| 摘要 |
In the receiver of an autdoor intruder detection apparatus, which receiver is spaced from and receives signals from a microwave transmitter and provides an alarm output upon the occurrence of change in the received signal, eliminator means is provided for eliminating pulses which may be superimposed on the signals e.g. from nearby radar. Such eliminator means comprises a wide band amplifier 12 which serves, by way of a monostable 13 to actuate a switch 14 which gates out, in synchronism with the superimposed pulses, the detected signals from aerial 10 and diode 11 as supplied by way of an amplifier 15, a delay line 16 and a wide band amplifier 17, to further signal-processing circuitry (not shown) as at 20.
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