[time-nuts] Advise on building a DIY GPSDO?

Herbert Poetzl herbert at 13thfloor.at
Fri Apr 8 11:06:21 UTC 2016


On Mon, Apr 04, 2016 at 06:07:54PM -0700, Alexander Pummer wrote:
> and it is relative easy to make 10MHz from 8MHz with analog
> frequency manipulation, which generates less jitter

Could you elaborate on this a little if time permits? 
I'm more a 'digital person' but it sounds interesting.

Thanks in advance,
Herbert

> 73

> On 4/4/2016 4:27 PM, Attila Kinali wrote:
>> On Mon, 4 Apr 2016 17:56:29 -0400
>> Bob Camp <kb8tq at n1k.org> wrote:

>>> The variable frequency output on the uBlox (and other) GPS
>>> receivers has come up many times in the past.

>>> If you dig into the archives you can find quite a bit of
>>> data on the (lack of) performance of the high(er) frequency
>>> outputs from the various GPS modules. They all depend on
>>> cycle add / drop at the frequency of their free running TCXO.
>>> Regardless of the output frequency, that will put a *lot* of
>>> jitter into the output.
>> That's why you should put the output frequency of the ublox modules
>> to an integer divisor of 24MHz. Ie 8MHz works but not 10MHz.

>> 			Attila Kinali


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