In the boating world there is a product out there that I think but do not know for sure made by Garmin that has two antennas separated by a small distance 2 meter) that gives you azimuth information. Bert Kehren In a message dated 8/26/2010 9:58:33 A.M. Eastern Daylight Time, [email protected] writes:
Attila Kinali wrote: > On Thu, 26 Aug 2010 11:04:01 +1000 > David Smith <[email protected]> wrote: > >> The system seems to work by taking the raw satellite phase information >> from two separate GPS systems and crunching the data to come up with an >> azimuth figure. Has anyone heard of a (Open Source?) program that could >> be used to do these calculations? > > AFAIK there is none out there (at least i've never seen one). > But it should be not too dificult write the software yourself. > The bigger problem is to get GPS receivers that provide you > with accurate phase information. Especially with a small baseline > you either need to sync the clocks of the two receivers or have > receivers with precise TCXO and take some additional samples to > calculate the frequency difference/drift. The precision you get > will mostly depend on the baseline and the number of samples you > use. The longer you have time to measure, the smaller your error-band > will be. > If you get a bit "closer to the metal" you could use two GPS L1 samplers running off a common clock, and do the PN code acq and track, which would give you carrier phase. If you do the nav solution, you know the "look angle" to the various SVs, which would tell you the phase differential vs azimuth. I believe that there are open source codes out there to do the processing. The data rate isn't all that high.. the GPS samplers are 1 bit. There's certainly lots of papers from grad students on this kind of thing. If you aren't concerned about acquisition time, and you can get the ephemeris from somewhere else (so your initial guess for acquisition isn't too far off), acquiring the signal isn't difficult. _______________________________________________ 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.
