[time-nuts] Older Lucent GPSDO and Rubidium combo

[Paul Cloud]

Oops I found more just as you suspected.

"Rb RF frequency stability
After a minimum of 22 minutes of warm-up at 25° C (77° F), interface
circuitry with 0.05-ppm 15-MHz accuracy can be maintained for a
minimum of seven years with CTU adjustment of the OM frequency.
For temperatures between 0-10° C (32-50° F), a minimum of 26
minutes warm-up is required for frequency stability."

It would appear that the Rb is disciplined if I'm reading the above correctly.

73, Paul



On Sun, Dec 12, 2010 at 11:35 PM, Paul Cloud <jpcloud04 at gmail.com> wrote:
> Well I suppose that my use of the word "spec" was incorrect the quote
> is listed below.
>
> "OM redundancy The Oscillator Module provides a highly stable timing reference
> capable of being disciplined from an external source, such as the GPS
> receiver or network clock. Two versions are available: Rubidium based
> (OMR), which is capable of running for 24 hrs without an external
> reference (flywheeling), and Quartz Crystal based (OMQ), which can
> flywheel for eight hours. The OMR serves as a primary timing
> reference where high long term accuracy is required. The OMQ can be
> used as a primary source, where long term drift accuracies are more
> relaxed or as a secondary (back-up), to be used upon the primary’s
> failure. The OMR may also be used as secondary if desired, in
> applications where low cost is not a requirement."
>
> I should also state that this is not from actual documentation for the
> unit that I have. But, it is actual documentation for a system later
> by some 3 years.
>
> Thanks and 73, Paul
>
>
>
> On Sun, Dec 12, 2010 at 11:00 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>>
>>> Are you under the impression that the Rb is disciplined also? I had thought
>>> that the GPSDO side was disciplined and the Rb was only for holdover, they
>>> seem to call it fly-wheeling. They spec 8 hour holdover for the GPSDO and 24
>>> hour holdover for the Rb in the limited info I've been able to snag. I'm
>>> still digging for more info.
>>
>> Holdover is more than just a single number.
>>
>> I'd expect something like:
>>  The PPS will be within X microseconds for Y hours.
>>
>> It might be that there are two sets of specs, one for a crystal and another
>> for a Rb option.  I'd expect the Rb option to have smaller X or longer Y.
>>
>>
>> Most Rb units have an adjustment (screwdriver or voltage) to correct for the
>> local magnetic field.  If you have that sort of adjustment voltage, you can
>> easily turn it into a GPSDO.
>>
>>
>> --
>> These are my opinions, not necessarily my employer's.  I hate spam.
>>
>>
>>
>>
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>