| 摘要 |
PURPOSE:To decide on accurately a vertical direction even when a noise signal level is high by storing an ultrasonic-wave received signal by a scanning received wave beam, and averaging a necessary read signal and performing subtraction processing. CONSTITUTION:Synchronizing codes from an oscillator of a fish net, etc., is scanned by a receiving wave beam which increases in distance on every scan in the range of 0-60 deg. outputted from a receiving wave beam former 21, and an ultrasonic wave received signal is written in a storage device 26. This writing is carried on until a synchronizing pulse generated in the ending of the synchronizing codes detected securely through a receiving wave beam former 22 and a pulse compressor 28 controlled by a CPU27 is applied to a writing control circuit 29. A signal containing noise and synchronizing codes, and a noise signal which are read out of the storage device 26 are averaged by the CPU27 and stored in a storage device 33, and subtraction processing between both storage contents is performed to detect securely the synchronizing codes, so that the vertical direction is determined accurately even when the noise level is high. |
