System for internally and externally detecting an ID transmitter for a vehicle having access openings to an interior of the vehicle, comprising a vehicle, a plurality of ultra-broadband transmitting and receiving devices arranged on the vehicle, and an ID transmitter having an additional ultra-broadband transmitting and receiving device, and an inertial sensor system arranged in the ID transmitter, by means of which system intrinsic movements of the ID transmitter can be detected, wherein each of the access openings is associated with at least one of the plurality of ultra-broadband transmitting and receiving devices arranged on the vehicle, the communication region of which devices fully covers an access region of the access opening in the open state of the access opening and which transmits ultra-broadband communication requests in the open state, wherein the ID transmitter is designed to transmit ultra-broadband communication responses via the additional ultra-broadband transmitting and receiving device, and is further designed to transmit information about the intrinsic movement of the ID transmitter to the vehicle, wherein the vehicle and the ID transmitter each have a vector field sensor system (17, 47) in order to determine, at least from an earth-bound vector field, its local direction, which is used as a reference direction for coordinate axis directions, with respect to which the information about the intrinsic movement of the ID transmitter is specified, wherein the earth-bound vector field is the Earth's magnetic field and a magnetic field strength of the Earth's magnetic field is determined as a vector size, wherein the vehicle is designed to detect, on the basis of the ultra-broadband communication and the information about the intrinsic movement of the ID transmitter transmitted by the ID transmitter, whether or not the ID transmitter moves into the interior or out of the interior of the vehicle, and accordingly to provide an interior signal of which value indicates whether or not the ID transmitter is detected as being located in the interior of the vehicle, wherein distances from one of the one or more ultra-broadband transmitting and receiving devices associated with the corresponding access opening to the ID transmitter are determined over time on the basis of the ultra-broadband communication, and the information about the intrinsic movement obtain data of a path segment of the movement of the ID transmitter or a path segment of the movement of the ID transmitter is determined from the information about the intrinsic movement, and the relevant path segment is positioned as a path curve relative to the access region on the basis of the determined distances and on the basis of the points in time of the determined distances and the points in time at which the corresponding locations of the relevant path segment were passed through relative to one another, and the entry into the interior is identified if the path curve through the access region points into the interior, and the exit from the interior is identified if the path curve points outward from the interior through the access region. wherein the vehicle and the ID transmitter each have a vector field sensor system (17, 47) in order to determine, at least from an earth-bound vector field, its local direction, which is used as a reference direction for coordinate axis directions, with respect to which the information about the intrinsic movement of the ID transmitter is specified, wherein the earth-bound vector field is the Earth's magnetic field and a magnetic field strength of the Earth's magnetic field is determined as a vector size, wherein the vehicle is designed to detect, on the basis of the ultra-broadband communication and the information about the intrinsic movement of the ID transmitter transmitted by the ID transmitter, whether or not the ID transmitter moves into the interior or out of the interior of the vehicle, and accordingly to provide an interior signal of which value indicates whether or not the ID transmitter is detected as being located in the interior of the vehicle, wherein distances from one of the one or more ultra-broadband transmitting and receiving devices associated with the corresponding access opening to the ID transmitter are determined over time on the basis of the ultra-broadband communication, and the information about the intrinsic movement obtain data of a path segment of the movement of the ID transmitter or a path segment of the movement of the ID transmitter is determined from the information about the intrinsic movement, and the relevant path segment is positioned as a path curve relative to the access region on the basis of the determined distances and on the basis of the points in time of the determined distances and the points in time at which the corresponding locations of the relevant path segment were passed through relative to one another, and the entry into the interior is identified if the path curve through the access region points into the interior, and the exit from the interior is identified if the path curve points outward from the interior through the access region.