| 摘要 |
PURPOSE:To record only a high level signal thickly and to discriminate the signal easily by differentiating a high level signal received by a fish finder and inputting the differentiated signal to a recording pen driving circuit together with a low level signal. CONSTITUTION:An ultrasonic wave projected from a vibrator 1 into water is received by the vibrator 1 as an echo. A signal amplified by a receiver 3 is divided into a high level signal and a low level signal by an A/D converter 5. The low level signal is inputted to the recording pen driving circuit 10 as it is. The high level signal is differentiated by a differential circuit 7 and then inputted to the circuit 10. The differentiated high level signal and the low level signal are composed. The composed signal is inputted to a transformer 17 and a high voltage corresponding to the composite signal is obtained on the basis of an output pulse from a pulse signal outputting circuit 18. Thus, the high level signal is recorded thickly and easily discriminated. |
