Abstract

To increase the responsiveness of a vehicle alarm system to, for example, unauthorized entry through windows, jacking up for removal of parts or vehicle theft as well violent impact by another vehicle, at least one position sensitive sensor has its output signal, which represents the instantaneous position of the vehicle stored after activation of the alarm system. Any change in that position is detected and triggers a warning device when the deviation exceeds a predeterminable amount. The position sensitive sensor may be a fluid-filled vessel the internal resistance of which is measured in a resistance bridge or it may be a variable inductance sensor which is connected to a frequency generator whose output signals are counted and compared with a given value. The system according to the invention may also serve as an accelerometer.