I have fixed a Samsung Note 10.1" tablet to my bike in order to record counter readings. See this report for details. I have compared two GPS logging apps:
GPS Stopwatch is an app developed by Good Run Guide Ltd. who run a web site for mapping running routes in Britain. They provide an app for mobiles and tablets which records routes, providing distance travelled and other featues for runners. The recorded routes can be uploaded to a personal account on the GRG website and displayed. Here is a section from a 16 mile out and back route I rode for a test:
I was alarmed to see on my outgoing route several 100 metres of my track had been missed out and a straight line drawn right across a building site which I certainly did not ride over! I think may be my tablet screen went into standby after 30 minutes. So that is something to watch for. On the return the track closely follows my route along the cycle way beside the main road, then crossing to another path, then a cycleway beside the road going over the railway bridge. The difference between the two routes at the junction at the top of the picture shows a real difference in my paths out and back.
At the same time that the above was recorded I also ran the GPSlogger app and after return home uploaded its gpx file to GRG. GPSlogger was set to record a GPS reading every second. So I ended up with a 2 MB file with over 7000 data samples to upload GRG, which then gave the following track for this portion:
This shows that the GPS in my tablet was definitely recording the correct path and GPSlogger was collecting the data.
However, even though I was logging every 1 second, it was clear that on upload to GRG data compression is taking place; the little chicane in the road centra at the bottom of the picture has been smoothed out, unlike on the return track of the GPS STOPwatch track.
I examined the GPSlogger data more closely by loading the gpx file into the GPS Utilities software program which enabled me to see the individual gps samples at 1 second intervals, here is the matching bit of the route ploted on the British Grid with a grid ine spacing of 50 mteres:
Now you see the individual 1 second interval points. The chicane crossing the road is clearly visible on both out and return legs. You can check my bike speed. On the bottom right when I was progressing fast along a smooth flat bike path beside the road there are about 7.5 points (seconds) per 50 metres, which gives a speed of 6.7m/s (14.5mph). In general the out and return tracks are within about 5m - and this is probably caused by satellite/ionosphere movements. The basic GLP daya from the Samsung looks very good.
My conclusion is that I should probably run both apps when I want to record a measurement ride.
GPS STOPWATCH - has a large display on my tablet screen giving distance travelled to within 10 metres - great for warning of the approach of a split location:.
GPSlogger for Android- has a tiny display - not easy to read without stopping, but combined with post-ride plotting using GPS UTILITY it gives very smooth detailed tracks.
Mike Sandford - 26 Juy 2014