[time-nuts] 10811 foam enclosure

[Mike S]

At 07:59 AM 1/10/2011, Bob Camp wrote...
>The spec they were after was a warmup to "on frequency +/- 1x10^-8" 
>from -40 C sort of thing. I believe the warmup  time was under 15 
>minutes, but I don't know the exact number.

Nope. It was only spec'd for operation from 0-50C. It was required to 
achieve satellite lock within 60 minutes of powerup, but only had to 
achieve +/- 1 us (PPS) while locked. Freq spec was < 10E-9 one day 
average. You don't even need an OCXO to do all of that.

As I already stated, the warmup/training spec allowed 24 hours, after 
which it was expected to be able to holdover for 24 hours within 7 us. 
This, while experiencing temperature cycles (0-30C, 20-50C). The 
successor, the GPSTM, doubled the warmup to 48 hours, but added an 
additional temperature range (35-65C) to the holdover requirement.

The double oven was there for holdover stability, not warmup time.