| 摘要 |
<p>A fish farm cage security system includes sound-emitting devices (13) attached to the cage (10) for detecting tampering with one or more of the nets (12) forming the cage (10). Detector means (14) are provided for detecting the sound emitted by the sound-emitting devices (13) and to ambient sounds. Also provided are discriminator means (15) responsive to the output of the detector means (14) and operable to determine whether the sounds detected by the detector means (14) represent a perceived threat to stock contained within the cage (10). The output of the discriminator means (15) may actuate alarm means (17) as appropriate to the perceived threat.</p> |
