| 摘要 |
PURPOSE:To facilitate the recognition of information on school of fish, by displaying detection information at a desired depth in a sonar signal with time with the newest one first. CONSTITUTION:An incoming reflected wave from all circumferential directions being transmitted from a transmitter/receiver 7 is converted 9 to digital from analog through the transmitter/receiver 7 and a receiving wave beam formation circuit 8 and supplied to a buffer memory 10. A signal read out of the memory 10 is stored into a display memory 18 having memory capacity of one screen. The memory contents of the memory 18 are read out or displayed based on a clock pulse generated 2. A reading address generation circuit 27 outputs (x) and (y) values for raster scanning each time clock pulse is fed, the (y) address is converted with a substraction circuit 28 to be fed into a memory 18. As a result, addressing is made back sequentially to older signals stored starting at the address in Y axis where the newest signal is stored. The signal thus read out is fed to a display 29 and displayed 29 with time by a raster scan signal formed with a deflection circuit 30 synchronized with the address being read out.
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