| 摘要 |
A security system a vehicle, such as a truck T having cab C and cargo doors 3, 4 to a cargo section S can emit an audible alarm when both a door is open and a driver 2 carrying a RF transponder goes beyond a defined distance, d, from the truck, possibly exposing cargo to theft. The time interval between successive received periodic signals from the RF transceiver 2 is measured by controller 12 and if the interval exceeds the preset interval, the driver is determined to be beyond the distance d. An alarm 9a, 10 may also be sounded if more than one door 3, 4 is open simultaneously. If an attempt is made to start the engine with a door open, the system sounds an alarm in the cab and ignition prevention means 9b is triggered.
|
