JPH042910B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an underwater detection device that performs underwater detection by transmitting and receiving ultrasonic signals underwater, and particularly relates to an underwater detection device that detects in a wide range of directions.

(Prior Art) Various devices have been proposed as devices for detecting underwater in a wide range of directions. As a relatively simple device, a device is used that transmits and receives an ultrasonic beam having directivity in one direction into water, and changes the direction of the wave transmission and reception over time. High-grade equipment simultaneously transmits ultrasonic waves in a wide range of directions and receives the detection signals returning from each direction with directional receivers installed in each direction. A device is used that converts the received signal into a time series at high speed.

Using such an underwater detection device, for example, the third
As shown in the figure, when detecting a wide range of seabed directions, the reflected waves returning from the seabed B ₀ directly below are received at a relatively strong level, whereas the reflected waves returning from the seabed B _s diagonally are received. A weak level of reflected waves are received.

When displaying such received signals on the display,
If the amplification of the received signal from the diagonal direction where the signal level is weak is increased, the reflected wave from directly below is saturated by the amplifier, making it impossible to obtain a display image faithful to the received signal. Furthermore, if the amplification degree of the amplifier is set so that the signal received from the direct direction is at the optimum level, the signal received from the diagonal direction will not be amplified to a sufficient level, and therefore the received signal will not be displayed on the display. Unable to distinguish signals.

(Problems to be Solved by the Invention) This invention addresses the above-mentioned drawbacks by amplifying the received signals from any direction to the same level and displaying the received signals from all directions on the display. To clearly display a signal without being affected by the strength of the signal level.

(Means for Solving the Problems) As a means for solving the above problems, means for controlling the amplification degree of the amplifier or the attenuation degree of the attenuator is provided. In this control means, the amplification degree control characteristic or the attenuation degree control characteristic is set in accordance with the arrival direction of the received signal.

(Function) The control means controls the degree of amplification to be small for a received signal of a strong level among the received signals returning from each direction, and to increase the degree of amplification for a received signal of a weak level. . Further, when controlling the attenuation degree of the attenuator, the attenuation degree is controlled to be large for a received signal of a strong level, and to be controlled to be small for a received signal of a weak level.

(Example) FIG. 1 shows a T ₁ to T _o ultrasonic transducer, which is excited by a transmitter 1 and transmits ultrasonic pulses in a wide range of directions. Note that the excitation signal of the transmitter 1 is guided to each of the ultrasonic transducers T ₁ to T _o via transmission/reception switching devices TR ₁ to TR _o .

As shown in FIG. 3, the ultrasonic signals transmitted from the ultrasonic transducers T ₁ to T _o are transmitted in a wide range of directions on the ocean floor. The reflected waves returning from a wide range of directions on the ocean floor are received by each of the ultrasonic transducers T ₁ to T o, and then transmitted to the transducer TR ₁ to T _o .
It is guided to the beam forming circuit 2 via TR _o . The beam forming circuit 2 detects a unidirectional received signal by phase-combining the received signals of the ultrasonic transducers T ₁ to T _o . A method of forming a unidirectional directional received beam by performing phase synthesis is well known. Most commonly, a directional received beam can be formed by delaying each of the received signals from the ultrasonic receivers T1 _{to T0} by a predetermined amount using a delay element and then combining them. . Alternatively, the applicant may
The beam forming device provided in No. 121439 can also be used. In other words, the phase of the received signal is equivalently shifted by mixing the local oscillator signal and the received signal generated in advance, and then the amount of phase shift is set appropriately by adjusting the phase of the local oscillator signal, and the signal is synthesized. to form a directional receiving beam.

The pointing direction of the directional received beam generated by the beam forming circuit 2 is controlled by the pointing direction control circuit 3. The pointing direction control circuit 3 changes the pointing direction by appropriately adjusting the amount of phase shift given to the received signal. For example, when using a delay element, the phase shift amount can be changed by appropriately switching between delay elements having different delay amounts. Furthermore, in a device that combines a received signal and a local oscillator signal as in Japanese Patent Application No. 121439/1982, the amount of phase shift can be changed by changing the phase of the local oscillator signal.

The directional reception beam signal generated by the beam forming circuit 2 is guided to an attenuator 4. The attenuator 4 uses an attenuation control circuit 5 to attenuate the received beam in a specific direction among the directional received beams compared to the received beam in other directions.

The attenuator 4 can have various analog and digital configurations.

When performed analogously, for example, the gain of the amplifier can be controlled according to the voltage level.
By changing the voltage level using the attenuation control circuit 5 according to the direction of the directional received beam, it is possible to attenuate the received beam in a specific direction. The attenuation control circuit 4 generates a characteristic voltage as shown in FIG. 2, for example. For example, a characteristic voltage is generated such that the gain of the amplifier is the smallest in the "0°" direction, that is, toward the ocean floor directly below, and a predetermined gain is obtained in other directions. Such a characteristic voltage generation circuit can be realized relatively easily.
For example, the pointing direction data of the directional reception beam designated by the pointing direction control circuit 3 can be converted into an analog voltage corresponding to FIG. 2.

Therefore, when the attenuator 4 is used to control the gain of the amplifier as described above, it can also be used as the amplifier 6 that amplifies the output of the attenuator 4.

Furthermore, when the attenuator 4 is configured digitally, it is possible to obtain attenuation characteristics as shown in FIG. 2 by preparing multiple sets of attenuators with different attenuators and switching the combination of attenuators as appropriate. can. For example, if you prepare attenuators with 1 dB, 2 dB, 4 dB, and 8 dB attenuation, use the 1 dB attenuator when you need 1 dB attenuation, and use the 1 dB attenuator when you need 4 dB attenuation.
Guide the received signal to a 4dB attenuator. Also, when 3dB attenuation is required, a 1dB attenuator and 2dB attenuator are combined to attenuate the received signal, and when 6dB attenuation is required, a 2dB attenuator and 4dB attenuator are used. In combination, the received signal is attenuated.

The attenuation control circuit 5 switches the combination of the attenuators in accordance with the received beam direction data specified by the directional control circuit 3. This switching can be done, for example, by using a memory circuit in the attenuation control circuit 5 to store the numbers of attenuators to be combined in accordance with the pointing direction of the received beam, and by using the pointing direction data specified by the pointing direction control circuit 3. This can be realized by reading the corresponding stored data.

The output of the attenuator 4 is led to a display 7 via an amplifier 6 and displayed. Pixel scanning of the display device 8 is performed based on the pixel scanning circuit 8, and the pixel scanning circuit 8 performs pixel scanning in conjunction with the pointing direction control circuit 3.
Therefore, the received beam transmitted from the beam forming circuit 2 is displayed at the corresponding azimuth position on the display screen of the display 7.

In Fig. 1, the beam forming circuit 2 is configured to electronically switch the directional beam, but it is not possible to form a directional beam in one direction and mechanically change the directional direction. May be used.

(Effects of the Invention) As described above, the present invention controls the degree of attenuation or amplification of the received beam in a specific direction when changing the directivity direction of the directional received beam. Therefore, when changing the directional receiving beam to a wide range of directions on the seabed, the degree of attenuation is increased for reflected waves returning from the direction of the seabed immediately below.
By reducing the degree of attenuation for reflected waves returning from oblique directions, reflected waves in any direction can be amplified to the same level, and a clear display image can be obtained on the display.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 2 is a characteristic diagram explaining its operation, and FIG. 3 shows a detection example. T ₁ to T _o ... Ultrasonic transducer, TR ₁ to TR _o
...Transmission/reception switch, 1... Transmitter, 2... Beam forming circuit, 3... Directional direction control circuit, 4... Attenuator, 5... Attenuation control circuit, 6... Amplifier, 7...
Display device, 8... pixel scanning circuit.

Claims (1)

[Claims] 1. A receiving beam in which an ultrasonic signal is uniformly transmitted in a wide range of directions on the ocean floor, and the reflected waves returning from various directions on the ocean floor are directional in a specific direction, and the directional direction changes rapidly. In an underwater detection device that detects the seabed over a wide area by receiving waves from the receiving beam, among the seafloor reflected waves in each direction obtained from the above-mentioned receiving beam, a received signal from a previously known direction with a high reflection intensity is used as a received signal from a previously known direction. A signal detection device for a wide range underwater detection device, characterized in that it equalizes seabed reflected waves in each direction by suppressing them compared to the waves.