[time-nuts] Speaking of Costas loops

[J. Forster]

More on your question:

I'm prettyt sure that just sticking up an antenna and hooking up a simple,
phase tracking receiver for GPS will yeild nothing useful, because there
are always several birds in view, so you will get a superposition of their
signals in the bandpass and each signal will be Dopplar shifted be a
different amount- a time-varying amount.

You have to use a complete GPS receiver that can unravel it all.

-John

================








> Here we go again - the first send didn't seem to get through. This is
> the second attempt.
>
> This talk of Costas loops reminded me of something I wanted to
> investigate some day. I read somewhere a while back about
> carrier-phase measurements, and various methods for recovering the
> GPS carrier frequencies, including the Costas loop, and something
> with carrier-squaring. Nothing I found showed actual examples or
> detail of how this is done, only high-order mathematical descriptions.
>
> For my needs, I'm more of a frequency-nut - I usually don't care
> about getting time info, but I'd like perfect 10 MHz for reference.
> Can using only the carriers lead to simple ways to get the same (or
> better) frequency stability as a conventional GPSDO, but without the
> time and location info, or is it pointless to worry about it, and
> just go with full GPS decoding of everything? Or, is carrier-phase
> just an enhancement only if you already have the full GPS info?
>
> I know that the group could redesign the whole GPS system with tubes
> if necessary, considering recent philosophical discussions on that,
> so I think there's plenty of knowledge here about carrier-phase
> related stuff too.
>
> Ed
>
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