JP3452019B2 - Active sonar device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active sonar device, and more particularly to an active sonar device for reducing received noise.

[0002]

2. Description of the Related Art Conventionally, an active sonar device of this type basically receives and receives an underwater sound wave including a reflected wave from an underwater target or a sound wave generated by the underwater target by a transmitter / receiver. The processed signal is processed by the signal processing unit, and the result is displayed on the display unit.

The transducer is generally arranged on the bottom of the bow, and in addition to natural noise, various noises such as the sound of the screw and the rotation of the propulsion machine generated by the ship are interfering noises. Is received as. When the sound wave is transmitted to the target object in the water and the reflected wave is received, this interference noise has a great influence on the target detection performance.

As a method of reducing the influence of this noise, there is a technique disclosed in, for example, Japanese Patent Laid-Open No. 5-142335. FIG. 9 is a block diagram showing this conventional active sonar device. 9, in addition to the configurations of the wave transmitter / receiver 13, the receiver 15 and the indicator 16, the wave receiver 11,
A control circuit 12 is provided, and an adder circuit 14 is further provided between the wave transmitter / receiver 13 and the receiver 15. The output of the control circuit 12 and the output of the wave transmitter / receiver 13 are given to the adder circuit 14, and the adder circuit 14 is provided.
Is output to the receiver 15.

The wave receiver 1 is arranged at the bottom of the ship on the stern side.
Therefore, the receiver 11 receives various types of noise generated exclusively by the ship. The received signal of the wave receiver 11 is the control circuit 1
Given to 2. The control circuit 12 uses the signal received by the wave receiver 11 to form a noise removal signal having the same level as the own-ship noise received by the wave transmitter / receiver 13 as described above and having the phase reversed. To do.

Therefore, if the output of the control circuit 12 and the output of the transmitter / receiver 13 are added together in the adder circuit 14, the receiver 5 has its own ship noise removed, that is, noise reduction in the low frequency range. A signal from the target which is sufficiently improved and the SN ratio is improved is input.

[0007]

As described above, in the conventional example, there is an effect of reducing the noise wave generated by the own ship included in the received signal, but noise generated by other than the own ship, for example, near There is a problem that it is not effective in reducing other ship noise such as propulsion sound generated by a ship navigating in the area. Even if the receiver that receives the noise of the ship is directed toward the noise source other than the ship, if the noise source is in the same direction as the direction of the underwater object, the noise is canceled out. Sometimes there is a problem that the reflected waves from the target are also canceled and cannot be received.

[0008]

The active sonar apparatus of the present invention is designed for a plurality of unit reflected waves obtained by dividing a reflected wave including a noise wave obtained by transmitting a sound wave into water on a time axis. Means for extracting a partial noise wave of a portion having the highest waveform correlation as a removing noise wave from the noise waves obtained when the sound wave is not transmitted, and the unit corresponding to each of the unit reflected waves. And a means for converting the noise-removed unit reflected wave that is sequentially generated into a continuous received reflected-wave signal and outputting it to the next step. There is.

More specifically, a wave transmitting / receiving unit that transmits / receives a sound wave in water and outputs the received sound wave as an electric wave receiving signal; and a wave transmitting / receiving unit that receives the wave receiving signal and transmits the sound wave. A switch that cuts and outputs a reflected wave signal containing a noise wave and a noise wave signal obtained when a sound wave is not transmitted to another terminal, and outputs the reflected wave signal by digitizing and storing it. The reflected wave signal stored according to the instruction of the first control signal is divided on the time axis and is divided into a plurality of first unit reflected wave data and a plurality of first unit reflected wave data which are delayed only in timing. And a reflected wave memory circuit for sequentially outputting the second unit reflected wave data, and the noise wave signal is input and digitized and stored, and at the same time, a noise wave of a predetermined time width is extracted by the instruction of the second control signal. This is Replica Noise Day Wherein the noise wave memory circuit which outputs, in accordance with an instruction of the third control signal inputs and said replica noise data and each of said first unit reflecting wave data as the first
The unit reflected wave data of is shifted on the time axis to extract the noise data of the portion having the highest correlation among the replica noise data, and the removal noise extraction circuit for sequentially outputting this as removal noise data; The second unit reflected wave data and each of the removal noise data are input, and the corresponding removal noise data is amplitude-subtracted from the second unit reflected wave data according to the instruction of the fourth control signal to perform noise reduction. And a subtraction processing circuit that sequentially outputs the noise-removed unit reflected wave data as noise-removed unit reflected wave data, and inputs each of the noise-removed unit reflected wave data that are sequentially output and receives the noise-reflective unit reflected wave data after noise removal. A buffer circuit that outputs a wave signal to the next step and a control circuit that generates and outputs the first to fourth control signals are provided.

A plurality of the removal noise extraction circuits and the subtraction processing circuits may be arranged in parallel for parallel processing of the plurality of first and second unit reflected wave data.

Further, the subtraction processing circuit includes a controller that controls the amplitude of the removal noise data by a fifth control signal, and a subtractor that subtracts the output data of the controller from the second unit reflected wave data. The fifth control using an adaptive algorithm so that the output data of the subtractor, that is, the direction of change in the residual noise amount of the received reflected wave signal after noise removal is determined and the residual noise amount converges to a minimum value. A configuration including a determination circuit that outputs a signal may be used.

In the noise wave memory circuit, the waveform of the stored noise wave signal is not natural noise having a flat amplitude value but a portion having a high amplitude value periodically occurs and the waveform of the portion having a high amplitude value is generated. When the pattern changes, the section in which the different waveform patterns are generated more may be extracted by the second control signal and output as the replica noise data.

Further, in the reflected wave memory circuit, a noise wave in which a portion of the stored reflected wave signal having a high amplitude value is periodically generated and a waveform pattern of the portion of a high amplitude value changes is weighted. In the case where the first unit reflected wave data is present, the first unit reflected wave data and the second unit reflected wave data may be sequentially output by dividing the period with a portion having a high amplitude value according to the instruction of the first control signal.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is a circuit diagram of a subtraction processing circuit in FIG. 1, FIG. 3 is a waveform diagram of a noise wave in FIG. 1, and FIG. 4 is reflection in FIG. 2 is a waveform diagram of the wave, FIG. 5 is a waveform showing the extraction process of the removal noise in FIG. 1, a characteristic diagram, and FIG.
FIG. 7 is a flow chart for explaining the operation in FIG. 2, (a) a waveform for explaining the operation in FIG. 2, (b) a waveform showing characteristics,
FIG. 8 is a characteristic diagram, and FIG. 8 is a block diagram showing a second embodiment of the present invention.

First, the configuration of the first embodiment of the present invention will be described with reference to FIG. The active sonar device of the present invention includes a transducer 1 for transmitting and receiving sound waves in water, a noise removing unit 2 for removing noise from a received signal and extracting only a reflected wave, and a received signal, that is, a reflected wave. The received signal processing unit that performs signal processing and the display operation unit 4 that displays the result and issues an operation signal are basically configured.

Hereinafter, the inside of the noise removing unit 2 relating to the present invention will be mainly described. That is, in the configuration of this portion, the wave reception / transmission unit 1 which receives and transmits the sound wave in water and outputs the received sound wave as an electric wave reception signal is input, and the wave transmission / reception unit 1 transmits the sound wave. A switch 21 that separates and outputs a reflected wave signal 101 including noise and a noise wave signal 103 obtained when a sound wave is not transmitted; and a reflected wave signal 101 that is input and digitized and stored. Control signal 107
The reflected wave signal 101 stored by the instruction is divided into predetermined unit times on the time axis, and this is divided into unit reflected wave data 102a.
And the reflected wave memory circuit 22 that sequentially outputs the unit reflected wave data 102a, which is the same as the unit reflected wave data 102a and is delayed only in timing, and the noise wave signal 103 is input and digitized and stored. At the same time, the control signal 108 is stored. The noise wave memory circuit 25 for extracting a noise wave having a predetermined time width according to the instruction
, The unit reflected wave data 102a and the replica noise data 104 are input, the unit reflected wave data 102a is shifted on the time axis according to the instruction of the control signal 109, and the noise of the highest correlation in the replica noise data 104 is obtained. A removal noise extraction circuit 26 that extracts data and sequentially outputs this as removal noise data 106, and each unit reflected wave data 10.
2b and the noise data for removal 106 are input to control signal 1
In accordance with the instruction of 10, the corresponding removal noise data 106 is amplitude-subtracted from the unit reflected wave data 102b to remove noise, and the subtraction processing circuit 23 sequentially outputs the noise-removed unit reflected wave data 105, and the subtraction processing circuit 23. A buffer circuit 24 for inputting each noise-removed unit reflected wave data 105 to be output and outputting this to the received-wave signal processing unit 3 as a received reflected wave signal after temporal noise removal, and four control signals 107 to And a control circuit 27 for generating and outputting 110.

In particular, the subtraction processing circuit 23 has a controller 231 for controlling the amplitude of the removal noise data 106 by a control signal 111, as shown in FIG.
2a, a subtracter 232 for subtracting the output data of the controller 231 and the output data of the subtractor 232, that is, the direction of change in the residual noise amount of the received reflected wave signal after noise removal is determined, and the control signal 111 is repeatedly output. And a determination circuit 233 which controls so as to minimize this.

Next, the operation will be described with reference to FIGS. This active sonar device mainly targets the propulsion noise of the own ship or other ships as the interference noise. That is, as shown in FIG. 3A, the noise waveform is not a natural noise having a flat amplitude value but a noise in which a high amplitude value portion periodically occurs and the waveform pattern of this high portion changes. is there.

The wave transmission / reception unit 1 transmits a sound wave for searching an underwater target with a predetermined time width. Prior to this wave transmission, for example, a few hundred ms before and at the start of wave transmission, switching signals are switched by the switch 21. Output to. The switching device 1 receives the received signal input from the transmitting / receiving unit 1 by the first switching signal, that is, the noise wave signal 103 shown in FIG. 3A, which is only the interfering noise when no sound wave is transmitted at this time. To the noise wave memory circuit 25 side. The reflected wave signal 10 shown in FIG. 4A, which is the reflected wave when the received signal is switched by the next switching signal and the sound wave is transmitted
1 is output to the reflected wave memory circuit 22 side. The reflected wave signal 101 at this time includes the noise wave signal 103.

In the reflected wave memory circuit 22, FIG.
The reflected wave signal 101 having the waveform shown in (a) is divided by a predetermined unit time, here a cycle in which a portion having a high amplitude value occurs, and the unit reflected wave data 102a shown in FIG. The delayed 102b are sequentially output. This signal processing is all digitally processed. That is, the input reflected wave signal 101 is first digitized and stored in the memory, and is sequentially read out at the timing designated by the control signal 107, and the unit reflected wave data 102a and thereby the processing time of the noise extraction circuit 26 for removal are processed. It is output as the unit reflected wave data 102b at the timing delayed by only. In the waveform of the reflected wave signal 101, the reflected wave is weighted by the noise wave as shown in the figure, and the desired reflected wave is shown at the left end.

In the noise memory circuit 25, FIG.
The noise wave in the designated section is extracted as the replica noise data 104 from the noise wave signal 103 having the waveform shown in FIG. Note that this signal processing is digitally processed. That is, the noise wave signal 103 is first digitized and stored, and at the same time, the section designated by the control signal 108 is read at a set timing and output as replica noise data 104. Control signal 108
The section designated by is selected as a section in which more different waveform patterns of a portion having a high amplitude value occur, but here, in order to simplify the description, the three central waveform pattern portions are selected. .

Next, in the removal noise extraction circuit 26,
The replica noise data 104 having the waveform shown in FIG. 5B and the unit reflected wave data 102a having the waveform shown in FIG. 5C are input, and the unit reflected wave data 102a is plotted on the time axis of the replica noise data 104 as shown. The above is shifted, the correlation value of both is calculated, the data shown in FIG. 5D is obtained, and the noise wave of the portion having the highest correlation value is removed noise data 106.
And output as. Here, replica noise data 1
An example in which the central part of 04 is extracted is shown. It should be noted that this process is sequentially performed serially for each unit reflected wave data at the timing indicated by the control signal 109.

Next, in the subtraction processing circuit 23, the unit reflected wave data 102b is processed in the procedure shown in the flowchart of FIG.
The noise data 106 for which the sub-control is performed is subtracted therefrom to optimally remove the noise. This process will be described below with reference to FIGS. 3 and 7.

First, the controller 23 performs sub-control of the removal noise data. The weight coefficient for amplitude control obtained at the n-th time is Wa _n (the initial value of Wa is 0),
Assuming that the removal noise data 106 is Xa and the amplitude-controlled removal noise data 106 is A _n , A _n = W a _n × X
a (step A1).

Next, the subtracter 23 subtracts the amplitude-controlled removal noise data A _n from the unit reflected wave data 102b ( _denoted by S) to cancel the noise. The difference between S and An is En
Then, E _n = S−A _n . That is, E _n is temporary removal processing data obtained by subtracting the noise component from the unit reflected wave data S when the weighting coefficient Wa for controlling the amplitude of the removal noise data obtained at the n-th time is used (step A).
2).

Next, in the decision circuit 223, it is decided whether or not this temporary removal processing data is optimally noise-removed,
If the result is positive, proceed to the next step, and if not, step A
In step 4, the weighting coefficient Wa _{n + 1} for controlling the amplitude of the noise data for removal is calculated and fed back to step A1 (step A3).

Step A performed by the controller 231
4 the operation of the calculation of the weighting coefficients Wa n _{+ 1} for the amplitude control of removing noise _{data, Wa n + 1 = Wa n} + μ
× C _n . Thus, the coefficient correction amount Cn is added to the weighting coefficient used last time to obtain the value. Note that μ is a constant that controls the magnitude of coefficient correction and controls the adaptive speed, and an arbitrary value is set in advance. Here, the coefficient correction amount Cn
Is calculated using an adaptive algorithm. For example, when the LMS method (least square method) is used, Cn = 2E _n Xa is given. That is, the weight coefficient Wa _{n + 1} is _{equal to} Wa _{n + 1.}
Is obtained by Wa _{n + 1} = W a _n +2 μ · E _n · Xa (step A4).

That is, steps A1 to A4 are repeated, and eventually the unit reflected wave data 1 is obtained as shown in FIG. 7 (a).
02b is optimally noise-removed, but the determination as to whether it is correct or not in step A3 is performed as shown in FIG. 7B. By repeating steps A1 to A4, the temporary removal processing data En converges to a certain value. Therefore, the squared value (E _n −E _n−1 ) ² of the difference between the temporary removal processing data En obtained by the repetition up to this time and the previously obtained En _n is calculated from a preset constant value D. If it becomes smaller, it is determined that the noise cannot be further removed, and it is determined that the optimum noise has been removed by this, and it is determined to be positive, and the noise-removed unit reflected wave data 105 is output.

The buffer 14 stores the noise removal unit processing data 105 sequentially output from the subtraction processing circuit 23, connects the separated data, and receives as a reception reflected wave signal subjected to interference noise removal processing. Signal processing unit 3
Is output to.

Next, a second embodiment of the present invention will be described with reference to FIG. This example of the embodiment is different from the first embodiment in the configuration of the noise removing unit 5. That is, in the noise removal unit 5, the removal noise extraction circuits 56a-j and the subtraction processing circuits 53a-j are respectively the number of unit reflected wave data 102,
That is, there are five each, and the difference is that they are arranged in parallel. In the first embodiment, each of the five divided unit reflected wave data is subjected to noise removal processing in series by one removal noise extraction circuit and one subtraction processing circuit. In the above, each of them is processed in parallel by using a noise extraction circuit for removing five noises and a subtraction processing circuit. Therefore, the processing speed is high.

Each circuit of the switch 51, the reflected wave memory circuit 52, the noise wave memory circuit 55, the removal noise extraction circuit 56, the subtraction processing circuit 53, the buffer circuit 54, and the control circuit 57 in this embodiment is the first circuit. The circuits have exactly the same functions as the corresponding circuits in the embodiments, and only the above-mentioned points differ in the overall configuration and operation, so detailed description will be omitted.

[0032]

As described above, the active sonar apparatus of the present invention is obtained when only the interfering noise is received in advance before transmitting the sound wave to the underwater target, and the sound wave is transmitted. Since the received interference noise is subtracted from the reflected wave containing noise to cancel and remove the noise, the noise can be removed even if the noise source is the own ship or another ship. There is also an effect that noise can be removed even if the noise source is in the same direction as the target.

Further, the received reflected wave is divided on the time axis, noise data having a strong correlation is extracted for each divided unit reflected wave, and the subtraction processing is performed using this, so that noise removal is performed accurately. This has the effect of reliably capturing the target reflected wave.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a detailed configuration of a subtraction processing circuit in FIG.

FIG. 3 is a waveform diagram showing a waveform of a noise wave in FIG.

FIG. 4 is a waveform diagram showing a waveform of a reflected wave in FIG.

FIG. 5 is a waveform characteristic diagram illustrating a process of extracting removal noise in FIG.

FIG. 6 is a flowchart illustrating the operation of FIG.

7A and 7B are waveforms and characteristic diagrams showing waveforms (a) and (b) characteristics for explaining the operation in FIG.

FIG. 8 is a block diagram showing a second exemplary embodiment of the present invention.

FIG. 9 is a block diagram showing a conventional example.

[Explanation of symbols]

1 Transceiver 2, 5 noise eliminator 3 Received signal processing unit 4 Display operation unit 21, 51 switch 22, 52 Reflected wave memory circuit 23, 53a-j Subtraction processing circuit 24, 54 buffer circuit 25, 55 Noise wave memory circuit 26, 56a-j removal noise extraction circuit 27, 57 control circuit

Continuation of front page (56) Reference JP-A-55-51375 (JP, A) JP-A-5-142335 (JP, A) JP-A-7-134061 (JP, A) JP-A-5-126941 (JP , A) JP-A-11-38127 (JP, A) JP-A-2-275379 (JP, A) SAIKAI Sho 58-177883 (JP, U) WEISS LG,, Wavet-based denoising of underwater acoustic charge. signals, Journal of Acoustic Society of America, USA, 1997, Vol. 101 / No. 1, P.I. 377-383 (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01S ⁷ /52-7/64 G01S 15/00-15/96

Claims (6)

(57) [Claims] 1. A plurality of unit reflected waves obtained by dividing a reflected wave including a noise wave obtained by transmitting a sound wave into water on the time axis, and a noise wave obtained when the sound wave is not transmitted. Means for extracting a partial noise wave of a portion having the highest waveform correlativity from the inside as a removing noise wave, and subtracting the removing noise wave corresponding to each unit reflected wave in amplitude. An active sonar device comprising means for generating a noise-removed unit reflected wave, converting the sequentially generated noise-removed unit reflected wave into a continuous received reflected wave signal, and outputting the signal to the next step. 2. A wave transmitting / receiving unit that transmits / receives a sound wave into water and electrically outputs the received sound wave as a received wave signal; and a wave transmitting / receiving unit that inputs the received wave signal and transmits / receives the sound wave. A switch that separates and outputs a reflected wave signal containing a noise wave and a noise wave signal obtained when a sound wave is not transmitted to another terminal, and a first switch that inputs the reflected wave signal and stores it in a digital form. The reflected wave signal stored according to the instruction of the control signal is divided on the time axis, and this is divided into a plurality of first unit reflected wave data and a plurality of second unit reflected wave data which are delayed only in timing. And a reflected wave memory circuit for sequentially outputting the unit reflected wave data, and the noise wave signal is input and digitized and stored, and at the same time, a noise wave having a predetermined time width is extracted according to the instruction of the second control signal. Output as replica noise data Noise wave memory circuit, and each of the first
The unit reflected wave data and the replica noise data are input, and the first unit reflected wave data is shifted on the time axis in accordance with the instruction of the third control signal to obtain the highest correlation among the replica noise data. Noise extraction circuit for extracting the noise data of 1) and sequentially outputting it as removal noise data, and inputting each of the second unit reflected wave data and each of the removal noise data, and instructing a fourth control signal. By the second
A corresponding subtraction noise data from the unit reflected wave data is amplitude-subtracted to cancel and cancel the noise to sequentially output the noise-removed unit reflected wave data, and each of the sequentially output noises. A buffer circuit for inputting the removal unit reflected wave data and outputting it to the next step as a received reflected wave signal after noise removal that is continuous in time;
An active sonar device comprising: a control circuit that generates and outputs a fourth control signal. 3. A wave transmitting / receiving unit that transmits / receives a sound wave into / from water and outputs the received sound wave as an electric wave receiving signal; and noise generated when the wave receiving / transmitting unit inputs the wave receiving signal and transmits the sound wave. And a switching device for cutting and outputting the reflected wave signal containing the noise wave signal and the noise wave signal obtained when the sound wave is not transmitted to another terminal and outputting the reflected wave signal by digitizing and storing the same. The reflected wave signal stored by the instruction of the signal is divided on the time axis, and this is divided into a plurality of first unit reflected wave data and a plurality of second unit reflected wave data which are delayed in timing only. A reflected wave memory circuit that sequentially outputs unit reflected wave data, and a noise wave signal that is input and digitized and stored. At the same time, a noise wave of a predetermined time width is extracted according to the instruction of the second control signal, and this is replicated. Output as noise data A noise wave memory circuit, one of the first unit reflected wave data and the replica noise data are input, and the first unit reflected wave data is shifted on the time axis according to an instruction of a third control signal, and the replica is generated. A plurality of removing noise extracting circuits arranged in parallel for extracting noise data having the highest correlation from the noise data and outputting the noise data as removing noise data, and one of the second unit reflected wave data. And the corresponding removal noise data are input, and the corresponding removal noise data is amplitude-subtracted from the third unit reflected wave data by the instruction of the fourth control signal to cancel the noise. And a plurality of subtraction processing circuits arranged in parallel for outputting the noise-removed unit reflected wave data, and the noise-removed unit reflected wave data sequentially output from each of the subtraction processing circuits. An active sonar apparatus comprising: a buffer circuit for outputting to the next step as a received reflected wave signal after noise removal which is continuous between noises and a control circuit for generating and outputting the first to fourth control signals. . 4. The subtraction processing circuit includes a controller that controls the amplitude of the removal noise data by a fifth control signal, and a subtractor that subtracts output data of the controller from the second unit reflected wave data. , Output data of the subtracter, that is, the direction of change of the residual noise amount of the received reflected wave signal after noise removal is determined, and the residual noise amount is generated using an adaptive algorithm so that the residual noise amount converges to a minimum value. 5. The active sonar device according to claim 2 or 3, further comprising a determination circuit that outputs the control signal of 5. 5. The noise wave memory circuit is characterized in that the stored waveform of the noise wave signal is not natural noise having a flat amplitude value but a portion having a high amplitude value periodically occurs and the waveform of the portion having a high amplitude value is generated. 5. The active sonar apparatus according to claim 2, wherein the section in which the different waveform patterns are generated more when the pattern changes is extracted by the second control signal and output as the replica noise data. . 6. The reflected wave memory circuit is characterized in that a noise wave in which a waveform of the stored reflected wave signal is periodically generated in a portion having a high amplitude value and a waveform pattern of the portion having a high amplitude value changes is weighted. When the first control signal is instructed, the first unit reflected wave data and the second unit reflected wave data are sequentially output by dividing in a cycle of a portion having a high amplitude value according to the instruction of the first control signal. Item 5. The active sonar device according to item 5.