----- Original Message ---- From: Bruce Griffiths <[EMAIL PROTECTED]> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Thursday, May 22, 2008 5:33:40 PM Subject: Re: [time-nuts] Comparing Reference Accuracy
Stanley Reynolds wrote: > Disabling all the GPS receivers at the same time would allow a comparison of > the hold over of each. As we are also logging the temp and power some changes > in these would also help determine how "good" each DO is as far as stability. > Stanley > > You still need a frequency comparison scheme with sufficient resolution and low intrinsic noise (perhaps 1E-12 or better at 1sec). Since the long term average frequencies of the various oscillators are not necessarily identical in hold mode, a phase comparison scheme with a relatively wide dynamic range is required to avoid frequent phase wrapping. Bruce With the default settings the reduced VE2ZAZ controler would count all 160,000,000 pluses in a 16s period, phase is not measured so it has no wrap just the +-1 count. Looking at the orginal Brooks Shera design you would not need the DAC chip and any neg power requlator to use it as a measuring device. And the clock U7 ECS300S-24 could be shared between the multi sets of boards. I'm not sure if it could be adapted futher for this meassuring task. <inserted another post> ----- Original Message ---- From: Didier Juges <[EMAIL PROTECTED]> To: [EMAIL PROTECTED]; Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Thursday, May 22, 2008 7:13:35 PM Subject: Re: [time-nuts] Comparing Reference Accuracy I started doing that some time ago using my Wiki, but got distracted. Anyone can contribute, you are certainly welcome to: http://www.ko4bb.com/cgi-bin/wiki/wiki.cgi Didier KO4BB <end insert> I have several HP-5334A on the way but not sure of their condition, also have a PCI card for GPIB with John's software I would need to adapt it to use multi counters and not the 59307A switch, as I don't have one. Stanley _______________________________________________ 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.
