Valid concerns all. What I am building is a squaring circuit for recovering the carrier from a WAAS GPS satellite. Granted there is still some Doppler and other issues, but the accuracy would not be bad and it just looks like a fun thing to do. Plus, I can use my four foot diameter dish antenna to reduce the number of satellites seen, reduce thermal ground noise, and get some signal gain.
John WA4WDL ---- "J. Forster" <[email protected]> wrote: > 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 > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
