[time-nuts] Speaking of Costas loops

[Hal Murray]

lists at rtty.us said:
> If the WAAS sats were purpose designed to provide a high accuracy carrier,
> then yes there are ways to do it. The fundamental design concept of a "bent
> pipe" is that you don't do any of that. You do not care what's going through
> the bird, it just maps the input frequencies to the output and amplifies
> them (a lot). Again, the WAAS signal is simply piggybacking on existing
> hardware. The conversion oscillator is not locked to the GPS carrier (or to
> any other carrier). It's simply a free running quartz based oscillator,
> running into a synthesizer to get the appropriate microwave frequency.  

If somebody wanted to use that path for a frequency reference, they could 
setup a ground station to measure the Doppler and distribute that so people 
could adjust their expectations.

I suspect measuring the Doppler is a common sanity check.



-- 
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