Re: [time-nuts] Racal-Dana 1992 switches
Charles S. Osborne wrote: Now the real question is... is there a clever way to make the Racal 1992 readout the difference in µHz between two GPS disciplined oscillators? My only other counter, an HP5384A, is offscale at 10.000 000.000 MHz . I'm referencing the counter with one Lucent RFTG-m-XO and clocking a Lucent RFTGm-II-XO. Things are working well enough to be beyond my counter's ability to see any jitter. The Racal says nanosecond time interval counter, so I bet there's a way to subtract and increase the resolution similar to an HP53131? tnx, Charles K4CSO Duluth, GA Charles One way to achieve microHertz resolution at 10MHz is to use a dual mixer time difference system or a variant thereof. The output from each GPDSDO is mixed with the same low noise offset source. This produces a pair of beat frequencies (one from each mixer) outputs. The zero crossing from one beat frequency output is used connected start a time interval counter whilst the zero crossing of the other beat frequency output is used to stop the time interval counter. The trick is to amplify the low slew rate beat frequency signal in such a way that the time interval counter sees 2 high slew rate low jitter signals. Just connecting the low pass filtered beat frequency outputs to the counter inputs isnt effective as the measured timing jitter will inevitably be much greater than the actual zero crossing jitter in the beat frequency signal itself. A resolution approaching 1E-14/sec is possible with this technique. Another approach is to use a series of cascaded frequency difference multipliers, this is the approach used by Quartzlock in their precision frequency comparators. This approach can also have a resolution approaching 1E-14/sec. If you are willing to wait a little longer to see microHertz frequency differences then an analog phase comparator can be used. A resolution approaching 1E-11/sec is possible with this technique if a high resolution ADC (eg a high res DVM) is connected to the phase detector output. 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] Racal-Dana 1992 switches
Actually, after two days of studying catalogs and datasheets, I think I found a suitable replacement switch. The trick is to find the ones made for tape packaging, which only have 2 pins -- the others have 4. The Omron B3F-6050, available through Digikey as part no. SW798-ND is $0.28 each for 100 ($0.39 each for singles). It has nearly the same dimensions as the original Toko, except it is about 3mm shorter so it will need to either be shimmed up or left sitting up on its pins and the plunger is the standard 2.4mm square instead of the cross, so the keycaps will need some modification. I'll let you all know how they work out once I receive and install them. Chris ___ time-nuts mailing 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] Tboltmon Serial Port Selection...??
My version of Tboltmon (version 2.60)accepts a command line argument which bypasses the selection menu e.g. TBOLTMON.EXE -c1 This does not appear to be documented. Michael Baker wrote: Hello, All-- Can anyone tell me why, when I click on the Tboltmon icon associated with my Trimble Thunderbolt, that a little Serial Port Selecton window pops up and why does my T-bolt only run after selecting COM-4? Why can't this be selected once and then forgotten about? It seems like an un-necessary step. Thanks!! Mike Baker WA4HFR Micanopy, FL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Stephen Tompsett ___ time-nuts mailing 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] Tboltmon Serial Port Selection...??
Thanks! How'd you find that option? -- john, KE5FX -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Stephen Tompsett Sent: Friday, March 28, 2008 1:12 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Tboltmon Serial Port Selection...?? My version of Tboltmon (version 2.60)accepts a command line argument which bypasses the selection menu e.g. TBOLTMON.EXE -c1 This does not appear to be documented. ___ time-nuts mailing 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] Tboltmon Serial Port Selection...??
That works for me, too! I also have version 2.60. Ken, WA2LBI On Fri, Mar 28, 2008 at 4:11 AM, Stephen Tompsett [EMAIL PROTECTED] wrote: My version of Tboltmon (version 2.60)accepts a command line argument which bypasses the selection menu e.g. TBOLTMON.EXE -c1 This does not appear to be documented. Michael Baker wrote: Hello, All-- Can anyone tell me why, when I click on the Tboltmon icon associated with my Trimble Thunderbolt, that a little Serial Port Selecton window pops up and why does my T-bolt only run after selecting COM-4? Why can't this be selected once and then forgotten about? It seems like an un-necessary step. Thanks!! Mike Baker WA4HFR Micanopy, FL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Stephen Tompsett ___ time-nuts mailing 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] TADD-1 six channel RF distribution amplifier
Steve said the following on 03/27/2008 09:35 PM: I'm thinking about using the TAPR TADD-1 six channel RF distribution amplifier to distribute the 10MHz output of my Trimble Thunderbolt to a few pieces of test equipment. What does the TADD-1 do to the phase noise characteristics of its outputs as compared to the phase noise characteristics of its input? Improve? Degrade? Little or no change? Thanks. Steve K8JQ I did some testing a while ago on a TADD-1 as well as an HP 5087A and Spectracom 8140T line amplifier. At 5 MHz, for offsets above 1 Hertz, the TADD-1 is better than the HP amp (the 5087A is better at very low offsets, though). The results are at http://www.febo.com/pages/amplifier_phase_noise/ I've learned a bit about technique since I did this test, and want to rerun it one of these days. But the data shouldn't be more than a few dB off. John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Racal-Dana 1992 switches
Back to the switches... I found a Jameco bag for the ones I bought way back, which fitted pretty well and work. The part number was 115086, then quoted for KIE22, but not the same as the current ones with that number. Jameco might know who made the 115086, but there are no clues from the few remaining in the bag... Dan ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
The phase plots on tvb's web site http://www.leapsecond.com/pages/tadd-1/3phase2.gif show that the device's temperature was never stabilized. The closest to being stable is at the 29 minute point on that plot. Particularly when the phase value goes up (not sure if it's when temperature goes up or down), because the phase was still changing at a pretty high rate when the compressor changed state. I think Tom should rerun that test with a much slower cycling, to make sure the phase was stable before the compressor was turned on (or off). Since the phase excursion was not complete, the 150pS/degree is probably underestimated. My guess is that the period should be at least doubled. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Mock Sent: Friday, March 28, 2008 12:29 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] TADD-1 six channel RF distribution amplifier Bruce Griffiths wrote: Steve wrote: I'm thinking about using the TAPR TADD-1 six channel RF distribution amplifier to distribute the 10MHz output of my Trimble Thunderbolt to a few pieces of test equipment. What does the TADD-1 do to the phase noise characteristics of its outputs as compared to the phase noise characteristics of its input? Improve? Degrade? Little or no change? Thanks. Steve K8JQ I've been using a TADD-1 for about 6-months now and I'm quite happy with it. You certainly can't beat the price. I added the optional 10MHz BPF and tuned it with a tracking generator and spectrum analyzer. The outputs are very clean. I've never tried to measure phase noise, but the op amps and the rest of the circuit seem to be good choices to me. tvb did some analysis of the box you might find interesting: http://www.leapsecond.com/pages/tadd-1/ jeff ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. No virus found in this incoming message. Checked by AVG. Version: 7.5.519 / Virus Database: 269.21.8/1339 - Release Date: 3/22/2008 4:43 PM No virus found in this outgoing message. Checked by AVG. Version: 7.5.519 / Virus Database: 269.21.8/1339 - Release Date: 3/22/2008 4:43 PM ___ time-nuts mailing 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] TADD-1 six channel RF distribution amplifier
Thanks for the info Bruce. I'm planning to use the Trimble Thunderbolt as the 10MHz source. The phase noise characteristics of that device are on the Trimble web site. I'm not versed enough in the specifications to call it good, bad or mediocre with respect to phase noise. Thoughts? Thanks. Steve K8JQ Bruce Griffiths wrote: Steve wrote: I'm thinking about using the TAPR TADD-1 six channel RF distribution amplifier to distribute the 10MHz output of my Trimble Thunderbolt to a few pieces of test equipment. What does the TADD-1 do to the phase noise characteristics of its outputs as compared to the phase noise characteristics of its input? Improve? Degrade? Little or no change? Thanks. Steve K8JQ Like any distribution amplifier it always degrades the signal phase noise. Whether the amount of degradation is significant or not depends on the phase noise characteristics of your source. If your signal source phase noise is 10dB greater than the intrinsic phase noise of the distribution amplifier than the increase in the phase noise at the distribution amplifier is relatively insignificant. Thus you need to know the phase noise characteristics of your source and of the distribution amplifier (when set to the gain you need). The phase noise characteristics of the distribution amplifier vary with its gain. The phase noise of your source and a distribution amplifier vary with the frequency offset at which they are measured. What source are you intending to use? Do you know its phase noise characteristics? 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.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
The phase plots on tvb's web site http://www.leapsecond.com/pages/tadd-1/3phase2.gif show that the device's temperature was never stabilized. The closest to being stable is at the 29 minute point on that plot. Particularly when the phase value goes up (not sure if it's when temperature goes up or down), because the phase was still changing at a pretty high rate when the compressor changed state. I think Tom should rerun that test with a much slower cycling, to make sure the phase was stable before the compressor Agreed. Actually, I don't have that A/C anymore so future tempco tests won't have that rapid cycling. was turned on (or off). Since the phase excursion was not complete, the 150pS/degree is probably underestimated. My guess is that the period should be at least doubled. Yeah, I think so. The main conclusion I had when I made those plots was that the input filter was a bad idea, at least if the TADD was to be used for precision work. Didier KO4BB /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] TADD-1 six channel RF distribution amplifier
Thanks for the info Bruce. I'm planning to use the Trimble Thunderbolt as the 10MHz source. The phase noise characteristics of that device are on the Trimble web site. I'm not versed enough in the specifications to call it good, bad or mediocre with respect to phase noise. Thoughts? Thanks. Steve K8JQ Here's an old plot of a random Thunderbolt I tested: Ignore the spurs (test setup problem). http://www.leapsecond.com/museum/tbolt/tbolt_pn.gif /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] TADD-1 six channel RF distribution amplifier
Steve wrote: Thanks for the info Bruce. I'm planning to use the Trimble Thunderbolt as the 10MHz source. The phase noise characteristics of that device are on the Trimble web site. I'm not versed enough in the specifications to call it good, bad or mediocre with respect to phase noise. Thoughts? Thanks. Steve K8JQ Steve If one compares TvB's plot of the phase noise of a Thunderbolt with John Ackermann's plot of the phase noise of a TADD-1 at 10MHz. Then the phase noise floor of this particular Thunderbolt is lower than the phase noise floor of the TADD-1 at the particular gain used in John's test. Thus using the TADD-1 at this gain will degrade the noise floor of that particular Thunderbolt by about 7dB. However at 1Hz and 10Hz the phase noise of the Thunderbolt exceeds that of the TADD-1 by 15dB or more so the phase noise of that Thunderbolt will not be significantly degraded by the TADD-1 at those offset frequencies. Distribution amplifiers with lower noise floors and equivalent or better reverse isolation do exist but tend to be expensive. A design employing cascaded common base stages can have a significantly lower phase noise floor. 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] TADD-1 six channel RF distribution amplifier
Bruce and others, Thank you for the assistance. Seems that the TADD-1 will meet my needs, I will probably acquire one in the near future. Steve K8JQ Bruce Griffiths wrote: Steve wrote: Thanks for the info Bruce. I'm planning to use the Trimble Thunderbolt as the 10MHz source. The phase noise characteristics of that device are on the Trimble web site. I'm not versed enough in the specifications to call it good, bad or mediocre with respect to phase noise. Thoughts? Thanks. Steve K8JQ Steve If one compares TvB's plot of the phase noise of a Thunderbolt with John Ackermann's plot of the phase noise of a TADD-1 at 10MHz. Then the phase noise floor of this particular Thunderbolt is lower than the phase noise floor of the TADD-1 at the particular gain used in John's test. Thus using the TADD-1 at this gain will degrade the noise floor of that particular Thunderbolt by about 7dB. However at 1Hz and 10Hz the phase noise of the Thunderbolt exceeds that of the TADD-1 by 15dB or more so the phase noise of that Thunderbolt will not be significantly degraded by the TADD-1 at those offset frequencies. Distribution amplifiers with lower noise floors and equivalent or better reverse isolation do exist but tend to be expensive. A design employing cascaded common base stages can have a significantly lower phase noise floor. 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. -- Read The Patriot It's Right -- It's Free http://PatriotPost.US/subscribe/ Veritas vos Liberabit ___ time-nuts mailing 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] Racal-Dana 1992 switches
Charles S. Osborne said, in part, Now the real question is... is there a clever way to make the Racal 1992 readout the difference in µHz between two GPS disciplined oscillators? My only other counter, an HP5384A, is offscale at 10.000 000.000 MHz . I'm referencing the counter with one Lucent RFTG-m-XO and clocking a Lucent RFTGm-II-XO. Things are working well enough to be beyond my counter's ability to see any jitter. The Racal says nanosecond time interval counter, so I bet there's a way to subtract and increase the resolution similar to an HP53131? Haven't seen the answer on this list, so perhaps it occurred privately. The Racal 1992 is able to read the phase error between two 10 MHz signals (A and B) in degrees. I have done this with the outputs of two 3801s, which are the only pair of frequency sources that I have. This would be sub-nanosecond accuracy except that the display shows 3-10 degrees of jitter (difference between two successive readings). This, however, is only 10E-9. Most people on this list are investigating areas at least two orders of magnitude lower. I find that the phase method gives me comparative drift errors soon enough. An hour gets you near 10E-12. Others require measurement intervals much shorter than that, but the phase angle method is more than adequate for time errors that humans will notice. A drift of one second per year is on the order of 10E-8. It all depends on your reason for pursuing accurate time/frequency measurement. Bill Hawkins ___ time-nuts mailing 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] Odetics 425: Damn... It's really dead now...
Fellow time-tickers, Well, I suppose it was due to happen. The GPS receiver in my Odetics 425 finally died. Hard. The thing's been intermittent for nearly the entire two years since I became its new owner, so I guess I shouldn't be surprised that the thing finally keeled. I would REALLY like to restore this grand old beastie, not just because I like the workmanship but because it has a unique history. Its last home, before I got it, was the Amundsen Antarctic Research Station as part of the AST/RO program. So -- Before I start stretching my brain cells, and those of a close friend, and try to come up with a way to interface a generic NMEA receiver module into this wonderful old beast, I have a couple of questions to put to the group, especially those who used to (or still do? Hopefully?) work for Odetics/Zyfer. (1) Does ANYone have a working Magellan OEM 5000 receiver module that they would be willing to part with? If so, please contact me off-list. (2) The schematics I have are poor-quality copies that were reduced to letter size from the original ANSI size D pages. Does anyone have schematics of this unit's MPU board that are more readable? (3) Failing finding a Magellan receiver -- Fitting a standard receiver to this beast is going to require some reverse-engineering, and perhaps modification of the firmware. The section that communicates with the GPS receiver uses a 68B09 CPU. Suggestions on what tools would be most useful to this effort, as well as any hints those who have worked with 6809's might have. I do have available a Fluke 9100 series CPU troubleshooting system, with a 6809 pod. (3) Was there EVER a case where a generic (as in NMEA-speaking) receiver was used with the 325/425 series? If so, please provide details. Or did they get retired before NMEA became the defacto standard? Keep in mind that if I can come up with a viable way to do this, it will likely mean a new lease on equipment life for all owners of 325/425 systems, because in the event it all works I will make the details of the process freely available. Looking forward to hearing anything that might help. Thanks much. -=-=-=-=-=-=-=-=-=-=-=- Bruce Lane, Owner Head Hardware Heavy, Blue Feather Technologies -- http://www.bluefeathertech.com kyrrin (at) bluefeathertech do/t c=o=m Quid Malmborg in Plano... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
