[time-nuts] Compensating phase differnces in dual frequency GPS receviers?

Attila Kinali attila at kinali.ch
Tue Nov 29 05:11:22 EST 2011


The recent thread on SDR GPS receivers lead me to think again about
a dual frequency GPS receiver design. But now something crossed my
feable mind that i havent seen before: When processing the L1 and L2
frquencies, they have to be seperated quite early in the process,
maybe even before the first mixer. Hence they will pass trough
different mixers filters and amplifiers and thus get different
delays (different phase components).

Now, for proper compensation of ionospheric distortion, these differences
in phase have to be known and accounted for. But this difference is
neither known, nor easy to calculate. And it is dependent on the temperature.

How do dual frequency receivers deal with that?

			Attila Kinali

The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
		-- Tirin, The Dispossessed, U. Le Guin

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