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Feb 3, 2008 7:05pm
Img_missing_medium bmartinek 22 posts

I am prototyping a GPS project and need the most accurate data possible for location. I understand that non-governmental GPS can only get within a 10’ radius. The best way to do this seems to be take as many data points possible during a trip.

Does anyone have any idea how fast the GPS module + BugBase could sample for a given time period? :?

Thanks in advance,
Ben

Feb 4, 2008 10:22am
Medium Bug Labs team kschultz 107 posts

Ben,

If you look at the GPS programs by myself and finsprings and others, we have been using a timer to poll the GPS. The timer period is in milliseconds so you can get the position as often as you want. I don't know what the actual sample rate of the hardware is, but I think signal quality is going to be more important than the frequency of the measurement. Here is some sample code.


final int UpdatePeriod = 60;
timer = new Timer();
timer.schedule( new TimerTask() {public void run() { update(); }}, 0, datePeriod );



private void update() {
currentPosition = gps.getLatitudeLongitude();
}


On the accuracy end, I believe the GPS module has a terminal for an external antenna, so a larger external antenna could get you closer to the limit of GPS. I don't think the government is throwing in bias in the data anymore, so it is just the limit of technology. I have a marine unit for navigation when sailing, with a big (12" diameter) external powered antenna, and it seems to me that the maps are more inaccurate than the position of the GPS, a lot of charts and maps in the country have not been truly updated in 50+ years. I might know where I am within 10' accuracy with that GPS, but I will still give a rock a 100'+ clearance because they didn't have GPS when they marked it on the map. I don't know exactly when more specs our GPS module will be available, but they will be available closer to the release date.

Hope that helps,
Feb 25, 2008 4:32pm
Img_missing_medium Kvjain 1 post

I’m looking to use the GPS module to essentially incorporate an odometer capability into a device, for highway speeds – so up to about 80 mph.

So wondering about the accuracy at speed – sounds like static accuracy may be as good as +/- 3 meters and then add in the potential movement during the time the reading is being made ?

KV Jain

Feb 26, 2008 5:41pm
Medium Bug Labs team mcaric 64 posts

Hi Kvjain,

The built in error is +/- 3 meters like you stated. The GPS device complies to NMEA output. You can write software that understands NMEA, but we do not have control over the hardware itself. The chip we are using is the Jupiter 32 Miniature 20 channel GPS receiver, if you want more information about it you can find it here in pdf format:<