I teaching several lessons and GPS, and the smartphone is a very attractive option for collecting positions since you already have one with you at all times.
The metrics for error measurements are not features very prominently by the cell phones, or even the recreational units.
So on our latest train trip, I realized we had been over that stretch of track on a trip to Tangier (going and return), a trip to Fes (going and return), another tip to Fes (just going, since we did camels en route to Marrakech), a trip to Meknes (going and return), and a trip to Kenitra (going and return). The GPS was logging the whole time, so I have 9 trips over that section of track.
There are double tracks (using the British road standard, drive on the left track), and we could be anywhere from the right to the left side of the railcar, but it should provide a good indication of how good the GPS is.
Square symbols show the GPS position. The square black grid is a 100 m UTM grid. This is an open section of track between Rabat and Kenitra, where the train cruises at about 135 km/hr. I have to think about the best way to quantify the results, but eyeballing shows the results are pretty good. I also have to see if there are some sections in Rabat, where we walk frequently on the sidewalk and where high buildings do not affect things, to see if that provides a better picture.
For the first time, since we've been here, I've noticed that my phone is getting the US, Russian, and European GNSS satellites, so with three times the satellites, results might well be much better than they were previously. As a result, I'm starting to think I should switch to calling the system GNSS instead of GPS; teaching African students is also an impetus to use the more generic terms.
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