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

[jmfranke]

The received WAAS signal strength is designed to be similar to that from 
regular GPS satellites.  And, I find that to be true in practice.

John

--------------------------------------------------
From: "Brooke Clarke" <brooke95482 at att.net>
Sent: Friday, October 08, 2010 2:09 PM
To: <jfor at quik.com>; "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Subject: Re: [time-nuts] GPS backup for the stationary time and 
frequencyuser

> 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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