- Length of particular trip = Mileage “B” – Mileage “A”
- Total distance traveled for selected date / time range = Mileage “B” – Mileage “A”
- The sum of lengths of all trips for the selected period – understandable and reliable
- The total distance traveled – raw value, based on GPS odometer
Normally, these two are very close. However, there are two common issues may happen, caused by GPS inaccuracy or lack of the device settings, which can lead to bigger difference in those figures:
- Faulty device mileage count. Some device can accidently get wrong location (far from real or even in the ocean). Then it will influence its internal counter and will have wrong results. Such things may happen, especially with budget devices. On the server side we filter out large inaccuracies, but in some cases it’s impossible to distinct real track points from faulty ones, because they look as “probable”, and we have to accept them for distance calculation.
- “Starts” drawn in the end of the tracks. When a car is parked for a long period of time, GPS module continues to update its position – as set by user (e.g. each 30 seconds). But it’s not quite accurate: some meters to the north-west-south-east all the time and thus we get that internal device counter is bigger than actual sum of the trips lengths. Some GPS trackers can be configured to “freeze” the location while G-sensor does not detect movement (or “ignition” is off, or GPS locations are too close within, e.g. 5 minutes). If it’s possible to configure that, we recommend to use it.