| 摘要 |
The system is characterised by a personal transmitter (1) designed to be actuated in an emergency to emit a signal, an antenna (2A, 3) for receiving said signal, and a receiver (2) for receiving the signal from the antenna to activate an alarm, said receiver including a detector circuit (2B to 2K) which responds to variations in signal strength from the antenna for producing an audible (2Q) or visual (20) indication of said strength. Thus, when the receiver alarm is activated by said signal, the rescuer can assess the direction of the signal transmission by said variations in signal strength. In one arrangement, two antennae (9, 10) are provided for fixing to the masthead so that they are spaced apart to port and starboard, any signal received from a personal transmitter (1) being amplified by the receiver (2) to activate a boat alarm and thereby enable the helmsman to initiate man-overboard procedures. Thereafter, for locating the direction of the signal, said two fixed antennae (9, 10) are phased to provide left/right signal information for said receiver (2), which latter includes a display of the appropriate signal strength. In another arrangement, one fixed omni-directional antenna (2A) is provided for fixing to the masthead to pick up a signal from a personal transmitter (1) and operate a boat alarm. For locating the direction of the signal, a second, portable, directional antenna (3) is provided which is connected to said receiver (2) and, in use, is handheld and swept around the vessel to obtain a reading (6) of greatest signal strength. A test facility is built in to the system where at any time a transmitter and a receiver can be operated to test their function without causing alarms to other users. |
