| 摘要 |
<p>An underwater communications device (10), wherein each device includes: a signal receiver, a signal transmitter, a transducer (12) associated with the signal receiver and with the signal transmitter, and having a first field of view; a controller for operating the signal receiver and the signal transmitter in at least first and second operative modes, wherein in the first mode, the transducer (12) is operative to receive output signals from the signal transmitter and to transmit output signals to the second device; a mode selector, associated with the controller, for selecting modes of operation; and selectably operable signal blocking apparatus (14) having a second field of view, and associated with the transducer (12), for blocking signals emanating from the second device from outside the second field of view, thereby to prevent their impinging on the transducer (12).</p> |
