[time-nuts] OCXO Phase Noise Measurement in Primitive Conditions

[Bob Stewart]

I found also that I have a hardware problem.  Bert posted recently that he keeps his OCXOs out in the open with at least one inch of free space on all six sides.  My chassis badly ignores that, with the OCXO up against the edge of the case.  I noticed that the EFC changed and then a bit later the thermistor reading changed and thought, hmmm, the OCXO on the edge of the case is seeing the temp changes first and causing unexpected changes to the loop condition.  I've hooked up my thermistor to the PLL controls.  Next is to reconfigure my GPSDO box to give the OCXO some room to breathe.  I feel like I'm finally getting somewhere with this random noise from the OCXO.


Bob



________________________________
 From: Poul-Henning Kamp <phk at phk.freebsd.dk>
To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
Sent: Thursday, August 28, 2014 1:04 AM
Subject: Re: [time-nuts] OCXO Phase Noise Measurement in Primitive Conditions
 

--------
In message <1409175707.2080.YahooMailNeo at web142706.mail.bf1.yahoo.com>, Bob Ste
wart writes:

This looks like a step in the right direction.

The "correct" allan plot will have a clearly visible horizontal
segment somewhere in the 100-10000 second range (depending on OCXO quality).

This is where the GPS long-term stability "takes over" from the OCXO's
better short-term stability.




-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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