Tow detection feature (unauthorized movement) is available in many automobile GPS/GLONASS trackers. Work of the function is based on the movement sensor which is built in a GPS tracker. After ignition switching off, the sensor passes into an operating mode and continuously analyzes vibrations of a car. If the device registers a hit, an inclination or a movement, a notification about that is immediately sent to the data-center. A user can set notification about an “Unauthorized movement” event per Email or SMS.
There is a separate panel for configuring this function in the "Device and settings" section. It allows you to set the sensitivity of the sensor (accelerometer) and other parameters:
- The sensitivity of the motion sensor - having chosen a threshold of operation of the accelerometer, you can adjust it to react even to light hits and rockings. If usage of a car leads to false reactions of the sensor, you can roughen its sensitivity.
- Motion power - determined by duration of the impact (shock) ranging from 0.1 to 1 second. Recommended value 0.3 seconds.
- Delayed control start - specify how much time has to pass after switching off of the ignition, before function of control of unauthorized movement starts working. Usually if you set the value of 3-5 minutes it is enough to leave a car and to close a door.
- Duration of the vibration - if you assume that in a place of a parking of a car casual vibrations are possible, specify the minimum duration – there will be no reaction to tremors and shakings that last less than the specified value.
- Vibration interval - the interval at which device will repeat message if unauthorized movement continues. Recommended 5 minutes.
- Return to rest time - time to determine the state of rest. If during this time interval there is no movement, transition to a state of rest will be fixed. Recommended value of 30 seconds.
The above set of parameters is the maximum possible. For some devices, the list of available settings may be less.