| 摘要 |
A warning system comprises a receiver adapted to receive and recognize a coded signal, and upon reception and recognition thereof to generate a warning signal; and a transmitter selectively actuable to transmit a coded signal receivable and recognizable by the receiver and including a monitor for monitoring the presence of an extraneous signal originating from another transmitter, the transmitter delaying transmission of the coded signal upon detection of the extraneous signal.
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