JPH01169384A - Listening system for active sonar - Google Patents

Abstract

PURPOSE:To facilitate a Doppler discrimination, by a method wherein a harmonic component is extracted from a pulsating current obtained by the rectification of an electrical signal of an echo sound and the component is converted into an audible frequency to release a sound from a speaker. CONSTITUTION:An echo sound of a sonar enters a full-wave rectifier 2 through a pre-amplifier 1 and a pulsating current as output thereof is inputted into a band pass filter 3 to extract a harmonic component. The harmonic component is mixed by a mixer 4 with a signal from a local oscillator 5 to be converted into an audible frequency by a heterodyne system. An output of the mixer 4 is supplied to a speaker 8 through a low pass filter 6 and an amplifier 7 and then, a sonar echo sound is released from a speaker 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a listening method for facilitating the discrimination of Doppler signals in reverberant sounds generated by the movement of an object to be detected in an active sonar.

[Conventional technology]

As a method for easily and reliably detecting underwater objects using ultrasonic waves, as described in Japanese Patent Publication No. 57-8144, the echo sound output of ultrasonic waves emitted into the water is converted into an audible frequency. , the power is divided into two circuits, one increasing in proportion to the frequency and the other decreasing in inverse proportion to the frequency, with separate receivers or detectors attached to the two circuits;
Dog2 - Reverberant sound Doppler discrimination method that makes it easy to distinguish between reverberant sounds and non-reverberant reverberants, and Japanese Patent Application Laid-Open No. 58-1224
As stated in Publication No. 83, the echo input t-2
By inputting the input into a set of listening devices and making the local frequency of each device equal above and below the Nona transmission frequency, it is easy to distinguish Doppler signals in the echoes from the detection target. It has been known.

[Problem that the invention seeks to solve]

In all of the above-mentioned conventional technologies, Doppler is determined by listening to the left and right ears through binaural receivers, so they are not suitable for allowing many people to simultaneously listen to sonar echo sounds using speakers. I failed.

The Actei Punner is a well-known system that transmits sound waves horizontally underwater, receives echoes from target objects underwater, and displays the direction, distance, etc. on a display device such as a PPI. This is converted into a proper audible sound as an audible signal, which is then used as a means of categorizing the type of underwater target detected based on the acoustic sharpness of the echo sound, the presence or absence of a Doppler, etc. There is. Particularly, when the target is a moving object such as a submarine, the most effective means is to classify whether the target is top 2 or not.

On the other hand, in Top 2 - Discrimination, the higher the frequency of the sound waves emitted into the water, the easier it is.In the case of a sonar aimed at long-distance detection, the transmitting station a is selected to have a low ridge and moves at a slow speed. Dog 2-discrimination of objects is limited to about d Hertz even by experienced sonar operators.

An object of the present invention is to provide a means for solving this problem and facilitating Doppler discrimination.

[Means for solving problems]

The object of the present invention is to rectify the electric signal of the reverberant sound to make it into a pulsating flow, extract high frequency components from the pulsating flow signal, and then convert the reverberant sound into an audible frequency using a heterodyne method to amplify the sound of the reverberant sound. By listening, the frequency of the reverberant sound is multiplied without losing its envelope and other characteristics.
This is accomplished by subsequent conversion to an appropriate audio frequency.

[Effect]

The actipunner lit method of this invention uses the electric signal of the echo sound! /1 flow to obtain the pulse R, extract the harmonic component from this pulsating flow, use the heterodyne method to convert this harmonic component to an audible frequency, amplify it, and send it to the echo f't- Use something that emits sound. Therefore, doubling the multiplier has the same effect as doubling the Noner transmission frequency69, and as a result, Doppler discrimination becomes twice as easy9, making accurate discrimination possible. Out.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. - FIG. 1 is a system diagram showing an embodiment of the present invention, and FIG. 2 is an example of signal waveforms conceptually showing signals in each part of FIG. 1.

Figure 1 shows the configuration of the @sound circuit for converting and listening to the anti-1# sound of Noner into an audible sound.) The waveform example in Figure 2 (the reverberation fill of a frequency fi such as -3 is It is amplified by the preamplifier 1 and input to the double-wave rectifier 2, which outputs the double-wave rectified waveform as shown in Fig. 2. 9. In this embodiment, the frequency component of 2fi, which is the second harmonic, is extracted in the band F wave generator 6 (waveform (C) in FIG. 2) L, and the frequency tIJL generated by the local oscillator 5 in the mixer 4 It is mixed with a signal of several fL and converted into a frequency of 2fi±fp, from which an audible frequency component of heterodyne frequency 2fi-fL is extracted via a low-frequency P wave generator (6) (waveform (dl) in Figure 2).
) After that, the sonar reverberation sound is amplified by an amplifier 7 and can be heard by a large number of people by a speaker 8.

〔Effect of the invention〕

According to this invention, as described above, without giving acoustic information only to a specific person using a binaural receiver or the like, and without giving the same acoustic information to many people at the same time, it is possible to simultaneously give the same acoustic information to many people. In addition to the method described above, by extracting higher harmonics, it is possible to obtain a dokuguho-enlarged red color that is effective for many pages, and the device is relatively simple. - There are young fruits that can achieve the purpose of easy identification.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the present invention, and FIG. 2 (a
) to (dJ are signal waveform diagrams conceptually showing the signals of each part in FIG. 1. Explanation of symbols 1... Preamplifier, 2... Double-wave rectifier, 5
...Band P-wave device, 4.-mixer, 5.. Local oscillator, 6.. Low-band P-wave device, 7.. Amplifier.
8...Speaker, 11...Reverberant sound. Representative Patent Attorney Katsuo Ogawa Pai,” 2
Ql: 1

Claims (1)

[Claims] 1. Presence or absence of Doppler frequency in the echo sound from the underwater target;
In active sonar, which aims to classify moving objects based on their size, etc., the electrical signal of the reverberating sound is rectified into a pulsating flow, and the harmonic components are extracted from the pulsating flow signal. A listening method for an active sonar, characterized in that the reverberant sound is amplified and received by converting it into an audible frequency using a method.