[time-nuts] The best GPSDO ?

[Azelio Boriani]

Have you a BVA? If you have a BVA then it is the best source for PN
measurements and, if disciplined, for AD measurements too. Anyway, for AD I
think that every GPSDOs can do (TBolt preferred).

On Fri, Sep 28, 2012 at 11:15 AM, Bruce Griffiths <
bruce.griffiths at xtra.co.nz> wrote:

> Ulrich Bangert wrote:
>
>> Gentlemen,
>>
>> I know that lots of you own a GPSDO, some of you two or even more. For
>> that
>> reason I conclude that there must be a lot of knowledge available on how
>> different GPSDOs perform against each other. This is why I want to put
>> forward the question for the BEST GPSDO in terms of
>>
>> a) phase noise up to 100 kHz from the carrier
>>
>> b) AD for tau>  0.1 s and<  say 7200 s (where the AD is controlled by LO
>> AND
>> GPS and not by GPS alone)
>>
>> The basic question is: If we want a reference that can be used for phase
>> noise measurements as well as for AD measurements, what shall we buy? If
>> you
>> come to the opinion that a) and b) cannot be satisfied by the same device,
>> then suggest different devices that you would use for a) and b).
>>
>> My personal guess is (without owning one) that a Z3815 may be a candidate
>> due to its E1938 oscillator.
>>
> The phase noise floor of the E1938 isnt all that low and there is an
> "interesting bump" in the region above a few kHz offset.
> If you want I can send you the data obtained using a Timepod with dual
> reference sources.
> The Z3815 PN floor should be somewhat higher due to its relatively low
> output signal level.
> The spurs due to the internal switching regulators may also be interesting.
>
>  But as to be seen on Tom's pages there are
>> better and worse specimen of this OCXO too. My own measurements with the
>> new
>> Timepod indicate that my Z3805 with the MTI260 OCXO can't be that bad. You
>> may even have luck with a double oven HP10811 in a Z3801 although the 6
>> channel gps receiver is surely not state of the art. Perhaps the
>> Thunderbolt
>> is the solution?
>>
>>
> The thunderbolt phase noise floor isn't stellar due principally to the
> noisy output buffer amp.
> However the PN floor of the OCXO used in some Thunderbolts can be quite
> low.
>
>  I will be glad to read what you judge!
>>
>> Ulrich Bangert
>> www.ulrich-bangert.de
>> Ortholzer Weg 1
>> 27243 Gross Ippener
>>
>>
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>>
>>
> Bruce
>
>
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