eng: start net interface timing tools / serial tools / eeprom tools / spi tools / flash tools / display tools / memory tools / intrinsic help Going further into one of them, root eng eeprom: ethernet address board serial number gain default filter constant low filter constant precision set eeprom get eeprom read serial eeprom write serial eeprom tx 16 bits to eeprom location for image info value eeprom_select intrinsic help So that's where the default gain and filter constants are set. You have to jumper across J4 on the PC board to allow EEPROM writes or you get an error. Not sure what the precision setting is for (it's currently -19). I don't have the proper OCXO (yet) but I do have an MV89A OCXO that I was able to wire into the circuit temporarily. There is 12V on the board and the 0.5-4.5V EFC range works well with the MV89A. I used a gain of +20 and a filter setting of 0.9994965 based on Jason Rabel's post from 9/26/2010 (note the sign change on the gain). The EFC algorithm had a pretty good overshoot during the first adjustment cycle and took over an hour to completely settle in but eventually the front panel Locked LED turned on. I couldn't find a way to change the starting value for EFC (d/a) value. I *think* an Abracon AOCJY1A-10.000MHz-E-SW part will be pin compatible on the board. Unfortunately nobody has that one in stock and it's a 10 week lead time so I may end up installing one off-board. The MV89A is too tall to fit with the lid on so it's not a long term option. I traced out the two SMA pads on the board and they are for the EFC out and RF in so I could always run them to the back of the unit and put the OCXO outside the unit. -Bob K5RLW ___ time-nuts mailing 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] STP2145A control voltage
Can anyone confirm the control/reference voltage for an STP2145A OCXO? The datasheet posted on eBay says 12V supply and 5V control voltage but it looks like they just copied the one for the MV89A. If they are truly the same spec that's fine but before I order it, I thought I'd see if anybody here actually has one. Thanks, -Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Oscillator questions
Hi, I'm new to the list and I'd appreciate some advice regarding my application. One of my hobbies is building and testing liquid fuel rocket engines (http://www.watzlavick.com/robert/rocket). As part of my instrumentation system, I have some Datum 9550 Video Time Overlay units which stamp time from IRIG-B onto NTSC video from various cameras positioned around the static test stand. I also have a Datum bc635PCI card which generates the IRIG-B signal and outputs a TTL start pulse to synchronize the data acquisition system so I can associate a particular video frame with the measured data. The data system uses National Instruments hardware (PXI-6030E, SCXI-1520) and can accept a start trigger and a reference clock. I discovered that the accuracy of the built-in 10 MHz reference clock in the PXI chassis is sufficiently different from the flywheeling bc635 card that even over a few minutes, they can drift by up to tens of milliseconds. That sort of negates the goal of lining up the video with the data so I routed the 10 MHz out from the bc635 into the PXI chassis CLKIN to lock them together. That seems to work fine as even after several hours, the data and video are still synchronized. When I did that experiment, I didn't have any good 10 MHz reference sources to compare against other than the PXI chassis which is rated at +/- 25 ppm and 5 ps RMS of jitter. The bc635 has a VCXO which probably isn't that good either. I looked at the 10 MHz out from the bc635 and it looked pretty clean and stable so I assumed it was good enough. A few months ago, I decided I needed a better 10 MHz reference source because I was trying to calibrate some pressure transducers against a Paroscientific DigiQuartz which has a frequency output as a function of pressure. On a related note, I had always wanted a GPS-based NTP server of my own (just because!) so I picked up a Datum TymServe TS2100 w/GPS from eBay. As an added bonus, it has a GPS-synchronized IRIG-B output I could use for the rocket testing and a disciplined 10 MHz I could use with my HP5316A and the Paroscientific. All good, or so I thought, until I compared the 10 MHz out from the TS2100 to the OCXO in the 5316A. When locked to GPS, the TS2100 jumps all over the place relative to the 5316A. I know it's the disciplining algorithm because when I turn it off, it's actually pretty stable compared to the 5316A. I see the same thing when I compare the ref clock out from the bc635 to the 5316A on a scope - it seems to be correcting once a second but the phase is all over the place, sometimes moving 2-3 cycles before it reverses. I'm not sure how to quantify it but I'm wondering whether the jitter from the TS2100 or bc635 will be enough to screw up the reference clock on the PXI chassis for the data system. The data sheet on the PXI-1042 chassis says it uses a PLL to phase lock to an incoming clock so maybe it dampens out the jitter and it's not a problem. But, I'm the type that likes to look at the details so I bought a Thunderbolt from eBay and I was able to confirm it is definitely the TS2100 and bc635 that has the issue. No amount of playing with the gain and filter settings in these units cuts down on the phase shifts so I'm guessing it's a byproduct of the cheap VCXO they use. I was thinking of upgrading both of those units to an OCXO to improve the stability, an MTI-240 for the TS2100 and an MTI-210 for the bc635. The boards appear to be pin compatible with these units so they should just work. I have the schematic for the bc635 and it looks straightforward to change it out but on both units I'll have to reprogram the OCXO gain settings each power cycle because I can't figure out how to make them stick in the EEPROM. I've talked to the MTI rep and he is going to see if he can waive the $1500 min order requirement for me. No idea how much the oscillators will cost, probably more than I want to pay. Has anybody successfully upgraded the oscillators in these units? For now, running the entire data system locked to GPS isn't necessarily a requirement (cool but not really needed) so I could use the 10 MHz from the Thunderbolt to run into the bc635 and on to the PXI chassis. I'd just have to manually set the time in the bc635 and let it flywheel. Another option is to jam-sync the bc635 to GPS and then let it flywheel during the test so it's 10 MHz output doesn't jump all over the place. Sorry for the long post but I'd appreciate any comments or advice you could offer an apprentice time-nut. Thanks -Bob K5RLW ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
