Bill, I guess my reason for wanting to see beyond 0.001 Hz is the usual, I have reached a limit and wonder if the equipment I have is capable of more, if I just understood the more esoteric functions I seldom use. The Racal seems like my scientific calculator.. lots of shift functions that might be hiding some useful capabilities with a little coaching and study.
Just saw Pete's answer, and I do have a PTS160 synthesizer. So the locked offset idea is do'able. Have mixers, phase detectors, but may need more info on the zero crossing detector opamp portion if you could point me in the right direction. >From a GPS equipment standpoint more resolution might tell me if my GPS receivers are working good enough or marginally. I passive split the antenna line four ways. The Lucent units lock to it with about 34~45 C/N readings. But my Z3801A has some other issue now that I've replaced the UT+. It hasn't locked and gives recurring "UTC receiver timeout" messages on GPScon. The previous UT+ receiver was somewhat lightning damaged and would only lock to one or two satellites for a few hours a day, but at least it was communicating. It may just be a comm issue between the Z3801A motherboard and my present UT+, since the Z3801A motherboard does answer back with serial number etc to GPScon. So I know the baud rate at that level is communicating between PC and Z3801A. The UT+ is a used one from one of the Lucent RFTGm units. So maybe there's a difference in the way they were setup. The UT+'s are 2000 vintage Synergy R5122U1112 to Lucent with V2.2 firmware and no battery. I actually have collected enough damaged UT+ boards (from the lightning prone place I previously worked) that I should build up an NMEA test fixture to verify they work outside the systems they normally reside in, and that all the parameters are set correctly. Then I can try to resurrect a few. The M1501 LNA chips are usually what goes. And I have some ideas I want to try, to dead bug in a MMIC fix for that obsoleted LNA chip. Charles Osborne K4CSO, EM74wa Duluth, GA ----- Original Message ----- From: "Bill Hawkins" <[EMAIL PROTECTED]> To: "'Discussion of precise time and frequency measurement'" <time-nuts@febo.com> Sent: Friday, March 28, 2008 9:09 PM Subject: 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 mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.