| 摘要 |
A vehicle intrusion alarm system protects against the pilferage of vehicles, such as trucks, that remain overnight or longer on parking lot. The system is based on the cooperation between a receiver in the parking lot and a transmitter in the vehicle, said transmitter adapted to be activated by the mere act of opening a vehicle door. As soon as an intruder opens such a door, this action causes the transmitter to produce a changing magnetic field; and a pickup wire of the receiver produces a signal voltage that is used to produce an alarm. |
