Passive keyless entry system.

摘要

A passive keyless entry system is specifically adapted for use with automotive vehicles. The system is designed to automatically unlock the vehicle (10) as the operator (12) approaches the vehicle. The system is further designed to automatically lock the vehicle as the operator carrying the beacon (24), moves away from the vehicle. The system includes a portable beacon that is carried by the operator, a receiver/controller (100) located in the vehicle, and an antenna connected to the receiver/controler (100) for receiving the encoded transmission from the beacon. The beacon includes a motion sensor to conserve battery life when the beacon is stationary. Transmission between the beacon and the receiver/controller is characterized by a magnetically coupled radio frequency signal embodying differential phase encoded data with error correction coding of data to enhance noice immunity and signal discrimination.