| 摘要 |
PURPOSE:To detect a buried object surely even if there is a long distance between a vessel and a surface to be searched, by emitting radio waves of >=2 different frequencies simultaneously or time dividedly, and receiving the same. CONSTITUTION:The radio waves oscillated by an oscillator 20a is emitted from a wave transmission antenna 22a and are received with wave receiving antennas 23a and 24a. Thereafter, the waves are converted to DC voltages by detecting amplifier circuits 25a and 26a. The signal for the difference of these two signals is transmitted to a logical circuit 28. On the other hand, the radio waves oscillated at the frequency differing from that of the oscillator 20a by an oscillator 20b are emitted from a wave transmitting antenna 22b and are received with wave receiving antennas 23b and 24b. The waves are converted to DC signals by detecting amplifiers 25b and 26b and the signal for the difference of the two signals is transmitted to the circuit 28. When a signal is produced in either of the differetial amplifier circuit 27a by the circuits 25a, 26a or the differential amplifier circuit 27b by the circuit 25b, 26b, the circuit 28 operates to produce an output. This output operates an indicator 30, thereby announcing the presence of a buried object. |
