Patent ID: 7319875

Claim:
A communications system, comprising: a base station with a first transmitter/receiver unit for communication signals and a transmitter unit for location interrogation signals; a response transmitter with a second transmitter/receiver unit for the communication signals and a receiver unit for location interrogation signals; and an interior space having walls impermeable to one frequency range, the communication signals being transmitted and received in a frequency range to which the walls are permeable, such that communication between the base station and response transmitter continues, and simultaneously the location interrogation signals being transmitted in a frequency range to which the walls are impermeable to determine whether the base station and response transmitter are on a same side of the walls, wherein the response transmitter includes code data which is transmitted collectively in response to the communications interrogation signal, and the communications system is a component of an anti-theft system of a motor vehicle, the base station being in a motor vehicle and the response transmitter being carried by a person.