After getting the gps running in the she ... / 2014-02-18

After getting the gps running in the shed I noticed a bit of variation in the output location as logged from the NMEA $GPGGA strings in the clockstats file. And reading Tom van Baak testing the MG1613S GPS Receiver noting the variation in location made me decide to do a bit of plotting of location on my own. As Tom notes, plotting distance in meters gives a better idea of scale. So I wrote a bit of perl to massage the lat/long pairs into X/Y meters from a starting point. I was lazy: I used the first measurement as starting point. The resulting X/Y pairs are graphed using gnuplot.

• holux gr-213 in the shed wanderings, 2 days Interesting first results with the GPS module inside the shed so the roof adds extra signal loss and reflections.
• holux gr-213 with the antenna on the shed roof wanderings, 2 days The better reception seems to help a lot, notice the difference in scale.
• holux gr-213 with the antenna on the shed roof wanderings, 6 days the range does not change much over 6 days.

Update: I'm a security specialist, not a programmer: I found some errors in the routines that convert output from the GPS to degrees to meters. Fixed them, so the first graph has been redrawn using data from 17 and 18 Februari.