| 摘要 |
The system is of the type comprising a warning device 14 and an intruder detection device 22, 24, the warning device being remote from the intruder detection device, wherein the warning device and the detection device are connected by an infra-red link 18, 30. The latter preferably includes an arrangement for sending coded, infra-red pulses to a receiver which, while receiving correctly coded pulses, maintains the warning device de-activated. Upon detection of intrusion, the transmission of the infra-red pulses is halted whereby the receiver causes the warning device to be activated. The detection device is preferably provided in a vehicle, in which case the receiver and warning device are located in a house or other premises so as to enable reception of the transmitted infra-red pulses. <IMAGE> |
