| 摘要 |
The method comprises placing in a target to be protected a wireless transmitter 11 adapted to provide a wireless output signal at least when the transmitter is subject to motion or vibration and providing at a location remote from the transmitter a wireless receiver 12 for an output signal from the transmitter. Preferably the transmitter is adapted to provide a wireless output signal at least when the transmitter is subject to motion over a first frequency range and to vibration over a second frequency range. If necessary an intermediate transmission stage can be provided between the transmitter and the receiver so that the output signal from the transmitter serves to cause the intermediate stage to generate an intermediate output signal for reception by the receiver either directly or indirectly. The, or an, output signal from the transmitter may serve to initiate the operation of a transducer, e.g. an incapacitating device, adapted to provide an output signal or function independent of an output signal from the transmitter received either directly or indirectly by the receiver. The wireless transmitter unit includes a movement transducer 15 having a component which when subject to displacement relative to the rest of the transducer causes the transmitter to transmit a distinct output signal by way of an integral antenna.
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