A motor vehicle has a detector for detecting the presence of a valid radio frequency transmitter only within a seating space inside the vehicle. Start control circuitry is responsive to a RUN signal, provided that the detector has detected the presence of a valid radio frequency transmitter within...http://www.google.com.hk/patents/US5751073?utm_source=gb-gplus-share專利 US5751073 - Vehicle passive keyless entry and passive engine starting system
