To detect variation of field of a vehicle incident to opening of door and to indicate the orientation of vehicle accurately by providing a field sensor delivering signal information indicative of opening of vehicle door, and a compass circuit having a detector.

An electronic compass 20 being set in a console comprises a field sensor 32, e.g. a flux gate sensor, for detecting the ambient field. The compass 20 comprises a sensor 32, and an associated interface circuit 32 for connecting the sensor with a microcontroller 34. The microcontroller 34 is connected, at an appropriate data input, with a door position detector 40 delivering information corresponding to the state of vehicle door to the microcontroller 34 in order to indicate a possible field disturbance being caused by opening of one or more door. The microcontroller 34 performs compensation and correction of variation thus preventing an external field disturbance from having any effect on a compass display.