I decided to try a little experiment; I have a QStarz BT-Q1000XT GPS datalogger (based on the MTK chipset), and it gives very good results.
But I recently got a smartphone with GPS, a Samsung Galaxy s3 mini, and have been recording tracks on it using the standard ‘My Tracks‘ app that comes from Google.
I’d noticed many errors and deviations on the results from my phone, so I decided to try a little experiment. I put both the phone and datalogger side-by-side in the cabin of my boat and sailed about for a bit, I then compared the results.
In the attached images the BT-Q100XT is the blue track, and the s3 mini the red one. You can clearly see the s3 mini is drifting off at times (causing ‘kinks’ in the track) while the BT-Q1000XT stays fully locked on. I guess this is a good demonstration that the GPS features in mobile phones still have some way to go compared to a dedicated device and chipset.
For reference: Both GPS devices were placed side by side within the open hatch of my boat, partly sheltered by the cabin roof.
- QStarz BT-Q1000XT set to fix every 500ms, recording a track point every 5 seconds or 1m (whichever is sooner), running firmware ANX_130-B_1.3_C01 and read via BT747 v2.x.1975
- Galaxy s3mini/MyTracks running with default (non user visible) configuration, Model GT-I8190, Android v4.1.2 (kernel 3.0.31-809600), My Tracks v2.0.4
[I exported the results from My Tracks, and imported them into the same app. that I use for downloading from my datalogger, and then used this to make two identical maps which I have combined (by cutting and pasting the relevant HTML) into one.]