JPH0772242A - Active sonar apparatus - Google Patents

Abstract

PURPOSE:To provide an active sonar apparatus which can detect a target object without being affected by the condition of a sea region. CONSTITUTION:The sonar apparatus is provided with a transmitter 7 which is used to send an acoustic signal A, with a receiver 2 which is used to receive a reflected signal B from the acoustic signal A and with a TVG(time-variable gain) circuit 3 which is provided with a TVG controller 10 which is used to output an average reverbration level signal S5 indicating an amplification degree corresponding to the level average of reverbration signals S1-2 contained in a received signal S1 and with a TVG amplifier 20 which is used to amplify the reverbration signals S1-2 at the amplification degree indicated by the average reverbratlon level signal 55. Concretely, the TVG controller 10 for the TVG circuit 3 is formed of a detector 11 used to detect the reverbration signals S1-2 from the received signal S1, of an everaging circuit 14 which is used to find the level average of the detected reverbration signals 31-2 in a plurality and of a reverbration/TNG control-signal converter 15 which is used to output, to the TVG amplifier 20, the average reverbration level signal S5 indicating the amplification degree corresponding to the level average of the reverbration signals S1-2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a TVG (Time V
The present invention relates to an active sonar device including an arable gain circuit.

[0002]

2. Description of the Related Art An active sonar device is a device for detecting a target by transmitting an acoustic signal into the sea and receiving an acoustic signal reflected from the target. The reflected acoustic signal includes a reverberation signal in addition to the echo signal indicating the target, and the received acoustic signal is attenuated with time. Therefore, for example, Japanese Patent Laid-Open No. 60-18167
As in the active sonar device described in Japanese Patent Publication No. 3, a TVG circuit that changes the gain of a received acoustic signal in accordance with the reception time is generally provided.

An active sonar device equipped with a TVG circuit has conventionally been constructed as shown in FIG. Code 3
Reference numeral 1 is a wave transmitter for transmitting the acoustic signal A to the target object, and the reflected acoustic signal B is received by the wave receiver 32. The received acoustic signal B is output to the target detector 34 after gain control by the TVG circuit 33, and the target object is detected by the target detector 34.

Specifically, when the acoustic signal B is received by the wave receiver 32, it is converted into an electric signal S1 'and output to the TVG amplifier 41 of the TVG circuit 33. Then, when the electric signal S1 ′ including the echo signal S1-1 ′ and the reverberation signal S1-2 ′ is input to the TVG amplifier 41, a fixed amplification control signal E selected in advance is output from the TVG controller 40. It is output to the TVG amplifier 41. Then, in the TVG amplifier 41, based on the amplification degree control signal E, the electric signal S
1'is amplified. That is, the reverberation signal S1-2 ′ of the electric signal S1 ′ is equalized to a threshold value L or less, and the output signal S2 ′ amplified so that the echo signal S1-1 ′ protrudes from the threshold value L is the target detection. The target detector 34 outputs the echo signal S1-1 ', and the target object is detected.

The degree of amplification of the TVG amplifier 41 selected in advance by the TVG controller 40 is determined by the following two methods. The first method is to input the reverberation signal S1- from the volume reverberation equation represented by the following equation (1) based on the transmission characteristics.
The reverberation level of 2'is calculated, and the amplification degree is controlled according to the calculated reverberation level. RL _S = SL-40 · logr + 10 · log (cτ / 2) ψr ² (1) where SL is the transmission level of the acoustic signal A, r is the distance of the reflection point, c is the speed of sound, and τ is the transmission pulse. The width, ψ, is the equivalent beam width. The second method is a method of controlling the amplification degree according to the reverberation level measured in advance in a specific sea area.

[0006]

However, in the above-described conventional active sonar apparatus, as shown in FIG. 4 (a), the reverberation signal S1-2 actually input depending on the sea area conditions in which the apparatus is used. Since the reverberation level change of ′ is often different from the reverberation estimation curve S, in such a case, the TV
In the TVG amplifier 41 of the G circuit 33, the received signal S1
′ Will be amplified to a waveform as shown in FIG. 4 (b). That is, the reverberation signal S1-2 'is not uniformized and protrudes above the threshold value L to generate the echo signal S1-1.
Since ′ is buried under the threshold value L, there is a problem that the echo signal S1-1 ′ cannot be accurately detected.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an active sonar device capable of detecting a target without being affected by the conditions of the sea area.

[0008]

In order to achieve the above object, an active sonar apparatus of the present invention is provided with a wave transmitter for transmitting an acoustic signal, and the acoustic signal transmitted from the wave transmitter. A wave receiver for receiving the reflected signal and the average level of the reverberation signal contained in the received signal received by this wave receiver, and the average reverberation level indicating the amplification degree corresponding to this level average. A TVG controller for outputting a signal and a TVG circuit having a TVG amplifier for amplifying the reverberation signal with the amplification degree indicated by the average reverberation level signal are provided.

Further, in the active sonar apparatus according to a second aspect, in the first aspect, the TVG controller of the TVG circuit includes a detector for detecting a reverberation signal from the received signal, and the detector. An averaging circuit for obtaining a level average of a plurality of reverberation signals detected by the above, and an average reverberation level signal indicating an amplification degree corresponding to the level average of the reverberation signals obtained by this averaging circuit is output to the TVG amplifier. And a reverberation / TVG control signal converter for this purpose.

[0010]

According to the active sonar device, when the acoustic signal is transmitted from the wave transmitter, the reflected signal of the acoustic signal is received by the wave receiver. And the TVG of the TVG circuit
The controller calculates the level average of the reverberation signals included in the received signal, and the average reverberation level signal indicating the amplification degree corresponding to the level average is output from the TVG controller to the TVG controller.
Output to the amplifier. As a result, in the TVG amplifier, the reverberation signal is amplified by the amplification degree indicated by the average reverberation level signal.

According to the active sonar apparatus of the second aspect, in the TVG controller of the TVG circuit, the reverberation signal is detected from the received signal by the wave detector, and the plurality of reverberation signals detected by the wave detector are detected. The level average of is calculated by the averaging circuit. Then, the average reverberation level signal indicating the amplification degree corresponding to the level average of the reverberation signal obtained by the averaging circuit is output from the reverberation / TVG control signal converter to the TV.
It is output to the G amplifier.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an active sonar device according to an embodiment of the present invention. The active sonar device of this embodiment includes a wave transmitter 1, a wave receiver 2, and a TVG.
The circuit 3 and the target detector 4 are provided.

The wave transmitter 1 transmits a predetermined electric signal to the acoustic signal A.
It is converted to and transmitted. The wave receiver 2 is the wave transmitter 1
Acoustic signal B, which is a reflection signal of acoustic signal A transmitted from
Is received and the acoustic signal B is converted into an electric signal S1. As shown in FIG. 2 (a), the received signal S1 received by the wave receiver 2 includes interference from the sea surface, the seabed, and underwater microorganisms in addition to the reflected echo signal S1-1 from the target object. The reverberation signal S1-2 as a sound is included. The level (reverberation level) of the reverberation signal S1-2 is determined by the transmission level of the acoustic signal A, the pulse width, the attitude of the active sonar device, the beam width of the transmitter 1, and the like. Therefore, the volume reverberation level changes with time as shown in FIG.

The TVG circuit 3 includes a TVG controller 10 and a TG controller 10.
It is composed of a VG amplifier 20. TVG controller 10
Is a detector 11, an AD converter 12, a memory 13,
It has an averaging circuit 14 and a reverberation / TVG control signal converter 15. The detector 11 detects the curve of the reverberation signal S1-2 from the received signal S1 received by the receiver 2,
The analog signal S2 is output.

The A / D converter 12 converts the reverberation signal S1-2 as the analog signal S2 from the detector 11 into a digital signal S3 and outputs it to the memory 13. The memory 13 has a function of always storing the digital signal S3 output from the A / D converter 12 for each transmission.

The averaging circuit 14 obtains an average value of the levels of a plurality of reverberation data stored in the memory 13 and obtained for each transmission, and outputs an average reverberation level signal S5 indicating the level average. Is. At this time, the number of sample data is specified from the outside as shown in the figure. That is, the number of N samples is externally input to the averaging circuit 14.

The reverberation / TVG control signal converter 15 converts the average reverberation level signal S5 from the averaging circuit 14 into a TVG control signal C and outputs it to the TVG amplifier 20. The TVG control signal C output by the reverberation / TVG control signal converter 15 is a signal for controlling the amplification degree of the TVG amplifier 20, and is amplified according to the average value of the reverberation levels indicated by the average reverberation level signal S5. Shows the degree.

The TVG amplifier 20 converts the reverberation signal S1-2 in the received signal S1 received by the receiver 2 into reverberation / TV.
The signal is amplified by the TVG control signal C from the G control signal converter 15. Specifically, the amplification degree is controlled according to the sea area conditions in which the active sonar device is used.
That is, as shown in (b) of FIG. 2, the reverberation level of the reverberation signal S1-2 is changed to (b) of FIG. 2 according to the amplification degree.
, The reverberation signal level S1-2 is equalized.
And an output signal S6 indicating the echo signal S1-1 is output to the target detector 4. At this time, the reverberation levels of the reverberation signal S1-2 are as shown in FIG.
In order to distinguish it from 1, it is controlled to a level below the threshold value L.

The target detector 4 detects a target based on the output signal S6 from the TVG amplifier 20. That is, since the reverberation signal S1-2 in the output signal S6 is equalized to a level below the threshold value L,
Only the echo signal S1-1 protruding above the threshold L is detected.

Next, the operation of the active sonar device of this embodiment will be described. When the acoustic signal A is transmitted from the wave transmitter 1, the reflected acoustic signal B is received by the wave receiver 2 and input to the TGV circuit 3. The received signal S1 received by the wave receiver 2 is output to the TGV controller 10 and the TGV amplifier 20 of the TGV circuit 3, and the TGV controller 1
The reverberation signal S1-2 in the received signal S1 is detected by the detector 11 of 0.

Reverberation signal S1-2 detected by the detector 11.
Is input to the A / D converter 12 and converted into a digital signal S3 indicating the reverberation signal S1-2. Such conversion is performed every time the wave is transmitted by the wave transmitter 1, and the digital signal S3 is output from the A / D converter 12 and stored in the memory 13 each time. The digital signal S3 stored in the memory 13 is converted by the averaging circuit 14 into
The average value of the levels of the reverberation data read and obtained by the plurality of digital signals S3 is obtained. Then, the averaging circuit 14 outputs the average reverberation signal S5 indicating the level average to the reverberation / TVG control signal converter 15.

When the average reverberation level signal S5 is input to the reverberation / TVG control signal converter 15, T indicating the amplification degree according to the average value of the reverberation levels indicated by the average reverberation signal level S5.
The VG control signal C is output to the TVG amplifier 20. That is, the reverberation signal S1-2 as shown in FIG.
The TVG control signal C indicating the amplification level that suppresses the level below the threshold value L as shown in FIG.
It is output to the G amplifier 20.

When the TVG control signal C is input to the TVG amplifier 20, the received signal from the receiver 2 is amplified according to the sea area conditions in which the active sonar device is used, and as a result, as shown in FIG. As shown in (b), the reverberation signal S1-
The reverberation level of 2 is made uniform, the reverberation signal is suppressed below the threshold value L, and the output signal S6 in a state where the echo signal S1-1 is projected beyond the threshold value L is output to the target detector. Is output. When the output signal S6 is input to the target detector 4, the echo signal S1-projected above the threshold value L
1 is clearly detected and the reverberation signal S below the threshold L
1-2 are removed.

As described above, according to the active sonar apparatus of the present embodiment, the reverberation signal S1-2 is suppressed below the threshold value L in a uniformed state, so that the reverberation signal S1-2 is suppressed. Therefore, the active sonar device does not malfunction. That is, the active sonar apparatus of the present embodiment can accurately detect the echo signal S1-1 of the target object without being affected by the conditions of the sea area.

[0025]

As described above, according to the active sonar apparatus of the present invention, the level average of the reverberation signal is obtained by the TVG controller of the TVG circuit, and the average reverberation level indicating the amplification degree corresponding to this level average. The signal is output from the TVG controller to the TVG amplifier, and in the TVG amplifier,
Since the reverberation signal is amplified by the amplification degree indicated by the average reverberation level signal, the reverberation signal level can be amplified corresponding to the sea area condition. As a result, the device can detect the echo signal of the target without being erroneously operated by reverberation.

[Brief description of drawings]

FIG. 1 is a block diagram showing an active sonar device according to an embodiment of the present invention.

2A and 2B are received waveform diagrams of the present embodiment, FIG. 2A shows a received waveform before processing by the TVG circuit, and FIG. 2B shows a received waveform after processing by the TVG circuit.

FIG. 3 is a block diagram showing an active sonar device according to a conventional example.

FIG. 4 is a reception waveform diagram of an active sonar device according to a conventional example, FIG. 3 (a) shows a reception waveform before processing by a TVG circuit, and FIG. 3 (b) shows reception after processing by a TVG circuit. The waveform is shown.

[Explanation of symbols]

 1 wave transmitter 2 wave receiver 3 TVG circuit 10 TVG controller 11 detector 14 average circuit 15 reverberation / TVG control signal converter 20 TVG amplifier A acoustic signal B reflected acoustic signal S1 received signal S1-2 reverberation signal S5 average Reverberation level signal

Claims (2)

[Claims] 1. A wave transmitter for transmitting an acoustic signal, a wave receiver for receiving a reflected signal of the acoustic signal transmitted from the wave transmitter, and a wave receiver for receiving the wave signal. A TVG controller for obtaining a level average of reverberation signals included in the received wave signal and outputting an average reverberation level signal indicating an amplification degree corresponding to the level average, and an amplification indicated by the average reverberation level signal. An active sonar device comprising a TVG circuit having a TVG amplifier for amplifying the reverberation signal at a frequency. 2. A TVG controller for the TVG circuit, a detector for detecting a reverberation signal from the received signal, and an averaging circuit for obtaining a level average of a plurality of reverberation signals detected by the detector. And a reverberation / TVG control signal converter for outputting the average reverberation level signal indicating the amplification degree corresponding to the level average of the reverberation signal obtained by the averaging circuit to the TVG amplifier. Active sonar device.