Vehicle remote central door locking system - uses code-timing generators with synchronised code pulse counters in transmitter and receiver for variable code-word recognition.

摘要

A central locking installation for a motor vehicle (1) has a remote transmitter (2, 3) for generating a codeword signal which is decoded by the vehicle receiver (5) resulting in a signal to an electronic controller (7) for unlocking the doors etc. (18). The coder (4) and decoder (6) each incorporate a code timing generator (8, 9) operating continuously at the same frequency e.g. 1Hz for producing pulses at constant rate and each has a code pulse counter (10, 11) continuously registering their transmission (16) and receipt (17). The counters (10, 11) are initialised/synchronised during first operation of the equipment and their accumulating count effectively changes the transmitted codeword each second. The coincidence of the registered counts of the coder (4) and decoder (6) is required within tolerance to generate an unlocking signal. USE/ADVANTAGE - Prevents unauthorised use by person acquiring fixed codeword. Is not affected by number of attempts to operate i.e. does not require resynchronisation.