[time-nuts] Thunderbolt stability and ambient temperature

Poul-Henning Kamp phk at phk.freebsd.dk
Thu Jun 11 06:50:10 EDT 2009

In message <E182724B9FCE4B9F9E914BCC4F374401 at athlon>, "Ulrich Bangert" writes:
>> For PLL steered devices, you want your device enclosed by a 
>> thermal mass which is again enclosed by a layer of thermal 
>> isolation.  The goal is to filter/average all rapid (daily ?) 
>> external temperature influences, only letting through such 
>> slow variations (seasonal ?) which the PLL can comfortably cope with.
>My impression with this thread is that two sligthly different things are
>being discussed here: 
>Some posters explain how a crystal oven shall be designed as Poul-Henning
>does with his words above. Absolute correct, no doubt about it!

I'm not talking about crystal ovens, I'm talking about timekeeping
kit in general: how to filter high frequency temperature fluctuations
out, so the PLL does not have to deal with them.

The above advice applies to GPSDO's and Rb's and Cs's as well as TCXOs,
OCXOs and voltage references.


Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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