[time-nuts] Comparing Reference Accuracy

Stanley Reynolds stanley_reynolds at yahoo.com
Thu May 22 22:37:09 EDT 2008



----- Original Message ----
From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
To: Discussion of precise time and frequency measurement <time-nuts at 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 <didier at cox.net>
To: robert8rpi at yahoo.co.uk; Discussion of precise time and frequency measurement <time-nuts at 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


      



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