JP6740658B2 - Device, method and program for passive sonar - Google Patents

Description

The present invention relates to an apparatus, method and program for passive sonar.

A passive sonar device is used to calculate the presence and position (direction/direction) of a target by detecting sound waves emitted by the target existing in water (including the water surface). At this time, in addition to the narrow band signal (narrow band signal) from the target, the received signal includes a wide band signal (broadband signal) from other than the target and noise (a signal having no regularity in direction/direction and signal level). include.

When the received signal data is obtained by performing the Fourier transform (FFT) on the received signal and the received signal data is displayed on the screen in a format in which the horizontal axis and the vertical axis respectively indicate frequency and time, the narrow band signal has a narrow band. Therefore, the broadband signal is displayed in a line shape, and the broadband signal is displayed in a band shape because of a wide band. Since noise has no regularity in direction/azimuth, it is sparsely displayed by coloring in each direction/azimuth on the screen.

Also, when the target is moving, the observed frequency changes due to the Doppler effect. Since the frequency of the target narrowband signal changes over time, a characteristic line is formed on the screen. By automatically detecting and analyzing this line, it is possible to identify the type of the target sound source and predict the position of the target, the course, the moving speed, and the like.

For example, Patent Documents 1 to 5 disclose signal processing in an active sonar device or a passive sonar device.

JP, 2014-3208, A JP, 2010-169644, A JP2012-208062A JP, 2014-32082, A JP, 2005-215175, A

For example, in the above-described automatic line detection, line detection is performed after low-level data is removed by threshold processing. In this case, if the level of the broadband signal and/or the noise is close to or higher than the level of the narrow band signal, the line that should be detected may be removed. Furthermore, one line may be interrupted in the middle, and as a result, a plurality of lines may be erroneously detected.

An object of the present invention is to provide an apparatus, a method and a program capable of detecting a line of a narrow band signal from a target with higher accuracy.

The device of the present invention, in the received signal data including the signal level of a plurality of discrete points in the time frequency domain and the signal arrival direction, the signal level of the attention point of the plurality of discrete points, the signal level of the peripheral region of the attention point. A first filter unit that replaces a first value calculated based on a signal level, and a degree of concentration in a signal arrival direction of a point of interest of the plurality of discrete points and a peripheral region of the point of interest in the received signal data. Is lower than a threshold value, a second filter unit that replaces the signal level of the point of interest with a second value, and a point of interest of the plurality of discrete points and a peripheral region of the point of interest in the received signal data. Calculating a density distribution in the signal arrival direction, replacing a signal level at a discrete point corresponding to the higher-order signal arrival direction in the density distribution with a third value, A fourth filter unit that replaces the signal level of the attention point with a fourth value when there is a discrete point having a signal level of 0 in the peripheral region of the attention point among the discrete points.

The method of the present invention, in the received signal data including the signal level of a plurality of discrete points in the time-frequency domain and the signal arrival direction, the signal level of the attention point of the plurality of discrete points, the signal level of the surrounding area of the attention point. Substituting the first value calculated based on the signal level, and in the received signal data, the degree of concentration in the signal arrival direction of the attention point of the plurality of discrete points and the peripheral region of the attention point is more than the threshold value. If the signal level at the point of interest is low, replacing the signal level of the point of interest with a second value, and in the received signal data, the density of the point of interest of the plurality of discrete points and the signal arrival direction in the peripheral region of the point of interest. Calculating a distribution and replacing the signal level of the discrete point corresponding to the higher-order signal arrival direction in the density distribution with a third value, and in the received signal data, around the attention point of the plurality of discrete points Replacing the signal level at the point of interest with a fourth value when there are discrete points having a signal level of 0 in the region.

A program of the present invention, in the received signal data including the signal level of a plurality of discrete points in the time-frequency domain and the signal arrival direction, the signal level of the point of interest among the plurality of discrete points, the signal level of the peripheral region of the point of interest. Substituting the first value calculated based on the signal level, and in the received signal data, the degree of concentration in the signal arrival direction of the attention point of the plurality of discrete points and the peripheral region of the attention point is more than the threshold value. If the signal level at the point of interest is low, replacing the signal level of the point of interest with a second value, and in the received signal data, the density of the point of interest of the plurality of discrete points and the signal arrival direction in the peripheral region of the point of interest. Calculating a distribution and replacing the signal level of the discrete point corresponding to the higher-order signal arrival direction in the density distribution with a third value, and in the received signal data, around the attention point of the plurality of discrete points When there are discrete points having a signal level of 0 in the area, the processor is caused to replace the signal level of the point of interest with a fourth value.

According to the present invention, it is possible to detect a narrow band signal line from a target with higher accuracy. Note that, according to the present invention, other effects may be exhibited instead of or in addition to the effects.

It is a block diagram which shows the example of a schematic structure of the passive sonar apparatus which concerns on 1st Embodiment. 6 is a flowchart for explaining an example of the flow of processing according to the first embodiment. It is a block diagram which shows the example of a schematic structure of the apparatus which concerns on 2nd Embodiment. 9 is a flowchart for explaining an example of the flow of processing according to the second embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, elements that can be described in the same manner are denoted by the same reference numerals, and repeated description may be omitted.

The description will be given in the following order.
1. 1. First Embodiment 1.1. Configuration of passive sonar device 1.2. Process flow 2. Second embodiment 2.1. Configuration of device 2.2. Process flow

<<1. First embodiment>>
First, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

<1.1. Configuration of passive sonar device>
An example of the configuration of the passive sonar apparatus 100 according to the first embodiment will be described with reference to FIG. 1. FIG. 1 is a block diagram showing an example of a schematic configuration of a passive sonar device 100 according to the first embodiment. Referring to FIG. 1, the passive sonar apparatus 100 includes a signal processing unit 101, a median filter unit 103, an azimuth concentration degree filter unit 105, an azimuth density distribution filter unit 107, a contraction filter unit 109, a binarization processing unit 111, and line detection. The processing unit 113, the display unit 115, and the target position calculation unit 117 are provided.

(1) Signal processing unit 101
The signal processing unit 101 generates received signal data by performing signal processing on the received signal (sound wave). The signal processing includes Fourier transform, and the received signal data includes signal levels at a plurality of discrete points in the time frequency domain. For example, the plurality of discrete points are lattice-shaped discrete points arranged in the time direction and the frequency direction.

(2) Median filter section 103
The median filter unit 103 performs median filter processing on the received signal data. Specifically, the median filter unit 103 performs a raster scan on the plurality of discrete points of the received signal data, and replaces the signal level of the point of interest with the median value of the signal levels of the peripheral area.

Thereby, noise included in the received signal can be reduced. This is because, for example, even if noise with a large signal level suddenly appears, the signal level of the noise can be suppressed so as to be close to the surrounding signal level.

The size of the peripheral area can be specified by an operator, for example.

In addition, the peripheral area of the attention point is, in other words, a local area around the attention point, and is a set of discrete points around the attention point (the same applies to the following description).

(3) Directional concentration degree filter unit 105
The azimuth concentration degree filter unit 105 performs azimuth concentration degree filter processing on the received signal data. Specifically, the azimuth concentration degree filter unit 105 performs raster scanning on the plurality of discrete points of the received signal data, and concentrates the signal arrival azimuths of the attention point and its peripheral region (hereinafter referred to as the attention region). Calculate the degree. Then, the direction concentration degree filter unit 105 replaces the signal level of the point of interest with 0 when the degree of concentration is lower than the threshold value. Further, the azimuth concentration degree filter unit 105 may replace the signal level of the attention point with 0 even when the concentration degree is equal to the threshold value.

For example, the degree of concentration is the magnitude of the average vector of the signal arrival directions of the attention area (the attention point and the peripheral area). Specifically, for example, each signal arrival direction is regarded as an angle with the X axis on the unit circle. In other words, each signal arrival direction is regarded as a vector of length 1 (unit vector). In this case, a sum vector is calculated as the sum of the signal arrival directions (vectors) of the region of interest (that is, the sum in the X axis direction and the sum in the Y axis direction are calculated). Then, the magnitude of the sum vector (that is, the distance from the origin) is calculated. Further, the magnitude of the total sum vector is divided by the number of discrete points in the attention area. The result of this division is used as the degree of concentration. If the signal arrival directions are the same in the attention area, the degree of concentration is 1, so the degree of concentration is any value between 0 and 1. It can be considered that the signal arrival directions are dispersed as the degree of concentration is closer to 0, and the signal arrival directions are concentrated as the degree of concentration is closer to 1.

Thereby, noise included in the received signal can be removed. This is because noise does not have regularity, and thus the signal arrival directions of noise are likely to be dispersed without being concentrated.

The size of the peripheral area and/or the threshold value can be specified by an operator, for example.

(4) Direction density distribution filter unit 107
The azimuth density distribution filter unit 107 performs azimuth density distribution filter processing on the received signal data. Specifically, the azimuth density distribution filter unit 107 performs a raster scan on the plurality of discrete points of the received signal data, and calculates the density distribution of the signal arrival azimuths of the target point and its peripheral region. Then, the azimuth density distribution filter unit 107 replaces the signal level of the discrete point (the above-mentioned point of interest or the discrete point in the above-mentioned peripheral region) corresponding to the signal arrival azimuth of the higher order in the density distribution with 0.

For example, the signal arrival direction that is higher in the density distribution is a predetermined number (N) of signal arrival directions that are larger in the density distribution. Specifically, for example, the signal arrival directions in the density distribution are sorted in descending order (that is, in the descending order of the number in the density distribution), and N signal arrival directions are selected from the top. Then, the signal levels of the discrete points (the above-mentioned point of interest or the discrete points in the peripheral area) corresponding to the selected N signal arrival directions are replaced with zero.

Thereby, the broadband signal (the signal from other than the target) included in the received signal can be removed. This is because the broadband signal is likely to exist at a high azimuth density.

The size of the peripheral area and/or the predetermined number can be specified by an operator, for example.

The density distribution may be a probability density distribution or a histogram. Alternatively, the density distribution may be data in other formats.

(5) Shrink filter section 109
The contraction filter unit 109 performs contraction filter processing on the received signal data. Specifically, the contraction filter unit 109 performs raster scanning on the plurality of discrete points of the received signal data, and if there are discrete points with a signal level of 0 in the peripheral area of the point of interest, The signal level at the point of interest is replaced with 0. For example, the contraction filter unit 109 attempts such replacement when the signal level at the point of interest is higher than 0.

Thereby, noise included in the received signal can be removed. This is because noise does not have regularity and may suddenly appear near the region where the signal level is zero.

The size of the peripheral area can be specified by an operator, for example.

(6) Binarization processing unit 111
The binarization processing unit 111 performs binarization processing on the received signal data. That is, the binarization processing unit 111 binarizes the signal level of each of the plurality of discrete points in the received signal data after each filtering process. Specifically, the binarization processing unit 111 performs raster scanning on the plurality of discrete points, and when the signal level of the target point is higher than the threshold value, the signal level of the target point is set to the maximum value (for example, When the signal level of the target point is smaller than the threshold value, the signal level of the target point is replaced with 0.

As a result, signals (noise and broadband signals) other than the signal from the target (narrowband signal) can be removed.

(7) Line detection processing unit 113
The line detection processing unit 113 performs line detection processing on the received signal data. That is, the line detection processing unit 113 detects a signal level line in the received signal data after the binarization processing. For example, the line detection processing unit 113 estimates (detects) a line by calculating an approximate curve by the least square method based on the received signal data after the binarization process.

(8) Display unit 115
The display unit 115 performs display processing. Specifically, the display unit 115 displays the result of the line detection process on the screen.

(9) Target position calculation unit 117
The target position calculation unit 117 calculates the target position based on the result of the line detection process. Further, the target position calculation unit 117 may predict the target course and/or moving speed. Further, the target position calculation unit 117 may identify the type of target.

The components included in the passive sonar device 100 have been described above. As an example, each component can be implemented by a processor, a program, and the like. For example, the signal processing unit 101 can be implemented by a processor and a passive sonar signal processing program. Also, other components can be implemented by a program and a line detection result display program.

By each of the filter processes as described above, it becomes possible to detect the line of the narrow band signal from the target with higher accuracy. For example, each filter processing as described above allows the line to be detected with higher accuracy even when the signal level of the narrow band signal from the target is low. Further, for example, even when the signal level of the narrow band signal from the target is close to the signal level of the other signal (broadband signal and noise) or lower than the signal level of the other signal by each of the above-described filter processes. , The line can be detected with higher accuracy.

The peripheral region used in each filter unit may be different from or the same as the peripheral region used in another filter unit. As an example, the peripheral region used in the azimuth density distribution filter unit 107 may be larger than the peripheral regions used in other filter units.

<1.2. Process flow>
Next, the flow of processing according to the first embodiment will be described with reference to FIG. FIG. 2 is a flowchart for explaining an example of the flow of processing according to the first embodiment.

The median filter unit 103 performs median filter processing on the received signal data (S201).

The azimuth concentration degree filter unit 105 performs azimuth concentration degree filter processing on the received signal data (S203).

The azimuth density distribution filter unit 107 performs azimuth density distribution filter processing on the received signal data (S205).

The contraction filter unit 109 performs contraction filter processing on the received signal data (S207).

The binarization processing unit 111 performs binarization processing on the received signal data (S209).

The line detection processing unit 113 performs line detection processing on the received signal data (S211).

The display unit 115 displays the result of the line detection processing on the screen (S213).

The details of the median filter process, the azimuth concentration degree filter process, the azimuth density distribution filter process, the contraction filter process, the binarization process, and the line detection process are as described above. Therefore, redundant description will be omitted here.

Note that each filter process may be performed in an order different from the order described above. Alternatively, each filtering process may be performed in parallel (eg, with only one raster scan). Further, the signal level replacement in the filter processing may be performed for each filter processing, or may be performed collectively for all filter processing.

<<2. Second embodiment>>
Subsequently, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4.

<2.1. Device configuration>
An example of the configuration of the device 300 according to the second embodiment will be described with reference to FIG. 3. FIG. 3 is a block diagram showing an example of a schematic configuration of a device 300 according to the second embodiment. Referring to FIG. 3, the device 300 includes a first filter unit 301, a second filter unit 303, a third filter unit 305, and a fourth filter unit 307. For example, the device 300 is a passive sonar device or a module for a passive sonar device.

(1) First filter unit 301
The first filter unit 301 performs a first filter process on received signal data including signal levels and signal arrival directions at a plurality of discrete points in the time frequency domain. Specifically, the first filter unit 301 calculates the signal level of the attention point of the plurality of discrete points in the received signal data based on the signal level of the peripheral region of the attention point. Replace with the value of. For example, the first value is the median value of the signal level of the peripheral area. Note that the first value may be a value other than the median value (for example, the average value of the signal levels of the peripheral area).

As an example, the first filter unit 301 operates similarly to the median filter unit 103 in the first embodiment, and the first filter process is the median filter process in the first embodiment. Details of these are as described above. Therefore, redundant description will be omitted here.

(2) Second filter unit 303
The second filter unit 303 performs second filter processing on the received signal data. Specifically, the second filter unit 303, in the received signal data, when the degree of concentration in the signal arrival direction of the attention point of the plurality of discrete points and the peripheral region of the attention point is lower than the threshold value, The signal level at the point of interest is replaced with a second value. For example, the degree of concentration in the signal arrival direction is the magnitude of the average vector in the signal arrival direction. For example, the second value is 0. For example, the signal arrival direction is a signal arrival direction.

As an example, the second filter unit 303 operates in the same manner as the azimuth concentration degree filter unit 105 in the first embodiment, and the second filter processing is the azimuth concentration degree filter processing in the first embodiment. Details of these are as described above. Therefore, redundant description will be omitted here.

(3) Third filter unit 305
The third filter unit 305 performs a third filter process on the received signal data. Specifically, the third filter unit 305 calculates, in the received signal data, a density distribution in the signal arrival direction of a point of interest of the plurality of discrete points and a peripheral region of the point of interest, and calculates the density distribution using the density distribution. The signal level at the discrete point corresponding to the direction of arrival of the upper signal is replaced with the third value. For example, the signal arrival direction that is higher in the density distribution is a predetermined number of signal arrival directions that are larger in the density distribution. For example, the third value is 0. For example, the signal arrival direction is a signal arrival direction.

As an example, the third filter unit 305 operates similarly to the azimuth density distribution filter unit 107 in the first embodiment, and the third filter process is the azimuth density distribution filter process in the first embodiment. Details of these are as described above. Therefore, redundant description will be omitted here.

(4) Fourth filter unit 307
The fourth filter unit 307 performs fourth filter processing on the received signal data. Specifically, the fourth filter unit 307 determines that if there is a discrete point having a signal level of 0 in the peripheral area of the focused point among the plurality of discrete points in the received signal data, Replace the signal level with a fourth value. For example, the fourth value is 0.

As an example, the fourth filter unit 307 operates similarly to the contraction filter unit 109 in the first embodiment, and the third filter process is the contraction filter process in the first embodiment. Details of these are as described above. Therefore, redundant description will be omitted here.

The components included in the device 300 have been described above. As an example, each component can be implemented by a processor, a program, and the like. Further, the device 300 includes one or more other components (for example, the signal processing unit 101, the binarization processing unit 111, the line detection processing unit 113, the display unit) included in the passive sonar device 100 of the first embodiment. 115 and/or a target position calculation unit 117) may be further included.

By each of the filter processes as described above, it becomes possible to detect the line of the narrow band signal from the target with higher accuracy. For example, each filter processing as described above allows the line to be detected with higher accuracy even when the signal level of the narrow band signal from the target is low. Further, for example, even when the signal level of the narrow band signal from the target is close to the signal level of the other signal (broadband signal and noise) or lower than the signal level of the other signal by each of the above-described filter processes. , The line can be detected with higher accuracy.

The peripheral region used in each filter unit may be different from or the same as the peripheral region used in another filter unit. As an example, the peripheral region used in the third filter unit 305 may be larger than the peripheral regions used in the other filter units.

<2.2. Process flow>
Next, the flow of processing according to the second embodiment will be described with reference to FIG. FIG. 4 is a flowchart for explaining an example of the flow of processing according to the second embodiment.

The first filter unit 301 performs first filter processing on the received signal data (S401).

The second filter unit 303 performs second filter processing on the received signal data (S403).

The third filter unit 305 performs a third filter process on the received signal data (S405).

The fourth filter unit 307 performs fourth filter processing on the received signal data (S407).

The details of the first filter process, the second filter process, the third filter process, and the fourth filter process are as described above. Therefore, redundant description will be omitted here.

Note that each filter process may be performed in an order different from the order described above. Alternatively, each filtering process may be performed in parallel (eg, with only one raster scan). Further, the signal level replacement in the filter processing may be performed for each filter processing, or may be performed collectively for all filter processing.

The embodiments of the present invention have been described above. The present invention is not limited to the above-described embodiments, but can be variously modified and implemented within the scope of the gist of the present invention. The above-described embodiments are mere examples, and various modifications can be made to the combinations of the embodiments, their respective constituent elements, and respective processing processes, and such modifications are also within the scope of the present invention. It is understood by the trader.

For example, the steps in the processes described in this specification do not necessarily have to be performed in chronological order in the order described in the flowcharts. For example, the steps in the process may be executed in an order different from the order described as the flowchart or may be executed in parallel.

Further, a method including processing of a component of the device described in the present specification may be provided, and a program for causing a processor to execute the processing of the component may be provided. A recording medium recording the program may be provided. Of course, such methods, programs, and recording media are also included in the present invention.

The whole or part of the exemplary embodiments disclosed above can be described as, but not limited to, the following supplementary notes.

(Appendix 1)
In the received signal data including the signal level of a plurality of discrete points in the time frequency domain and the signal arrival direction, the signal level of the attention point of the plurality of discrete points is calculated based on the signal level of the peripheral area of the attention point. A first filter unit that replaces the calculated first value,
In the received signal data, when the concentration of the attention point of the plurality of discrete points and the signal arrival direction of the peripheral region of the attention point is lower than a threshold value, the signal level of the attention point is set to a second value. A second filter unit to be replaced,
In the received signal data, a density distribution in a signal arrival direction of a point of interest among the plurality of discrete points and a peripheral region of the point of interest is calculated, and a signal of a discrete point corresponding to an upper direction signal arrival direction in the density distribution. A third filter part for replacing the level with a third value,
A fourth filter that replaces the signal level of the point of interest with a fourth value when there is a discrete point having a signal level of 0 in the peripheral region of the point of interest among the plurality of discrete points in the received signal data. Department,
A device comprising.

(Appendix 2)
The device according to appendix 1, wherein the first value calculated based on the signal level of the peripheral area is a median value of the signal level of the peripheral area.

(Appendix 3)
The device according to appendix 1 or 2, wherein the second value, the third value, and the fourth value are 0.

(Appendix 4)
4. The apparatus according to any one of appendices 1 to 3, wherein the signal arrival direction is a signal arrival direction.

(Appendix 5)
5. The apparatus according to any one of appendices 1 to 4, wherein the concentration degree in the signal arrival direction is a magnitude of an average vector in the signal arrival direction.

(Appendix 6)
6. The apparatus according to any one of appendices 1 to 5, wherein the signal arrival direction that is higher in the density distribution is a predetermined number of signal arrival directions that is larger in the density distribution.

(Appendix 7)
A binary value that binarizes the signal level of each of the plurality of discrete points in the received signal data after being processed by the first filter unit, the second filter unit, the third filter unit, and the fourth filter unit. A chemical processing unit,
A line detection processing unit that detects a signal level line in the received signal data that has been processed by the binarization unit;
The apparatus according to any one of appendices 1 to 6, further comprising:

(Appendix 8)
8. The device according to any one of appendices 1 to 7, wherein the device is a passive sonar device or a module for a passive sonar device.

(Appendix 9)
In the received signal data including the signal level of a plurality of discrete points in the time frequency domain and the signal arrival direction, the signal level of the attention point of the plurality of discrete points is calculated based on the signal level of the peripheral area of the attention point. Replaced with the first value
In the received signal data, when the concentration of the attention point of the plurality of discrete points and the signal arrival direction of the peripheral region of the attention point is lower than a threshold value, the signal level of the attention point is set to a second value. Replacing
In the received signal data, a density distribution in a signal arrival direction of a point of interest of the plurality of discrete points and a peripheral region of the point of interest is calculated, and a signal of a discrete point corresponding to an upper signal arrival direction in the density distribution. Replacing the level with a third value,
In the received signal data, when there is a discrete point having a signal level of 0 in a peripheral region of the attention point among the plurality of discrete points, replacing the signal level of the attention point with a fourth value,
Including the method.

(Appendix 10)
In the received signal data including the signal level of a plurality of discrete points in the time frequency domain and the signal arrival direction, the signal level of the attention point of the plurality of discrete points is calculated based on the signal level of the peripheral area of the attention point. Replaced with the first value
In the received signal data, when the concentration of the attention point of the plurality of discrete points and the signal arrival direction of the peripheral region of the attention point is lower than a threshold value, the signal level of the attention point is set to a second value. Replacing
In the received signal data, a density distribution in a signal arrival direction of a point of interest among the plurality of discrete points and a peripheral region of the point of interest is calculated, and a signal of a discrete point corresponding to an upper direction signal arrival direction in the density distribution. Replacing the level with a third value,
In the received signal data, when there is a discrete point having a signal level of 0 in a peripheral region of the attention point among the plurality of discrete points, replacing the signal level of the attention point with a fourth value,
A program that causes the processor to execute.

100 Passive Sonar Device 103 Median Filter Unit 105 Azimuth Concentration Filter Unit 107 Azimuth Density Distribution Filter Unit 109 Contraction Filter Unit 111 Binarization Processing Unit 113 Line Detection Processing Unit 300 Device 301 First Filter Unit 303 Second Filter Unit 305 Third Filter unit 307 Fourth filter unit

Claims (10)

In the received signal data including the signal level of a plurality of discrete points in the time frequency domain and the signal arrival direction, the signal level of the attention point of the plurality of discrete points is calculated based on the signal level of the peripheral area of the attention point. A first filter unit that replaces the calculated first value,
In the received signal data, when the concentration of the attention point of the plurality of discrete points and the signal arrival direction of the peripheral region of the attention point is lower than a threshold value, the signal level of the attention point is set to a second value. A second filter unit to be replaced,
In the received signal data, a density distribution in a signal arrival direction of a point of interest among the plurality of discrete points and a peripheral region of the point of interest is calculated, and a signal of a discrete point corresponding to an upper direction signal arrival direction in the density distribution. A third filter part for replacing the level with a third value,
A fourth filter that replaces the signal level of the point of interest with a fourth value when there is a discrete point having a signal level of 0 in the peripheral region of the point of interest among the plurality of discrete points in the received signal data. Department,
A device comprising. The apparatus according to claim 1, wherein the first value calculated based on the signal level of the peripheral area is a median value of the signal levels of the peripheral area. The device according to claim 1 or 2, wherein the second value, the third value and the fourth value are zero. The device according to claim 1, wherein the signal arrival direction is a signal arrival direction. The device according to claim 1, wherein the concentration degree in the signal arrival direction is a magnitude of an average vector in the signal arrival direction. 6. The apparatus according to claim 1, wherein the signal arrival direction that is higher in the density distribution is a predetermined number of signal arrival directions that are larger in number than the density distribution. A binary value that binarizes the signal level of each of the plurality of discrete points in the received signal data after being processed by the first filter unit, the second filter unit, the third filter unit, and the fourth filter unit. A chemical processing unit,
A line detection processing unit that detects a signal level line in the received signal data that has been processed by the binarization processing unit;
The device according to claim 1, further comprising: 8. The device according to any one of claims 1 to 7, wherein the device is a passive sonar device or a module for a passive sonar device. In the received signal data including the signal level of a plurality of discrete points in the time frequency domain and the signal arrival direction, the signal level of the attention point of the plurality of discrete points is calculated based on the signal level of the peripheral area of the attention point. Replaced with the first value
In the received signal data, when the concentration of the attention point of the plurality of discrete points and the signal arrival direction of the peripheral region of the attention point is lower than a threshold value, the signal level of the attention point is set to a second value. Replacing
In the received signal data, a density distribution in a signal arrival direction of a point of interest among the plurality of discrete points and a peripheral region of the point of interest is calculated, and a signal of a discrete point corresponding to an upper direction signal arrival direction in the density distribution. Replacing the level with a third value,
In the received signal data, when there is a discrete point having a signal level of 0 in a peripheral region of the attention point among the plurality of discrete points, replacing the signal level of the attention point with a fourth value,
Including the method. In the received signal data including the signal level of a plurality of discrete points in the time frequency domain and the signal arrival direction, the signal level of the attention point of the plurality of discrete points is calculated based on the signal level of the peripheral area of the attention point. Replaced with the first value
In the received signal data, when the concentration of the attention point of the plurality of discrete points and the signal arrival direction of the peripheral region of the attention point is lower than a threshold value, the signal level of the attention point is set to a second value. Replacing
In the received signal data, a density distribution in a signal arrival direction of a point of interest among the plurality of discrete points and a peripheral region of the point of interest is calculated, and a signal of a discrete point corresponding to an upper direction signal arrival direction in the density distribution. Replacing the level with a third value,
In the received signal data, when there is a discrete point having a signal level of 0 in a peripheral region of the attention point among the plurality of discrete points, replacing the signal level of the attention point with a fourth value,
A program that causes the processor to execute.

Images