| 摘要 |
A fish farm cage security system includes sound-emitting devices (13), bells for example, attached to the cage (10), the disturbance of which causes sound to be emitted which, in turn, indicates tampering with one or more of the nets (12) forming the cage (10). Detector means (14) are provided which detect both sound emitted by the sound-emitting devices (13) and 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) or are merely due to tide, weather, etc. The output of the discriminator means (15) may actuate alarm means (17) as appropriate to the perceived threat. |
