JPS6144382A - Active sonar apparatus - Google Patents

Abstract

PURPOSE:To make it possible to take out only the signal from a target by avoiding sea-surface or sea-bottom reverberation, by detecting the depth of water and pitch angle of an active sonar apparatus and changing the frequency of a transmission signal corresponding to a detection signal. CONSTITUTION:The pitch angle of a sonar apparatus is detected by a pitch angle sensor 9 and the depth of said apparatus is detected by a depth sensor 8 and detection signals are applied to a transmission frequency controller 4 and a receiving frequency controller 1. Both controllers 4, 7 receive the control of the frequencies thereof so as to narrow the width of sonic beam emitted from a transmitter receiver 1 as the pitch angle becomes larger or the depth becomes shallower. Therefore, sea-surface or sea-bottom reverberation is hard to contain in the signal received by a receiver 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an active sonar device, and particularly to an active sonar device that changes the directivity of a transducer depending on depth and pitch angle.

(Prior Art) Generally, this type of active sonar device transmits sound waves underwater, receives reflected sound from a target, and detects the target's direction, distance, characteristics, etc. In active sonar devices,
Strong sound reflections from the sea surface or the ocean floor can interfere with target detection. Therefore, in order to reduce the intensity of reflected sound from the sea surface or the seabed, it is necessary to select the directivity of the acoustic beam that is appropriate for the depth and pitch angle of the active sonar device.

For example, when the pitch angle is 0 degrees (horizontal) and the depth is shallow or deep, the sound wave beam approaches the sea surface or seabed, so the width of the sound wave beam is narrowed to reduce the intensity of the sound wave reflected from the sea surface or sea bed. Try to reduce it. In addition, even if the pitch angle is the same (0 and 1), if the generated beam is sufficiently far from the sea surface (water depth of 8 degrees), the width of the sound beam is widened so that 4 targets can be detected over a wide range. Furthermore, even if the water depth is moderate and the transducer is far from the sea surface or the seabed,
If the pitch angle is large in the positive (upward) or negative (downward) direction (for example, 45 degrees), the width of the sound wave beam is reduced to reduce the intensity of the reflected sound waves from the sea surface or the seabed. Conventionally, in order to change the directivity of the acoustic beam and the width of the acoustic beam, the number of sensors excited in the transducer was increased or decreased, or the output of the transducers was weighted.

(Problems to be Solved by the Invention) In order to change the directivity of a sound wave beam using the conventional method described above, a complex switching circuit must be provided in the excitation circuit that excites the vibrator, or the power of each channel of the excitation circuit must be changed. A complex control circuit is required to control the Therefore, conventional Actizo sonar devices are expensive and cannot be made sufficiently reliable. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an Actizo sonar device that can change the directivity of a sound beam and is inexpensive and highly reliable.

(Means for Solving the Problems) The Actizo sonar device according to the present invention includes a means for generating a transmission signal, a means for converting the transmission signal into a sound wave, transmitting the sound wave into the water, and reflecting the sound wave from an object in the water. a transceiver that generates a received signal by receiving a sound wave; a means for detecting the object from the received signal; and a means for detecting water depth;
Means for detecting a pitch angle is provided, and the transmitting signal generating means is characterized in that the frequency of the transmitting signal is changed depending on the water depth and the pitch angle.

(Operation) In the present invention, the directivity of the acoustic beam is changed by controlling the frequency of the transmission signal supplied to the transducer. The frequency is controlled according to the water depth and pitch angle.

(Example) Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. This embodiment uses a transducer l, power amplification? 52, signal generator 3
, a transmission frequency controller 4, a receiver 5, a target detector 6, a reception frequency controller 7, a depth sensor 8, and a pitch angle sensor 9. In this embodiment, a low power transmission signal 103 outputted by a signal generator 3 is powered up by a power amplifier 2 to generate a high power transmission signal 102, and this transmission signal 102 is converted into a sound wave by a transducer 1. The sound wave reflected by an underwater object is converted into a received signal 101 by a transducer 1, and the received signal 101 is amplified by a receiver 5 to generate a received signal 105, and a target is detected from the received signal 105. device 6 detects the direction and distance of the target. The depth sensor 8 detects the depth in this embodiment and outputs a depth signal 108. The pitch angle detector 9 detects the pitch angle in this embodiment and outputs a pitch angle signal 109. The transmission frequency controller 4 outputs a transmission frequency designation signal 104 t- which designates the frequency of the transmission signal 103 based on the depth represented by the depth signal 108 and the pitch angle represented by the pitch angle signal 109 . The reception frequency controller 7 tunes the frequency specified by the signal 104 to the receiver 5.
The reception frequency designation signal 107 is outputted so that the reception frequency designation signal 107 is received by the receiver.

With such a configuration, the present embodiment reduces interfering sounds from the sea surface and the ffσ bottom by changing the directivity of the sound wave beam depending on the depth and pitch angle.

Generally, the directivity coefficient of a transducer in which transducers are arranged linearly is expressed by the following equation.

d, 　　　　, d.

R(r)=sin(nK dings+r+r)/na+n(K
−ys+nr) −・”(1) n: number of camera elements,
K=wave number constant=2π/λ, d: sensor array gap, λ=wavelength=c/f, r: orientation.

, speed of sound, f: frequency.

As is clear from this equation (1), the directivity coefficient R(r) can be changed by changing the frequency.

Appropriate directivity that generates low disturbance noise from the sea surface and the seabed and that allows for detection of targets even when it is low can be known in advance according to the water depth and pitch angle. Therefore, frequencies at which optimum directivity can be obtained in accordance with water depth and pitch angle are stored in advance in the transmission frequency controller 4 and the reception frequency controller 7. Then, depending on the depth represented by the depth signal 108 and the pitch angle represented by the pitch angle signal 109, the frequency controllers 4 and 7 respectively output signals 104 and 107 specifying the optimum frequency.

2 and 3 are diagrams showing the directivity of the sound wave beam according to the embodiment of FIG.
indicates a directivity pattern with a wide beam width, and n indicates a directivity axis. Figure 2 shows the case where the pitch angle is Oge, and when the water depth is shallow, the beam width is narrow (and when the water depth is quite deep but far from the seabed n, the beam width is widened.
The figure shows a case where the pitch angle is about 451. Because the pitch angle is large, the water depth is considerable, even if you are far from sea level 2].
Beam width should be narrow.

In this embodiment, the directivity of the acoustic beam is changed depending on the frequency of the transmission signal 103. The frequency of the transmission signal 103 can be arbitrarily selected in the signal generator 3 using an extremely simple circuit. Therefore, this embodiment is inexpensive and highly reliable.

(Effects of the Invention) According to the present invention, as described above, it is possible to provide an actuator device that can change the directivity of a sound wave beam and is inexpensive and reliable. Furthermore, by using the present invention, it is possible to automatically form a sound wave beam with optimal directionality according to water depth and pitch angle, making it easy to extract only the signal from the target while avoiding sea surface reverberation or submarine reverberation. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIGS. 2 and 3 are diagrams showing the directivity pattern of the sound wave beam according to the embodiment of FIG. DESCRIPTION OF SYMBOLS 1... Transducer/receiver, 2... Power amplifier, 3... Signal generator, 4... Transmission frequency controller, 5... Receiver,
6...Target detector, 7...Reception frequency controller, 8.
...R friend sensor, 9...pitch angle sensor. History...

Claims (1)

[Claims] means for generating a transmission signal; a transducer for converting the transmission signal into a sound wave and transmitting the wave into water; and generating a reception signal by receiving the sound wave reflected by an object in the water; A means for detecting an object, a means for detecting water depth, and a means for detecting a pitch angle are provided.
An active sonar device characterized in that the transmission signal generating means changes the frequency of the transmission signal according to the water depth and pitch angle.