Sonar
First Claim
Patent Images
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.
1 Assignment
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Accused Products
Abstract
A sonar emits an ultrasonic wave into the water from a transducer on the basis of a transmission signal outputted from a transmission circuit, receives an echo reflected in the water with the transducer and converts the echo into an electric signal, and displays underwater information on a display unit on the basis of an echo signal extracted by processing the electric signal. A tailing signal removing unit for removing a tailing signal and extracting only the echo signal is provided in the sonar such that a video of a surface layer fish shoal is clearly displayed on a screen of the display unit without being hidden by a video of the tailing signal.
4 Citations
8 Claims
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1. A sonar comprising:
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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. - View Dependent Claims (2, 3, 4)
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5. A sonar comprising:
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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 frequency 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 high-pass filter for extracting only the echo signal out of the tailing signal and the echo signal included in the reception signal outputted from the A/D converter. - View Dependent Claims (6, 7, 8)
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Specification