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

Javier Herrero jherrero at hvsistemas.es
Sun Jun 3 19:45:16 UTC 2012


Hi, Said,

I think that all of the last cheap ebay lot are of the second variety 
(60MHz osc + 5.3125MHz DDS, very narrow tuning range through serial port 
message). I remember your phase noise and adev plots on them. But I 
don't know if the first variety (the ones with a 55MHz or so crystal 
oscillator and 10MHz DDS-derived output, with wide range of frequency 
settability through the serial port) are better or worse in the phase 
noise, spurious and adev sections compared with the second one.

Regards,

Javier

El 03/06/2012 21:35, Said Jackson escribió:
> Hello Javier,
>
> I have a couple from that last Ebay lot , and the phase noise/spurs are so bad on these that I figured the 10MHz must have been generated by a DDS. I posted the phase noise and ADEV plots of this unit to this list earlier this year.
>
> bye,
> Said
>
> Sent From iPhone
>
> On Jun 3, 2012, at 2:19, Javier Herrero<jherrero at hvsistemas.es>  wrote:
>
>> Hello,
>>
>> El 03/06/2012 10:46, SAIDJACK at aol.com escribió:
>>>
>>> The FEI-5680A Rubidium that we discussed here some time ago has a much
>>> worse phase noise plot of course, because the 10MHz is generated digitally
>>> through a DDS, not a 10MHz crystal oscillator..
>>>
>> There is a version that generates 10MHz directly through DDS, but the particular version we recently discussed a lot about generates the 10MHz signal from a 60MHz oscillator, and the DDS is used for generating the ~5.3125MHz signal for mixing with the 114th harmonic of the 60MHz to obtain the Rb resonance frequency.
>>
>> I don't remember if someone did a comparison in PN performance between the two FE-5680A flavours.
>>
>> Regards,
>>
>> Javier
>>
>>
>>
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-- 
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Javier Herrero
Chief Technology Officer                  EMAIL: jherrero at hvsistemas.com
HV Sistemas S.L.                          PHONE:         +34 949 336 806
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