| 摘要 |
A vehicle alarm broadcasts a low frequency modulated radio frequency alarm signal at the citizen band distress frequency upon a drop in the vehicle power supply voltage induced by an unauthorized intrusion. Networks of citizen band radio detectors, mobile dedicated alarm detectors, and fixed dedicated alarm detectors accompanied by a display unit, can receive the alarm signal. In the vehicle (Fig. 4), timers 30, 31, push-button 32 and thumbwheel security switch 36 permit the authorised user to avoid actuating the alarm on entering or leaving, and the transmitter 40 may be a wafer sandwiched between the layers of the windshield. <IMAGE> |
