[time-nuts] Another "atomic" clock question

Hal Murray hmurray at megapathdsl.net
Sun Mar 2 02:45:25 EST 2014

bob91343 at yahoo.com said:
> Okay you want numbers.  Well, I think 10 ppb or thereabouts should do it. 
> Somewhere there is a discontinuity in accuracy plotted against cost and I
> don't want to cross that barrier just yet.  If I can get 1 ppb without a big
> increase in cost, I'll take that. 

How good is your crystal?

Junk crystals are good thermometers.  Ballpark is 1 ppm/degree-C
If you are running ntpd, turn on loopstats and measure the temperature...

I've been watching a 3 MHz ovenized crystal.  It was something like 4 for $25 
from ebay.  It's a 2 in sq can, over an inch high.  It's got a few ppb of 
noise over minutes/hours and a few more ppb of drift/wander over days/months. 
 It took several weeks to stabilize after power on.

These are my opinions.  I hate spam.

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