[time-nuts] GPSDO Alternatives

Bob Camp lists at rtty.us
Wed Dec 5 17:31:57 UTC 2012


Hi

I was hoping somebody had worked out a way around that. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bruce Griffiths
Sent: Wednesday, December 05, 2012 12:27 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] GPSDO Alternatives

A low noise sample and hold is still required.

Bruce

Bob Camp wrote:
> Hi
>
> Does the synchronous filter on the PWM  still have a sample and hold in
it, or has somebody come up with a different approach?
>
> Bob
>
> On Dec 5, 2012, at 3:06 AM, Bruce Griffiths<bruce.griffiths at xtra.co.nz>
wrote:
>
>    
>> Hal Murray wrote:
>>      
>>> albertson.chris at gmail.com said:
>>>
>>>        
>>>> What is the simplest phase detecter that could work?  I think only
that, and
>>>> then a duouble oven crystal from eBay, a GPS and and Arduido.
>>>>
>>>>          
>>> You also need a good D2A to drive the EFC on the osc.
>>>
>>>
>>>
>>>        
>> A synchronous filter of a suitably level translated (CMOS analog switch
plus low noise reference) PWM output should work well.
>>      
>>>> Yes the Aruino is expensive compared to a bare uP chip but using one, I
thin
>>>> you could build a GPSDO without a PCB and the Arduino's USB connection
could
>>>> be usful for power and logging/control.
>>>>
>>>>          
>>> I wouldn't want to power a GPSDO from USB.  It will get power cycled
every
>>> time I need to work on the logging PC.  Besides, you only get 2.5 watts.
The
>>> oven will probably take more than that during warm-up.
>>>
>>>
>>>
>>>        
>> Bruce
>>
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>
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