JP6654106B2 - Sound wave monitoring device and airframe - Google Patents

Description

  The present invention relates to a sound wave monitoring device, and more particularly, to a device for determining a frequency spectrum of a sound wave.

  Autonomous underwater vehicles (UUV: Unmanned Underwater Vehicle) are widely used as sailboats for searching underwater. The UUV includes a positioning device that performs positioning by measuring its own moving distance and moving direction. UUV observes underwater while diving according to a pre-programmed route using the positioning result of the positioning device. Observation targets include the sea floor, other submarines, and ships.

  Generally, the UUV is equipped with a sound wave monitoring device for observing underwater. A sound wave monitoring device for observing the shape of the seabed transmits a sound wave, receives a sound wave reflected on the seabed, and acquires shape data of the seabed based on a received signal. A sound wave monitoring device for observing a target such as another submarine or ship receives a sound wave propagating in water and acquires position data of the target based on a received signal.

  Patent Documents 1 and 2 below disclose devices for observing sound waves in water. Patent Literature 3 describes a piezoelectric element used for such an apparatus.

JP-A-8-61952 JP 2013-160682 A JP-A-6-269091

  The received signal of the sound wave monitoring device includes a noise component in addition to a desired sound wave component required for observation. If the noise component is large, it may be difficult to analyze data based on the desired sound component.

  An object of the present invention is to make a desired sound component observed by a sound wave monitoring device sufficiently large with respect to a noise component.

The present invention provides a plurality of sensor units each for detecting a sound wave, a conversion unit provided for each of the plurality of sensor units, and performing a frequency conversion process on a detection signal from the sensor unit; A synthesis processing unit that performs synthesis processing on frequency spectrum data output from the unit, a frequency detection unit that detects a peak frequency component of a signal obtained by the synthesis processing by the synthesis processing unit, and a plurality of the sensors. A phase synchronizing unit that aligns the phases of the peak frequency components included in each of the plurality of detection signals, and a synthesizing process that synthesizes a plurality of synchronizing signals output from the phase synchronizing unit after the phases are aligned. and parts, and wherein Rukoto and a second converter for performing frequency conversion processing to the composite signal by the synchronization combination processing unit.

  Preferably, the synthesis processing unit includes a multiplier that multiplies the same frequency component included in each of the detection signals based on the frequency spectrum data output from each of the conversion units.

  Preferably, the synchronization synthesis processing unit adds and sums a plurality of the synchronization signals.

The related art of the present invention is obtained by dividing the detection signal by a sensor unit that detects a sound wave, a division unit that divides a detection signal by the sensor unit into signals of a predetermined time length in chronological order, and divides the detection signal. A conversion unit that is provided for each of the plurality of divided signals, and performs a frequency conversion process on the divided signal, and a synthesis processing unit that performs a synthesis process on the frequency spectrum data output from each of the conversion units. wherein the combining processing unit on the basis of the frequency spectrum data output from each of said conversion unit, including a multiplier for multiplying the same frequency components included in each of the divided signals.

The related art of the present invention is obtained by dividing the detection signal by a sensor unit that detects a sound wave, a division unit that divides a detection signal by the sensor unit into signals of a predetermined time length in chronological order, and divides the detection signal. A conversion unit that is provided for each of the plurality of divided signals, and performs a frequency conversion process on the divided signal, and a synthesis processing unit that performs a synthesis process on the frequency spectrum data output from each of the conversion units. The synthesis processing unit includes an adder that adds and sums the same frequency components included in each of the divided signals based on the frequency spectrum data output from each of the conversion units.

  Preferably, each of the sensor units includes a piezo film sensor.

  Preferably, each of the sensor units includes a plurality of transducers and a directivity control unit that adaptively changes directivity based on the plurality of transducers.

  The navigation body according to the present invention is desirably equipped with the sound wave monitoring device.

  ADVANTAGE OF THE INVENTION According to this invention, the desired sound wave component observed by a sound wave monitoring apparatus can be made sufficiently large with respect to a noise component.

It is a figure showing composition of a sound wave monitoring device concerning an embodiment of the present invention. It is a figure which shows the acoustic sensor and the vibration sensor fixed to UUV typically. FIG. 3 is a diagram illustrating a configuration of a first signal processing unit. FIG. 3 is a diagram illustrating a configuration of a second signal processing unit. FIG. 9 is a diagram illustrating a configuration of a third signal processing unit. FIG. 2 is a diagram illustrating a sound wave monitoring device including an image generation unit and a display unit.

  FIG. 1 shows a configuration of a sound wave monitoring device according to an embodiment of the present invention. The sound wave monitoring device is mounted on, for example, a UUV and detects sound waves emitted from other submarines, ships, and the like. The sound wave monitoring device includes sound sensors 10-1 to 10-n, sound receiving units 12-1 to 12-n, S / N improvement processing unit 14, signal processing unit 16, sound wave data storage unit 18, vibration sensor 20, vibration A receiving unit 22, a vibration fast Fourier transform unit (vibration FFT) 24, a vibration data storage unit 26, an operation unit 28, a control unit 30, and a positioning unit 31 are provided.

  Each of the acoustic sensors 10-1 to 10-n has a function as a sensor unit for detecting a sound wave, and is fixed to, for example, a UUV body. For the acoustic sensors 10-1 to 10-n, for example, a piezoelectric element such as a piezo film sensor is used. The acoustic sensors 10-1 to 10-n convert sound waves arriving at the UUV into electric signals and output the electric signals to the sound receiving units 12-1 to 12-n, respectively, as reception signals. The acoustic receiver 12-q (q = 1 to n) amplifies the received signal output from the acoustic sensor 10-q, further converts the received signal into a digital signal sampled on the time axis, and performs S / Output to the N improvement processing unit 14.

  The vibration sensor 20 is fixed to a UUV body, for example. As the vibration sensor 20, for example, a piezoelectric element such as a piezo film sensor is used. The vibration sensor 20 converts the vibration of the UUV body into an electric signal and outputs the electric signal to the vibration receiving unit 22 as a vibration signal. The vibration receiving unit 22 amplifies the vibration signal output from the vibration sensor 20, further converts the vibration signal into a digital signal sampled on a time axis, and converts the digital signal into an S / N improvement processing unit 14 and a vibration signal. Output to the fast Fourier transform unit 24.

  The vibration fast Fourier transform unit 24 performs a fast Fourier transform process on the vibration signal, generates vibration frequency spectrum data, and outputs it to the vibration data storage unit 26. Note that the vibration signal may be stored in the vibration data storage unit 26 without being subjected to Fourier transform processing.

  The positioning unit 31 includes an acceleration sensor for each of a plurality of directions, and obtains UUV position information based on position information when the UUV starts traveling and acceleration detected for each direction. The positioning unit 31 outputs the position information to the vibration data storage unit 26. The vibration data storage unit 26 stores the vibration frequency spectrum data or the vibration signal in the time domain and the position information output from the positioning unit 31 in association with each other.

  The S / N improvement processing unit 14 uses the vibration signal output from the vibration reception unit 22 for each reception signal output from the sound reception units 12-1 to 12-n, and A process for increasing the ratio (S / N), that is, a process for improving the S / N is performed. In the S / N improvement processing, a single operation is performed for each sample time for a sample value of a received signal discretely connected on a time axis and a sample value of a vibration signal discretely connected on a time axis. There is an adaptive algorithm for performing the sequential calculation performed, for example, an LMS algorithm.

  In addition, the S / N improvement processing unit 14 may further perform adaptive line spectrum enhancement processing on each of the received signals on which the S / N improvement processing using the vibration signal has been performed. The adaptive line spectrum enhancement process is a filter process for increasing a periodic component included in a signal to be processed. In the adaptive line spectrum enhancement processing, there is an adaptive algorithm that performs a sequential calculation in which a single calculation is performed for each sample time for sample values of a received signal that is discretely continuous on a time axis. The adaptive line spectrum enhancement processing is disclosed in, for example, JP-A-5-268105 and JP-A-5-75391.

  As described later, the signal processing unit 16 generates a plurality of types of frequency spectrum data generated by different processes for the sound waves observed by one or a plurality of acoustic sensors, and stores the generated frequency spectrum data in the sound wave data storage unit 18. The positioning unit 31 outputs position information to the sound wave data storage unit 18 in addition to the vibration data storage unit 26. The sound wave data storage unit 18 stores the frequency spectrum data output from the signal processing unit 16 and the position information output from the positioning unit 31 in association with each other.

  The operation unit 28 generates control information for the sound wave monitoring device based on a user operation. The control unit 30 controls the sound wave monitoring device based on the control information. This control includes, for example, turning on / off the power supply, reading data stored in the sound wave data storage unit 18 and the vibration data storage unit 26, and the like.

  FIG. 2A schematically shows the acoustic sensors 10-1 to 10-n fixed to the UUV32. FIG. 2B schematically shows a cross section of the acoustic sensor 10-q, the vibration sensor 20, and the body 34, which are one of the acoustic sensors 10-1 to 10-n. In this figure, the vibration sensor 20 is fixed to the surface of the body 34, and the acoustic sensor 10-q is fixed on the vibration sensor 20 so as to overlap. Thus, the vibration sensor 20 detects the vibration of the body 34 of the UUV 32 and outputs a vibration signal based on the vibration of the body 34. The acoustic sensor 10-q outputs a reception signal based on the sound wave arriving at the UUV32.

  The signal processing unit 16 in FIG. 1 includes a first signal processing unit 16-1, a second signal processing unit 16-2, and a third signal processing unit 16-3. These signal processing units generate frequency spectrum data by different processes for sound waves observed by one or more acoustic sensors.

FIG. 3 shows the configuration of the first signal processing unit 16-1. Received signal is shown in FIG. _{3 x 1 (t) ~x n} (t) are those respectively, output from the S / N improving module 14 shown in FIG. “(T)” indicates a value in the time domain. Received signal _{x 1 (t) ~x n (} t) are inputted fast Fourier transform unit (FFT) in 36-1 to 36-n. Received signal _{x 1 (t) ~x n (} t) is also input to the phase synchronization unit 42.

The fast Fourier transform unit 36-q (q = 1 to n) performs a fast Fourier transform process on the received signal x _q (t), obtains frequency spectrum data for the received signal x _q (t), and performs power calculation. Output to the unit 38-q.

  The fast Fourier transform process is performed on a received signal of k samples (the number of discrete values on the time axis) connected on the time axis. One set of frequency spectrum data obtained by the fast Fourier transform process includes m complex numbers representing a plurality of m frequency components.

The received signal x _q (t) subjected to the fast Fourier transform processing is represented as (Equation 1).

(Equation 1) x _q (t) = [x _q (t ₁ ), x _q (t ₂ ),..., X _q (t _k )]

The real part and the imaginary part of each frequency component obtained by performing the fast Fourier transform on the received signal x _q (t) are expressed as (Equation 2) and (Equation 3), respectively.

(Equation 2) R _q = [R _q (f ₁ ), R _q (f ₂ ),..., R _q (f _m )]
(Equation 3) I _q = [I _q (f ₁ ), I _q (f ₂ ),..., I _q (f _m )]

Frequency _{f 1,} f 2 of the received signal _x q (t), _·····, each component of _{f m} is the complex number of the j and imaginary _{unit, R q (f 1) +} j · I q (f 1 ), R _q (f ₂ ) + j · I _q (f ₂ ), R _q (f ₃ ) + j · I _q (f ₃ ),..., R _q (f _m ) + j · I _q (f _m ).

  The power calculator 38-q obtains a power value for each frequency component. The power value is defined as the square of the absolute value of a complex number representing a frequency component. That is, the power value output by the power calculation unit 38-q is expressed as (Equation 4).

(Equation 4) P _q = [L _q (f ₁ ), L _q (f ₂ ),..., L _q (f _m )]
However, as h any integer of from 1 _m, which is ^{_{L q (f h) = R}} q (f h) 2 + I q (f h) 2.

  The multiplier 40 functions as a synthesis processing unit that executes a synthesis process on a plurality of frequency spectrum data. That is, the multiplier 40 multiplies the same frequency components of the power values output from the power calculators 38-1 to 38-n to generate integrated frequency spectrum data Pα including m new power values. The data is output to the first sound wave data storage unit 18. The integrated frequency spectrum data Pα is expressed as (Equation 5). Here, the symbol Π means that all of q = 1 to n are multiplied.

(Equation 5) Pα = [ΠL _q (f ₁ ), ΠL _q (f ₂ ),..., ΠL _q (f _m )]

  The peak frequency detector 50 detects the peak frequency of the integrated frequency spectrum based on the integrated frequency spectrum data Pα output from the multiplier 40. Here, the peak frequency refers to the frequency of the largest frequency component among the frequency components indicated by the integrated frequency spectrum data Pα. The peak frequency detection section 50 outputs the peak frequency to the phase synchronization section 42.

The phase synchronization unit 42 executes a process of aligning the phases of the received signals x ₁ (t) to x _n (t) with respect to the components of the peak frequency determined by the peak frequency detection unit 50. The phase synchronizer 42 outputs the received signals x ₁ (t) to x _n (t) on which the phase synchronization processing has been performed to the adder 44.

The adder 44 has a function as a combining processing unit for combining the received signal as a synchronization signal _{x 1 (t) ~x n (} t). That is, the adder 44 adds and totals the received signals x ₁ (t) to x _n (t) that have been subjected to the phase synchronization processing, and outputs the added total / received signal (synthesized signal) obtained by the fast Fourier transform. Output to the conversion unit 46. The fast Fourier transform unit 46 performs a fast Fourier transform process on the summation / reception signal, obtains frequency spectrum data on the summation / reception signal, and outputs the frequency spectrum data to the power calculation unit 48. The power calculation unit 48 obtains a power value for each frequency component and outputs phase-locked frequency spectrum data Pβ including m power values to the sound wave data storage unit 18 in FIG.

  Specific processes executed by the fast Fourier transform unit 46 and the power operation unit 48 are the same as the above-described processes executed by the fast Fourier transform unit 36-q and the power operation unit 38-q, respectively.

  Here, the processing in which the peak frequency detection unit 50 detects the peak frequency and outputs the peak frequency to the phase synchronization unit 42 has been described. Instead of performing such processing, the peak frequency may be input to the phase synchronization unit 42 by a user operation.

  By the processing executed by the first signal processing unit 16-1, the integrated frequency spectrum data Pα and the phase synchronization frequency spectrum data Pβ are output to the sound wave data storage unit 18 in FIG. The sound wave data storage unit 18 stores the integrated frequency spectrum data Pα and the phase synchronization frequency spectrum data Pβ in association with the position information output from the positioning unit 31.

FIG. 4 shows the configuration of the second signal processing unit 16-2. Received signal is shown in FIG. _{4 x 1 (t) ~x n} (t) are those respectively, output from the S / N improving module 14 shown in FIG. Received signal _{x 1 (t) ~x n (} t) are respectively input to the fast Fourier transform unit 52-1 to 52-n. The fast Fourier transform unit 52-q (q = 1 to n) performs a fast Fourier transform process on the received signal x _q (t), obtains frequency spectrum data on the received signal x _q (t), and performs complex addition. Output to the unit 54.

The fast Fourier transform performed by the fast Fourier transforms 52-1 to 52-n is the same as the fast Fourier transform performed by the fast Fourier transforms 36-1 to 36-n in FIG. That is, by _performing fast Fourier transform on the received signal x _q (t), m frequency components are obtained. The real and imaginary parts of each frequency component is represented as the respective (number 2) and (Equation 3), the frequency _{f 1,} f 2 of the received signal _{x q (t), ·····,} f m Are represented by R _q (f ₁ ) + j · I _q (f ₁ ), R _q (f ₂ ) + j · I _q (f ₂ ), and R _q (f ₃ ) + j · I _q (f _3), ... _{it is} expressed as _{R q (f m) + j} · Iq (f m).

Complex addition unit 54, the frequency _{f 1,} f 2 of the received signal _x q (t), _·····, per each component of _{f m,} adds the sum of each of the real and imaginary parts. The addition sum of the real part is represented as (Equation 6), and the addition sum of the imaginary part is represented as (Equation 7). However, the symbol Σ means that all of q = 1 to n are added and summed.

(Equation 6) R = [ΣR _q (f ₁ ), ΣR _q (f ₂ ),..., ΣR _q (fm)]
(Equation 7) I = [ΣI _q (f ₁ ), ΣI _q (f ₂ ),..., ΣI _q (fm)]

The processing executed by the complex addition unit 54 can be said to be the processing of adding and summing the complex vectors of the respective frequency components on a complex plane having the real part on the horizontal axis and the imaginary part on the vertical axis. The complex addition unit 54, a frequency _{f 1,} f 2 of the received signal _x q (t), _·····, for each of the components of _{f m,} sum total value of the real part, and, adding the total value of the imaginary part Is output to the power calculation unit 56. The power calculator 56 adds the square of the real part and the square of the imaginary part for each frequency component to obtain the sum total frequency spectrum data Pγ. The addition total frequency spectrum data Pγ is represented as (Equation 8).

(Number _{8) Pγ = [{ΣR q} (f 1)} 2 + {ΣI q (f 1)} 2, {ΣR q (f 2)} 2 + {ΣI q (f 2)} 2, ··· _{··, {ΣR q (f m} )} 2 + {ΣI q (f m)} 2]

  The power calculation unit 56 outputs the added total frequency spectrum data Pγ to the sound wave data storage unit 18 in FIG.

  By the processing executed by the second signal processing unit 16-2, the sum total frequency spectrum data Pγ is output to the sound wave data storage unit 18 in FIG. The sound wave data storage unit 18 stores the added total frequency spectrum data Pγ in association with the position information output from the positioning unit 31.

The integrated frequency spectrum data Pα, the phase-locked frequency spectrum data Pβ, and the sum total frequency spectrum data Pγ have the following features. As described above, the integrated frequency spectrum data Pα is obtained through a process of multiplying the same frequency component value of the frequency spectrum data output from the power calculators 38-1 to 38-n. Further, the phase-locked frequency spectrum data Pβ is obtained by adding the received signals x _q (t) to x _n (t) after aligning the phases of the components of the peak frequency, and applying a fast Fourier transform to the obtained signal. It is obtained through a process of performing a conversion process. Then, the sum total frequency spectrum data Pγ is obtained through a process of summing the same frequency component values of the frequency spectrum data output from the fast Fourier transform units 52-1 to 52-n for each of the real part and the imaginary part. Can be

  Generally, the noise component has no regularity between the observation position and the size, and the noise component usually has a different size depending on the observation position. On the other hand, a sound wave having a specific frequency component has a smaller difference in magnitude with respect to the observation position than a noise component.

  Therefore, the ratio of the value obtained by multiplying the value of the noise component detected by the plurality of acoustic sensors fixed at different positions to the value obtained by multiplying the value of the frequency component of the sound wave detected by the plurality of acoustic sensors is obtained. A certain S / N increases as the number of acoustic sensors increases.

  For the same reason, a value obtained by adding and adding values of noise components detected by a plurality of acoustic sensors fixed at different positions, and a value obtained by adding and adding frequency component values of sound waves detected by the plurality of acoustic sensors are used. S / N, which is the ratio of, increases as the number of acoustic sensors increases.

  Based on such a principle, the integrated frequency spectrum data Pα is obtained by multiplying each frequency component of the frequency spectrum data observed by a plurality of acoustic sensors arranged at different positions to obtain a frequency spectrum observed at one position. To improve S / N.

  Assuming that the S / N of the frequency spectrum observed by one acoustic sensor is α [dB], the S / N of the integrated frequency spectrum is αn = α + α (n−1) [dB]. This is based on the magnitude of the observed sound wave being raised to the nth power. Therefore, the S / N is increased by α (n−1) on the decibel scale, and the S / N is improved.

  The phase-locked frequency spectrum data Pβ and the sum total frequency spectrum data Pγ are obtained by adding and summing the same frequency components of the frequency spectrum observed by a plurality of acoustic sensors arranged at different positions based on the same principle. This is to make the S / N better than the frequency spectrum observed at the position. While the phase-synchronous frequency spectrum data Pβ is to add and sum the phases of certain specific frequency components, the sum total frequency spectrum data Pγ is obtained by keeping the phase of each frequency component as it is, The difference is that the complex vectors of the components are added and summed on a complex plane. However, the effect obtained with these frequency spectrum data is the same.

  Assuming that the S / N of the frequency spectrum observed by one acoustic sensor is α [dB], the S / N of each of the phase locked frequency spectrum and the sum total frequency spectrum is α + 10 log (n) [dB]. This is based on the fact that the magnitude of the observed sound wave becomes n times. Therefore, the S / N is increased by 10 log (n) on the decibel scale, and the S / N is improved.

FIG. 5 shows the configuration of the third signal processing unit 16-3. The received signal x ₁ (t) shown in FIG. 5 is output from the S / N improvement processing unit 14 based on the detection value of the acoustic sensor 10-1 shown in FIG. 58 is input.

The dividing unit 58 has a function of dividing a reception signal as a detection signal from the acoustic sensor 10-1 into a signal of a predetermined time length in a time series manner. That is, the dividing unit 58 divides the received signal x ₁ (t) that continues on the time axis into p samples, and obtains x ₁₁ (t), x ₁₂ (t), x ₁₃ (t),. In the order of x _1s (t), x ₁₁ (t) to x _1s (t) are output to the fast Fourier transform units 60-1 to 60-s at p-sample breaks, respectively. That is, the dividing unit 58 divides the sp sample values continuous on the time axis into s, and outputs the divided signals x ₁₁ (t) to x _1s (t). Each of x ₁₁ (t) to x _1s (t) includes p sample values connected on the time axis.

The fast Fourier transform unit 60-u (u = _{1 to s} ) performs a fast Fourier transform process on the divided signal x _1u (t), obtains frequency spectrum data on the divided signal x _1u (t), and performs power calculation. Output to the unit 62-u.

  The fast Fourier transform process performed by the fast Fourier transform unit 60-u is performed on a received signal of p samples connected on the time axis. One set of frequency spectrum data obtained by the fast Fourier transform process includes m complex numbers representing a plurality of m frequency components.

Here, the divided signal x _1u (t) to be subjected to the fast Fourier transform processing in the fast Fourier transform unit 60-u is expressed as in ( _Equation 9).

( _Equation 9) x _1u (t) = [x _1u (t ₁ ), x _1u (t ₂ ),..., X _1u (t _p )]

The real part and the imaginary part of each frequency component obtained by _{performing the} fast Fourier transform on the divided signal x _1u (t) are expressed as (Equation 10) and (Equation 11), respectively.

( _Equation 10) R _1u = [R _1u (f ₁ ), R _1u (f ₂ ),..., R _1u (f _m )]
( _Equation 11) I _1u = [I _1u (f ₁ ), I _1u (f ₂ ),..., I _1u (f _m )]

Each component of the frequency _{f 1, f 2, ·····,} f m split signal _x 1u (t) is the complex number of the j and imaginary _{unit, R 1u (f 1) +} j · I 1u (f 1 ), R _1u (f ₂ ) + j · I _1u (f ₂ ), R _1u (f ₃ ) + j · I _1u (f ₃ ),..., R _1u (f _m ) + j · I _1u (f _m ).

  The power calculation unit 62-u calculates a power value for each frequency component. The power value is defined as the square of the absolute value of a complex number representing a frequency component. That is, the power value output from the power calculation unit 62-u is represented as (Equation 12).

( _Equation 12) P _1u = [L _1u (f ₁ ), L _1u (f ₂ ),..., L _1u (f _m )]
However, as h any integer of from 1 _m, which is ^{_{L 1u (f h) = R}} 1u (f h) 2 + I 1u (f h) 2.

  Each of the multiplier 64 and the adder 66 functions as a synthesis processing unit that executes synthesis processing on a plurality of frequency spectrum data. That is, the multiplier 64 multiplies the same frequency components of the power values output from the power calculation units 62-1 to 62-s to generate divided / integrated frequency spectrum data Pδ including m new power values. Are output to the sound wave data storage unit 18 in FIG. The divided / integrated frequency spectrum data Pδ is expressed as (Equation 13). Here, the symbol Π means that all of u = 1 to s are multiplied.

(Equation 13) Pδ = [ΠL _1u (f ₁ ), ΠL _1u (f ₂ ),..., ΠL _1u (f _m )]

  The adder 66 adds and sums the same frequency components of the power values output from the power calculation units 62-1 to 62-s, and generates division / sum total frequency spectrum data Pε including m new power values. Are output to the sound wave data storage unit 18 in FIG. The division / addition total frequency spectrum data Pε is expressed as (Equation 14). However, the symbol Σ means that addition and sum are performed for u = 1 to s.

(Equation 14) Pε = [ΣL _1u (f ₁ ), ΣL _1u (f ₂ ),..., ΣL _1u (f _m )]

  By the processing executed by the third signal processing unit 16-3, the divided / integrated frequency spectrum data Pδ and the divided / added total frequency spectrum data Pε are output to the sound wave data storage unit 18 in FIG. The sound wave data storage unit 18 stores the divided / integrated frequency spectrum data Pδ and the divided / added total frequency spectrum data Pε in association with the position information output from the positioning unit 31.

Here, the configuration has been described in which the divided / integrated frequency spectrum data Pδ and the divided / added total frequency spectrum data Pε are generated based on the reception signal x ₁ (t) based on the acoustic sensor 10-1. The third signal processing unit 16-3 has the same configuration, and based on the received signal based on any of the other acoustic sensors 10-1 to 10-n, the divided / integrated frequency spectrum data Pδ and the divided / added total frequency The spectrum data Pε may be generated.

The divided / integrated frequency spectrum data Pδ and the divided / added total frequency spectrum data Pε have the following features. As described above, the divided / integrated frequency spectrum data Pδ is obtained by dividing x ₁ (t), which is continuous on the time axis, into p samples, and obtaining x ₁₁ (t), x ₁₂ (t), x ₁₃ (t),. _..., in the order of _x 1s (t), _x 11 in separator p samples _{(t) ~x 1s (t)} , respectively, and outputs the fast Fourier transform unit 60-1 to 60-s, fast Fourier It is obtained through a process of multiplying the same frequency component values of the frequency spectrum data output from the conversion units 60-1 to 60-n. The divided / added total frequency spectrum data is obtained through a process of adding and adding the same frequency component values of the frequency spectrum data output from the fast Fourier transform units 60-1 to 60-n.

  Generally, the noise component does not have a regularity with respect to time, and the noise component usually changes randomly with the passage of time. On the other hand, a sound wave having a specific frequency component has a smaller difference in magnitude over time than the noise component.

  Accordingly, S / S is a ratio of a value obtained by multiplying the value of the noise component detected in a plurality of different time periods and a value obtained by multiplying the frequency component value of the sound wave detected in the plurality of time periods. N increases as the number s of divided time zones increases.

  For the same reason, the ratio of the value obtained by adding and summing the values of the noise components detected in a plurality of different divided time periods and the value obtained by adding and summing the frequency component values of the sound waves detected in the plurality of divided time periods is used. A certain S / N increases as the number s of divided time zones increases.

  The divided / integrated frequency spectrum data Pδ is observed in one divided time zone by multiplying each frequency component of the frequency spectrum data observed in each of a plurality of different divided time zones based on such a principle. This is to improve the S / N with respect to the frequency spectrum.

  Assuming that the S / N of the frequency spectrum observed in one divided time zone is α [dB], the S / N of the divided / integrated frequency spectrum is αs = α + α (s−1) [dB]. This is based on the magnitude of the observed sound wave being raised to the s power. Therefore, the S / N is increased by α (s−1) on the decibel scale, and the S / N is improved.

  Based on the same principle, the division / addition total frequency spectrum Pε is obtained by adding and adding the same frequency components of the frequency spectrum observed in a plurality of different division time zones to obtain a frequency spectrum observed in one division time zone. Also improve S / N.

  Assuming that the S / N of the frequency spectrum observed in one divided time zone is α [dB], the S / N of the divided and added total frequency spectrum is α + 10 log (s) [dB]. This is based on the fact that the magnitude of the observed sound wave becomes s times. Therefore, the S / N is increased by 10 log (s) on the decibel scale, and the S / N is improved.

  Returning to FIG. 1, the sound wave monitoring device will be described. A UUV equipped with an acoustic wave monitoring device is collected by a user after navigating a pre-programmed route. The user collects the data stored in the sound wave data storage unit 18 and the vibration data storage unit 26 using a computer for sound wave monitoring.

  The integrated frequency spectrum data Pα, the phase-locked frequency spectrum data Pβ, the sum total frequency spectrum data Pγ, the divided / integrated frequency spectrum data Pδ, and the divided / added total frequency spectrum data Pε stored in the sound wave data storage unit 18 are included in the position information. Are associated. Based on the data stored in the sound wave data storage unit 18, the sound wave arriving at the UUV is analyzed for each UUV navigation position. For example, the computer for sound wave monitoring may generate sound wave monitoring image data based on one or a combination of these frequency spectrum data, and display an image based on the sound wave monitoring image data.

  Further, the vibration frequency spectrum data stored in the vibration data storage unit 26 is associated with the position information. Based on the data stored in the vibration data storage unit 26, the analysis of the vibration of the UUV body is performed for each UUV navigation position. For example, the sound wave monitoring computer may generate vibration monitoring image data based on the vibration frequency spectrum data, and display an image based on the vibration monitoring image data.

  The sound wave monitoring device may be mounted on a manned submarine or ship as a vehicle. In this case, the sound wave monitoring device includes an image generation unit that generates the sound wave monitoring image data and the vibration monitoring image data, and a display unit that displays an image based on the sound wave monitoring image data or the vibration monitoring image data. When the sound wave monitoring device is mounted on a ship, the positioning unit 31 may be a device that receives a signal from a positioning satellite, such as a GPS positioning device.

  FIG. 6 shows a sound wave monitoring device including an image generation unit 68 and a display unit 70. The image generation unit 68 includes the integrated frequency spectrum data Pα, the phase-locked frequency spectrum data Pβ, the sum total frequency spectrum data Pγ, the division / summation frequency spectrum data Pδ, and the division / summation total frequency spectrum data output from the signal processing unit 16. The sound wave monitoring image data is generated based on any one of Pε or any combination. Further, the image generation unit 68 generates vibration monitoring image data based on the vibration frequency spectrum data output from the vibration fast Fourier transform unit 24. The image generation unit 68 causes the sound wave monitoring image data and the vibration monitoring image data to include information indicating a position where each image data is obtained. The image generation unit 68 generates display image data based on the sound wave monitoring image data and the vibration monitoring image data, and outputs the display image data to the display unit 70. The display image data is image data representing an image based on sound wave monitoring image data, vibration monitoring image data, or a combination thereof. The display unit 70 displays an image based on the display image data. Further, the display unit 70 may display an image based on the display image data and information indicating a position where the image is obtained.

  According to such a configuration, the user boarding the navigation body refers to the display unit 70 when the navigation body is navigating, so that the sound waves arriving at the navigation body and the body of the navigation body can be displayed. Vibration can be observed.

  In the above, the sound wave monitoring device using n acoustic sensors has been described. One acoustic sensor may be replaced by an acoustic sensor array. The acoustic sensor array includes a plurality of transducers and a directivity control unit. The directivity control unit adjusts and synthesizes at least one of the magnitude and the delay time of the signal output from each transducer. Thus, a sensor unit whose reception directivity changes according to the arrival direction of the sound wave is configured.

  In addition, the S / N improvement processing unit 14, the signal processing unit 16, the vibration FFT 24, the control unit 30, and the image generation unit 68 illustrated in FIG. 6 illustrated in FIG. You may comprise. In this case, each function may be executed by a program read in advance. Further, each function may be individually configured by hardware.

10-1 to 10-n sound sensor, 12-1 to 12-n sound receiving unit, 14 S / N improvement processing unit, 16 signal processing unit, 16-1 first signal processing unit, 16-2 second signal processing Unit, 16-3 third signal processing unit, 18 sound wave data storage unit, 20 vibration sensor, 22 vibration reception unit, 24 vibration fast Fourier transform unit, 26 vibration data storage unit, 28 operation unit, 30 control unit, 31 positioning unit , 32 UUV, 34 bodies, 36-1 to 36-n, 46, 52-1 to 52-n, 60-1 to 60-s Fast Fourier transform units, 38-1 to 38-n, 48, 56, 62 -1 to 62-s power operation unit, 40, 64 multiplier, 42 phase synchronization unit, 44 adder, 50 peak frequency detection unit, 54 complex addition unit, 58 division unit, 66 adder, 68 image generation unit, 70 Display section.

Claims (6)

A plurality of sensor units each detecting a sound wave,
A conversion unit that is provided for each of the plurality of sensor units and performs a frequency conversion process on a detection signal from the sensor unit;
A synthesis processing unit that performs synthesis processing on the frequency spectrum data output from each of the conversion units,
With
A frequency detection unit that detects a peak frequency component of a signal obtained by the synthesis processing by the synthesis processing unit,
A phase synchronization unit that aligns the phase of the peak frequency component included in each of the plurality of detection signals by the plurality of sensor units,
A synchronization synthesis processing unit that synthesizes a plurality of synchronization signals output from the phase synchronization unit after the phases are aligned,
A second conversion unit that performs a frequency conversion process on a synthesized signal by the synchronous synthesis processing unit;
A sound wave monitoring device comprising: The sound wave monitoring device according to claim 1,
The synthesis processing unit includes:
A sound wave monitoring apparatus comprising: a multiplier that multiplies the same frequency component included in each of the detection signals based on frequency spectrum data output from each of the conversion units. In the sound wave monitoring device according to claim 1 or 2,
The synchronous synthesis processing unit,
A sound wave monitoring device, wherein a plurality of the synchronization signals are added and totalized. In the sound wave monitoring device according to any one of claims 1 to 3 ,
The sound wave monitoring device, wherein each of the sensor units includes a piezo film sensor. In the sound wave monitoring device according to any one of claims 1 to 4 ,
Each of the sensor units,
A plurality of transducers,
A directivity control unit that adaptively changes the directivity based on the plurality of transducers,
A sound wave monitoring device comprising: A marine vehicle equipped with the sound wave monitoring device according to any one of claims 1 to 5 .

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