JP2013068553A - Active sonar device, and signal normalizing method of active sonar device and program thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active sonar device capable of suppressing degrading of S/N of an echo signal even when a strong seabed reflection wave enters, and a signal normalizing method of the active sonar device and a program thereof.SOLUTION: The active sonar device 10 includes transmission means 20 which generates the echo signal having a prescribed time length, and transmits it as a sound wave; reception means 30 which receives a reflection wave containing an echo signal reflected from a target object as a receiving signal; sectioning means 40 which cuts out the received signal in a prescribed direction and divides the signal contained in a cut out section into a plurality of cells; extraction means 50 which rearranges the cells according to levels of signals contained in cells in the section, and extracts signals in cells present in a range corresponding to the length of the echo signal; and normalization means 60 which performs normalization by using the extracted signals.

Description

  The present invention relates to an active sonar apparatus, and more particularly to a normalization method and program for an active sonar.

  An active sonar device oscillates a sound wave from a transmitter, receives a reflected wave from a target with a receiver, and based on information such as the level, frequency, and direction of the received signal, the position of the target, Measure speed, direction of travel, etc. Here, the received signal includes a reverberation signal and the like in addition to the echo signal reflected from the target. In general, reverberant signals have a wider band than echo signals and often have strong energy. For this reason, when performing echo signal detection processing on a received signal, it is desirable to remove the influence of the reverberant signal.

  For example, Patent Document 1 divides a received signal for each predetermined elapsed time, integrates the received signal at each time for each divided predetermined elapsed time by a predetermined number of transmission times, and averages for each predetermined elapsed time. An active sonar apparatus that acquires reverberation characteristics and removes the influence of reverberation signals from a received signal using the acquired average reverberation characteristics is disclosed.

Japanese Patent Laid-Open No. 04-116488

  However, when the average reverberation characteristic is acquired by integration as in the active sonar device of Patent Document 1, when a strong seabed reflected wave enters, the average reverberation characteristic is affected by the seabed reflected wave, and the echo signal S / N decreases.

  An object of the present invention is to provide an active sonar device, a signal normalization method in an active sonar device, and a program thereof that can suppress a decrease in S / N of an echo signal even when a strong reflected seabed wave enters. It is to provide.

  In order to achieve the above object, an active sonar device according to the present invention generates an echo signal having a predetermined time length and transmits it as a sound wave, and receives a reflected wave including an echo signal reflected from a target. Receiving means for receiving as a signal, sectioning means for cutting out the received signal in a predetermined direction, dividing the signal included in the cut out section into a plurality of cells, and rearranging the cells in the order of the level of the signal included in the cell in the section Extraction means for extracting a signal in a cell located in a range corresponding to the length of the echo signal, and normalization means for normalizing using the extracted signal.

  In order to achieve the above object, a signal normalization method in an active sonar apparatus according to the present invention generates an echo signal having a predetermined time length, transmits it as a sound wave, and includes a reflected wave including an echo signal reflected from a target. Is received as a received signal, the received signal is cut out in a predetermined direction, the signal included in the cut out section is divided into a plurality of cells, the cells are rearranged in the order of the level of the signal included in the cell, and the echo signal A signal in a cell located in a range corresponding to the length is extracted and normalized using the extracted signal.

  In order to achieve the above object, a program according to the present invention is a computer-executable program for normalizing a signal in an active sonar device, and generates an echo signal having a predetermined time length and transmits it as a sound wave. Function, a function to receive a reflected wave including an echo signal reflected from a target as a received signal, a function to cut out a received signal in a predetermined direction, a function to divide a signal included in the cut out section into a plurality of cells, and a cell in the section The cell is rearranged in the order of the levels of the signals contained in it, and the function of extracting the signal in the cell located in the range corresponding to the length of the echo signal and the function of normalizing using the extracted signal are executed on the computer. Let

  The active sonar device, the signal normalization method in the active sonar device, and the program thereof according to the present invention can suppress a decrease in the S / N of the echo signal even when a strong seabed reflected wave or the like enters.

1 is a block diagram of an active sonar device 10 according to a first embodiment of the present invention. It is a block diagram of the active sonar apparatus 100 which concerns on the 2nd Embodiment of this invention. It is a waveform of (a) echo signal, (b) reverberation signal, (c) noise signal, and (d) reception signal received by the wave receiving unit 130 according to the second embodiment of the present invention. It is a block diagram of the time direction normalization process part 150 which concerns on the 2nd Embodiment of this invention. It is a process sequence of the time direction normalization process part 150 which concerns on the 2nd Embodiment of this invention. It is the signal waveform after (a) normalization of the time direction normalization process part 150 which concerns on the 2nd Embodiment of this invention, and (b) normalization. It is a block diagram of computer 400 concerning a 2nd embodiment of the present invention. It is a block diagram of the active sonar apparatus 500 which concerns on the 3rd Embodiment of this invention. It is a waveform of a signal used in normalization processing by PDAGC.

(First embodiment)
A first embodiment will be described. A block diagram of an active sonar apparatus according to this embodiment is shown in FIG. In FIG. 1, the active sonar apparatus 10 according to the present embodiment includes a transmitting unit 20, a receiving unit 30, a sorting unit 40, an extracting unit 50, and a normalizing unit 60.

  The transmission means 20 generates an echo signal having a predetermined time length and transmits it as a sound wave. The receiving means 30 receives a reflected wave including an echo signal reflected from the target as a received signal.

  The sorting unit 40 cuts the received signal received by the receiving unit 30 in a predetermined direction such as a time axis direction or a frequency axis direction, and divides the signal included in the cut section into a plurality of cells. The sorting unit 40 according to the present embodiment cuts out a plurality of sections from the received signal so that adjacent sections overlap each other, and further divides the received signal in each cut out section into a plurality of cells.

  The extracting unit 50 rearranges the plurality of cells divided by the sorting unit 40 in the order of the magnitudes of signals included in the cells. In the present embodiment, the extraction unit 50 digitizes the signal levels of the signals included in the cells divided by the sorting unit 40, and rearranges the cells in the section in descending order of the signal level. Further, the extraction means 50 deletes the cells from the larger one that has been rearranged by the number of cells corresponding to the length of the echo signal generated by the transmission means 20, and extracts the signal in the remaining cells as a reverberation signal, The data is output to the normalizing means 60.

  The normalization unit 60 performs normalization processing using the reverberation signal output from the extraction unit 50. In the present embodiment, the normalizing unit 60 determines the floor level by interpolating the output reverberation signal into a characteristic curve such as an attenuation characteristic curve or a spectrum characteristic curve of the reverberation signal. Further, the normalizing means 60 performs normalization by dividing the determined floor level by the signal level at the center position of the section cut out by the sorting means 40. Here, the floor level is a level of a signal including a reverberation signal and a noise signal excluding an echo signal.

  As described above, the active sonar device 10 according to the present embodiment distinguishes the echo signal and the reverberation signal by rearranging the signal levels instead of using the integration or the average value. When a strong reflected wave from a target other than the target is mixed, the integrated value or the average value is affected by being pulled by this reflected wave in the calculation result, whereas this is applied when sorting is applied. The influence of the reflected wave can be minimized. Therefore, it is possible to suppress a decrease in the S / N ratio due to a strong level fluctuation.

(Second Embodiment)
A second embodiment will be described. A block diagram of the active sonar apparatus according to the present embodiment is shown in FIG. 2, the active sonar apparatus 100 according to the present embodiment includes a transmission signal generation unit 110, a transmission unit 120, a reception unit 130, an FFT (Fast Fourier Transform) processing unit 140, and a time direction normalization process. Part 150.

  The transmission signal generation unit 110 generates a pulsed transmission signal 310 and outputs it to the transmission unit 120.

  The wave transmission unit 120 converts the transmission signal 310 output from the transmission signal generation unit 110 into a sound wave 320 and transmits the sound wave to the outside.

  The wave receiving unit 130 receives the reflected wave 330 including the target 200 echo generated when the sound wave 320 transmitted from the wave transmitting unit 120 is reflected by the target 200 and receives the reflected wave 330 as the received signal 340 to the FFT processing unit 140. Output.

  The FFT processing unit 140 performs frequency analysis and normalization on the received signal 340 output from the wave receiving unit 130, and outputs the processing result to the time direction normalization processing unit 150 as the frequency analysis result 350.

  The time direction normalization processing unit 150 removes an echo signal from the frequency analysis result 350 output from the FFT processing unit 140, determines a floor level using a decay characteristic curve of reverberation, normalizes the determined floor level, and measures. The result 360 is output. The function of the time direction normalization processing unit 150 will be described later.

  Next, when the pulse-like transmission signal 310 output to the sea as the sound wave 320 by the wave receiving unit 130 is reflected by the target and received as the reflected wave 330, the reception signal output from the wave receiving unit 130 340 will be described.

  The pulsed transmission signal 310 output as the sound wave 320 is reflected by the target 200 and received by the wave receiving unit 130 as the pulsed echo signal 341 shown in FIG. Here, the duration of the echo signal 341 is known because it is determined by the time when the transmission signal generator 110 generates the transmission signal 310.

  In addition, when the pulsed transmission signal 310 output as the sound wave 320 is output to the sea, the transmission signal 310 is multiple-reflected by a non-uniform substance distributed on the sea floor or underwater, as shown in FIG. The reverberation signal 342 is received by the receiving unit 130. In general, the duration of the reverberation signal 342 is longer than the duration of the reflected wave (echo signal 341) from the target 200 and gradually attenuates.

  Furthermore, the wave receiving unit 130 receives the noise signal 343 shown in FIG. Accordingly, when the sound wave 320 including the pulsed transmission signal 310 is output, the wave receiving unit 130 outputs the reception signal 340 shown in FIG. Since the reverberation signal 342 has a broader band than the echo signal 341 and has strong energy, when the echo signal 341 is detected from the reception signal 340, the reverberation signal 342 may be erroneously detected. In this case, the detection performance of the target 200 of the active sonar device 100 is lowered. In the active sonar device 100 according to the present embodiment, the time direction normalization processing unit 150 separates the echo signal 341, the reverberation signal 342, and the noise signal 343, thereby detecting the target 200 of the active sonar device 100. Is suppressed.

  The function of the time direction normalization processing unit 150 will be described in detail. FIG. 4 shows a block diagram of the time direction normalization processing unit 150 according to the present embodiment. In FIG. 4, the time direction normalization processing unit 150 includes a floor level calculation unit 151 and a normalization unit 155. The floor level calculation unit 151 includes a signal cutout unit 152, a rearrangement unit 153, and a floor level determination unit 154, removes the echo signal 341 from the frequency analysis result 350 output from the FFT processing unit 140, and determines the floor level. . The normalization unit 155 normalizes the floor level determined by the floor level calculation unit 151 and outputs a measurement result 360.

  The operation of the time direction normalization processing unit 150 will be described with reference to FIG. The floor level calculation unit 151 uses the signal extraction unit 152 to extract the frequency analysis result 350 output from the FFT processing unit 140 in a certain time interval centered on a certain time. In this embodiment, the signal cutout unit 152 sets the center time and the section length so that a part of adjacent sections overlap each other, and cuts out the entire frequency analysis result 350 in a plurality of time sections. FIG. 5A illustrates three sections (section a, section b, section c) in the vicinity of the echo signal 341. In FIG. 5A, a part of section a and a part of section b overlap, and a part of section b and a part of section c overlap.

  Next, the floor level calculation unit 151 uses the rearrangement unit 153 to divide the section into a plurality of cells for each time section extracted by the signal extraction unit 152, and digitize the signal strength level in the cell. The cells in the time interval are rearranged in order of the signal strength level. FIG. 5B shows an example in which the rearrangement unit 153 rearranges the plurality of cells in the section c in the order of the signal strength level. In FIG. 5B, the left side is a cell before rearrangement, and the right side is a cell after rearrangement. Further, the upper level is the cell number, and the lower level is the signal strength level. As shown in FIG. 5B, the rearrangement unit 153 divides the section c into 11 cells (cell (1) -cell (11)). Then, the signal strength level in each cell is digitized and rearranged in ascending order. For example, the signal level of the cell (1) is “16”, and the cell (1) is arranged fourth from the right by rearrangement.

  Furthermore, since the duration of the echo signal 341 is known, the rearrangement unit 153 sets a range corresponding to the duration of the echo signal 341 as an echo signal appearance range, and signals within the echo signal appearance range Remove. That is, a signal in the echo signal appearance range is an echo signal 341, and signals in other ranges (referred to as a reverberation signal appearance range) are a reverberation signal 342 and a noise signal 343.

  That is, in FIG. 5B, the rearrangement unit 153 sets the signals included in the echo signal appearance range (up to a signal level of 25-16) in the ascending order as the echo signals 341. Then, rearrangement section 153 extracts signals included in the reverberation signal appearance range (signal level is 15 or less) as reverberation signal 342 and noise signal 343, and outputs them to floor level determination section 154.

  Further, the floor level calculation unit 151 uses the floor level determination unit 154 to interpolate the extracted reverberation signal 342 and noise signal 343 into the reverberation attenuation characteristic curve shown in FIG. Find the floor level. The reverberation attenuation characteristic curve is a curve that takes into account noise representing the attenuation characteristic of the reverberation over time. The reverberation attenuation characteristic curve can be obtained by transmitting a sound wave in an actual environment and measuring the reverberation level.

  Next, the normalization unit 155 of the time direction normalization processing unit 150 normalizes the floor level calculated by the floor level calculation unit 151 and outputs it as a measurement result 360. In this embodiment, the normalization unit 155 cuts out the floor level determined by the floor level calculation unit 151 from the original signal (that is, the frequency analysis result 350) input to the time direction normalization processing unit 150. Normalize by dividing by the intensity level of the signal at the center time.

  The time direction normalization processing unit 150 performs a series of normalization processes for each time interval. That is, when the process up to the normalization process for one time interval is completed, the signal extraction center time and the signal extraction time interval are moved to the next time, and the normalization process for the next time interval is started. And the time direction normalization process part 150 outputs the result of having normalized with respect to the floor level of all the cut-out time sections as the measurement result 360. FIG.

  Here, the reverberation attenuation characteristic curve used for interpolation is not only the measured value, but also the empirical formula constructed based on the measured value considering the seafloor topography and water temperature structure for each sea area, and the statistics obtained by summing up for each season. An attenuation characteristic curve obtained from data, a theoretical model of reverberation attenuation, or the like may be used. In addition, if the duration of the echo signal is sufficiently shorter than the length of the signal cut-out section, or if the attenuation of reverberation is small in the cut-out section and the level difference before and after removing the echo signal is small, The floor level may be selected from the signals of the reverberation / noise portions obtained by the rearrangement without performing interpolation on the attenuation characteristic curve. At the time of selection, the average value, the median value, a specific position before and after the echo signal removal may be determined.

  Further, when determining the floor level of a section that does not include an echo signal such as section a shown in FIG. 5A, the reverberation signal is arranged within the echo signal appearance range, and the reverberation signal within the echo signal appearance range is shown. And the floor level is determined using only signals within the reverberation signal range. Since the signal within the reverberation signal range is not affected, the floor level can be obtained by interpolating the reverberation signal range extracted as the reverberation signal 342 and the noise signal 343 into the reverberation attenuation characteristic curve. . When a strong seafloor reflected wave enters the section, the data of the seafloor reflected wave is arranged in the echo signal range and deleted. Since the data within the reverberation signal range is not affected, the floor level can be obtained by interpolating the reverberation attenuation characteristic curve.

  As described above, the active sonar device 100 according to the present embodiment rearranges the signal intensity levels within the cut-out time interval, determines the floor level from the signal from which the echo signal 341 is removed, and normalizes it. Since the component of the echo signal 341 is not mixed into the determined floor level, a decrease in the S / N ratio in normalization can be minimized.

  Furthermore, the active sonar apparatus 100 according to the present embodiment can perform signal normalization without deteriorating the echo signal. That is, since the reverberation signal and the noise signal are apparently removed from the output result after the normalization process, levels other than the echo signal (reverberation signal and noise signal) can be normalized. FIG. 6A shows a signal waveform before normalization, and FIG. 6B shows a signal waveform after normalization.

  Here, the function of the time direction normalization processing unit 150 can be realized as a normalization processing program, and the normalization processing program can be executed by the computer 400. A block diagram of the computer 400 is shown in FIG. In FIG. 7, a computer 400 includes a CPU 410, a RAM 420, a ROM 430, an input / output interface 440, and the like. When the frequency analysis result 350 is input from the FFT processing unit 140 to the computer 400, the CPU 410 reads the normalization processing program stored in the RAM 420 or the ROM 430, and performs cutout processing, rearrangement processing, floor level determination processing, and the like. Normalization processing is executed, and a measurement result 360 is output. The normalization processing program may be recorded on a non-transitory storage medium such as an optical disk or a semiconductor memory. In that case, the normalization processing program is read from the recording medium by the computer 400 and executed.

  The normalization process described above is not limited to the case where sound waves are transmitted into the sea, but the same effect can be obtained when sound waves are transmitted into the air. When radio waves are transmitted in the air, reverberation mainly becomes ground reflected waves or sea surface reflected waves, and the same effect can be obtained by using the time direction normalization processing unit 150 according to this embodiment. When a radio wave is transmitted from the air to the air, particularly when a radio wave is transmitted from the air to a lower air, the ground reflection wave or the sea surface reflection wave increases, and the effect appears more remarkably. That is, the time direction normalization processing unit 150 can be applied to a radar apparatus.

  Further, application to LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) using light instead of sound waves and radio waves is also possible. Here, even when sound waves are transmitted in the air and when applied to LIDAR, the normalization method is not limited to normalization in the time axis direction, but may be applied to normalization in the frequency axis direction. good.

(Third embodiment)
A third embodiment will be described. FIG. 8 shows a block diagram of the active sonar device according to this embodiment. 8, the active sonar apparatus 500 according to the present embodiment includes a transmission signal generation unit 511, a transmission signal amplification unit 512, a transmission unit 513, a reception unit 521, a reception signal amplification unit 522, a band filtering unit 523, an A / A D conversion unit 524, an FFT processing unit 525, a frequency direction normalization processing unit 526, a signal detection unit 531 and a display unit 532 are provided.

  The transmission signal generation unit 511 generates a pulse signal of a frequency-modulated wave whose frequency changes with time as the transmission signal 610 and outputs it to the transmission signal amplification unit 512. This transmission signal 610 is an electric signal, which is a frequency-modulated wave signal whose frequency changes linearly.

  The transmission signal amplification unit 512 amplifies the power of the transmission signal 610 output from the transmission signal generation unit 511 and outputs it to the transmission unit 120. The transmission unit 513 converts the transmission signal 610 that has been power-amplified in the transmission signal amplification unit 512 into an acoustic signal, and outputs the acoustic signal 620 to the water.

  The sound wave 620 output into the water is reflected by the target 200 and received by the wave receiving unit 521. When the target 200 is moving, the reflected wave is Doppler shifted and received by the wave receiving unit 521 together with the noise signal. The wave receiving unit 521 receives the reflected wave 630 including the echo signal, converts the received reflected wave 630 into an electric signal, and outputs the received signal 640 to the received signal amplifying unit 522.

  Reception signal amplification section 522 amplifies the power of reception signal 640 input from reception section 521 and outputs the amplified signal to band filtering section 523. The band filtering unit 523 removes an unnecessary band signal from the power signal input from the reception signal amplification unit 522. For example, when the transmission signal generation unit 511 generates a transmission signal 610 having a center frequency of 1000 Hz and a bandwidth of 50 Hz, for example, a signal between 925 and 1075 Hz is passed in consideration of frequency fluctuation due to Doppler shift.

  The A / D converter 524 A / D converts the analog signal between 925 and 1075 Hz output from the bandpass filter 523 at a predetermined sampling frequency. The A / D converted digital signal is output to the FFT processing unit 525.

  The FFT processing unit 525 performs fast Fourier transform on the digital signal output from the A / D conversion unit 524 to perform frequency analysis and normalization, and outputs the result as a frequency analysis result 650 to the frequency direction normalization processing unit 526.

  The frequency direction normalization processing unit 526 cuts out the frequency analysis result 650 output from the FFT processing unit 525 in the frequency direction, and further divides the signal in the cut out section into a plurality of cells. The frequency direction normalization processing unit 526 rearranges the signals in the plurality of cells in descending order of the spectrum level, and deletes the signal located within the range corresponding to the echo signal 641 as the echo signal 641. That is, the frequency direction normalization processing unit 526 extracts the reverberation signal 642 and the noise signal 643 by regarding the signal that has entered the echo signal appearance range as the echo signal 641 and deleting it.

  Further, the frequency direction normalization processing unit 526 determines the floor level by interpolating the extracted reverberation signal 642 and noise signal 643 into the spectrum characteristic curve, and the spectrum of the center position of the section where the determined floor level is cut out. Normalize by dividing by level. Then, the above signal processing is continuously repeated while shifting the position where the signal is cut out, and the measurement result 660 is output to the signal detection unit 531 and the display unit 532.

  In addition to obtaining the floor level by interpolating the spectrum characteristic curve of the actual measurement value, the floor level in the frequency direction can be determined by empirical formulas, statistical data, theoretical models, selection from the extracted signal, or the like.

  The signal detection unit 531 outputs a determination result to the display unit 532 after performing a threshold determination process using S / N. The display unit 532 displays the measurement result 660 input from the frequency direction normalization processing unit 526 based on the determination result input from the signal detection unit 531 as a frequency analysis result on a monitor unit (not shown). In the present embodiment, the monitor unit displays a graph having a signal having two axes of time-frequency and expressing the signal level by luminance or the like. Note that since the S / N is good, problems such as the reverberation signal being displayed stronger than the echo signal and the difficulty in identifying the echo signal due to a change in luminance over time are reduced.

  As described above, the active sonar device 500 according to the present embodiment rearranges the signals cut out in the frequency direction, separates the echo signal and the reverberation signal, and determines the floor level according to the spectrum characteristics. Then, the signal is normalized without causing a decrease in S / N by dividing. Thereby, the detection performance in the active sonar apparatus 500 can be improved, and the discriminability of the echo signal 641 in the signal display can be improved.

  It should be noted that, when the signal is cut out, it is cut out as two-dimensional data of time and frequency, and using the reverberation attenuation characteristic curve and the spectral characteristic curve, the time direction normalization described in the second embodiment and the present embodiment described. Frequency direction normalization can be performed simultaneously.

  Here, as a general normalization process in an active sonar apparatus, a PDAGC (Post Detection Automatic Gain Control) process that normalizes an input signal with its own integral value and makes a false alarm probability constant is widely used. In this signal normalization method using PDAGC processing or the like, the S / N decreases due to a change in floor level before and after a large level change such as a S / N reduction due to normalization or reception of a reflected seabed wave. The detection performance of the sonar device is lowered and the echo visibility of the display is lowered. The reason will be described with reference to FIG.

  In FIG. 9, 651 is a signal obtained by short integration of the frequency analysis result 650, 652 is a signal obtained by long integration of the frequency analysis result 650, and 653 is a normalized signal obtained by dividing the short integration signal 651 by a signal 652 obtained by long integration. In PDAGC, the frequency analysis result 650 is normalized by dividing the short integration signal 651 by the long integration signal 652, but as can be seen from FIG. 9, the normalized signal 653 reduces the S / N by dividing the integral value. Occurs. This is because the component of the echo signal 641 is included in the long integration signal 652 itself divided as the floor level.

  In addition, since the signal level of the long integration signal 652 is delayed later than that of the frequency analysis result 650, the signal level of the normalized signal 653 decreases when an echo signal enters immediately after a signal such as a strong seafloor reflected wave. This is a factor that lowers the level of the echo signal 641.

  Therefore, when normalization processing is performed such that the floor level of the signal is constant in time series by PDAGC processing, floor level fluctuations before and after sudden signal level changes and smoothing due to integration occur, and normalization processing occurs. As a result, the S / N of the echo signal is lowered, and the detection performance of the active sonar device and the echo visibility in the graph display are lowered.

  While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Any design change or the like within a range not departing from the gist of the present invention is also included in the present invention.

DESCRIPTION OF SYMBOLS 10 Active sonar apparatus 20 Transmission means 30 Reception means 40 Classification means 50 Extraction means 60 Normalization means 100 Active sonar apparatus 110 Transmission signal generation part 120 Transmission part 130 Wave reception part 140 FFT process part 150 Time direction normalization process part 151 Floor Level calculation unit 152 Signal extraction unit 153 Rearrangement unit 154 Floor level determination unit 155 Normalization unit 200 Target 310, 610 Transmission signal 320, 620 Sound wave 330, 630 Reflected wave 340, 640 Reception signal 341 Echo signal 342 Reverberation signal 343 Noise signal 350, 650 Frequency analysis result 360, 660 Measurement result 400 Computer 410 CPU
420 RAM
430 ROM
440 Input / output interface 500 Active sonar device 511 Transmission signal generation unit 512 Transmission signal amplification unit 513 Transmission unit 521 Reception unit 522 Reception signal amplification unit 523 Bandpass filtering unit 524 A / D conversion unit 525 FFT processing unit 526 Frequency direction normalization Processing unit 531 Signal detection unit 532 Display unit

Claims (9)

Transmitting means for generating an echo signal having a predetermined time length and transmitting it as a sound wave;
Receiving means for receiving a reflected wave including the echo signal reflected from the target as a received signal;
Segmenting means for segmenting the received signal in a predetermined direction and dividing a signal included in the segmented segment into a plurality of cells;
Extraction means for rearranging the cells in the order of the levels of signals contained in the cells within the section and extracting signals in the cells located in a range corresponding to the length of the echo signal;
Normalizing means for normalizing using the extracted signal;
An active sonar device comprising: The sorting means cuts out the received signal in a time direction,
The extraction means rearranges the cells in order of the intensity level of signals included in the cells.
The active sonar device according to claim 1. The normalization means performs normalization by interpolating the extracted signal into an attenuation characteristic curve of a reverberation signal, determining a floor level, and dividing by the intensity level of the center position of the cut-out section. 2. The active sonar device according to 2. The sorting means cuts out the received signal in the frequency direction,
The extraction means rearranges the cells in the order of spectral levels of signals included in the cells.
The active sonar device according to claim 1. The normalization unit performs normalization by interpolating the extracted signal into a spectrum characteristic curve to determine a floor level, and dividing by a spectrum level at a center position of the cut-out section. Active sonar device. The active sonar apparatus according to claim 1, wherein the sorting unit cuts out a plurality of sections from the received signal so that adjacent sections overlap each other. The active sonar device according to claim 1, wherein the transmission unit generates a pulse signal of a frequency-modulated wave whose frequency changes with time as the echo signal. An echo signal having a predetermined time length is generated and transmitted as a sound wave,
A reflected wave including the echo signal reflected from the target is received as a received signal;
The received signal is cut out in a predetermined direction, the signal included in the cut out section is divided into a plurality of cells,
Rearranging the cells in the order of the level of the signal contained in the cell in the section, extracting the signal in the cell located in the range corresponding to the length of the echo signal,
Normalize using the extracted signal;
A signal normalization method in an active sonar apparatus. A computer executable program for signal normalization in an active sonar device,
A function of generating an echo signal having a predetermined time length and transmitting it as a sound wave,
A function of receiving a reflected wave including the echo signal reflected from the target as a received signal;
A function of cutting the received signal in a predetermined direction and dividing a signal included in the cut section into a plurality of cells;
A function of rearranging the cells in the order of the levels of signals contained in the cells within the section and extracting signals in the cells located in a range corresponding to the length of the echo signal;
A function to normalize using the extracted signal;
For causing the computer to execute.

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