JP5565865B2 - Navigation body detection apparatus and navigation body detection method - Google Patents

Description

  The present invention relates to a traveling body detection apparatus that detects a traveling body, and more particularly, to a traveling body detection apparatus that separately detects a surface traveling body and an underwater traveling body.

  Underwater vehicles such as torpedoes fired from submarines and submarines are a great threat to ships. As a technique for detecting an underwater vehicle, a technique for detecting a sound wave generated from a screw rotating at high speed and detecting a source of the sound wave as an underwater vehicle has been put into practical use. However, even in a watercraft that can travel at high speed, such as a motor boat, the screw may rotate at a high speed, so the above technology erroneously detects a watercraft that can travel at high speed as an underwater vehicle. I had to do it.

  On the other hand, Patent Document 1 describes a traveling body monitoring apparatus capable of determining the type of traveling body.

  The navigation vehicle monitoring apparatus described in Patent Document 1 detects a time change of a signature such as magnetism, sound, water pressure, and underwater electric field as a waveform signal. Further, in the navigation body monitoring apparatus, signature information related to the signature emitted from the navigation body is stored in a database for each type of navigation body. The traveling vehicle monitoring device analyzes the detected waveform signal based on the above database, and identifies the type of the traveling vehicle.

  Therefore, in the navigation body monitoring device described in Patent Document 1, if the signature information corresponding to the underwater vehicle is appropriately databased, the detection accuracy of the underwater vehicle can be improved.

JP 2008-290626 A

  In the navigation vehicle monitoring apparatus described in Patent Document 1, since the signature information must be stored in a database in advance, in order to improve the detection accuracy of the underwater vehicle, the signature information corresponding to the underwater vehicle is known in advance. It is necessary to keep.

  However, Patent Document 1 does not specifically describe the signature information corresponding to the underwater vehicle. Further, since there are various types of underwater vehicles, it is difficult to know all the signature information corresponding to these underwater vehicles. Therefore, with the technique described in Patent Document 1, it is difficult to improve the detection accuracy of the underwater vehicle.

  The present invention has been made in view of the above problems, and an object thereof is to realize a traveling body detection device and a traveling body detection method capable of improving the detection accuracy of an underwater vehicle. .

  The traveling body detection device according to the present invention includes an acoustic sensor that detects a sound wave generated in the traveling body and outputs the acoustic wave signal as a sound wave signal, and a frequency component at which a ratio of the sound wave to noise is less than a threshold value from the sound wave signal. , Extracted as a wave breaking sound presence / absence signal indicating the presence / absence of wave breaking sound generated when a watercraft breaks a wave, and based on the wave breaking sound presence / absence signal, the vehicle is either a watercraft or an underwater vehicle. A control unit that generates display information representing the above and a display unit that displays the display information.

  Further, the traveling body detection method according to the present invention detects a sound wave generated in the traveling body and outputs it as a sound wave signal.From the sound wave signal, a frequency component at which the ratio of the sound wave to noise is less than a threshold value, Extracted as a wave breaking sound presence / absence signal generated when the watercraft breaks the wave, and based on the wave breaking sound presence / absence signal, display information indicating whether the watercraft is a watercraft or underwater vehicle is generated. The display information is displayed.

  According to the present invention, it is possible to improve the detection accuracy of an underwater vehicle.

It is a figure which shows the structure of the underwater vehicle identification apparatus of one Embodiment of this invention. It is a figure which shows an example of the installation location of an acoustic sensor, and a detection sound wave. It is a figure which shows an example of the display screen of a display. It is a figure which shows the other example of the display screen of a display. It is a flowchart for demonstrating an example of operation | movement of an underwater vehicle identification apparatus. It is a figure which shows the other example of the installation location of an acoustic sensor, and a detection sound wave.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, components having the same function may be denoted by the same reference numerals and description thereof may be omitted.

  FIG. 1 is a diagram illustrating a configuration of an underwater vehicle identification device that is a vehicle detection device according to an embodiment of the present invention. In FIG. 1, the underwater vehicle identification device includes an acoustic sensor 1, an LPF (Low Pass Filter) 2, an A / D conversion unit 3, an FFT (Fast Fourier Transform) processing unit 4, and a noise averaging unit 5. Then, the threshold value detection unit 6, the breaking sound extraction unit 7, the inverse FFT processing unit 8, and the display 9 are performed. The A / D conversion unit 3, the FFT processing unit 4, the noise averaging unit 5, the threshold value detection unit 6, the breaking wave sound extraction unit 7, and the inverse FFT processing unit 8 constitute a control unit 10.

  The acoustic sensor 1 detects a sound wave in the water, converts the detection result into an electrical signal, and outputs the signal as a sound wave signal to the LPF 2. Here, the sound wave signal is a time domain analog signal.

  FIG. 2 is a diagram illustrating an example of an installation location of the acoustic sensor 1 and a detected sound wave. As shown in FIG. 2, the acoustic sensor 1 is provided in water and is connected to the ship 12 via a communication wire 11. In addition, a buoy 14 floating on the sea surface 13 is provided at a predetermined position of the communication wire 11, and the position of the acoustic sensor 1 is adjusted so as not to become too deep. Although the display 9 and the control unit 10 are not illustrated in FIG. 2, it is assumed that they are provided inside the ship 12. The control unit 10 is connected to the acoustic sensor 1 via the communication wire 11 so as to be communicable.

  The sound wave detected by the acoustic sensor 1 is a traveling body sound wave generated by the traveling body. The navigation body sound wave includes a marine navigation body sound 21 generated by the marine navigation body 15 traveling on the sea surface 13 and an underwater navigation body sound 22 generated by the underwater navigation body 16 traveling in the sea. is there. The marine vessel 15 is a ship such as a motor boat, and is sometimes called a marine vessel. The underwater vehicle 16 is a submarine, a torpedo or the like.

  The marine navigation body sound 21 includes a mechanical sound of the marine navigation body 15 and a breaking sound generated when the marine navigation body 15 collides with a wave on the sea surface 13 and cuts the wave. Moreover, since the underwater vehicle 16 normally does not cut the wave of the sea surface 13, the underwater vehicle sound 22 includes the mechanical sound of the underwater vehicle 16, but does not include the wave breaking sound. The mechanical sound is a sound generated from machinery provided in the traveling body such as an engine or a propulsion device (such as a screw).

  The mechanical sound usually has a substantially constant frequency and is continuously generated. On the other hand, the breaking sound usually has various frequencies and is intermittently generated because the marine vehicle 15 intermittently cuts the waves.

  Returning to the description of FIG. The control unit 10 receives a sound wave signal from the acoustic sensor 1. The control unit 10 uses the sound wave signal to obtain a frequency component having a signal-to-noise ratio (S / N ratio: Signal / Noise ratio), which is a ratio of the traveling body sound wave to noise, less than a predetermined threshold value, It is extracted as a wave breaking sound presence / absence signal indicating presence / absence. And the control part 10 produces | generates the display information showing whether a navigation body is a surface navigation body or an underwater navigation body based on a wave breaking sound presence / absence signal. More specifically, each unit of the control unit 10 performs the following processing.

  The LPF 2 receives a sound wave signal from the acoustic sensor 1 and performs LPF processing on the sound wave signal. The LPF process is a pre-process for an A / D conversion process, which will be described later, and is a process for removing a high-frequency component from a sound wave signal.

  The A / D conversion unit 3 performs an A / D conversion process on the sound wave signal subjected to the LPF process, and converts the sound wave signal into a digital signal. The A / D conversion process is a process of converting an analog signal into a digital signal by converting the voltage of the analog signal into a digital numerical value.

  The FFT processing unit 4 is also simply referred to as a conversion unit, and performs a fast Fourier transform (FFT) process on the sound wave signal subjected to the A / D conversion process to convert the sound wave signal into a frequency signal that is a frequency domain signal. To do.

  The noise averaging unit 5 is also called a calculation unit, and obtains a signal-to-noise ratio for each frequency component of the frequency signal converted by the FFT process.

  Here, when focusing on one frequency component, the noise averaging unit 5 obtains an average value of frequency components in the vicinity of the target component that is the focused frequency component as noise included in the target component, and the noise is included in the noise. Based on this, the signal-to-noise ratio of the target component is obtained. And the noise averaging part 5 calculates | requires the signal-to-noise ratio of each frequency component by performing this process with respect to all the frequency components. The frequency component in the vicinity of the target component is a frequency component in a predetermined frequency region including the target component. Further, the frequency component in the vicinity of the target component may be a frequency component obtained by removing the target component from the frequency component in the predetermined frequency region.

  The threshold value detection unit 6 is also called a specifying unit, and among the frequency components of the detection signal, a frequency component having a signal-to-noise ratio obtained by the noise averaging unit 5 that is equal to or higher than the threshold value is used as a wave breaking sound outside signal. Identify.

  The breaking sound extraction unit 7 extracts a breaking sound presence / absence signal from the frequency signal by removing the outside breaking wave signal specified by the threshold detection unit 6 from the frequency signal converted by the FFT processing.

  Since the mechanical sound has a substantially constant frequency as described above, when a large mechanical sound is generated, a specific frequency component in the traveling body sound wave is increased, and a signal-to-noise ratio in the frequency component is increased. On the other hand, since the breaking sound has various frequencies, even if a large breaking sound is generated, the signal-to-noise ratio at a specific frequency component does not usually increase.

  For this reason, a signal outside the breaking sound, which is a frequency component having a signal-to-noise ratio equal to or higher than a threshold value, is a signal indicating a relatively large mechanical sound. Therefore, the breaking sound presence / absence signal is a signal obtained by removing the breaking wave sound signal from the frequency signal. Therefore, when the traveling body sound wave is the marine traveling body sound 21, it becomes a signal indicating the breaking sound and a relatively small mechanical sound. When the traveling body sound wave is the underwater traveling body sound 22, the signal indicates a relatively small mechanical sound. For this reason, the breaking sound presence / absence signal indicates the presence / absence of breaking sound.

  The inverse FFT processing unit 8 is also called a generation unit, and generates display information indicating whether the traveling body is a surface traveling body or an underwater traveling body based on the breaking sound presence / absence signal generated by the breaking wave sound extracting unit 7. To do. More specifically, the inverse FFT processing unit 8 performs inverse fast Fourier transform (inverse FFT) processing on the breaking sound presence / absence signal, and uses the signal obtained by converting the breaking wave presence / absence signal as a signal in the time domain as display information. Generate.

  The display 9 is also called a display unit, and displays the display signal generated by the inverse FFT processing unit 8. For example, the display unit 9 displays the display signal using a graph in which the horizontal axis represents time, the vertical axis represents the azimuth, and the signal intensity of the display signal is represented by shading. The azimuth is the azimuth | direction which looked at the navigation body from the acoustic sensor 1. FIG.

  For example, when the acoustic sensor 1 is configured by a plurality of receivers provided at different positions, the azimuth can be obtained from the time difference between the output signals of the receivers. However, the specific configuration of the acoustic sensor 1 and the specific processing for detecting the orientation are not directly related to the present invention, and are well known to those skilled in the art. Description is omitted.

  3 and 4 are diagrams showing an example of the display screen of the display unit 9. FIG.

  In FIG. 3, the example 31 of a display screen when the acoustic sensor 1 detects the underwater navigation body sound 22 is shown. Since the underwater vehicle 16 does not generate breaking sound, the display signal is a signal indicating only a relatively small mechanical sound. Therefore, since the mechanical sound is continuously generated, in the display screen example 31, a continuous dark portion 32 appears.

  FIG. 4 shows a display screen example 41 when the acoustic sensor 1 detects the marine navigation body sound 21. Since the marine navigation body 15 generates breaking sound, the display signal is a signal indicating breaking sound and relatively small mechanical sound. Accordingly, since the breaking sound is generated intermittently, in the display screen example 41, in addition to the continuous dark portion 42 corresponding to the mechanical sound, the intermittent dark portion 43 corresponding to the breaking sound appears, and the horizontal stripe pattern appears. It can be seen.

  As shown in FIG. 3 and FIG. 4, the user can know that the underwater vehicle 16 is present near the ship if a dark portion where no horizontal stripe pattern is seen appears on the display screen. If a dark portion where a horizontal stripe pattern is seen appears, it can be seen that the marine vessel 15 is present near the ship.

  Next, the operation of the underwater vehicle identification device will be described.

  FIG. 5 is a flowchart for explaining an example of the operation of the underwater vehicle identification apparatus in the present embodiment.

  First, the acoustic sensor 1 detects an underwater sound wave, converts the detection result into an electric signal, and outputs the sound signal to the LPF 2 through the communication wire 11 (step S501). A high frequency component is removed from the sound wave signal by the LPF 2 (step S502), converted into a digital signal by the A / D conversion unit 3, and input to the FFT processing unit 4 (step S503). The sound wave signal of the digital signal is converted into a frequency signal in the frequency domain by the FFT processing unit 4 and input to each of the noise averaging unit 5 and the breaking sound extraction unit 7 (step S504).

  The noise averaging unit 5 obtains a signal-to-noise ratio for each frequency component of the frequency signal, and inputs the signal-to-noise ratio of each frequency component to the threshold value detecting unit 6 (step S505).

  The threshold value detection unit 6 identifies a frequency component having a signal-to-noise ratio equal to or greater than the threshold value among the frequency components as a wave breaking sound outside signal, and inputs the identified wave breaking sound outside signal to the wave breaking sound extraction unit 7 ( Step S506).

  The breaking sound extraction unit 7 extracts a breaking sound presence / absence signal by removing the breaking sound outside signal input from the threshold detection unit 6 from the frequency signal input from the FFT processing unit 4, and the breaking sound presence / absence signal is extracted. Is input to the inverse FFT processing unit 8 (step S507).

  The inverse FFT processing unit 8 converts the breaking sound presence / absence signal into display information in the time domain (step S508), inputs the display information to the display 9, and displays it on the display 9 (step S509).

  As described above, according to the present embodiment, the acoustic sensor 1 detects a sound wave generated in the navigation body and outputs it as a sound wave signal. The control unit 10 extracts, as a sound wave presence / absence signal, a signal having a frequency component in which a signal-to-noise ratio, which is a ratio of sound waves to noise, is less than a threshold value, from the sound wave signal, and based on the sound wave presence / absence signal, navigation Display information indicating whether the body is a watercraft or an underwater vehicle is generated. The display 9 displays the display information.

  Therefore, since the display information indicating whether the navigation body is a surface navigation body or an underwater navigation body is generated based on the presence / absence of a breaking sound, which is a frequency component with a signal-to-noise ratio less than a threshold value, Even if the signature information corresponding to the traveling body is not made into a database, it is possible to determine whether or not the traveling body is an underwater traveling body, and the detection accuracy of the underwater traveling body can be improved.

  In each embodiment described above, the illustrated configuration is merely an example, and the present invention is not limited to the configuration.

  For example, the display information is not limited to the information shown in FIG. 3 and FIG. 4 and can be changed as appropriate as long as it indicates whether the vehicle is a surface or underwater vehicle.

  Moreover, although the acoustic sensor 1 was provided in the sea, it should just be provided in water, for example, may be provided in the river or the lake. The acoustic sensor 1 may be attached to the bottom of the ship 12 as shown in FIG.

1 Acoustic sensor 2 LPF
3 A / D conversion unit 4 FFT processing unit 5 Noise averaging unit 6 Threshold value detection unit 7 Breaking sound extraction unit 8 Inverse FFT processing unit 9 Display unit 10 Control unit

Claims (5)

An acoustic sensor that detects sound waves generated in the navigation body and outputs them as sound wave signals;
From the sound wave signal, a frequency component at which the ratio of the sound wave to noise is less than a threshold value is extracted as a wave breaking sound presence / absence signal indicating the presence / absence of wave breaking sound generated when the watercraft cuts the wave, and the wave breaking Based on the sound presence / absence signal, a control unit that generates display information indicating whether the vehicle is a surface vehicle or an underwater vehicle,
And a display unit for displaying the display information. The controller is
A converter that converts the sound wave signal into a frequency signal that is a frequency domain signal;
For each frequency component of the frequency signal, a calculation unit for obtaining the ratio;
Among the frequency components of the frequency signal, a specifying unit that specifies a frequency component whose ratio is equal to or greater than the threshold as a signal outside the breaking sound,
A wave breaking sound extraction unit that removes the wave breaking sound outside signal from the sound wave signal and extracts the wave breaking sound presence / absence signal;
The navigation body detection device according to claim 1, further comprising: a generation unit that generates the display information based on the wave breaking sound presence / absence signal.   The traveling body according to claim 2, wherein the calculation unit obtains, for each frequency component, an average value of frequency components in a predetermined frequency region including the frequency component as the noise, and obtains the ratio according to the noise. Detection device.   The said generating part is a navigation body detection apparatus of Claim 2 or 3 which converts the said breaking wave sound presence / absence signal into the signal of a time domain, and produces | generates the said display information. Detect sound waves generated in the navigation body and output as sound wave signals,
From the sound wave signal, the frequency component at which the ratio of the sound wave to noise is less than a threshold value is extracted as a wave breaking sound presence / absence signal generated when the watercraft cuts the wave,
Based on the sound wave presence / absence signal, generating display information indicating whether the vehicle is a surface or underwater vehicle,
A navigation object detection method for displaying the display information.

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