| 摘要 |
<p>Disclosed is a remote alarm system useful in detecting, protecting and maintaining the security of vehicles, structures or areas. The system involve: two elements, a transmitter and a receiver. The receiver is portable and can receive electromagnetic signals propagated through the atmosphere, the receiver being adapted to be carried about on the person. The transmitter is stationary and is operatively tuned to transmit to the receiver. The transmitter, situated at the vehicle or other protected location, transmits an immutable coded multitone electromagnetic signal. The receiver responds only to the code generated by its matched transmitter to provide a great number of discrete codes to enable a plurality of alarm systems to operate in proximity to each other without interference.</p> |
