[time-nuts] Reference oscillator accuracy

[paul swed]

I use GPS and LORAN. Always nice to have a backup
With LORAN being shut down, have resurrected the ole wwvb rcvr and built an
amplified loop ant.
Can work but it takes about 3-5 hours to get to 1X10^11 accuracy. Still
observing various strange ness shuch as diurnal shift ...
Odd wwvb works at least for me most stable in the day. I seem to remember
night was supposed to be better.
The signal is much stronger at night.
So I guess its a play but sure not as easy as gud ole LORAN C has been.

On Fri, Nov 13, 2009 at 12:48 PM, Brian Kirby
<kilodelta4foxmike at gmail.com>wrote:

> 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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