[time-nuts] Speaking of Costas loops

[jmfranke]

Exactly! It just seems like an interesting set of facts. I plan on doing 
some more work on my WAAS dish antenna tomorrow.

John  WA4WDL

--------------------------------------------------
From: "Dennis Ferguson" <dennis.c.ferguson at gmail.com>
Sent: Friday, July 05, 2013 7:55 PM
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Subject: Re: [time-nuts] Speaking of Costas loops

>
> On 5 Jul, 2013, at 08:33 , Bob Camp <lists at rtty.us> wrote:
>> The sat needs to transmit at the GPS frequencies and have an uplink that 
>> works exclusively with those frequencies. (or at least that sub band). A 
>> "normal" transponder probably would not radiate at the GPS allocation, 
>> simply to be a good citizen. I believe the "specialization" is simply a 
>> frequency mod to allow WAAS to pass through. There is no mention of a 
>> space qualified Cs and / or Rb flying on those birds and no indication 
>> that the ground segment is controlling such a payload. If all that *was* 
>> present, then including them in the normal navigation solutions would be 
>> a "zero cost" next step.
>
> Addressing the last sentence I found a government WAAS reference
> which indicates that the WAAS satellites are indeed interchangeable
> with GPS satellites in navigation solutions.  It is is on page 7 of
> this
>
>    http://www.gps.gov/technical/ps/2008-WAAS-performance-standard.pdf
>
> where it says
>
>    The WAAS GEO broadcast also provides an additional ranging source
>    for improved availability of navigation services. When a WAAS receiver
>    is using the corrections and integrity messages broadcast by the GEO,
>    only four GPS or GEO satellites are needed, which increases the
>    availability of service versus RAIM or RAIM/FDE.
>
> While what is or isn't required in the satellite to support this is
> still a mystery it seems like the timing accuracy coming back must
> end up being equivalent to a real GPS satellite.  What this is good
> for is interesting to think about.
>
> Dennis Ferguson
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