You will need a receiver to compare your references to. It appears that
LORAN will be shut off, so that leaves two services available, either
WWV 60 Khz or GPS. I do not use WWV any more, I can tell you about GPS.
To compare against GPS you will need a timing receiver, there are
several available. A lot of us got Motorola Oncore VPs, UTs, or M12+,
The Rockwell Jupiter is one and there are several more. They provide a
1 PPS signal that is locked to the on board standards on the GPS
satellite. You put this signal in one input of a time interval
counter. You use a 1 PPS divider on your local reference and put its
signal in the other input of the time interval counter. You can record
continuous or take daily 24 hour readings and derive your drift rates.
GPS corrections are published at NIST;
http://tf.nist.gov/service/gpstrace.htm
You can also compare against a GPS disciplined oscillator. In the long
term it should be dead on, you will have to have it characterized for
the short term. The HP Z3801A was on the surplus market several years
back, its probably one of the best. The Trimble Thunderbolts were
available to the group a while back.
Brian KD4FM
Glenn Little WB4UIV wrote:
While I was in the US Navy we had two Cesium standards for the
navigation center on SSBN submarines.
While in port, we would track LORAN C and compute the drift rate of
the two cesium standards.
Is there a service, that has drift rates published, that I can compare
my standards to, so that I can determine the standard drift rate.
I do not remember the drift rates that we determined on the submarine,
that was a few years ago, but, I seem to remember that the rate was in
the low nanoseconds.
If a rubidium standard drifts in one direction (does it?) a drift rate
could be calculated and, after a comparison to a known standard, with
known drift rate, a very accurate standard could be had for the lab.
What would I expect the drift rate, or jitter, to be in a FRK class
rubidium oscillator?
Is the drift rate constant enough that a drift rate could be applied
to a rubidium oscillator to determine it's real frequency at any given
time.
We calibrated the submarine Cesium standards every three months.
We had to know the drift rate of our standard as well as the drift
rate of the standard in each of the LORAN stations to be able to do
the type of LORAN navigation that we did.
I would like to be able to verify that my PTB-100 rubidium oscillator
is on frequency.
If I compare two rubidium oscillators, what would I expect the
relative drift rate to be?
Thanks
73
Glenn
WB4UIV
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