JP2016191629A - Underwater Detection System - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underwater detection system capable of precisely performing detection of an object by suitably eliminating noise radiated from other sailing bodies.SOLUTION: An underwater detection system performs underwater detection based on a signal to be detected acquired by eliminating a noise component emitted from a second sailing body from a reception signal of a sonar system mounted to a first sailing body sailing on the water or under the water. The noise radiated from the second sailing body is detected as an external reference signal, and performs adaptive processing for delay processing of the external reference signal by a delay parameter based on distance between the first and second sailing bodies to the reception signal.SELECTED DRAWING: Figure 2

Description

  The present disclosure is based on a detection target signal obtained by removing a noise component emitted from a second traveling body from a received signal of a sonar system mounted on a first traveling body traveling on or under water. The present invention relates to an underwater detection system that performs underwater detection.

  Some navigating bodies such as ships are equipped with underwater acoustic equipment for detecting the position of an object such as other navigating bodies or obstacles existing on the surface of the water, that is, a sonar system. This type of sonar system obtains information on the presence and position of an object by receiving a sound wave signal such as a reflected sound or a radiated sound from another ship by a receiving element installed in water. . Here, the sound wave received by the wave receiving element includes various noises in addition to signals (detection target signals) necessary for detection of reflected sound and radiated sound from the target. Such noise is a factor that lowers the S / N ratio and lowers the detection performance, and thus needs to be removed.

As one of such noise removal techniques, adaptive processing using an adaptive filter is known. FIG. 13 is a schematic diagram for explaining the principle of noise removal using the adaptive filter 70. The adaptive filter 70 includes a delay circuit 72 and an adaptive processor 74. The main signal (s + n) in which the noise signal n is mixed in the detection target signal s received by the receiving sensor, and the generation source ( A reference signal (noise signal measured separately from the noise signal n) v from the noise source is input. The main signal (s + n) is converted into the signal d by being delayed by the delay circuit 72, and the reference signal v is converted into the signal g by the adaptive processor 74, and the difference ε = g−n (1).
Is fed back to the adaptive processor 74. In the adaptive processor 74, the filter coefficient is controlled so that the error ε is minimized in the mean squared manner, and an output ε corresponding to the detection target signal s is obtained. This type of noise removal technique is disclosed in, for example, Patent Document 1.

Japanese Patent No. 3815735

  In adaptive processing as in Patent Document 1, noise from a noise source is detected as a reference signal and removed from the received signal. However, for example, when there is another navigation body that is different from the detection target for a navigation body equipped with a sonar system (for example, when a navigation body equipped with a sonar system is in a fleet, In the sonar system, it is difficult to detect noise radiated from other navigators etc. as a reference signal by separating it from the detection target signal. The adaptive processing may make it difficult to remove noise effectively.

  In order to deal with such a problem, for example, it is conceivable to acquire in advance a sound wave (background noise) from only another traveling body which is a noise source in a state where the detection target signal is zero as a reference signal. However, in this case, there is a time lag between the acquisition timing of the reference signal and the acquisition timing of the detection target signal, and real-time measurement cannot be performed. For example, when the noise level or frequency from the noise source fluctuates with time, the detection accuracy is lowered.

  At least one embodiment of the present invention has been made in view of the above-mentioned problems, and underwater detection capable of accurately detecting an object by appropriately removing noise radiated from another traveling body. The purpose is to provide a system.

(1) In order to solve the above problem, an underwater detection system according to at least one embodiment of the present invention is based on a second received signal from a received signal of a sonar system mounted on a first traveling body that travels on or under water. An underwater detection system that performs underwater detection based on a detection target signal obtained by removing a noise component emitted from a traveling body of the vehicle, the second traveling body being provided in the second traveling body An external reference signal detector that detects noise radiated from the vehicle as an external reference signal, and the first navigation body and the second navigation body based on positional information of the first navigation body and the second navigation body. A first distance calculation unit for calculating a distance between the second traveling bodies, and a delay process using a delay parameter for setting the external reference signal based on the distance calculated by the first distance calculation unit. Adaptive processing is performed on the received signal. By, and a adaptive filter for outputting the detection target signal.

  According to the configuration of (1) above, the noise radiated from the second traveling body is generated as an external reference signal by the external reference signal detection unit included in the second traveling body away from the first traveling body. Detected. By detecting noise with the second navigation body in this way, a reference signal necessary for noise removal can be obtained accurately and in real time. The detection accuracy can be improved by removing noise from the received signal acquired by the sonar system based on the external reference signal acquired in this way.

(2) In some embodiments, in the configuration of (1) above, a first position information acquisition unit that acquires position information of the first traveling body, and position information of the second traveling body And a communication network provided between the first traveling body and the second traveling body, and the first distance calculating section includes the first distance calculating section, At least one of the position information acquired by the first position information acquisition unit and the second position information acquisition unit is acquired via the communication network.

  According to the configuration of (2) above, even if the first traveling body and the second traveling body are separated from each other in distance, the position information is exchanged via the communication network. Based on the information, it is possible to realize adaptive processing in consideration of the time lag of noise propagation based on the distance between the traveling bodies calculated by the first distance calculation unit.

(3) In some embodiments, in the configuration of (1) or (2), at least one noise included in the second traveling body from a reference point of the position information in the second traveling body. A second distance calculating unit that calculates a distance to the source, wherein the first distance calculating unit is configured to calculate the first traveling body based on the distance calculated by the second distance calculating unit; A distance between the second traveling bodies is calculated.

  According to the configuration of (3) above, the second distance calculation unit calculates the distance from the reference point of the position information on the second traveling body to at least one noise source included in the second traveling body. The result is used to calculate the distance between the first traveling body and the second traveling body by the first distance calculation unit. Thereby, since the distance between the 1st traveling body and the 2nd traveling body can be calculated | required more accurately, detection accuracy can be improved more.

(4) In some embodiments, in the configuration of the above (3), the noise source of the second traveling body is a propeller provided behind the ship bottom of the second traveling body, the second Equipment mounted on the inside of the navigation body, and at least one of the membrane wave or breaking wave generated in the vicinity of the bow of the second navigation body.

  According to the configuration of (4) above, the first navigation body is based on the propeller, equipment, and the position of the membrane wave or breaking wave in the second navigation body, which are noise sources included in the second navigation body. And since the distance between the 2nd navigation bodies can be calculated | required more accurately, detection accuracy can be improved more.

(5) In some embodiments, in any one of the configurations (1) to (4) described above, noise provided in the first traveling body and radiated from the first traveling body is internally generated. An internal reference signal detection unit that detects a reference signal; and a second distance calculation unit that calculates a distance between a noise source and the sonar system in the first vehicle, and the adaptive filter includes the adaptive filter, An adaptive process for delaying the internal reference signal using a delay parameter set based on the distance calculated by the second distance calculating unit is performed on the received signal.

  According to the configuration of (5) above, noise generated from the first traveling body is detected as an internal reference signal, and is removed from the signal acquired by the sonar system, thereby being emitted from the second traveling body. In addition to noise, noise emitted from the first vehicle can be removed. As a result, a detection target signal from which noise components have been removed more accurately can be obtained.

(6) In some embodiments, in any one of the configurations (1) to (5) above, a third traveling body having the first distance calculation unit and the adaptive filter may be configured as the first navigation unit. It is configured to be able to communicate with the running body and the second traveling body via a communication network.

  According to the configuration of (6) above, by providing the first distance calculation unit and the adaptive filter on the third traveling body, the calculation processing burden on the first traveling body on which the sonar system body is mounted is reduced. And further expandability of the entire system can be obtained.

(7) In some embodiments, in any one of the configurations (1) to (6), there are a plurality of the second traveling bodies, and the external signal detection unit and the second position information acquisition unit Is provided for each of the plurality of second traveling bodies.

  According to the configuration of (7) above, even when there are a plurality of second traveling bodies, adaptive processing is performed based on the external reference signals detected by the external reference signal detectors provided for each of the second navigation bodies. Thus, it is possible to effectively remove noise components respectively emitted from the second traveling body and to perform accurate underwater detection.

(8) In some embodiments, in any one of the configurations (1) to (7), the adaptive filter includes an LMS algorithm, and the LMS algorithm has a transient variation in the external reference signal. In this case, the number of filter coefficients is set to be increased as compared with the case where the external reference signal does not change transiently.

According to the configuration of (8) above, when the external reference signal fluctuates transiently, increasing the number of filter coefficients reduces the responsiveness due to an increase in the load required for arithmetic processing, but noise reduction This improves the accuracy of the underwater detection and enables highly reliable underwater detection. Conversely, by reducing the number of filter coefficients when the external reference signal does not fluctuate transiently, it is possible to reduce the load required for arithmetic processing and improve responsiveness while ensuring underwater detection with reliability. Become.
In an environment where there are many reflections, increasing the number of filter coefficients is also an effective means.

  Note that the technical idea of the present invention may be similarly applied to an adaptive filter including another method such as an RLS algorithm instead of the LMS algorithm.

  According to at least one embodiment of the present invention, it is possible to provide an underwater detection system capable of accurately detecting an object by appropriately removing noise radiated from another traveling body.

It is a schematic diagram which shows an example of the fleet which consists of the 1st navigation body and the 2nd navigation body to which the underwater detection system which concerns on at least 1 embodiment of this invention is applied. It is a block block diagram which shows the structure of the underwater detection system which concerns on at least 1 embodiment of this invention. It is a schematic diagram which shows 1 structural example of a 2nd traveling body. FIG. 3 is a control circuit diagram illustrating a configuration example of an adaptive filter in FIG. 2. It is a figure which shows the specific structural example of the adaptive processor of FIG. It is a block block diagram which shows the structure of the underwater detection system which concerns on at least 1 embodiment of this invention. It is a schematic diagram which shows 1 structural example of the 2nd traveling body to which the underwater detection system of FIG. 6 is applied. It is a block block diagram which shows the structure of the underwater detection system which concerns on at least 1 embodiment of this invention. It is a schematic diagram which shows 1 structural example of a 1st navigation body. It is a schematic diagram which shows an example of the fleet which consists of a 1st traveling body, a 2nd traveling body, and a 3rd traveling body to which the underwater detection system which concerns on at least 1 embodiment of this invention is applied. It is a block diagram which shows the structure of the underwater detection system which concerns on at least 1 embodiment of this invention as a functional block. It is a circuit diagram which shows the internal structure of the adaptive filter in the underwater detection system which concerns on at least 1 embodiment of this invention. It is a schematic diagram for demonstrating the principle of the noise removal using an adaptive filter.

(First embodiment)
Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.

  For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.

  In addition, for example, expressions representing shapes such as quadrangular shapes and cylindrical shapes not only represent shapes such as quadrangular shapes and cylindrical shapes in a strict geometric sense, but also within the range where the same effect can be obtained. A shape including a chamfered portion or the like is also expressed.

  On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

  FIG. 1 is a schematic diagram illustrating an example of a fleet including a first navigation body 10 and a second navigation body 20 to which an underwater detection system 100 according to at least one embodiment of the present invention is applied. FIG. 3 is a configuration diagram illustrating a configuration of an underwater detection system 100 according to at least one embodiment of the present invention as a functional block, FIG. 3 is a schematic diagram illustrating a configuration example of a second traveling body 20, and FIG. 2 is a control circuit diagram showing one configuration example of the second adaptive filter 115, and FIG. 5 is a diagram showing a specific configuration example of the adaptive processor 50 in FIG.

  In the following description, a ship that sails on the water will be described as an example of a traveling body, but the same technical idea can be applied to a traveling body such as a submersible that travels underwater instead. Needless to say.

  As shown in FIG. 1, in the present embodiment, an example is given in which the first traveling body 10 and the second traveling body 20 are positioned at a predetermined distance R from each other on the water. The first navigation body 10 and the second navigation body 20 are ships that sail on the water. The first traveling body 10 and the second traveling body 20 are driven by rotating a propeller for propulsion (see reference numeral 22a in FIG. 3) by a power source (not shown) such as an engine or a motor. It is configured to be navigable.

  The first traveling body 10 and the second traveling body 20 may be submersibles that sail underwater. Moreover, the 1st navigation body 10 and the 2nd navigation body 20 may be navigating, respectively, and may be anchored.

  The first navigation body 10 is equipped with a sonar system 12 as an acoustic detection device. The sonar system 12 is a passive sonar system that identifies the presence and position of the detection target 30 by receiving a sound wave signal emitted from the detection target 30, but by actively irradiating the sonar beam. An active method may be used in which detection is performed by receiving a reflected wave from a detection target.

  The sonar system 12 mounted on the first traveling body 10 detects a detection object 30 that exists at a position away from the first traveling body 10 and the second traveling body 20. At this time, the sonar system 12 performs detection by receiving a sound wave signal radiated from the detection target 30. Generally, in addition to the detection target signal s from the detection target 30, The extra noise n from the second vehicle 20 is included. The ratio of the noise component n to the detection target signal s is called a so-called S / N ratio, and in order to perform accurate detection, the noise signal n is removed from the received signal (s + n), and the S / N ratio is obtained. It is effective to improve the N ratio. In particular, when the detection target 30 is further away from the second traveling body 20 than the first traveling body 10 on which the sonar system 12 is mounted, the S / N ratio tends to deteriorate. .

  As shown in FIG. 2, the underwater detection system 100 is constructed across the first navigation body 10 and the second navigation body 20 via the communication network 40. In the underwater detection system 100, the first traveling vehicle side 110 receives a received signal p (= s + n) from the detection target 30, and various types transmitted from the second traveling vehicle 20. A receiving unit 112 that receives information, a first position information acquiring unit 113 that acquires position information P1 of the first traveling body 10, and a distance between the first traveling body 10 and the second traveling body 20; A first distance calculation unit 114 that calculates the distance R, an adaptive filter 115 that performs adaptive processing, and a detection unit 116 that detects the detection target 30 based on a processing signal from the adaptive filter 115 are provided.

  On the other hand, in the underwater detection system, the second traveling vehicle side 120 includes an external reference signal detection unit 121 that detects noise from the second traveling vehicle 20 as an external reference signal v, and the second traveling vehicle 20. A second position information acquisition unit 122 that acquires the position information P2, and a transmission unit 123 that transmits various information from the second traveling body 20 to the first traveling body 10 via the communication network 40. .

  The communication network 40 is preferably wireless, but may be wired.

  The received wave signal p (= s + n) from the detection target 30 is received by the wave receiving unit 111 of the first traveling body 10. On the other hand, on the second traveling vehicle side 120, noise radiated from the second traveling vehicle 20 is detected as an external reference signal v by the external reference signal detection unit 121. Here, as shown in FIG. 3, the second traveling body 20 has a propeller 22a provided near the bottom of the ship bottom to obtain a propulsive force as a noise source, and a power source (engine, turbine, A main wave including a motor, etc.), a main machine, or equipment 22b mounted in a ship including various auxiliary machines, and a membrane wave or breaking wave 22c generated in the vicinity of the bow of the second traveling body 20 are shown. . In this example, in particular, each noise source is provided with a corresponding noise sensor 24. These noise sensors are installed in such a manner that noise can be accurately detected according to the characteristics of each noise source. Specifically, the noise sensor 24a is provided at a position facing the propeller 22a, the noise sensor 24b is provided on the base 25 on which the devices 22b are installed, and the noise sensor 24c is the second cruise. The hull exposed on the water surface of the body 20 is provided at a position close to the film wave or break wave 22c that is a noise source.

  The noise sensor 24 may be any sensor that can detect noise, such as a pressure sensor, a vibration sensor, and a strain sensor, and may be appropriately selected depending on the type of the noise source.

  The second position information acquisition unit 122 acquires position information P2 of the second traveling body 20. Here, the position information P2 is information on the latitude and lightness of the second traveling body 20 such as a GPS signal acquired from a GPS satellite.

  The external reference signal v and the position information P2 acquired by the second traveling body 20 are transmitted to the first traveling body 20 by the transmission unit 123 via the communication network 40, and the first traveling body 20 Received by the receiving unit 112. That is, the receiving unit 112 of the first traveling body 10 and the transmitting unit 123 of the second traveling body 20 function as an interface to the communication network 40. As a result, the external reference signal v and the position information P2 acquired by the second traveling body 20 are used for the adaptation process by the first traveling body 20.

  The first position information acquisition unit 113 acquires the position information P1 of the first traveling body 10. Here, the position information P1 is information related to the latitude and lightness of the first traveling body 10 as in the case of the above-described position information P2, for example, a GPS signal acquired from a GPS satellite.

  The first distance calculation unit 114 includes the position information P1 acquired by the first position information acquisition unit 113 and the position information P2 received by the reception unit 112 (acquired by the second position information acquisition unit 122). Based on the above, the distance R between the first traveling body 10 and the second traveling body 20 is calculated. That is, the distance R is calculated by geometrically obtaining the relative positional relationship from the coordinates of the first traveling body 10 and the second traveling body 20 specified by the position information P1 and P2.

  The adaptive filter 115 acquires the distance R calculated by the first distance calculation unit 114 and the external reference signal v received by the reception unit 112 (detected by the external reference signal detection unit 121), and receives the wave. The detection target signal d is output by adaptively processing the signal.

  Here, as shown in FIG. 4, the distance R and the external reference signal v are input to the adaptive filter 115, and the noise signal n is output by the adaptive processor 50. The noise signal n is subtracted from the received signal p (= s + n) of the sonar system 12 by the subtractor 52, so that the detection target signal d (= s) is output. The detection target signal d thus obtained is fed back to the adaptive processor 50.

  Here, the adaptive processing in the adaptive processor 50 will be described. As shown in FIG. 5, the external reference signal v input to the adaptive processor 50 is output as a signal v ′ by performing delay processing according to the delay parameter τ by the delay circuit 54. Here, the delay parameter τ is the propagation speed until the noise radiated from the second traveling body 20 reaches the first traveling body 10, and the first traveling body 10 and the second traveling. It is set based on the distance R between the bodies 20. That is, the delay parameter τ is set based on a time lag generated between the timing at which the external reference signal detection unit 122 detects predetermined noise and the timing at which the sonar system 12 detects the noise. In this way, by using the delay circuit 54 that employs the delay parameter τ based on the distance R, the time lag can be eliminated, and noise from the second traveling body 20 can be appropriately removed.

  The propagation speed when the noise radiated from the second traveling body 20 reaches the first traveling body 10 may be set in advance as a constant value (propagation speed in water). It may be variably set according to the above. For example, the delay parameter τ may be set as “τ <distance R / sound velocity”. Since the speed of sound is about 1500 m / s in water, the data is actually obtained discretely, so the number of samples corresponding to the time τ may be skipped.

Subsequently, the output signal v ′ of the delay circuit 54 is input to L (L is an arbitrary natural number) Z conversion circuits 56, and each output signal has coefficients w ₀ , w ₁ ,. .., W _L is used to obtain a noise signal n by the following equation: n = v′w ₀ + v′w ₁ + v′w ₂ + v′w ₃ + (2)
Here, the coefficients w ₀ , w ₁ ,..., W _L are sequentially calculated by the LMS algorithm 58 based on the following equation.
w _i (t + 1) = w _i (t) +2 μdv (3)
In the equation (3), μ is a step size parameter.

  Here, the constant L is preferably set based on the surrounding environment as well as the characteristics of the noise source. In other words, in a sea area where the influence of reflection is large (for example, shallow water), it is necessary to take a long L so as to capture the noise waveform after reflection (at the sea floor), and a place where the influence of reflection is small (for example, In the case of the deep sea) structure, L can be taken short. In particular, it may be set based on whether the noise signal is a transient signal or a stationary signal, based on the frequency to be evaluated or the sampling frequency. However, it should be considered that the processing load on the adaptive processor 50 increases as L increases. is there. For example, since the noise signals from the noise sources 22a and 22c of the second traveling body 20 described above change every moment depending on the traveling state of the second traveling body 20, L may be set large. Further, by monitoring the traveling state of the second traveling body 20, L is temporarily increased when a state in which the noise signal from the noise source changes transiently as in acceleration / deceleration is detected. You may control as follows. As a result, L can be suppressed to a small value in a steady state where the noise signal is relatively stable, so that the processing load can be reduced.

The noise signal n thus obtained is subtracted from the received signal p (= s + n) of the sonar system 12 to obtain the detection target signal d (= s). The detection target signal d thus obtained is analyzed by being output to the sonar system 12. The detection target signal d is fed back to the LMS algorithm 58 to update the coefficients w ₀ , w ₁ ,..., W _L , advance the time by one sample, and repeat the above processing.

  As described above, according to the present embodiment, the noise emitted from the second traveling body 20 is detected from the external reference signal provided in the second traveling body 20 away from the first traveling body 10. This is detected by the unit 121 as the external reference signal v. Thereby, only the noise component contained in the detection target signal is accurately acquired as the external reference signal. The external reference signal acquired in this way is transmitted from the second traveling body 20 to the first traveling body 10 and is removed from the signal acquired by the sonar system 12. In this way, it is possible to obtain a detection target signal from which noise components emitted from the second traveling body 20 are accurately removed.

(Second Embodiment)
Next, an underwater detection system 100 according to the second embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 is a block configuration diagram showing the configuration of the underwater detection system 100 according to at least one embodiment of the present invention, and FIG. 7 is one configuration of the second traveling body 20 to which the underwater detection system 100 of FIG. 6 is applied. It is a schematic diagram which shows an example.

  In the present embodiment, as shown in FIG. 6, a second distance calculation unit 117 is provided on the first traveling body side 110 in the underwater detection system 100. The second distance calculation unit 117 is disposed in the radar mast 26 included in the second traveling body 20 (for example, as shown in FIG. 7), the reference acquisition position of the position information P2 of the second traveling body 20. The distances r1, r2, and r3 between the GPS sensor 27) and the noise sources 22a, 22b, and 22c of the second traveling body 20 are calculated. Since such distances r1, r2, and r3 are fixedly defined in the specifications of the second traveling body 20, they can be stored in advance in storage means such as a memory and read by the second distance calculation unit 117. It is good to have a configuration.

  The distances r1, r2, and r3 calculated by the second distance calculation unit 117 are sent to the first distance calculation unit 114. The first distance calculation unit 114 calculates the distance R by considering the distances r1, r2, and r3 in addition to the position information P1 and P2. As described above, in the present embodiment, the distance R is calculated in consideration of the detailed position of each noise source 22 in the second traveling body 20, so that more accurate adaptive processing is possible.

(Third embodiment)
Next, an underwater detection system 100 according to the third embodiment will be described with reference to FIG. FIG. 8 is a block diagram showing a configuration of the underwater detection system 100 according to at least one embodiment of the present invention, and FIG. 9 is a schematic diagram showing a configuration example of the first traveling body 10.

  In another embodiment, the case where noise is removed by performing adaptive processing on noise radiated from the second traveling body 20 is illustrated, but in this embodiment, in addition to this, the first traveling body is also added. The adaptive processing is also performed for noise radiated from 20 itself. In this case, as shown in FIG. 8, the first traveling vehicle side 110 includes an internal reference signal detection unit 118 that detects noise radiated from a noise source included in the first traveling vehicle 10 as an internal reference signal. And a third distance calculation unit 119 that calculates the distance between each noise source of the first traveling body 10 and the sonar system 12. The adaptive filter 115 that performs the adaptive process includes an adaptive filter 115a that performs the adaptive process based on the external reference signal acquired from the second vehicle body 120, and an adaptive that performs the adaptive process based on the internal reference signal. And a filter 115b.

  The internal reference signal detection unit 119 detects noise radiated from the first navigation body 10 as the internal reference signal V. Here, as shown in FIG. 9, the first traveling body 10 has a propeller 14a provided in the vicinity of the rear of the bottom of the ship to obtain a propulsive force as a noise source, similarly to the second traveling body 20 described above. The propeller 14a includes a power source (engine, turbine, motor, etc.) including the main engine, main engine, or various auxiliary machines mounted on the ship 14b, near the bow of the first traveling body 10. It has a generated film wave or breaking wave 14c. In this example, in particular, each noise source is provided with a corresponding noise sensor 15. These noise sensors are installed in such a manner that noise can be accurately detected according to the characteristics of each noise source. Specifically, the noise sensor 15a is provided at a position facing the propeller 14a, the noise sensor 15b is provided on the base 16 on which the equipment 14b is installed, and the noise sensor 15c is the first cruise. The hull exposed on the water surface of the body 10 is provided at a position close to the film wave or break wave 14c which is a noise source.

  The third distance calculator 119 calculates the sonar system 12 that receives the detection signal and the distances ra, rb, and rc to each noise sensor. Since such distances ra, rb, and rc are fixedly defined in the specifications of the second traveling body 20, they can be stored in advance in storage means such as a memory and read out by the third distance calculation unit 119. It is good to have a configuration.

  In the adaptive filter 115a, the adaptive process based on the external reference signal acquired from the 2nd navigation body 20 is performed like other embodiment. On the other hand, in the adaptive filter 115b, the adaptive processing according to the above-described external reference signal is performed on the internal reference signal V. That is, the adaptive filter 115b obtains a delay parameter τ for the internal reference signal V based on the distances ra, rb, and rc calculated by the third distance calculation unit 119, and performs an adaptive process based on the delay parameter τ. Thereby, since not only the noise radiated from the second traveling body 20 but also the noise radiated from the first traveling body 10 itself can be accurately removed, underwater detection with higher accuracy can be realized.

(Fourth embodiment)
Next, an underwater detection system 100 according to the fourth embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 shows an example of a fleet composed of a first traveling body 10, a second traveling body 20, and a third traveling body 60 to which the underwater detection system 100 according to at least one embodiment of the present invention is applied. FIG. 11 is a block diagram showing the configuration of the underwater detection system 100 according to at least one embodiment of the present invention as a functional block.

  First, as shown in FIG. 10, in the present embodiment, a third traveling body 60 is present in addition to the first traveling body 10 and the second traveling body 20 described above. The third traveling body 60 is also a ship that sails on the water like the first traveling body 10 and the second traveling body 20, but instead of this, it is a submarine that travels underwater. There may be.

  As shown in FIG. 11, the underwater detection system 100 according to the present embodiment is connected to the first traveling body 10, the second traveling body 20, and the third traveling body 60 via the communication network 40. It is built across. In the underwater detection system 100, the first traveling vehicle side 110 receives a received signal p (= s + n) from the detection target 30, and various types transmitted from the second traveling vehicle 20. A reception unit 112 that receives information, a first position information acquisition unit 113 that acquires position information P1 of the first traveling body 10, and a detection unit 116 that detects a detection target 30 are provided. That is, compared to the above-described embodiment, the first traveling body side 110 includes a first distance calculation unit 114 that calculates the distance R between the first traveling body 10 and the second traveling body 20, An adaptive filter 115 that performs adaptive processing is not provided, and the configuration is simplified. On the other hand, the first traveling body side 110 is provided with a transmission unit 141 configured to be able to transmit the position information P1 acquired by the first position information acquisition unit 113 via the communication network 40. .

  On the other hand, the second traveling vehicle side 120 of the underwater detection system 100 includes an external reference signal detection unit 121 that detects noise from the second traveling vehicle 20 as an external reference signal v, and the second traveling vehicle 20. A second position information acquisition unit 122 that acquires the position information P2 of the first transmission unit 123, and a transmission unit 123 that transmits various information from the second navigation unit 20 to the first navigation unit 10 via the communication network 40. Prepare.

  The third traveling vehicle side 130 in the underwater detection system 100 receives a variety of information transmitted from the first traveling vehicle 10 and the second traveling vehicle 20, and the reception unit 131 receives the information. A first distance calculation unit 132 that calculates a distance R between the first navigation body 10 and the second navigation body 20 based on the position information P1 and P2 that are generated, an adaptive filter 133 that performs an adaptive process, And a transmission unit 134 that transmits the output signal d after the adaptive processing. That is, the first distance calculation unit 114 and the adaptive filter 115 provided on the first navigation body side 110 in the first embodiment are provided on the third navigation body 60 in the present embodiment. As described above, the calculation and adaptation processing of the distance R with a large calculation processing burden is performed on the third navigation body side 130, so that the calculation processing can be concentrated on the third navigation body 60, and the calculation processing in the first navigation body 10 is performed. The burden is effectively reduced.

  When the underwater detection system 100 includes the third distance calculation unit 119 as in the third embodiment, the third distance calculation unit 119 may be provided on the third traveling body side 130. Also in this case, the processing load on the first navigation body 10 on which the sonar system 12 is mounted can be effectively reduced by consolidating the calculation processing burden on the entire system into the third navigation body 60.

(Fifth embodiment)
In the first to fourth embodiments, the case where there is a single second traveling body 20 has been described. However, a plurality of second traveling bodies 20 may actually exist. This embodiment demonstrates the case where the 2nd navigation body 20 has k (k is a natural number more than 2) ship.

  FIG. 12 is a circuit diagram showing an internal configuration of the adaptive filter 115 in the underwater detection system according to at least one embodiment of the present invention.

In the present embodiment, external reference signal detectors 121 are provided for the k second traveling bodies 20, and external reference signals detected by the external reference signal detectors 121 are represented by v ¹ , v ² , ..., it is indicated by ^{v k.} Each external reference signal ^{v 1,} v 2, · · ·, ^{v k} is input into the adaptive filter 115, the adaptive processor ^{50 1,} 50 2, by being adaptive processing at · · · 50 ^k, the corresponding Noise signals n ¹ , n ² ,..., N ^k are obtained. Adaptive processors ^{50 1,} 50 2, · · · 50 ^k each have a configuration similar to that of the adaptive processor 50 in the above embodiment, the external reference signal ^{v 1,} v 2, · · ·, a ^{v k,} each delay circuit ^{54 1,} 54 2, signal ^{v 1} and the delay processing in ^{··· 54 k ', v 2'} , ···, and ^{v k} '. Signal ^{v 1 ', v 2',} ···, v k ' are each LMS algorithm ^{58 1,} 58 2,..., By multiplying the coefficient ^w _{k i} by 58 ^k, the equation (2) Based on this, noise signals n ¹ , n ² ,..., ^Nk are determined. The noise signals n ¹ , n ² ,..., ^Nk correspond to the noise signals corresponding to the k second traveling bodies 20, respectively, and the total noise signal n can be obtained by adding them. . The total noise signal n obtained in this way is taken as a difference from the received signal p of the sonar system 12, whereby a detection target signal d is obtained.

It should be noted that the delay parameter τ in the delay circuits 54 ¹ , 54 ² ,... 54 ^k is the distance R ¹ , L ² from the first traveling body 10 to each of the k second traveling bodies 20, ..., individually set according to L ^k . As a result, even when there are a plurality of second traveling bodies 20, the external reference signal detected by each of the second traveling bodies 20 is subjected to delay parameter processing, so that the noise detection timing can be reduced. Real-time accurate noise removal is possible in consideration of the time lag.

  As described above, according to at least one embodiment of the present invention, it is possible to accurately detect an object based on a signal from a detection target by accurately removing noise radiated from another traveling body. An underwater detection system and an underwater detection method can be provided.

  At least one embodiment of the present invention is obtained by removing a noise component emitted from a second traveling body from a received signal of a sonar system mounted on a first traveling body that travels on or in water. The present invention is applicable to an underwater detection system and an underwater detection method that perform underwater detection based on a detection target signal.

DESCRIPTION OF SYMBOLS 10 1st traveling body 12 sonar system 20 2nd traveling body 22 Noise source 24 Noise sensor 25 Base 30 Detection object 40 Communication network 50 Adaptive processor 52 Subtractor 54 Delay circuit 56 Z conversion circuit 58 LMS algorithm 60 3rd Underwater vehicle 100 underwater detection system 110 first underwater vehicle side (underwater detection system)
111 Wave receiver 112 Receiver 113 First position information acquisition unit 114 First distance calculation unit 115 Adaptive filter 116 Detection unit 120 Second vehicle side (underwater detection system)
121 External reference signal detection unit 122 Second position information acquisition unit 123 Transmission unit 124 Second distance calculation unit 130 Third vehicle body side (underwater detection system)
131 Receiver 132 First Distance Calculator 133 Adaptive Filter 134 Transmitter

Claims (8)

Underwater detection based on the detection target signal obtained by removing the noise component emitted from the second traveling body from the received signal of the sonar system mounted on the first traveling body traveling on or under water. An underwater detection system to perform,
An external reference signal detector that is provided in the second navigation body and detects noise radiated from the second navigation body as an external reference signal;
A first distance calculating unit that calculates a distance between the first traveling body and the second traveling body based on positional information of the first traveling body and the second traveling body; ,
By performing an adaptive process on the received signal by delay processing the external reference signal using a delay parameter set based on the distance calculated by the first distance calculation unit, the detection target signal An adaptive filter that outputs
An underwater detection system characterized by comprising: A first position information acquisition unit for acquiring position information of the first traveling body;
A second position information acquisition unit for acquiring position information of the second traveling body;
A communication network provided between the first traveling body and the second traveling body;
Further comprising
The first distance calculation unit acquires at least one of the position information acquired by the first position information acquisition unit and the second position information acquisition unit via the communication network. The underwater detection system according to 1. A second distance calculating unit that calculates a distance from a reference point of the position information in the second traveling body to at least one noise source included in the second traveling body;
The first distance calculation unit calculates a distance between the first traveling body and the second traveling body based on the distance calculated by the second distance calculation unit. The underwater detection system according to claim 1 or 2.   The noise source of the second traveling body includes a propeller provided at the rear of the bottom of the second traveling body, equipment mounted in the second traveling body, and a second The underwater detection system according to claim 3, comprising at least one of a membrane wave or a breaking wave generated in the vicinity of the bow of the navigation body. An internal reference signal detector provided in the first navigation body for detecting noise radiated from the first navigation body as an internal reference signal;
A second distance calculator for calculating a distance between a noise source in the first vehicle and the sonar system;
Further comprising
The adaptive filter performs an adaptive process on the received signal by delaying the internal reference signal using a delay parameter set based on the distance calculated by the second distance calculation unit. The underwater detection system according to any one of claims 1 to 4, wherein the underwater detection system is characterized.   The third traveling body having the first distance calculating unit and the adaptive filter is configured to be able to communicate with the first traveling body and the second traveling body via a communication network. The underwater detection system according to any one of claims 1 to 5. There are a plurality of the second navigation bodies,
The underwater according to any one of claims 1 to 6, wherein the external signal detection unit and the second position information acquisition unit are provided for each of the plurality of second traveling bodies. Detection system. The adaptive filter includes an LMS algorithm;
The LMS algorithm is configured to increase the number of filter coefficients when the external reference signal fluctuates transiently compared to when the external reference signal does not fluctuate transiently. The underwater detection system according to any one of claims 1 to 7.

Images