1. Mileage-based calculation
In a standard situation, all calculations of fuel level are mileage-based. That means data from the FLS is taken only during intervals of movement (trips). Those trips are defined according to parameters set in the trip detector.
Thefts and fillings are detected if there is a difference between fuel level in following trip (X) and fuel level in previous trip (Y). If (X — Y) > 0, it is a filling; if (X — Y) < 0, it is a theft; if X = Y, it is neither. Of course, there can be some inaccuracy in data coming from the FLS. That is why, to avoid false thefts and fillings, set the following parameters on the Fuel Consumption tab of unit properties:
2. Time-based calculation
This type of calculation is more complicated and is based on the following algorithm: the speed of the decrease of fuel level according to the FLS is compared with the consumption calculated mathematically. The time-based calculation is necessary for stationary units. It is also widely used for moving units for controlling thefts during the movement, for example.