[time-nuts] measuring my GPSDO : length of TimeLab run?

Bob Camp lists at rtty.us
Mon Feb 4 08:56:32 EST 2013


Runs of ten days are not at all uncommon. Since GPS has some 24 / 48 hour
"bumps" in it, you will get better data with a month long run. You need at
least 10X (and preferably 100X) the data span relative to the "stuff" you
are looking for.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Chris Howard
Sent: Monday, February 04, 2013 6:40 AM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] measuring my GPSDO : length of TimeLab run?

I took my recently acquired cesium clock to the hamfest
in Jackson, MS a couple of weeks ago in the hope that I could
cash in big and retire in splendor.  But no one bought it.

So, instead I spent some of my hamfest earnings on a GPIB/USB
dongle and I've been using TimeLab and looking at the
VE2ZAZ GPSDO that got me into all of this in the first place.

The numbers I get are very gratifying.  The GPSDO seems to work
better than I expected.  This is really cool.

But I have a question.

The GPSDO is set up to do a potential correction every hour.
It seems to me that a TimeLab run of less than X hours will
only be measuring the fine properties of the oscillator
and not the whole system.  The question is, how many
hours of data collection are needed to capture a
characterization of the GPSDO as a whole?

What do people to with Thunderbolts and other similar systems?

Chris Howard

After I get done playing around with this cesium standard
I still think I would like to sell it.  I would like
to get enough out of it to buy an Elecraft K2 with some
of the options.  I don't really know if that is realistic.
If anyone has comments on that plan, would also love
to hear them.

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