Hi Bob, Doppler shift is +-3.5kHz. Bandwidth for the CA signal is ca 2MHz, narrow correlator receivers takes in >10MHz to mitigate multipath errors.
So doppler spread is about 1/1000 of the spread spectrum signal. Does the filter delay really change that much with 7kHz total doppler variation? For Glonass receivers this is more of a problem, since Glonass is a FDMA system. -- Björn > Hi > > Once the sat's all arrive at the antenna, a fixed delay (in general) does > not impact things a lot. The gotcha with the filter is that it's delay is > unequal across the GPS band. Doppler puts the sat's all over the place. > That gives some more delay than others. Having unequal delay on sats is > indeed an issue. As the filter changes delay with temperature things will > move a bit more. Since it's a "frequency high on approach / low on > departure" sort of thing it will average out on each pass. The main impact > would be an increase in wander. > > Bob > > On Sep 16, 2013, at 1:24 AM, David J Taylor > <david-tay...@blueyonder.co.uk> wrote: > >> From: Bob Camp >> >> Hi >> >> All of the ones I've opened up or seen dis-assembled have had the >> ceramic plate antennas in them. That very much surprised me early on, >> since I *assumed* they had something fancy inside based on their shape. >> >> No argument about the filtering, I'm not sure if the temp-co of filter >> delay on an exposed antenna makes it a plus or a minus . >> >> Bob >> =================================== >> >> .. and would the true time-nut add the delay through the filter to the >> delay in the feeder co-ax? I suppose that means you could only buy an >> antenna with a stated, calibrated delay? Limits the choice, a little! >> >> Cheers, >> David >> -- >> SatSignal Software - Quality software written to your requirements >> Web: http://www.satsignal.eu >> Email: david-tay...@blueyonder.co.uk >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.