On 5/11/12 2:38 AM, Hal Murray wrote:
Why in the hell would anybody build a 50 channel receiver? At most you
MIGHT see 12 usable GPS sats... I don't think that I've seen over 10. WAAS
should be fairly useless for a timing receiver.
I can think of a couple of reasons. I'm sure there are more.
One would be marketing type bragging rights. I can scan more channels than
you.
Another area would be cold-start time. If you have to search N slots, more
searchers runing in parallel is likely to speed things up.
Searchers and trackers are often different logic, these days..
Searching is very efficiently done with a FFT correlator, because you
can search all lags simultaneously with NlogN effort as opposed to
O(N/2) effort with a sequential search. Same for Doppler.
But once you've acquired, you track with a conventional
Early/Prompt/Late scheme.
When you get into full-up implementations, where there is coupling
between the tracking loops (think of a 2 frequency receiver.. L1 and L5
will have related doppler), there are other "economies of scale" possible.
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