[time-nuts] Sound Cards for locking to GPSDO 10 MHz references
connie.marshall at suddenlink.net
Wed Jun 3 16:40:11 EDT 2009
You know, I probably need to run the test again and do a better job of
tracking room temp. My thermometer is high up on the wall in the shack. The
computer sets under the bench in a corner. It does represent a typical
afternoon in my shack however.
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of Hal Murray
Sent: Wednesday, June 03, 2009 12:24 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Sound Cards for locking to GPSDO 10 MHz
connie.marshall at suddenlink.net said:
> Sound card drift over this four hour period is about 250 micro Hertz.
> The temp in the shack was going up during the measurement period.
> Unfortunately I did not track the exact temp rise, but was about
> around 4 to 6 degrees F.
250 micro Hz relative to 1000 Hz is 1/4 ppm.
My memory is that junk PC crystals are ballpark of 1 ppm/degree. (That's
probably per degree C rather than F, but that's only a factor of 2.)
So 1/4 ppm for 4 degrees is better than I would have guessed.
These are my opinions, not necessarily my employer's. I hate spam.
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