GPS temporal displacement

Everybody uses GPS.

We already know that the positioning provided has an error, usually in the range of 4 to 10 meters.

That's about space, but what about time?

By using Torque we can estimate it.

Torque log files contains GPS coordinates and the speed calculated from GPS readings: we can try to relate it to the speed reading from OBD, that is instantaneous, while the GPS speed is subjected to the delay induced by the GPS itself.

From the chart, we can say that the OBD speed is accurate, but the GPS value is delayed by an interval between 1 and 2 seconds.

Comparison of GPS performance across different Android devices

I had the chance to test GPS on a Galaxy Mini 2 and a Galaxy S2 Plus.
The test was done in the same place, one phone after the other.
Both phones didn't have any data connection, cellular of Wi-Fi, so positioning was done using only plain GPS.
Here is the Galaxy Mini 2.
Locking took 60 seconds with 5 satellites.

The Galaxy S2 Plus got its lock in 3 seconds with 16 satellites.

Note that on both phones, compass was way off.