On Thu, Jan 9, 2014 at 12:21 PM, Hal Murray <[email protected]> wrote:
> > [email protected] said: > > navigation system that is going up. For that matter, is anyone running > one > > of the new multi-system receivers? I notice that Garmin is selling them > as a > > matter of course now. The prevalence of jamming might be the reason why. > > Aren't the alternatives using frequencies that are very close? Close > enough > so one the same receiver can pick up all the satellites. How much wider is > the total bandwidth? Does the filter on a typical L1 antenna reject, or > maybe just weaken, any of the other systems? > GLONASS works on 1602.0 MHz (+/- ~4MHz). GPS works on 1575.42 MHz. There is only about 20 MHz difference at 1.6GHz so it is entirely possible that a wideband (noise-based) jammer would take out both, but be quite limited in range. A narrow-band jammer would probably take out GPS but GLONASS uses FDMA and separates each satellite in frequency by 0.5625 MHz. That means that a narrow-band jammer might get one, two, or three birds but probably not all of them. It does seem to me that a combined GPS/GLONASS receiver is going to be more resistant to jamming than a GPS-only receiver. And I make no claims to being an expert. I am just mostly thinking aloud here. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 [email protected] +1.916.877.5067 _______________________________________________ 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.
