| 摘要 |
The present system provides a traffic signal control system which will allow moving emergency vehicles to remotely take control of the traffic signals at an intersection. The transmitter part of the system utilizes a microwave transmitter that is mounted on each emergency vehicle, which transmitter emits a pulse coded message which is received by a permanently fixed receiver at each intersection to be controlled. The receiver includes decoding logic to verify that a valid code request has been transmitted by the vehicle. The receiver includes a directional antenna that faces each direction to be controlled which therefore automatically discriminates against signals being received from other directions, and if the appropriate code is received during a predetermined interval of time, the receiver will cause the traffic signals to cycle so that a green or go phase will be directed to the oncoming emergency vehicle and cross traffic will be warned by red signals facing it. After the emergency vehicle has entered the intersection, lack of direct transmission from it will conclude the control after a fixed delay to allow the vehicle time to clear the intersection. The same fixed delay will enable the vehicle to maintain control of the intersection even if it should momentarily lose direct microwave contact because of an intervening large truck or bus.
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