Security lock and theft alarm for motor vehicle - has electronic transmitter and receiver linked by non-electrical circuit

摘要

The circuit gives high security vehicle lock which cannot be defeated through bypassing electrical circuits. The security system comprises a transmitter, and a receiver linked with that part of the vehicle chosen to effect the immobilisation. The link between transmitter and receiver is non-electrical. The receiver and associated locks are contained in an armoured box. Typically the transmitter generates an eight digit code word in which each digit has sixty four possibilities. The word is transmitted serially, for example as modulated light pulses along a light guide. The receiver checks the incoming word for validity and then acts upon the instruction. The electrical circuit of transmitter and receiver are separate. Action upon a correct word arriving at the receiver may be time delayed to prolong the time required for any attempt to defeat the system by trial and error. The system would normally also incorporate an audible or visible alarm to give warning if the vehicle is tampered with.