Patent ID: 7245557
Filing Date: 2007-07-17
Classification: G01S,Y10S

Abstract:
1. A sonar comprising: a transmission circuit for outputting a transmission signal of a predetermined frequency; a transducer for emitting an ultrasonic wave into water in response to the transmission signal from the transmission circuit and receiving an echo reflected in the water and converting the echo into an electric signal; a reception circuit for receiving the electric signal converted by the transducer and extracting a reception signal in a predetermined freciuency band; an A/D converter for sampling the reception signal extracted by the reception circuit at a fixed time interval and converting the reception signal into a digital signal; a tailing signal removing unit for removing the tailing signal included in the digital reception signal from the A/D converter; a detection circuit for applying detection processing to an echo signal outputted from the tailing signal removing unit; and a display unit for displaying the echo signal from the detection circuit, wherein the tailing signal removing unit comprises; a low-pass filter for extracting only the tailing signal out of the tailing signal and the echo signal included in the reception signal outputted from the A/D converter; and a differential arithmetic unit for calculating a difference between the output of the A/D converter and the output of the low-pass filter and extracting only the echo signal.