Re: [time-nuts] PPS offset between GPS receivers
I'm now using the SKG25A1 as a PPS source for an NTP server. Aside from the offset, I noticed a large offset jump in the NTP loopstats (attached) occurring about once a day. This is not the server oscillator drifting since the frequency graph looks good at this point and this behavior can sometimes be triggered by issuing an NMEA hot start command. I saw this report showing large differences between the PPS outputs of different receivers: http://www.gmat.unsw.edu.au/snap/publications/mumford_2003a.pdf I'm planning on getting two receivers for comparison, an iLotus M12M and a Synergy SSR-6T (preferably with the discount). No replies from both yet. = Gabs, I've seen similar jumps, and it happens when the GPS/PPS signal drops out for a while. In my case, the GPS receiver is sitting just in an upstairs room, not near a window or the root (as I normally have my other receivers). http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#u-blox Watching a low-current LED connected to the PPS signal (through an appropriate 680-ohm current-limiting resistor), I sometimes see the PPS stop flashing. If it stops for long enough, NTP will revert to a different reference. The hot-start may also result in a re-acquisition, and hence a break in the PPS pulses. I now need a 10-channel 'scope, as I have Rapco 1804M, Trimble Resolution SMT, a couple of Garmin GPS-18/x, Sure Electronics boards, and the u-blox (navigation) receivers shown above. Comparing the PPS outputs they are all within about 100 ns, more or less. G Quite adequate for running NTP on my systems. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PPS offset between GPS receivers
On Tue, Dec 11, 2012 at 5:55 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: Gabs, I've seen similar jumps, and it happens when the GPS/PPS signal drops out for a while. In my case, the GPS receiver is sitting just in an upstairs room, not near a window or the root (as I normally have my other receivers). http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#u-blox Watching a low-current LED connected to the PPS signal (through an appropriate 680-ohm current-limiting resistor), I sometimes see the PPS stop flashing. If it stops for long enough, NTP will revert to a different reference. The hot-start may also result in a re-acquisition, and hence a break in the PPS pulses. I now need a 10-channel 'scope, as I have Rapco 1804M, Trimble Resolution SMT, a couple of Garmin GPS-18/x, Sure Electronics boards, and the u-blox (navigation) receivers shown above. Comparing the PPS outputs they are all within about 100 ns, more or less. G Quite adequate for running NTP on my systems. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk David, I forgot to thank you for your helpful site and NTP plotter. I have the antenna outside with a 180 degree view of the sky, outages should be rare. Looking at the loopstats, the outage during the 4 us jump is about 12 seconds. This is a test server, I only have the LOCAL and PPS refclocks configured so during the outage the clock just flywheels. I agree these cheap GPS receivers are more than enough for a stratum 1 NTP server. How about a 10 channel TIC? I'm sure someone could suggest a way to do it, probably several PICTIC II's? ___ time-nuts mailing 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] PPS offset between GPS receivers
From: Gabs Ricalde [] David, I forgot to thank you for your helpful site and NTP plotter. I have the antenna outside with a 180 degree view of the sky, outages should be rare. Looking at the loopstats, the outage during the 4 us jump is about 12 seconds. This is a test server, I only have the LOCAL and PPS refclocks configured so during the outage the clock just flywheels. I agree these cheap GPS receivers are more than enough for a stratum 1 NTP server. How about a 10 channel TIC? I'm sure someone could suggest a way to do it, probably several PICTIC II's? Agreed, that if your antenna has a good view of the sky you should not be seeing these drop-outs, at least not on a regular basis. There are atmospheric conditions which will affect the GPS signals, though, but they should be rare. No chance you get a trucker with a GPS jammer driving by at the problem times, I suppose? You say LOCAL and PPS - no seconds reference such as GPS/NMEA? You might also want to check what's happening on the box at the time of the jump. If it's regular, perhaps some scheduled task is the cause? Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt oven / non-stable operating temperature
Hi I suspect that to use the temperature chip data, it needs to be running on GPS for several days while ramping temperature. After that, put it in holdover, observe the time drift over the next four hours with a similar ramp. Since they work with the later chip, the ramp would have to be pretty aggressive (many degrees C per hour). Bob On Dec 10, 2012, at 11:23 PM, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: That temperature sensor does have an effect on the final outcome as it is part of the internal equation. So buffering the ambient temperature is important. I've heard this before, but the evidence I have seen does not seem to support the proposition. While switching the Dallas chip in one, I used the opportunity to bring the chip temporarily outside of the Tbolt housing on a cable to investigate whether the Tbolt makes any internal use of the temperature data. Neither freeze spray nor bringing a soldering iron near the chip, when it was outside of the Tbolt housing and the Tbolt housing was well insulated from the changes in chip temperature, seemed to have any effect on the operation of the Tbolt, either normal or in holdover. I have also run Tbolts with the newer (wrong) temperature chips for long periods, and have not observed any systematic differences in performance between them and units with the older chips, either in normal operation or in holdover. In Tbolts with the newer chips, the reported temperature often has little connection with the actual temperature and, at times, jumps abruptly, yet the Thunderbolts operate normally with no corresponding jumps in operating parameters. My supposition/conclusion is that the temperature sensor was provided so telcom operators could get a rough idea of the temperature in remote cell-site transmitter shacks, not for internal use by the Tbolt. As long as the Tbolt is housed so that its reported temperature does not change too rapidly, the oven control loop will keep the crystal very close to its set temperature over a wide range of ambient temperatures. I have used this approach and have also actively controlled the housing temperature, and have not observed any material difference in frequency or timing stability between the two approaches. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt oven / non-stable operating temperature
Bill wrote: Well, perhaps you are not looking close enough. That is you need to be observing at a finer level of comparison. The changes, observed here and at another location, are in parts in 10-10 to 10-11 range, sometimes larger. At one of the locations there was a direct correlation to the air conditioning cycle. It is not clear what part of my message you are referring to. My main point was that the information from the DS1620 temperature sensor does not appear to be used internally by the Tbolt. In my observation, subjecting the sensor alone (thermally isolated from the rest of the Tbolt) to wide temperature swings (-10 to +120 C) did not produce any observabe effect on the operation of the Tbolt. If the temp sensor data were used internally by the Tbolt, one would expect a significant effect from such a wide swing -- one that couldn't be missed. If that large and fast a reported temperature swing produced effects only at the e-10 or 11 level, I would attribute it to imperfect thermal isolation of the Tbolt from the temperature stimulus (i.e., stimulus affecting the oven temperature or EFC circuitry of the Tbolt), not as the Tbolt's response to the temperature change reported by the DS1620 sensor. If you were referring to my side point -- that allowing slow changes to the Tbolt housing temperature does not appear to be materially different from regulating the housing temperature -- my observations were that this was true down to at least 5e-13. Of course, there are two variables -- total swing and rate of change. By slow, I mean a rate of change of 0.25C per hour or less [DS1620 reported temperature]. My diurnal swings are no more than 2C per day and usually less [DS1620 reported temperature] (they can be as much as 5 or 6C seasonally, but those changes happen over weeks). A/C cycling likely subjects the Tbolt to a significantly greater rate of change than what I mean by slow, even if basic precautions are taken (e.g., putting it in a cardboard box). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PPS offset between GPS receivers
On Tue, Dec 11, 2012 at 8:00 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: From: Gabs Ricalde [] David, I forgot to thank you for your helpful site and NTP plotter. I have the antenna outside with a 180 degree view of the sky, outages should be rare. Looking at the loopstats, the outage during the 4 us jump is about 12 seconds. This is a test server, I only have the LOCAL and PPS refclocks configured so during the outage the clock just flywheels. I agree these cheap GPS receivers are more than enough for a stratum 1 NTP server. How about a 10 channel TIC? I'm sure someone could suggest a way to do it, probably several PICTIC II's? Agreed, that if your antenna has a good view of the sky you should not be seeing these drop-outs, at least not on a regular basis. There are atmospheric conditions which will affect the GPS signals, though, but they should be rare. No chance you get a trucker with a GPS jammer driving by at the problem times, I suppose? You say LOCAL and PPS - no seconds reference such as GPS/NMEA? You might also want to check what's happening on the box at the time of the jump. If it's regular, perhaps some scheduled task is the cause? Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk I'm not sure about the jammer but I'm running a timing receiver in position hold several floors up, I haven't seen dropouts like this. ntpd is running with a noselect NMEA source since I'm having problems with ntpd marking the PPS and NMEA as falsetickers. The startup sequence for the server is this: * run ntpd -g -q with NMEA enabled * run chronyd for 3 minutes to set the time and frequency offset * copy the current frequency to ntpd's drift file, then run ntpd with NMEA disabled This hack seems to work everytime with ntpd ready in less than 4 minutes after turning on. I just hope nothing would happen that changes the time. I have seen 0.2 us spikes every hour from some unknown task but the larger spikes are rare. Another device running the same OpenWrt firmware but with a timing receiver has only the small periodic spikes. ___ time-nuts mailing 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] 5061A Beam Current question
Pete, There are two HV power supplies, +3500 (A18) and -2500 (A19), both of which can 'sing'. A18 comes on when power is applied and in CS OFF mode. A19 comes on when you move to any mode other than CS OFF. There is also a battery back up option, Option 002, that has a battery charger board (A2), that can sing when trying to charge 'dead' NiCd's. It comes on when power is applied and in CS OFF mode as well. A2 can be removed with no effect on the rest of the unit to test that theory. When does your unit start singing? The BEAM I indication can be adjusted by the BEAM I METER pot on the control panel. It only adjusts the meter indication, not the beam current. The beam current can be affected/changed by the C FIELD adjustment and by following the instructions in the manual to align the oven controller (A11) and the Electron Multiplier on the Power Regulator board (A15). Once aligned, adjust the BEAM I METER pot for an 'on scale' indication. This is different on the 5061B where BEAM I METER on the control panel is replaced by BEAM I and is, in fact, the Electron Multiplier adjustment. There are different versions of the A15 board, some of which have a pot to adjust the electron multiplier and others with fixed resistors. The change in BEAM I indication as you adjust the COARSE freq can be very small. The larger the beam current, the greater the fluctuation, but it can still be very small, a division or two. The figures in the manual are quite 'magnified' in my experience. However, I have never played with a 'new' CS tube. The change in BEAM I indication as you adjust the COARSE freq is also very easy to miss and it takes only a very small adjustment of COARSE to go through the entire range. My usual procedure is to let the 5061A warm up for several hours, in the CS OFF mode, make sure the OCXO is stable, then compare it's frequency to that of a GPSDO, then adjust the COARSE freq (with FINE set to 250) to precisely match the GPSDO. I have a TBolt that I use it's 10 MHz to trigger the horizontal of a scope and put the 5 MHz of the 5061A to the vertical. That done, I then select LOOP OPEN, let the CS oven warm up, the BEAM I come up, the 2nd HARMONIC come up, then select CONT OPER and hit the RESET button. If the OCXO is 'on frequency', CONTROL should indicate zero and you should be on the top of the center peak. Adjustment of the COARSE should then be able to demonstrate the 'peaks' to prove you are on the top of the center peak. I don't recall any 'false' modes that will give an erroneous indication. However, I have had failures in the LOGIC board (A14) that have caused indication problems. These units are fun to play with and work on. They make great 'house standards'. I leave them in CS OFF all the time, which lets the OCXO and ion pump run continuously. Hope this helps. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Pete Lancashire Sent: Monday, December 10, 2012 10:59 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] 5061A Beam Current question I've got a couple questions on a early S/N 5061A I got a few days ago. It took a couple days but the Ion Pump current is now down to zero or at least less then one division on the meter. I'm able to get the unit to go into continuous operation mode by following the TURN-ON PROCEDURES but have a few qestions 1. The unit 'sings' I'm tone deaf but its a high pitch. It could take some doing to isolate where it is coming from. Any ideas ? 2. How much should the beam current change when turning the OSC FREQUENCY COARSE adjustment ? On time about 45 to 60 minutes The current scribbled on the door is 19, I'm running pretty much 30. When making the adjustment the difference between the peak and any other position is only plus/minus a max of 2 or 3. 3 And i guess for last, are there any false modes that will turn off the ALARM and turn on the Con't Operation light ? Thanks -pete PS Anyone have a side panel without the front handle broken ? ___ time-nuts mailing 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] Lady Heather for Linux?
11/12/2012 13:53 Is there a version of Lady Heather for Linux, or any equivalent application please? Thanks. -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ time-nuts mailing 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] OT: Question on dead HP34401
Gentlemen, I own a dead HP34401. On switching it on the display stays dark. It will however react on pressing the SHIFT key. By changing pcbs against a working one the display board has shown to be ok. There must be a problem with the main board. Without knowing whats inside the ASICs make trapping the problem difficult. One strange thing that I see is that there is a 7 kHz repeating reset signal on the reset line that does NOT come from the voltage regulator's reset output but must be generated by the processor or an ASIC. Anyone having an idea to that? Best regards and TIA for your answers Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing 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] New EZGPIB version
Gentlemen, a new EZGPIB version is available from the usual place. The improvement against the former version is increased speed in writing large data files. Enjoy Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing 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] Real YIG data was: YIG oscillator drift question
Antonio, when I read the question I went into my cellar to return with an AVANTEK 2-4 GHz YIG that I had once moved out of a defective spectrum analyzer. I used an analogue regulated power supply for the oscillator power and my HP6632 in constant current mode (this YIG NEEDS a tuning current) to supply a tuning current of app. 125 mA. Before starting the measurements I let it warm up for a day or so. Then I recorded temperature with a PT100 measured with A HP3457A in four wire mode and frequency with my U6200A counter (referenced to my Z3805) using my EZGPIB utility. You can download the results from my download page http://ulrich-bangert.de/html/downloads.html Look at the bottom for YIG Data. Note that the .zip contains a configuration file for my PLOTTER utility so that looking at the data is a snap with it. Just take care that the Overide binary data Graphic settings in the File menu is disabled and Open the file. While it is surely not comparable to even the worst Xtal it is not as bad as has been reported here from Bob. 73s and Best regards Ulrich Bangert, DF6JB -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von iov...@inwind.it Gesendet: Samstag, 8. Dezember 2012 15:18 An: time-nuts@febo.com Betreff: [time-nuts] YIG oscillator drift question Does anybody have direct experience on playing with YIG oscillators? I have read some specs on drift, but I know they are usually worst cases. I would like to get a raw idea about real measured drifts in reasonably stable temperature for a free running YIG with no tuning current. Yes, of course this depends on make, model etc, but any advise would be appreciated.Thanks in advance,Antonio I8IOV ___ time-nuts mailing 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] Lady Heather for Linux?
Lady Heather runs very nicely from Wine. -Chuck Harris Chris Wilson wrote: 11/12/2012 13:53 Is there a version of Lady Heather for Linux, or any equivalent application please? Thanks. ___ time-nuts mailing 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 for Linux?
On Tue, 11 Dec 2012 13:54:24 +, Chris Wilson wrote: Is there a version of Lady Heather for Linux, or any equivalent application please? Thanks. LH runs fine in Wine - I have 2 instances running on my Ubuntu server. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: Question on dead HP34401
Ulrich, Yes indeed modern stuff is tough. I believe what you are seeing is a dead man timer. The system is not booting correctly, times out and resets and the process keeps going. Typically a good place to look is at the interrupt lines to see what is triggering the behavior. If neither of these are then you are really stuck with tracing down what device is asserting the reset. If it is an ASIC then you are blind. The other thing that could cause this to happen is corrupted uproc eproms. Hard to believe since this is a fairly new device. Regards Paul WB8TSL On Tue, Dec 11, 2012 at 8:52 AM, Ulrich Bangert df...@ulrich-bangert.dewrote: Gentlemen, I own a dead HP34401. On switching it on the display stays dark. It will however react on pressing the SHIFT key. By changing pcbs against a working one the display board has shown to be ok. There must be a problem with the main board. Without knowing whats inside the ASICs make trapping the problem difficult. One strange thing that I see is that there is a 7 kHz repeating reset signal on the reset line that does NOT come from the voltage regulator's reset output but must be generated by the processor or an ASIC. Anyone having an idea to that? Best regards and TIA for your answers Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing 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] PPS offset between GPS receivers
I'm not sure about the jammer but I'm running a timing receiver in position hold several floors up, I haven't seen dropouts like this. ntpd is running with a noselect NMEA source since I'm having problems with ntpd marking the PPS and NMEA as falsetickers. The startup sequence for the server is this: * run ntpd -g -q with NMEA enabled * run chronyd for 3 minutes to set the time and frequency offset * copy the current frequency to ntpd's drift file, then run ntpd with NMEA disabled This hack seems to work everytime with ntpd ready in less than 4 minutes after turning on. I just hope nothing would happen that changes the time. I have seen 0.2 us spikes every hour from some unknown task but the larger spikes are rare. Another device running the same OpenWrt firmware but with a timing receiver has only the small periodic spikes. === Gabs, Sorry, I'm not familiar enough with Linux to be able to help. On my systems there's just the automated start of ntpd, with no 3rd party software, and the PPS is a separate kernel-mode driver, not the one integrated into the NMEA driver. It may be best to ask on the Usenet comp.protocols.time.ntp group to get NTP working properly. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Nifty MINI TIC for DMTD work please hold off, 4 channel pic...
Rex, let me check status and I will get back with you by Thursday. I am presently finalizing a detailed outline of the total package. Bert In a message dated 12/10/2012 7:23:43 A.M. Eastern Standard Time, r...@sonic.net writes: Bert, I have been waiting for more details to become available. Thanks for the update. Not sure exactly what this means: but I have to depend on volunteers to do the drawings and they have to make their time available when convenient. Depending on if the input is in some kind of standard, or a transmittable sketch format, and what the desired output is, maybe I could help. Contact me if you think another cook could possibly help the broth. -Rex in San Jose, CA On 12/9/2012 3:20 AM, ewkeh...@aol.com wrote: We have a choice of two dual mixers, my copy of the original NBS with minor changes and Bill Riley's unit. Comparison tests are ongoing to pick the best. If Bill's shows better results I plan on laying one out using leaded components. 2 channel and 4 channel counters are completed and are being used for testing. Corby has done some more tests plotting single channel using the period mode. Great results. Can use phase or period. A documentation package is being prepared to be placed on Didier's site, but I have to depend on volunteers to do the drawings and they have to make their time available when convenient. Juerg is continuing his work on programming a PIC for LCD display but that will only be an added feature one can use the counters direct with a PC and as you may have noticed Corby sold his SR 620. Bert Kehren In a message dated 12/8/2012 5:50:35 P.M. Eastern Standard Time, w1...@earthlink.net writes: What is the status of this project ? I may have missed a few e-mails. Thanks, Dick, W1KSZ ___ time-nuts mailing 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] FE-5680A OSMT connector / RS232
Thanks for all your suggestions! Ends up that I seem to have found yet a different version of the 5680a :) My DDS board did have an RS232 level shifter but for some reason, the RS232 TX signal was not being brought out to the 5 pin connector. Once I soldered the TX wire directly to the SP233ACT level shifter (pin 5), I was able to communicate with the device. Thanks, James Date: Sun, 09 Dec 2012 23:25:25 -0800 From: Hal Murray hmur...@megapathdsl.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A OSMT connector / RS232 Message-ID: 20121210072525.7b0ef800...@ip-64-139-1-69.sjc.megapath.net Content-Type: text/plain; charset=us-ascii ja...@peroulas.com said: I'm not able to get it to respond to the 'S' command and when I measure the voltage on the RS232 TX pin (#2 from the left) it's always 0v. Shouldn't it be -12v when idle? Newer RS-232 allows 6V rather than 12. In practice, it's not all that uncommon for designers to save a chip and just send 5V CMOS signals. That works fine for short distances. If you can get a scope on it, sometimes embedded boxes send out a hello message at power up. I'd also check pin 3 in case you or they got things swapped. -- These are my opinions. I hate spam. -- *Integrity is a binary state - either you have it or you don’t.* - John Doerr ___ time-nuts mailing 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 oven / non-stable operating temperature
If it is used for tempco it should affect the temp by stabilizing offset with temp changes correct? Maybe a more correct approach would be to disconnect it and test. Has been awhile since I read that testing stuff. Doc Sent from mobile On Dec 11, 2012, at 6:39 AM, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: Bill wrote: Well, perhaps you are not looking close enough. That is you need to be observing at a finer level of comparison. The changes, observed here and at another location, are in parts in 10-10 to 10-11 range, sometimes larger. At one of the locations there was a direct correlation to the air conditioning cycle. It is not clear what part of my message you are referring to. My main point was that the information from the DS1620 temperature sensor does not appear to be used internally by the Tbolt. In my observation, subjecting the sensor alone (thermally isolated from the rest of the Tbolt) to wide temperature swings (-10 to +120 C) did not produce any observabe effect on the operation of the Tbolt. If the temp sensor data were used internally by the Tbolt, one would expect a significant effect from such a wide swing -- one that couldn't be missed. If that large and fast a reported temperature swing produced effects only at the e-10 or 11 level, I would attribute it to imperfect thermal isolation of the Tbolt from the temperature stimulus (i.e., stimulus affecting the oven temperature or EFC circuitry of the Tbolt), not as the Tbolt's response to the temperature change reported by the DS1620 sensor. If you were referring to my side point -- that allowing slow changes to the Tbolt housing temperature does not appear to be materially different from regulating the housing temperature -- my observations were that this was true down to at least 5e-13. Of course, there are two variables -- total swing and rate of change. By slow, I mean a rate of change of 0.25C per hour or less [DS1620 reported temperature]. My diurnal swings are no more than 2C per day and usually less [DS1620 reported temperature] (they can be as much as 5 or 6C seasonally, but those changes happen over weeks). A/C cycling likely subjects the Tbolt to a significantly greater rate of change than what I mean by slow, even if basic precautions are taken (e.g., putting it in a cardboard box). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5061A Beam Current question
Pete Joe sure gave you the answer. So you have fallen prey to the time-nuttery CS drug. I would never have thought you would have. So Not that I can out do what Joe told you. But on my sad frankenstein of a 5061running on fumes of CS the beam current is so low that I have to use a magnifying glass to watch the peaks! we are talking approx 3-4 on the meter and thats with the pot all the way up. I am amazed that it all locks consistently actually. Its tough so as Joe says use a solid reference to align the OCXO first. He also hit all of the singing dc to dc convereters. Its normal. Thats what earplugs are for. ;-) Sounds like you are in far better shape. Regards Paul WB8TSL On Tue, Dec 11, 2012 at 8:46 AM, J. L. Trantham jlt...@att.net wrote: Pete, There are two HV power supplies, +3500 (A18) and -2500 (A19), both of which can 'sing'. A18 comes on when power is applied and in CS OFF mode. A19 comes on when you move to any mode other than CS OFF. There is also a battery back up option, Option 002, that has a battery charger board (A2), that can sing when trying to charge 'dead' NiCd's. It comes on when power is applied and in CS OFF mode as well. A2 can be removed with no effect on the rest of the unit to test that theory. When does your unit start singing? The BEAM I indication can be adjusted by the BEAM I METER pot on the control panel. It only adjusts the meter indication, not the beam current. The beam current can be affected/changed by the C FIELD adjustment and by following the instructions in the manual to align the oven controller (A11) and the Electron Multiplier on the Power Regulator board (A15). Once aligned, adjust the BEAM I METER pot for an 'on scale' indication. This is different on the 5061B where BEAM I METER on the control panel is replaced by BEAM I and is, in fact, the Electron Multiplier adjustment. There are different versions of the A15 board, some of which have a pot to adjust the electron multiplier and others with fixed resistors. The change in BEAM I indication as you adjust the COARSE freq can be very small. The larger the beam current, the greater the fluctuation, but it can still be very small, a division or two. The figures in the manual are quite 'magnified' in my experience. However, I have never played with a 'new' CS tube. The change in BEAM I indication as you adjust the COARSE freq is also very easy to miss and it takes only a very small adjustment of COARSE to go through the entire range. My usual procedure is to let the 5061A warm up for several hours, in the CS OFF mode, make sure the OCXO is stable, then compare it's frequency to that of a GPSDO, then adjust the COARSE freq (with FINE set to 250) to precisely match the GPSDO. I have a TBolt that I use it's 10 MHz to trigger the horizontal of a scope and put the 5 MHz of the 5061A to the vertical. That done, I then select LOOP OPEN, let the CS oven warm up, the BEAM I come up, the 2nd HARMONIC come up, then select CONT OPER and hit the RESET button. If the OCXO is 'on frequency', CONTROL should indicate zero and you should be on the top of the center peak. Adjustment of the COARSE should then be able to demonstrate the 'peaks' to prove you are on the top of the center peak. I don't recall any 'false' modes that will give an erroneous indication. However, I have had failures in the LOGIC board (A14) that have caused indication problems. These units are fun to play with and work on. They make great 'house standards'. I leave them in CS OFF all the time, which lets the OCXO and ion pump run continuously. Hope this helps. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Pete Lancashire Sent: Monday, December 10, 2012 10:59 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] 5061A Beam Current question I've got a couple questions on a early S/N 5061A I got a few days ago. It took a couple days but the Ion Pump current is now down to zero or at least less then one division on the meter. I'm able to get the unit to go into continuous operation mode by following the TURN-ON PROCEDURES but have a few qestions 1. The unit 'sings' I'm tone deaf but its a high pitch. It could take some doing to isolate where it is coming from. Any ideas ? 2. How much should the beam current change when turning the OSC FREQUENCY COARSE adjustment ? On time about 45 to 60 minutes The current scribbled on the door is 19, I'm running pretty much 30. When making the adjustment the difference between the peak and any other position is only plus/minus a max of 2 or 3. 3 And i guess for last, are there any false modes that will turn off the ALARM and turn on the Con't Operation light ? Thanks -pete PS Anyone have a side panel without the front handle broken ? ___ time-nuts mailing list --
Re: [time-nuts] Thunderbolt oven / non-stable operating temperature
Hi The only place the sensor *might* be used is during holdover. There is no practical reason to use it while the TBolt is locked to GPS. *If* it's used in holdover, it gets trained by watching the control voltage and the temperature while the beast is locked to GPS. That information is then used when it goes into holdover to improve time drift while in holdover. The first test would be to put one in holdover and see if the DAC voltage changes at all while it's there. If it changes, the next step would be to see if the change is simply a function of time (= aging correction). Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bill Dailey Sent: Tuesday, December 11, 2012 10:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt oven / non-stable operating temperature If it is used for tempco it should affect the temp by stabilizing offset with temp changes correct? Maybe a more correct approach would be to disconnect it and test. Has been awhile since I read that testing stuff. Doc Sent from mobile On Dec 11, 2012, at 6:39 AM, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: Bill wrote: Well, perhaps you are not looking close enough. That is you need to be observing at a finer level of comparison. The changes, observed here and at another location, are in parts in 10-10 to 10-11 range, sometimes larger. At one of the locations there was a direct correlation to the air conditioning cycle. It is not clear what part of my message you are referring to. My main point was that the information from the DS1620 temperature sensor does not appear to be used internally by the Tbolt. In my observation, subjecting the sensor alone (thermally isolated from the rest of the Tbolt) to wide temperature swings (-10 to +120 C) did not produce any observabe effect on the operation of the Tbolt. If the temp sensor data were used internally by the Tbolt, one would expect a significant effect from such a wide swing -- one that couldn't be missed. If that large and fast a reported temperature swing produced effects only at the e-10 or 11 level, I would attribute it to imperfect thermal isolation of the Tbolt from the temperature stimulus (i.e., stimulus affecting the oven temperature or EFC circuitry of the Tbolt), not as the Tbolt's response to the temperature change reported by the DS1620 sensor. If you were referring to my side point -- that allowing slow changes to the Tbolt housing temperature does not appear to be materially different from regulating the housing temperature -- my observations were that this was true down to at least 5e-13. Of course, there are two variables -- total swing and rate of change. By slow, I mean a rate of change of 0.25C per hour or less [DS1620 reported temperature]. My diurnal swings are no more than 2C per day and usually less [DS1620 reported temperature] (they can be as much as 5 or 6C seasonally, but those changes happen over weeks). A/C cycling likely subjects the Tbolt to a significantly greater rate of change than what I mean by slow, even if basic precautions are taken (e.g., putting it in a cardboard box). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] Real YIG data was: YIG oscillator drift question
Neat data set! This says a lot about the stability of your HP supply. The choice of current-sense element makes a big difference in a YIG driver circuit, and most wirewound resistors fall into the Don't ask category. Would be interesting to try the same test with one of the cheap Chinese power supplies that use generic cement-encapsulated resistors. -- john, KE5FX -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Ulrich Bangert Sent: Tuesday, December 11, 2012 5:52 AM To: iov...@inwind.it; 'Discussion of precise time and frequency measurement' Subject: [time-nuts] Real YIG data was: YIG oscillator drift question Antonio, when I read the question I went into my cellar to return with an AVANTEK 2- 4 GHz YIG that I had once moved out of a defective spectrum analyzer. I used an analogue regulated power supply for the oscillator power and my HP6632 in constant current mode (this YIG NEEDS a tuning current) to supply a tuning current of app. 125 mA. Before starting the measurements I let it warm up for a day or so. Then I recorded temperature with a PT100 measured with A HP3457A in four wire mode and frequency with my U6200A counter (referenced to my Z3805) using my EZGPIB utility. You can download the results from my download page http://ulrich-bangert.de/html/downloads.html Look at the bottom for YIG Data. Note that the .zip contains a configuration file for my PLOTTER utility so that looking at the data is a snap with it. Just take care that the Overide binary data Graphic settings in the File menu is disabled and Open the file. While it is surely not comparable to even the worst Xtal it is not as bad as has been reported here from Bob. 73s and Best regards Ulrich Bangert, DF6JB -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von iov...@inwind.it Gesendet: Samstag, 8. Dezember 2012 15:18 An: time-nuts@febo.com Betreff: [time-nuts] YIG oscillator drift question Does anybody have direct experience on playing with YIG oscillators? I have read some specs on drift, but I know they are usually worst cases. I would like to get a raw idea about real measured drifts in reasonably stable temperature for a free running YIG with no tuning current. Yes, of course this depends on make, model etc, but any advise would be appreciated.Thanks in advance,Antonio I8IOV ___ time-nuts mailing 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] Nortel NTPB15AA (Trimble) GPSDO
I picked up one of the Nortel NTPB15AA (Trimble) GPSDO from the common auction site and decided adding a monitor display to the front panel would be a good idea. The entire unit draws about 300ma at 48vdc at power up and there is room inside the case for a small AC power supply. There is already a switching triple output dc-dc converter so I'm not too worried about added noise, at least for my application. This will make a nice self contained package that I can use to supply 10Mhz to my counters. There is a link below to a photo of the unit with the added monitor to show what it looks like. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/NTPB15AA05.jpg ___ time-nuts mailing 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] 5061A Beam Current question
Pete, The more likely singing offender is the old style A11 oven controller module. It also is off in the Cs off mode so the singing should stop when in that mode. The newer style A11 modules do not sing! Corby ___ time-nuts mailing 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] 5061A Beam Current question
Thanks This weekend I'll stick a microphone inside a piece of tubing and go looking. The singing only occurs when the unit is in LOOP OPEN or OPER mode. -pete On Tue, Dec 11, 2012 at 11:26 AM, cdel...@juno.com wrote: Pete, The more likely singing offender is the old style A11 oven controller module. It also is off in the Cs off mode so the singing should stop when in that mode. The newer style A11 modules do not sing! Corby ___ time-nuts mailing 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] Real YIG data was: YIG oscillator drift question
There are also YIG synthesizers available on epay, see eg 140894282834 Don John Miles Neat data set! This says a lot about the stability of your HP supply. The choice of current-sense element makes a big difference in a YIG driver circuit, and most wirewound resistors fall into the Don't ask category. Would be interesting to try the same test with one of the cheap Chinese power supplies that use generic cement-encapsulated resistors. -- john, KE5FX -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Ulrich Bangert Sent: Tuesday, December 11, 2012 5:52 AM To: iov...@inwind.it; 'Discussion of precise time and frequency measurement' Subject: [time-nuts] Real YIG data was: YIG oscillator drift question Antonio, when I read the question I went into my cellar to return with an AVANTEK 2- 4 GHz YIG that I had once moved out of a defective spectrum analyzer. I used an analogue regulated power supply for the oscillator power and my HP6632 in constant current mode (this YIG NEEDS a tuning current) to supply a tuning current of app. 125 mA. Before starting the measurements I let it warm up for a day or so. Then I recorded temperature with a PT100 measured with A HP3457A in four wire mode and frequency with my U6200A counter (referenced to my Z3805) using my EZGPIB utility. You can download the results from my download page http://ulrich-bangert.de/html/downloads.html Look at the bottom for YIG Data. Note that the .zip contains a configuration file for my PLOTTER utility so that looking at the data is a snap with it. Just take care that the Overide binary data Graphic settings in the File menu is disabled and Open the file. While it is surely not comparable to even the worst Xtal it is not as bad as has been reported here from Bob. 73s and Best regards Ulrich Bangert, DF6JB -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von iov...@inwind.it Gesendet: Samstag, 8. Dezember 2012 15:18 An: time-nuts@febo.com Betreff: [time-nuts] YIG oscillator drift question Does anybody have direct experience on playing with YIG oscillators? I have read some specs on drift, but I know they are usually worst cases. I would like to get a raw idea about real measured drifts in reasonably stable temperature for a free running YIG with no tuning current. Yes, of course this depends on make, model etc, but any advise would be appreciated.Thanks in advance,Antonio I8IOV ___ time-nuts mailing 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. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: Question on dead HP34401
Ulrich Bangert wrote: Gentlemen, I own a dead HP34401. On switching it on the display stays dark. It will however react on pressing the SHIFT key. By changing pcbs against a working one the display board has shown to be ok. There must be a problem with the main board. Without knowing whats inside the ASICs make trapping the problem difficult. One strange thing that I see is that there is a 7 kHz repeating reset signal on the reset line that does NOT come from the voltage regulator's reset output but must be generated by the processor or an ASIC. Anyone having an idea to that? Best regards and TIA for your answers Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Which reset? Assuming the circuit is the same as mine (Setember 1991 -October 1991) The Floating logic reset, the Earth referenced resets: 8051 reset (generated by absence of crossguard comms) or the 9914 reset? The only ASICS are U101(analog switch array), U102(resistor array) and U501 (gate array), none of which generate a reset. Bruce Bruce ___ time-nuts mailing 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 oven / non-stable operating temperature
Guys, So much speculation on how the Tbolt uses it's temperature sensor data. Having spending hundreds of man hrs and thousands of Tbolt running hrs, testing all kinds of things to find ways to improve my Tbolt's performance. This is what I've found happens on My Non E TBolt with version#3 firmware, when in an indoor environment concerning it's temperature sensor. During normal operation my Tbolt uses the temperature and ADC data to in its Kalman filter that then can predict a simple linear temperature constant, and simple linear ageing rate. Starting from a factory reset, it has something it will use in under 1/2 day. If the temperature has not been thru a few cycles and /or the Ageing is still at a high initial cold start rate and still changing, the Kalman filter can give very poor results and actually make things worse. It gets better as time goes on, and after a few days with a predicable Osc, the Klaman filter will improve enough to help. But the **Only** time the Kalman filter is used is during Holdover. It does this by adjusting the EFC voltage in small steps making a simple linear ramp as a function of time, Plus a simple linear output as function of delta temperature. I've also found that if the Temperature chip is the new one that gives only about 1 deg of resolution, All still works the same, But during hold over instead of seeing small continuous DAC changes as temperature changes, you see Big EFC steps. It is a shame the Kalman filter is not also used during normal non holdover run time. With a more advanced PID control loop it could be made to work much better. As it is, because the known systematic error information is not used as a feed-forward term to help the PID loop, any temperature change or ageing that does take place during control has to be totally corrected by an error signal. In short this means there will be unnecessary errors caused by both changing temperature or time if the Oscillator is not perfect. The bottom line is, these errors then limits how good of control you get, and why the Tbolt should be in a stable, less than 0.1 deg /hr environment to get the best performance from it. (or can use LH's temperature controller or use an external double oven Oscillator) So what does this mean for the average Nut's Tbolt? Mostly nothing. The only time the temperature sensor has any effect is during holdover. If the Tbolt is going into holdover long enough for any of this to have an effect there are many worse things to be concerned about. If the Tbolt does not go into holdover, none of the aging rate or temperature data is used (except for an over temperature alarm). There is one exception that I have tested for: If the Tbolt has a high resolution temperature sensor and a good Osc where both the aging rate and the temperature TC are constant enough to be correctly modeled by the simple linear 1st order predictor used in its Kalman filter, then the open loop Kalman filter correction can improve the frequency accuracy over time by 3 to 1 or better during very long holdover periods like days. ws *** ___ time-nuts mailing 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] 5061A Beam Current question
As Corby said oven control Bert Kehren In a message dated 12/11/2012 2:47:03 P.M. Eastern Standard Time, p...@petelancashire.com writes: Thanks This weekend I'll stick a microphone inside a piece of tubing and go looking. The singing only occurs when the unit is in LOOP OPEN or OPER mode. -pete On Tue, Dec 11, 2012 at 11:26 AM, cdel...@juno.com wrote: Pete, The more likely singing offender is the old style A11 oven controller module. It also is off in the Cs off mode so the singing should stop when in that mode. The newer style A11 modules do not sing! Corby ___ time-nuts mailing 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] OT: Question on dead HP34401
Two comments the manuals available on agilent What on earth is a crossguard? On Tue, Dec 11, 2012 at 3:16 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Ulrich Bangert wrote: Gentlemen, I own a dead HP34401. On switching it on the display stays dark. It will however react on pressing the SHIFT key. By changing pcbs against a working one the display board has shown to be ok. There must be a problem with the main board. Without knowing whats inside the ASICs make trapping the problem difficult. One strange thing that I see is that there is a 7 kHz repeating reset signal on the reset line that does NOT come from the voltage regulator's reset output but must be generated by the processor or an ASIC. Anyone having an idea to that? Best regards and TIA for your answers Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Which reset? Assuming the circuit is the same as mine (Setember 1991 -October 1991) The Floating logic reset, the Earth referenced resets: 8051 reset (generated by absence of crossguard comms) or the 9914 reset? The only ASICS are U101(analog switch array), U102(resistor array) and U501 (gate array), none of which generate a reset. Bruce Bruce __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: Question on dead HP34401
paul swed wrote: Two comments the manuals available on agilent What on earth is a crossguard? Crossguard comms (Agilents term) refers to the optoisolators used for serial communication between the floating and earth referenced logic sections. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: Question on dead HP34401
At 21:40 11/12/2012, you wrote: Two comments the manuals available on agilent What on earth is a crossguard? Data exchange between a floating, guarded circuit and a ground referenced one? Marco IK1ODO ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: Question on dead HP34401
OK but why would it tie to the reset line? On Tue, Dec 11, 2012 at 3:48 PM, Marco IK1ODO -2 ik1...@spin-it.com wrote: At 21:40 11/12/2012, you wrote: Two comments the manuals available on agilent What on earth is a crossguard? Data exchange between a floating, guarded circuit and a ground referenced one? Marco IK1ODO __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: Question on dead HP34401
Long shot remedy : There is a front pannel push button sequence to turn off/on the display. --- On Tue, 12/11/12, Ulrich Bangert df...@ulrich-bangert.de wrote: From: Ulrich Bangert df...@ulrich-bangert.de Subject: [time-nuts] OT: Question on dead HP34401 To: Time nuts time-nuts@febo.com Date: Tuesday, December 11, 2012, 5:52 AM Gentlemen, I own a dead HP34401. On switching it on the display stays dark. It will however react on pressing the SHIFT key. By changing pcbs against a working one the display board has shown to be ok. There must be a problem with the main board. Without knowing whats inside the ASICs make trapping the problem difficult. One strange thing that I see is that there is a 7 kHz repeating reset signal on the reset line that does NOT come from the voltage regulator's reset output but must be generated by the processor or an ASIC. Anyone having an idea to that? Best regards and TIA for your answers Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: Question on dead HP34401
It only resets the earth referenced micro (8051) on power up and when pulses on the optocoupler output arent present. There is no other connection to the reset pin of this micro. The floating logic is reset by the LM2925 5V regulator reset output. There is no connection to this reset line aprt from the Gate array reset input and the micro (80196) reset input. The relay drivers are reset by a 80196 output pin. The display logic is reset by another 90196 output pin. Bruce paul swed wrote: OK but why would it tie to the reset line? On Tue, Dec 11, 2012 at 3:48 PM, Marco IK1ODO -2ik1...@spin-it.com wrote: At 21:40 11/12/2012, you wrote: Two comments the manuals available on agilent What on earth is a crossguard? Data exchange between a floating, guarded circuit and a ground referenced one? Marco IK1ODO __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] Thunderbolt schematics
Hi, Does anyone have a set of schematics for this guy? My bolt has suffered a significant loss of sensitivity, the AMU values have dropped 30 dB. It is not the motorola antenna or feedline, works fine on an Oncore. This appeared to have happened when I tried to operate 160 meters! Thanks guys, Dave Garnier - wb9own ___ time-nuts mailing 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 schematics
You might try doing a cold reset. I had the same issue and that got it back. You need to use the trimble software. Tom - Original Message - From: David Garnier dgarn...@wi.rr.com To: time-nuts@febo.com Sent: Tuesday, December 11, 2012 5:27 PM Subject: [time-nuts] Thunderbolt schematics Hi, Does anyone have a set of schematics for this guy? My bolt has suffered a significant loss of sensitivity, the AMU values have dropped 30 dB. It is not the motorola antenna or feedline, works fine on an Oncore. This appeared to have happened when I tried to operate 160 meters! Thanks guys, Dave Garnier - wb9own ___ time-nuts mailing 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] Thunderbolt schematics
I think that the TBolt's schematic(s) are sort of HolyGrail for TimeNuts. On Tue, Dec 11, 2012 at 11:43 PM, Tom Miller tmil...@skylinenet.net wrote: You might try doing a cold reset. I had the same issue and that got it back. You need to use the trimble software. Tom - Original Message - From: David Garnier dgarn...@wi.rr.com To: time-nuts@febo.com Sent: Tuesday, December 11, 2012 5:27 PM Subject: [time-nuts] Thunderbolt schematics Hi, Does anyone have a set of schematics for this guy? My bolt has suffered a significant loss of sensitivity, the AMU values have dropped 30 dB. It is not the motorola antenna or feedline, works fine on an Oncore. This appeared to have happened when I tried to operate 160 meters! Thanks guys, Dave Garnier - wb9own ___ time-nuts mailing 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] Thunderbolt schematics
On 12/11/2012 11:50 PM, Azelio Boriani wrote: I think that the TBolt's schematic(s) are sort of HolyGrail for TimeNuts. They are pretty simple, so I am amazed that there has been no major attempt to reverse engineer them. The GPS front-end chip I haven't been able to find a datasheet for, and then the CPU/GPS-baseband chip seems to be an ASIC, but most pins should be fairly simple to explain. I have only one Tbolt, so I don't want to put that into pieces (again). 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] Thunderbolt schematics
Magnus Danielson wrote: On 12/11/2012 11:50 PM, Azelio Boriani wrote: I think that the TBolt's schematic(s) are sort of HolyGrail for TimeNuts. They are pretty simple, so I am amazed that there has been no major attempt to reverse engineer them. The GPS front-end chip I haven't been able to find a datasheet for, and then the CPU/GPS-baseband chip seems to be an ASIC, but most pins should be fairly simple to explain. I have only one Tbolt, so I don't want to put that into pieces (again). 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. I have 4, two of which have had the low phase noise OCXO removed for use in a PN interferometer. The TBolt output buffer has relatively high phase noise. Bruce ___ time-nuts mailing 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 schematics
Magnus, you said it: The GPS front-end chip I haven't been able to find a datasheet for the CPU/GPS-baseband chip seems to be an ASIC Quest for the HolyGrail... On Wed, Dec 12, 2012 at 12:23 AM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Magnus Danielson wrote: On 12/11/2012 11:50 PM, Azelio Boriani wrote: I think that the TBolt's schematic(s) are sort of HolyGrail for TimeNuts. They are pretty simple, so I am amazed that there has been no major attempt to reverse engineer them. The GPS front-end chip I haven't been able to find a datasheet for, and then the CPU/GPS-baseband chip seems to be an ASIC, but most pins should be fairly simple to explain. I have only one Tbolt, so I don't want to put that into pieces (again). 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. I have 4, two of which have had the low phase noise OCXO removed for use in a PN interferometer. The TBolt output buffer has relatively high phase noise. Bruce ___ time-nuts mailing 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] MT3339 PA6H and Racal Dana GPIB
Hello, this afternoon the post(wo)man handed to me the little box with the PA6H GPS modules. I bought also an antenna with 5mt cable, so I can use it in the lab. The module is up and running, requiring only 3V3 supply, locking very fast, about 30s from cold start, here is it, working with ext antenna: http://www.flickr.com/photos/14336723@N08/8264614897/ And now I'm trying to setup a logging session to try to log interval measurements with the counter: http://www.flickr.com/photos/14336723@N08/8265684680/ Now this is what I have done, the goal is to try to have some jitter measurements for the PPS output: - A FE5680A is the timebase for the counter - the counter is a Racal Dana 1992 - the FE5680A 1Vpp output is connected directly to rear reference input of the counter - the counter measures the PPS signal from the GPS module, Time interval A, 9 digits (single shot) 1nS resolution. After fighting with the counter's GPIB interface now I'm logging a stream of time intervals. I'm not catching all the pulses, but only one each 2 or 3, depends. - Is this setup enough to get meaningful data? - If so how long should I log the data? - If not what should I modify? - Once collected the data, what kind of analysis should I do? And for who have ever used the Racal Dana 1992 with GPIB interface: I feel dumb, but I could not figure how to poll the instrument for the availability of last data. Now the sequence i do is this: - T1 - wait for trigger - T2 - trigger - wait 4 seconds - read result - T2 - trigger - wait 4s etc... Doing so I catch only part of the pulses, is there a way to make it better? This is a graph of the first thousand records: http://www.flickr.com/photos/14336723@N08/8265826150/ Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing 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 schematics
On 12/12/2012 12:28 AM, Azelio Boriani wrote: Magnus, you said it: The GPS front-end chip I haven't been able to find a datasheet for the CPU/GPS-baseband chip seems to be an ASIC Quest for the HolyGrail... On the other hand, it's not all that many pins, so a bit of advanced guessing should not be too hard to do. Tossing a sine in I bet you will find mixed-down versions occuring in one or two IF-filtered versions before breaking free as digitized version. Most probably as 2 bits and clock going to the GPS baseband chip. This is what a typical GPS front-end chip does. You toss it a reference frequency, and it steps it up, amplifies the GPS signal, mixes it down. It will be one or two SAW filters with balanced outputs and inputs. Fairly trivial stuff. 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] Thunderbolt schematics
I think that the TBolt's schematic(s) are sort of HolyGrail for TimeNuts. Some French time nuts told us they already have one. It's very nice. /tvb ___ time-nuts mailing 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 schematics
Tom, On 12/12/2012 12:44 AM, Tom Van Baak wrote: I think that the TBolt's schematic(s) are sort of HolyGrail for TimeNuts. Some French time nuts told us they already have one. It's very nice. Would you be able to share? Do you have a pointer? If it was here, then more people than me missed it. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt oven / non-stable operating temperature
Warren wrote: During normal operation my Tbolt uses the temperature and ADC data to in its Kalman filter that then can predict a simple linear temperature constant, and simple linear ageing rate. * * * But the **Only** time the Kalman filter is used is during Holdover. It does this by adjusting the EFC voltage in small steps making a simple linear ramp as a function of time, Plus a simple linear output as function of delta temperature. I've also found that if the Temperature chip is the new one that gives only about 1 deg of resolution, All still works the same, But during hold over instead of seeing small continuous DAC changes as temperature changes, you see Big EFC steps. That all sounds like the way it should work, if the temp sensor data is used internally by the Tbolt. My notes indicate that I tried cooling and warming the isolated sensor during holdover and observed no effect. However, the Kalman filter may not have been operating because I tested the unit immediately after it reached basic stability, before it had time to learn anything. So what does this mean for the average Nut's Tbolt? Mostly nothing. I agree. I presume that most time nuts would not ordinarily rely on a GPSDO during holdover -- particularly, a long holdover. Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Z3805A cooling requirements?
This may be a newbie question, but I'm a newbie, so: Do the HP telecom GPSDOs (Z38xx) require external airflow for cooling? They don't have built-in fans, but they sorta look like they depend on a rack-level cooling fan, which a telecom rack would almost certainly have. I ask because I bought a Z3816 awhile back which worked for about a week and then failed. I traced the failure to an internal power supply brick, which had a big finned heat-sink attached but nevertheless smelled overheated and was shorted internally. I never found a replacement power brick, and I don't have time to mess with it right now, so I recently bought a Z3805A. It, too, looks like it's working, but it started to feel awfully warm after a few hours, so I unplugged it for now. It probably wouldn't take much of a fan to bring the internal temperature down close to ambient, and the fan could be powered easily enough from the supply rails. But that might create a temperature gradient where the designers didn't intend one. Or it might cause problems I don't even know about yet. At the moment, the Z3805A is in a fan-less 19-inch rack with a bunch of other equipment, in a lab environment. Should it have its own fan? Cheers! --Stu ___ time-nuts mailing 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 oven / non-stable operating temperature
Another thing that could of effected the results when measuring the effect of a low resolution sensor chip during holdover, is that it is real hard for the Klaman filter to learn anything useful from it, without some careful manipulation of the variables. Mostly all it would normally record would look like seemingly random freq changes with no temperature change and then large temperature changes but with very little frequency change. ws Charles P. Steinmetz charles_steinmetz at lavabit.com posted Warren wrote: During normal operation my Tbolt uses the temperature and ADC data to in its Kalman filter that then can predict a simple linear temperature constant, and simple linear ageing rate. * * * But the **Only** time the Kalman filter is used is during Holdover. It does this by adjusting the EFC voltage in small steps making a simple linear ramp as a function of time, Plus a simple linear output as function of delta temperature. I've also found that if the Temperature chip is the new one that gives only about 1 deg of resolution, All still works the same, But during hold over instead of seeing small continuous DAC changes as temperature changes, you see Big EFC steps. That all sounds like the way it should work, if the temp sensor data is used internally by the Tbolt. My notes indicate that I tried cooling and warming the isolated sensor during holdover and observed no effect. However, the Kalman filter may not have been operating because I tested the unit immediately after it reached basic stability, before it had time to learn anything. So what does this mean for the average Nut's Tbolt? Mostly nothing. I agree. I presume that most time nuts would not ordinarily rely on a GPSDO during holdover -- particularly, a long holdover. Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt schematics
On Dec 11, 2012, at 6:57 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Tom, On 12/12/2012 12:44 AM, Tom Van Baak wrote: I think that the TBolt's schematic(s) are sort of HolyGrail for TimeNuts. Some French time nuts told us they already have one. It's very nice. Would you be able to share? Do you have a pointer? If it was here, then more people than me missed it. Cheers, Magnus Tom forgot to include the MontyPython tags... ___ time-nuts mailing 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 schematics
On 12/12/2012 01:52 AM, John Ackermann N8UR wrote: On Dec 11, 2012, at 6:57 PM, Magnus Danielsonmag...@rubidium.dyndns.org wrote: Tom, On 12/12/2012 12:44 AM, Tom Van Baak wrote: I think that the TBolt's schematic(s) are sort of HolyGrail for TimeNuts. Some French time nuts told us they already have one. It's very nice. Would you be able to share? Do you have a pointer? If it was here, then more people than me missed it. Cheers, Magnus Tom forgot to include theMontyPython tags... So I learned from off-list email. Lack of smiley also didn't have me revoke long lost memory cells. While enjoying Monty Python and having seen the movie at least twice, I fill my brain with other stuff... labeled TF amongst others... There is at least one better time-joke in that movie... thou count shall be three... 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] Z3805A cooling requirements?
Stu, a fan is about the worst thing you can do for your Z3805 it will significantly worsen the stability of the output frequency. The oven inside does get warm, that's why it is an oven :) The power consumption will go down once it heats itself up, the unit is designed to work without a fan sitting on a desk etc. Just make sure the vent holes are not clogged. Sounds like your Z3816 had a failure that caused the units power supply to overheat. bye, Said In a message dated 12/11/2012 16:22:10 Pacific Standard Time, stewart.c...@gmail.com writes: This may be a newbie question, but I'm a newbie, so: Do the HP telecom GPSDOs (Z38xx) require external airflow for cooling? They don't have built-in fans, but they sorta look like they depend on a rack-level cooling fan, which a telecom rack would almost certainly have. I ask because I bought a Z3816 awhile back which worked for about a week and then failed. I traced the failure to an internal power supply brick, which had a big finned heat-sink attached but nevertheless smelled overheated and was shorted internally. I never found a replacement power brick, and I don't have time to mess with it right now, so I recently bought a Z3805A. It, too, looks like it's working, but it started to feel awfully warm after a few hours, so I unplugged it for now. It probably wouldn't take much of a fan to bring the internal temperature down close to ambient, and the fan could be powered easily enough from the supply rails. But that might create a temperature gradient where the designers didn't intend one. Or it might cause problems I don't even know about yet. At the moment, the Z3805A is in a fan-less 19-inch rack with a bunch of other equipment, in a lab environment. Should it have its own fan? Cheers! --Stu ___ time-nuts mailing 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] Z3805A cooling requirements?
The telecom closets and data centers I've visited have a significant amount of airflow. Could it be that there is an assumption that these telecom-rack GPSDO expect some level of air? /tvb - Original Message - From: saidj...@aol.com To: time-nuts@febo.com Sent: Tuesday, December 11, 2012 5:20 PM Subject: Re: [time-nuts] Z3805A cooling requirements? Stu, a fan is about the worst thing you can do for your Z3805 it will significantly worsen the stability of the output frequency. The oven inside does get warm, that's why it is an oven :) The power consumption will go down once it heats itself up, the unit is designed to work without a fan sitting on a desk etc. Just make sure the vent holes are not clogged. Sounds like your Z3816 had a failure that caused the units power supply to overheat. bye, Said In a message dated 12/11/2012 16:22:10 Pacific Standard Time, stewart.c...@gmail.com writes: This may be a newbie question, but I'm a newbie, so: Do the HP telecom GPSDOs (Z38xx) require external airflow for cooling? They don't have built-in fans, but they sorta look like they depend on a rack-level cooling fan, which a telecom rack would almost certainly have. I ask because I bought a Z3816 awhile back which worked for about a week and then failed. I traced the failure to an internal power supply brick, which had a big finned heat-sink attached but nevertheless smelled overheated and was shorted internally. I never found a replacement power brick, and I don't have time to mess with it right now, so I recently bought a Z3805A. It, too, looks like it's working, but it started to feel awfully warm after a few hours, so I unplugged it for now. It probably wouldn't take much of a fan to bring the internal temperature down close to ambient, and the fan could be powered easily enough from the supply rails. But that might create a temperature gradient where the designers didn't intend one. Or it might cause problems I don't even know about yet. At the moment, the Z3805A is in a fan-less 19-inch rack with a bunch of other equipment, in a lab environment. Should it have its own fan? Cheers! --Stu ___ time-nuts mailing 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] Thunderbolt oven / non-stable operating temperature
Hi Warren, Starting from a factory reset, it has something it will use in under 1/2 day. And that would explain my and Charles' null results. Nice. If the temperature has not been thru a few cycles and /or the Ageing is still at a high initial cold start rate and still changing, the Kalman filter can give very poor results and actually make things worse. It gets better as time goes on, and after a few days with a predicable Osc, the Klaman filter will improve enough to help. Were you able to test how quickly, or how well, the filter learned the tempco of the OCXO? It is a shame the Kalman filter is not also used during normal non holdover run time. With a more advanced PID control loop it could be made to work much better. Yes (although please define much; are you talking 1% better or 10% better or 2x better). Would it be possible to implement this advanced PID in LH? Or as a first step, and to veryify your conclusions, would it be possible for LH to control the DAC during TBolt hold-over mode? As it is, because the known systematic error information is not used as a feed-forward term to help the PID loop, any temperature change or ageing that does take place during control has to be totally corrected by an error signal. In short this means there will be unnecessary errors caused by both changing temperature or time if the Oscillator is not perfect. I agree this is true in theory (where epsilon != zero), but it's hard for me to believe true in practice. I would guess the error term is totally dominated by short-term GPS noise, and anything else, like tempco or frequency drift, is secondary. That's why it makes sense to apply these 2nd or 3rd order corrections during hold-over mode (where there is no GPS noise) but not for normal operation. So what does this mean for the average Nut's Tbolt? Mostly nothing. The only time the temperature sensor has any effect is during holdover. Thanks for stating both these facts so clearly. I cringe every time I hear someone replacing a 1C DS1620 sensor in their TBolt. The TAPR TBolts I tested years ago worked equally well regardless if they were 1C TBolts or ten milli-C TBolts. /tvb ___ time-nuts mailing 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] Z3805A cooling requirements?
Yes they do assume this. Or at least a standard relay rack. Most of these units should have come out of mobile telcom sites. The air in these facilities is reasonable but often not all that great. They do get hot. But the relay racks are 2 posters nothing else surrounding the racked equipment so there is the ability to radiate heat. What started the thread I think was the gear was in a closed 4 post rack. That would tend to be an oven or allow hot spots to develop. Further we get gear thats X years old. In my experience the switching supplies are towards the end of their life. Really just the filter caps. But as mentioned they are epoxy blocks so you can't easily change the caps out. Suspect thats an easy way to fry these supplies. Age + heat = death. :-) My 3801 lost one of its supplies ages ago. I adapted another newer one in that I had. Hey what are you going to do. Regards Paul WB8TSL On Tue, Dec 11, 2012 at 8:55 PM, Tom Van Baak t...@leapsecond.com wrote: The telecom closets and data centers I've visited have a significant amount of airflow. Could it be that there is an assumption that these telecom-rack GPSDO expect some level of air? /tvb - Original Message - From: saidj...@aol.com To: time-nuts@febo.com Sent: Tuesday, December 11, 2012 5:20 PM Subject: Re: [time-nuts] Z3805A cooling requirements? Stu, a fan is about the worst thing you can do for your Z3805 it will significantly worsen the stability of the output frequency. The oven inside does get warm, that's why it is an oven :) The power consumption will go down once it heats itself up, the unit is designed to work without a fan sitting on a desk etc. Just make sure the vent holes are not clogged. Sounds like your Z3816 had a failure that caused the units power supply to overheat. bye, Said In a message dated 12/11/2012 16:22:10 Pacific Standard Time, stewart.c...@gmail.com writes: This may be a newbie question, but I'm a newbie, so: Do the HP telecom GPSDOs (Z38xx) require external airflow for cooling? They don't have built-in fans, but they sorta look like they depend on a rack-level cooling fan, which a telecom rack would almost certainly have. I ask because I bought a Z3816 awhile back which worked for about a week and then failed. I traced the failure to an internal power supply brick, which had a big finned heat-sink attached but nevertheless smelled overheated and was shorted internally. I never found a replacement power brick, and I don't have time to mess with it right now, so I recently bought a Z3805A. It, too, looks like it's working, but it started to feel awfully warm after a few hours, so I unplugged it for now. It probably wouldn't take much of a fan to bring the internal temperature down close to ambient, and the fan could be powered easily enough from the supply rails. But that might create a temperature gradient where the designers didn't intend one. Or it might cause problems I don't even know about yet. At the moment, the Z3805A is in a fan-less 19-inch rack with a bunch of other equipment, in a lab environment. Should it have its own fan? Cheers! --Stu ___ time-nuts mailing 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] Thunderbolt oven / non-stable operating temperature
Although the Trimble oscillator has superb phase noise performance, it has TERRIBLE temperature sensitivity. It appears to be a single oven oscillator, not a double oven. The PWM'ed fan temperature control implemented in Lady Heather effectively makes the unit a double oven. Also, by stabilizing the temperature of the rest of the tbolt electronics and power supply (if included in the temperature controlled box) you get additional performance out of the unit. Some testing indicates that a temperature stabilized tbolt/power supply can improve the performance by an order of magnitude (around 30% of that is due to issues outside of the oscillator can). And yes, Lady Heather can control the Tbolt DAC. There is a PID controller in there for controlling the DAC (based upon the 1PPS error signal, if I remember correctly... it could be the OSC error signal). ___ time-nuts mailing 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] 5061A Beam Current question
Oops. Forgot about A11. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ewkeh...@aol.com Sent: Tuesday, December 11, 2012 2:33 PM To: time-nuts@febo.com Subject: Re: [time-nuts] 5061A Beam Current question As Corby said oven control Bert Kehren In a message dated 12/11/2012 2:47:03 P.M. Eastern Standard Time, p...@petelancashire.com writes: Thanks This weekend I'll stick a microphone inside a piece of tubing and go looking. The singing only occurs when the unit is in LOOP OPEN or OPER mode. -pete On Tue, Dec 11, 2012 at 11:26 AM, cdel...@juno.com wrote: Pete, The more likely singing offender is the old style A11 oven controller module. It also is off in the Cs off mode so the singing should stop when in that mode. The newer style A11 modules do not sing! Corby ___ time-nuts mailing 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] MT3339 PA6H and Racal Dana GPIB
I've written GPIB stuff for the Racal-Dana counter et al. running under 32 bit Fedora Linux and the Linux GPIB package. It is available at ftp.omen.com in the pub/tek directory. On 12/11/2012 03:36 PM, Fabio Eboli wrote: Hello, this afternoon the post(wo)man handed to me the little box with the PA6H GPS modules. I bought also an antenna with 5mt cable, so I can use it in the lab. The module is up and running, requiring only 3V3 supply, locking very fast, about 30s from cold start, here is it, working with ext antenna: http://www.flickr.com/photos/14336723@N08/8264614897/ And now I'm trying to setup a logging session to try to log interval measurements with the counter: http://www.flickr.com/photos/14336723@N08/8265684680/ Now this is what I have done, the goal is to try to have some jitter measurements for the PPS output: - A FE5680A is the timebase for the counter - the counter is a Racal Dana 1992 - the FE5680A 1Vpp output is connected directly to rear reference input of the counter - the counter measures the PPS signal from the GPS module, Time interval A, 9 digits (single shot) 1nS resolution. After fighting with the counter's GPIB interface now I'm logging a stream of time intervals. I'm not catching all the pulses, but only one each 2 or 3, depends. - Is this setup enough to get meaningful data? - If so how long should I log the data? - If not what should I modify? - Once collected the data, what kind of analysis should I do? And for who have ever used the Racal Dana 1992 with GPIB interface: I feel dumb, but I could not figure how to poll the instrument for the availability of last data. Now the sequence i do is this: - T1 - wait for trigger - T2 - trigger - wait 4 seconds - read result - T2 - trigger - wait 4s etc... Doing so I catch only part of the pulses, is there a way to make it better? This is a graph of the first thousand records: http://www.flickr.com/photos/14336723@N08/8265826150/ Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ time-nuts mailing 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] Z3805A cooling requirements?
On 12/12/2012 02:55 AM, Tom Van Baak wrote: The telecom closets and data centers I've visited have a significant amount of airflow. Could it be that there is an assumption that these telecom-rack GPSDO expect some level of air? Well yes and no. Traditional telecom is supposed to work with self-convection. That may have worked reasonably well, when they where doing 300W per rack. At 3 kW per rack, forced air for some units at least is needed, and as you go up from there, it will be needed for all. For modern equipment, it's maybe not the power consumption per unit, but the power density which causes problems. So, I would expect the unit to assume *some* convection, but not significant forced convection, and certainly not clogged inputs. In large datacenters, you need to consider that side-to-side airflows can cause sequence heat-up as the air go sideways from rack to rack. In one they had the same switch unit on the top of the rack, and they died in the direction opposite to their side-by-side air-flow, as hottest air got killed first. Anyway, OCXOs doesn't like forced convection, but do enjoy self convection for best performance. 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] Stable Watch Clocks
Typical 32KHz clock crystals are very stable in frequency if you can keep them close to the turnover temp. If you can hold 1 degC it is .04 ppm. That is 40ppb - very good. If you can hold .1 deg C it is .0004 ppm. That is .4 ppb. Very expensive. (it goes as the square of the difference in temperature from the turn over temp - which varies from crystal to crystal. ). The turn over temp is around 25 degC. I saw some 40mm on a side thermoelectric heaters/coolers units for $15 at Spark Fun. I thought I might have some fun. Two units and a power supply. Plus a honking current amp. Although with milliwatts for the oscillator it might not take a lot of heat pumping to keep the osc at a constant temp. And +/- 10C to 20C is probably enough range for experiments. Be interesting to see if this could be engineered to compete with OCXOs. A VariCap would be included in later experiments for tuning. If the initial experiments show promise. 6 wires out to start: 2 pwr, 2 thermistor, and 2 Freq out. with the oscillator in the center of the coolers the material arrangement: Osc potted in high thermal conductivity. Void. Outer Insulation. With another thermistor or temp sensor in the outer insulation. Another in the vicinity on the outside. I'm open to suggestion. And also possible proof I'm barking up the wrong tree. The idea is to keep the whole package as thin as possible to minimize heat flow to or from the outside - except through the coolers/heaters. Some uP to run a PID loop for temp. An update rate of 100 times a second for the PID should make it fine grained enough. DACs and ADCs good to 16 bits. Initial exploration eqpt need not be so good. Unless it is cheap. And then once you have the contraption running, disciplining it with 1 PPS might be of further interest. I currently have no method for testing such a rig for stability. Simon Engineering is the art of making what you want from what you can get at a profit. ___ time-nuts mailing 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 oven / non-stable operating temperature
Mark wrote: Although the Trimble oscillator has superb phase noise performance, it has TERRIBLE temperature sensitivity. It appears that most do but some don't. Between the results I have seen posted on the list (Lady Heather screen shots) and my own data, they seem to fall into two groups. I have two with excellent oscillator tempcos, but a third unit I have is about 100x worse and the sign of its tempco is reversed compared to the first two. That one appears to consume approximately the same oven power as the other two, and heats the housing approximately equally, so the oven does not appear to have a gross failure. All three have Trimble 37265 OCXOs. I initially thought the third unit's oven controller was broken (low gain). Then I noticed that the great majority of posted Lady Heather plots appear to be from units similar to that one, with the much higher tempco and reversed tempco sign compared to my two low-tempco units. But I have seen a few other plots that appear to be from units similar to my first two. The two with the low tempcos do not appear to be inferior to other Tbolts with respect to stability, PN, or aging. I'm inclined to think that all 37265 OCXOs are supposed to work like my first two, and that the ones with large tempcos are the result of a supply or manufacturing error (most likely, a mismatch between the oven set point and the crystal). But who knows? There do seem to be many more of the ones with large tempcos around. It would be interesting to take a few 37265s apart to see if there are any obvious differences between the high- and low-tempco units, and if tweaking the oven set points would reduce the tempcos of the high-tempco units. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt oven / non-stable operating temperature
tvb posted Were you able to test how quickly, or how well, the filter learned the tempco of the OCXO? Only at a couple of very general data points. Using a very Bad unit, the Kalman filter had an effect, although not very good in under 1/2 day. After a week or so on a good unit, it helped maybe 3 to1 with ageing and Temperature TC. Yes (although please define much; are you talking 1% better or 10% better or 2x better). Much is a 2 to 10 times improvement in the errors cause the undesirable compensated effects. As an example, say your unit gives a 1e-10 freq ripple error when you turn on the over head Air condition, then that would go down by a factor of 3 or so. Of course you could also just move your unit away for the AC and get a similar improvement. For the best performance improvement, you do both. Would it be possible to implement this advanced PID in LH? Or as a first step, and to verify your conclusions, would it be possible for LH to control the DAC during TBolt hold-over mode? Yes, There is already a very flexible, but very user unfriendly 'prove of concept' version, in LH. It does have some of the feed-forward capability already there, along with lots of other things, as part of the many undocumented features of the external advanced PID controller now in LH. but I do not see a reason for using it during hold over, Because the Tbolt S/W already does a good job with that now. but the external PID does help the non holdover mode. LH's external PID even works remotely over the internet. So I have, in the past, controlled someone's Tbolt from my computer, getting better results than where available from the Tbolt's internal PID. (Works until the connection is lost). The terms I think that are available in the latest LH's internal PID controller are Phase error, Freq error, time, Dac offset, and maybe temperature. Basically for the feed-forward in hold-over mode, just need to add the sum of K1 x temp_change (since start of holdover) with K2 x lapse_time (since start of hold over) to the Dac value (since start of hold over) The hard part is to automatically find the best value for K1 and K2 during run time. In LH all the various variable K values are manually set. Last count I think the Advanced PID had 7 or 8 K's that could be tuned. I agree this is true in theory (where epsilon != zero), but it's hard for me to believe true in practice. I would guess the error term is totally dominated by short-term GPS noise, and anything else, like tempco or frequency drift, is secondary. That's why it makes sense to apply these 2nd or 3rd order corrections during hold-over mode (where there is no GPS noise) but not for normal operation. The reason it works even during normal operation is that the GPS noise is mostly plus and minus (basically AC), where as the time drift and temperature drift errors are in one polarity. When these AC errors are filtered thru the LP integrator of the PID, the GPS noise cancels but the DC time and offset errors, even though smaller than the GPS noise, tend to dominate short term. Short term being less than the PID's Time constant. ws Tom Van Baak tvb at LeapSecond.com Posted Hi Warren, Starting from a factory reset, it has something it will use in under 1/2 day. And that would explain my and Charles' null results. Nice. If the temperature has not been thru a few cycles and /or the Ageing is still at a high initial cold start rate and still changing, the Kalman filter can give very poor results and actually make things worse. It gets better as time goes on, and after a few days with a predicable Osc, the Klaman filter will improve enough to help. Were you able to test how quickly, or how well, the filter learned the tempco of the OCXO? It is a shame the Kalman filter is not also used during normal non holdover run time. With a more advanced PID control loop it could be made to work much better. Yes (although please define much; are you talking 1% better or 10% better or 2x better). Would it be possible to implement this advanced PID in LH? Or as a first step, and to veryify your conclusions, would it be possible for LH to control the DAC during TBolt hold-over mode? As it is, because the known systematic error information is not used as a feed-forward term to help the PID loop, any temperature change or ageing that does take place during control has to be totally corrected by an error signal. In short this means there will be unnecessary errors caused by both changing temperature or time if the Oscillator is not perfect. I agree this is true in theory (where epsilon != zero), but it's hard for me to believe true in practice. I would guess the error term is totally dominated by short-term GPS noise, and anything else, like tempco or frequency drift, is secondary. That's why it makes sense to apply these 2nd or 3rd order corrections during
Re: [time-nuts] Stable Watch Clocks
Typical 32KHz clock crystals are very stable in frequency if you can keep them close to the turnover temp. If you can hold 1 degC it is .04 ppm. That's far better than I thought. Do you have a reference for this spec? I agree you might be able to make one accurate to 0.04 ppm, however briefly, but I've never seen one stable to 0.04 ppm. I mean, that's like 1 second a year. I currently have no method for testing such a rig for stability. Oh, the slipperly slope you are on. I have just the solution for you ... /tvb ___ time-nuts mailing 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] Stable Watch Clocks
http://www.abracon.com/Resonators/AB26T.pdf This quotes .038 ppm/C^2 delta T from the turn over point: http://www.iqdfrequencyproducts.com/app-notes/timekeeping/ The fly in the ointment is the aging rate of 5 ppm the first year (13ppb/day) and 3 ppm (8ppb/day) after. I'm sure holding 1 degC is easy. .1 C with some care and .01 C - my measuring eqpt ain't that good. So temperature ceases to be a problem. Is the other stuff workable? I would go with a 32KHz crystal for a production version to make it easy to multiply up to 10MHz. Simon Engineering is the art of making what you want from what you can get at a profit. From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, December 12, 2012 3:55 AM Subject: Re: [time-nuts] Stable Watch Clocks Typical 32KHz clock crystals are very stable in frequency if you can keep them close to the turnover temp. If you can hold 1 degC it is .04 ppm. That's far better than I thought. Do you have a reference for this spec? I agree you might be able to make one accurate to 0.04 ppm, however briefly, but I've never seen one stable to 0.04 ppm. I mean, that's like 1 second a year. I currently have no method for testing such a rig for stability. Oh, the slipperly slope you are on. I have just the solution for you ... /tvb ___ time-nuts mailing 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] Thunderbolt oven / non-stable operating temperature
Although the Trimble oscillator has superb phase noise performance, it has TERRIBLE temperature sensitivity. It appears that most do but some don't. Between the results I have seen posted on the list (Lady Heather screen shots) and my own data, they seem to fall into two groups. I have two with excellent oscillator tempcos, but a third unit I have is about 100x worse and the sign of its tempco is reversed compared to the first two. That Mark, Charles, This is interesting and I'd like to pursue it. I still have a pile of original TAPR-Thunderbolts here so without too much effort I can gather tempco statistics for you. I tested the TAPR lots for phase noise and ADEV and DS1620 granularity, but did not test free-run tempco of the OCXO. rant Please don't use the word TERRIBLE. It's relative to XO, TCXO, OCXO, DOCXO, etc. This is time-nuts, not some feel-good audiophile list. We are allowed to make objective experiments and use scientific notation. The units for tempco involve Hz and C, or dF/F per K, etc. Given that, do either of you have actual tempco numbers? /rant Bob, do you have experience or an explanation for the bi-model tempco grouping that they have observed? Thanks, /tvb ___ time-nuts mailing 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] Stable Watch Clocks
Hi Simon, Thanks for the URL. That's one of those tiny 6x2 mm crystals, 20 ppm crystals (ouch). The tempco (-0.034 ± 0.006 ppm/ T²) is excellent, though. Now, you can adjust rate; and temperature you can control. Notice they don't specify the stability, which is the key to timekeeping. So I see a very interesting experiment/opportunity for you. Get one of these xtals and have it generate 1PPS. Then: 1) measure the accuracy (vs. spec) 2) confirm the tempco (vs. spec) 3) measure the stability (note: no spec given) 4) measure the daily or monthly or annual drift (vs. spec) If you get one of these 32 kHz xtals, I'm happy to send you the other gear you need, if you have the time to do the experiment(s). You'll end up with some very nice plots and a wonderful article or series of articles for your electronics blog. /tvb - Original Message - From: M. Simon To: Tom Van Baak ; Discussion of precise time and frequency measurement Sent: Tuesday, December 11, 2012 9:01 PM Subject: Re: [time-nuts] Stable Watch Clocks http://www.abracon.com/Resonators/AB26T.pdf This quotes .038 ppm/C^2 delta T from the turn over point: http://www.iqdfrequencyproducts.com/app-notes/timekeeping/ The fly in the ointment is the aging rate of 5 ppm the first year (13ppb/day) and 3 ppm (8ppb/day) after. I'm sure holding 1 degC is easy. .1 C with some care and .01 C - my measuring eqpt ain't that good. So temperature ceases to be a problem. Is the other stuff workable? I would go with a 32KHz crystal for a production version to make it easy to multiply up to 10MHz. Simon Engineering is the art of making what you want from what you can get at a profit. From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, December 12, 2012 3:55 AM Subject: Re: [time-nuts] Stable Watch Clocks Typical 32KHz clock crystals are very stable in frequency if you can keep them close to the turnover temp. If you can hold 1 degC it is .04 ppm. That's far better than I thought. Do you have a reference for this spec? I agree you might be able to make one accurate to 0.04 ppm, however briefly, but I've never seen one stable to 0.04 ppm. I mean, that's like 1 second a year. I currently have no method for testing such a rig for stability. Oh, the slipperly slope you are on. I have just the solution for you ... /tvb ___ time-nuts mailing 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] Thunderbolt oven / non-stable operating temperature
Hello Tom, the GPS noise dominates for typical double oven OCXO's where the tempcos are very small (say below 5E-012 per degree C). On single oven units, the tempcos are typically 50 to 200 times larger, and thus the required EFC change over temperature is also that much larger. If I am not mistaken Thunderbolts have double oven units, and Mini-T's have single oven units? That EFC change can only be done through either prediction (sensing temperature and applying a correction factor) or through generating a phase error that feeds through the loop system. Crystal aging also typically requires a constant phase error which will in turn create a constant change in EFC voltage to correct for aging until active aging compensation can measure and apply this change in EFC. The magnitude of this phase error typically depends on the loop gain and the rate of change of the crystal frequency over time. In summary, we see fairly significant improvements in single oven systems with active compensation even during GPS reception, and we don't see much improvement in double oven units for temperature, but similar improvements for double oven units on aging. Now double oven units typically have SC-cut crystals, and single oven units typically have AT-cut crystals where the AT cuts typically have larger aging and retrace than SC cut crystals, so that can skew the performance in favor of double oven units as well. Bye, Said In a message dated 12/11/2012 19:41:58 Pacific Standard Time, warrensjmail-...@yahoo.com writes: I agree this is true in theory (where epsilon != zero), but it's hard for me to believe true in practice. I would guess the error term is totally dominated by short-term GPS noise, and anything else, like tempco or frequency drift, is secondary. That's why it makes sense to apply these 2nd or 3rd order corrections during hold-over mode (where there is no GPS noise) but not for normal operation. So what does this mean for the average Nut's Tbolt? Mostly nothing. The only time the temperature sensor has any effect is during holdover. Thanks for stating both these facts so clearly. I cringe every time I hear someone replacing a 1C DS1620 sensor in their TBolt. The TAPR TBolts I tested years ago worked equally well regardless if they were 1C TBolts or ten milli-C TBolts. /tvb ___ time-nuts mailing 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] 12-12-12, precisely
Coming very soon to a clock near you: 2012-12-12 12:12:12 UTC = MJD 56273 + STOD 43932 = MJD 56273.508472 A special prize for anyone who can capture their local microsecond time standard: 12/12/12 12:12:12.121212 Those of you left of Greenwich and using 12/24 local time get an extra chance: just after midnight (12AM) or noon (12PM). /tvb ___ time-nuts mailing 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] Stable Watch Clocks
Yes. I have already decided to do it. I want some feedback from the list before I get past the thinking stage though. Initial rough calibration will be easy once the temp control is functional. Let every thing get nice and stable. Read Freq. Step 1 deg C. Wait 10 minutes. Read frequency. Step temp. 1 degC. etc. Plot the results. Compute the aprox peak of the parabola. Home in with .1 deg steps. OTOH consider the same design with a 40MHz or ???MHz TCVCXO. What would .1C (.01C?) room temperature control give you? Lots of different oscs might be suitable. The power cost will probably be higher than an OCXO - at least to start. But the range of things that might be done is wide. Or consider running an AT Cut crystal at its lower inflection point. It will probably age slower. But a thousand hour bake at the higher inflection point might be good. As I like to tell beginners - when you get close enough to fundamentals it is all made of rubber or silly putty. Simon Engineering is the art of making what you want from what you can get at a profit. From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, December 12, 2012 5:20 AM Subject: Re: [time-nuts] Stable Watch Clocks Hi Simon, Thanks for the URL. That's one of those tiny 6x2 mm crystals, 20 ppm crystals (ouch). The tempco (-0.034 ± 0.006 ppm/ T²) is excellent, though. Now, you can adjust rate; and temperature you can control. Notice they don't specify the stability, which is the key to timekeeping. So I see a very interesting experiment/opportunity for you. Get one of these xtals and have it generate 1PPS. Then: 1) measure the accuracy (vs. spec) 2) confirm the tempco (vs. spec) 3) measure the stability (note: no spec given) 4) measure the daily or monthly or annual drift (vs. spec) If you get one of these 32 kHz xtals, I'm happy to send you the other gear you need, if you have the time to do the experiment(s). You'll end up with some very nice plots and a wonderful article or series of articles for your electronics blog. /tvb - Original Message - From: M. Simon To: Tom Van Baak ; Discussion of precise time and frequency measurement Sent: Tuesday, December 11, 2012 9:01 PM Subject: Re: [time-nuts] Stable Watch Clocks http://www.abracon.com/Resonators/AB26T.pdf This quotes .038 ppm/C^2 delta T from the turn over point: http://www.iqdfrequencyproducts.com/app-notes/timekeeping/ The fly in the ointment is the aging rate of 5 ppm the first year (13ppb/day) and 3 ppm (8ppb/day) after. I'm sure holding 1 degC is easy. .1 C with some care and .01 C - my measuring eqpt ain't that good. So temperature ceases to be a problem. Is the other stuff workable? I would go with a 32KHz crystal for a production version to make it easy to multiply up to 10MHz. Simon Engineering is the art of making what you want from what you can get at a profit. From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, December 12, 2012 3:55 AM Subject: Re: [time-nuts] Stable Watch Clocks Typical 32KHz clock crystals are very stable in frequency if you can keep them close to the turnover temp. If you can hold 1 degC it is .04 ppm. That's far better than I thought. Do you have a reference for this spec? I agree you might be able to make one accurate to 0.04 ppm, however briefly, but I've never seen one stable to 0.04 ppm. I mean, that's like 1 second a year. I currently have no method for testing such a rig for stability. Oh, the slipperly slope you are on. I have just the solution for you ... /tvb ___ time-nuts mailing 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.
