[time-nuts] GPS and Rubidium frequency standards and noise question (newbie).

[Jerry Mulchin]

Chris,

To answer your question regarding using a Rubidium standard as a frequency reference
for your Transverters.

GPS really has nothing to do the main requirement regarding Phase Noise and your
Transceivers. But the 10MHz oscillator inside the Rubidium standard is the item
that will be the Phase Noise problem if you get the wrong Rubidium standard. There
are cheap Rubidiums and there are good Rubidium standards to consider.

An LPRO-101 is actually a very good Rubidium standard, and exhibits Phase Noise
values of  -96dBc/Hz @ 10Hz, -138dBc/Hz @ 100Hz, -152dBc/Hz @ 1KHz offsets
from carrier. This is what I use for my 10GHz Transverter reference, but I don't lock it
to GPS when in the field. LPRO-101's can be gotten pretty reasonably.

Locking the LPRO-101 to a GPS will require more support circuitry, and most of the
folks on this list can help you with that.

Also, Thunderbolt GPS disciplined units are nice, but I do not know the Phase Noise
numbers of a typical Thunderbolt unit. Others here probably know the answer to that.

The important thing to remember is you don't what to use 10MHz oscillators that have
poor Phase Noise performance as it will effect your weak signal capability if you use
a poor Phase Noise oscillator.

Jerry

At 03:05 PM 6/2/2012, you wrote:
>If you want a frequency reference.  There is nothing better than GPS.   In
>fact it you bought a Rubidium you would still need the GPS so you could
>calibrate its frequency.
>
>Some GPSes might be noisy but then you can lock a good double oven crystal
>oscillator to it and have what they call a "GPS disciplined crystal
>oscillator or "GPSDO".
>
>
>
>On Sat, Jun 2, 2012 at 2:57 PM, Chris Wilson <chris at chriswilson.tv> wrote:
>
>>
>>
>>  I am looking to get a frequency standard for my amateur radio shack,
>>  initially for verifying test gear readings, but later as a standard
>>  to lock receiver and transmitter oscillators to. I was going to buy
>>  a GPS frequency standard but a friend warned me these may have noise
>>  issues when I come to use it with an oscillator in RX / TX
>>  applications. It's not something I had considered, so what's the
>>  score here please? Should I not buy a GPS standard? Thanks. Any
>>  links to known safe suitable purchase sources from personal
>>  experience welcome, either here or by PM or e-mail. I am in the UK.
>>
>> --
>> Best regards,
>>  Chris Wilson                          mailto:chris at chriswilson.tv
>>
>>
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>
>
>
>-- 
>
>Chris Albertson
>Redondo Beach, California
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Jerry Mulchin