Hi all, I've been doing some experimentation using the gps instrument for navigation functions but I've hit a minor problem due to the gps instrument update rate.
I'm running a nasal loop at 1/(frame-rate/2), which typically works out to between 10-20 Hz, but because the gps update rate is much slower (0.45 sec if I'm interpreting the code correctly) the results aren't very smooth - the effect is that the results follow a sawtooth pattern i.e. they ramp up while the gps output is unchanged but then drop back down when the gps output is updated, and then start to ramp up again. Increasing the gps update rate to 0.1 sec in instrument_mgr helps to smooth the output because each 'tooth' is smaller, with the result that each ramp-up and drop-back is similarly reduced in size. What I was wondering though, is what is the max update rate for NAVSTAR gps receivers? I dug out my Garmin e-trex manual, because I knew that had a battery save mode that reduces the update rate but it only says that the unit will update once per second or 'continuously'. After a bit of digging around on the web I found a discussion where it was stated that "The theoretical limit is down to the integration time for the receiver, typically 1-10ms" but the practical limit turns out to be more down to the receiver's processing power. Does anyone else here know anything about this? Ideally, I'd like to make the gps update rate configurable - can anyone foresee any problems in doing this? LeeE ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
