[time-nuts] Good Phase-noise?

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed Feb 28 20:07:28 EST 2007


Larry Gadallah wrote:
> Hello Bruce:
>
>> Larry
>>
>> Obtaining a lower phase noise COTS OCXO in this price range is unlikely
>> unless Wenzel oscillators are unusually cheap.
>>
>> http://www.wenzel.com/catalog.html#HF%20Oscillators
>
> Is Wenzel the leader of the pack in this sort of technology? I know
> that there are a number of players (i.e. Valpey, Bliley, etc.).
>
They appear to be. Austron also used to make low phase noise oscillators.
Valpey and Bliley don't appear to offer anything comparable.
>
> I don't need 100 Mhz, only 10 Mhz, and I'd be looking to discipline
> this oscillator directly rather than rely on another GPSDO. All other
> things being equal, I'd rather just find an HP Z3801A, but the supply
> seems to have dried up and those that do appear these days seem to be
> overpriced.
>
The phase noise of these is at least 10-15dB shy of the state of the art.
>> They are used in at least one Radio astronomy application in the local
>> oscillator distribution system of an antenna array that operates at
>> frequencies of up to 40GHz.
>
> I can only imagine the constraints of radio astronomy, where precise
> timing and phase are required...
>
>
The constraints are eased a little for an array where phase noise in the 
local oscillator distribution system is common to all elements of the array.
Radio astronomy signals are largely just incoherent noise after all, 
which is why in the absence of strong interference 1-2 bit ADCs suffice.
> Thanks again for the info.
>
> Cheers,




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