Integrating multiple NMEA streams to one COM port

rsd212 · 04-15-2006, 06:46 PM

We have COM splitters for sending data from one GPS to multiple programs. What about the opposite? Two GPS units, located in different parts of the car, with a driver to sends their data to one port. Some decision making would have to be made as to which has the better data, but it doesnt seem like it would be bad at all. Any interest?

DeltaFX · 04-16-2006, 05:09 AM

If you use high precision gps, there is no need for more than one.

with low precision gps, theorically you could compute an average position, but they update their position when they want (you may have to wait .5 sec between gps A and gps B)... So you'll need to decode lat,lon,speed,heading, and more important, timestamp from each gps, add some serious maths, then recode output into a NMEA format......

If you're about to devellop a logic board to mix 2 lowcost gps units then you'd better have a look on "asynchronous / switched kalman filters" and build a high precision DR-proof board that would read your gps, a 2D accelerometer /gyrocompas and the speed signal from your car to output a highly reliable NMEA sentence.

Just my 0.02€

nkotch · 04-16-2006, 05:33 AM

Really no need for it so don't waste your time on it. There was a similar thread about using multiple antennas with a GPS unit so you could do a search for that and read some of the comments. For in car use spending the time and effort to build some sort of custome hardware/software to do that won't get you much (in my opinion) and it's possible it may not even work the way you're thinking it would.