[time-nuts] GPS backup for the stationary time and frequencyuser

Brooke Clarke brooke95482 at att.net
Fri Oct 8 18:09:53 UTC 2010


Hi John:

The WAAS birds may be too weak to receive with an omni antenna, hence 
the desire to get some gain.
The normal GPS sats will pass through the beam and the GPS antenna will 
pick up some sats directly so you do get some TRAIM.
Doppler is not an issue in timing mode (i.e. position is known) and only 
one sat is required.

Have Fun,

Brooke Clarke
http://www.PRC68.com


J. Forster wrote:
> KISS. This seems like a lot of work for not particularily good results.
> Among other things, you have no closure so no measure of how good your
> measuremwent is.
>
> FWIW,
>
> -John
>
> ================
>
>
>    
>> On Oct 8, 2010, at 10:27 AM, J. Forster wrote:
>>      
>>> GPS needs several birds to lock up,
>>>        
>> To get a position fix, this is true; 3 birds minimum for a 2D fix, 4 birds
>> minimum for a 3D fix.
>>
>>
>>      
>>> and if you look at a single bird, Dopplar will make the signal useless
>>> as
>>> a frequency reference.
>>>        
>> Only if you don't already know your position. Once your position has been
>> determined accurately and you have the current ephemeris data for the bird
>> you're listening to, you can factor out the predictable doppler and use a
>> single bird for timing and frequency.
>>
>>
>>
>> --
>> Mark J. Blair, NF6X<nf6x at nf6x.net>
>> Web page: http://www.nf6x.net/
>> GnuPG public key available from my web page.
>>
>>
>>
>>
>>
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>>      
>
>
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>    

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com





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