JP2013044670A - Apparatus and method for monitoring hydrosphere organism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and highly reliably trace a plurality of individuals of hydrosphere organisms over a long period.SOLUTION: A monitoring apparatus 100 includes a housing 120 with a watertight structure and an electronic circuit 144 arranged in the housing 120 and capable of respectively recording first and second signals outputted from first and second underwater microphones in first and second channels respectively. The electronic circuit 144 shifts frequency bands of the first and second signals to the low band side only by a predetermined frequency, digitizes the frequency-shifted first and second signals and records the digitized first and second signals in a hard disk or the like as signals of the first and second channels.

Description

  The present invention relates to monitoring of aquatic organisms such as fish and marine mammals, and more particularly to a monitoring apparatus and method that enable monitoring of the behavior of a plurality of organisms over a long period of time.

  Monitoring wildlife behavior is not only important academically, but also in terms of the use of biological resources. Technologies for such monitoring include biologging and biotelemetry.

  Biologging is a device ("logger") that includes a target organism, a position measurement device using GPS (Global Positioning System) or a microminiature camera, and a storage device that stores information generated by those devices. It is a technology that attaches to the target organism. By collecting the logger later, you can know the movement path, range of action, etc. of the target organism.

  Biotelemetry is a technology that monitors the behavior of organisms by attaching an ultrasonic or radio wave transmitter to the target organism and receiving radio waves from the transmitter at a remote location. Unlike the biologging described above, there is an advantage that there is no need to collect the device.

  The current situation is that the boundaries between biotelemetry and biologging are not necessarily clear due to advances in miniaturization of hardware such as GPS devices, cameras, and transmitters.

  By the way, the living telemetry and biologging techniques described above are useful for organisms (aquatic organisms) whose action range is the hydrosphere such as seas, rivers, and lakes because these organisms cannot be visually observed.

  For example, as shown in FIG. 1, a logger 32 is attached to the target individual 30, and the logger 32 is detached from the target individual 30 and floats on the water surface after a predetermined time has elapsed. The logger 32 can be collected by the survey ship 44 or the like by sending a signal that informs the position when it rises on the surface of the water.

  Non-Patent Document 1 described later proposes the following system in order to track the behavior of an individual 34 (FIG. 1) in the sea. That is, in this system, a pinger 36 that transmits an ultrasonic signal to a target individual 34 is attached. In addition, the system uses at least three sonobuoys 40 installed to form a triangle at a known location. Each sonobuoy 40 processes the signal received by the underwater microphone 42 while switching the reception frequency at a certain time interval with the underwater microphone 42 that receives the ultrasonic signal from the pinger 36, thereby generating the signal of the Pinger that generated the signal. A processing device for detecting a number, and a transmitter for transmitting a radio wave indicating a reception time and a Pinger number. The radio waves are received by the survey ship 44 or the base on the ground, and the position of each pinger, that is, the position of each individual is determined by the principle of triangulation from the difference in arrival time of the ultrasonic signals from the pinger to the three sonobuoys 40. Identify and display on the display device in real time.

Klimley, AP, le Boeuf, BJ, Cantara, KM, Richert, JE, Davis, SF & Van Sommeran, S. 2001.Radio-acoustic positioning as a tool for studying site-specific behavior of the white shark and other large marine species Marine Biology, 138, 429-446.

  In biologging, there is a problem that it is difficult to record a movement route using GPS when the target individual 30 acts underwater. There is also a problem that the logger 32 must be searched because it is unknown where the logger 32 leaves the individual 30. In particular, when the monitoring period is long, there is a problem that it is very difficult to collect the logger 32.

  On the other hand, in the biotelemetry method using the Sonobuoy 40, in order to measure the positions of a plurality of individuals, the frequency emitted by each pinger is set separately, and the reception frequency is switched at regular intervals to receive ultrasonic waves from the pinger. Yes. For this reason, when there are a plurality of target individuals, it is not possible to continuously receive signals generated by the plurality of pinger. That is, with this technique, there is a problem that it is difficult to track the continuous behavior of multiple individuals. Also, the Sonobuoy 40 detects and processes an ultrasonic signal therein, and transmits only the resulting Pinger number and reception time to the survey ship 44 and the like. Therefore, there is a problem that the reception status of the ultrasonic signal at each underwater microphone 42 is not clearly understood, and the reliability of the survey result is impaired. Furthermore, since it is necessary to use radio waves for communication between the Sonobuoy 40 and the survey ship 44 and receive the radio waves in real time on the survey ship 44, there is also a problem that the survey range is limited to a communicable range. In addition, in the Sonobuoy 40, it is necessary to put out an antenna necessary for communication on the sea surface. As a result, the position of the sonobuoy 40 is likely to change due to the influence of the ocean current. Therefore, the position (reception position) of the underwater microphone 42 that is the basis of triangulation changes irregularly, and there is a problem that it is difficult to perform highly accurate positioning.

  Accordingly, an object of the present invention is to provide an aquatic organism monitoring apparatus and method that can stably and reliably track a plurality of individuals of aquatic organisms over a long period of time.

  The aquatic organism monitoring apparatus according to the first aspect of the present invention includes a watertight casing, and first and second signals provided in the casing and output from first and second underwater microphones, respectively. Recording means for recording on the first and second channels. The recording means digitizes the frequency shift means for shifting the frequency bands of the first and second signals to a low frequency side by a predetermined frequency, and the first and second signals output by the frequency shift means, And a recording device for recording as signals of the first and second channels, respectively.

  The frequency shift means shifts the frequency of the signal arriving at the first and second underwater microphones to the low frequency side, and records the shifted signal on the recording device. Since recording is performed after the frequency is shifted to the low frequency side, waveform shape deterioration can be avoided even if the sampling frequency during digitization is lowered accordingly. Therefore, it is possible to record the audio signal that has arrived at the underwater microphone for a long time on the recording device. Furthermore, since the recording means is recording the underwater sound arriving at the underwater microphone, the recorded underwater sound is extracted and analyzed, so that the incoming pinger sound can be separated and positioned. As a result, it is possible to provide a monitoring device for aquatic organisms that can stably and reliably track a plurality of individuals of aquatic organisms over a long period of time.

  Preferably, the casing is hollow and has a cylindrical member having an opening at one end thereof, a cover member that covers the opening of the cylindrical member, a fixture that fixes the cover member to the opening of the cylindrical member in a watertight manner, A first submersible connector and a second submersible connector which are provided on the cover member and guide an electric signal from the outside to an input of frequency shift means inside the cylindrical member.

  Since the underwater microphone can be connected to the monitoring device by the underwater connector, the position of the underwater microphone is not restricted by the position of the monitoring device. Since the distance between the first and second underwater microphones can be widened, the accuracy during positioning can be increased.

  More preferably, the recording means can be pulled out from the inside of the tubular member with the cover member removed from the tubular member.

  Since the recording means can be pulled out to the meeting part of the cylindrical member, the signal recorded in the recording means can be easily taken out.

  Preferably, the recording means further includes a mounting plate having one end fixed to the back surface of the cover member and completely accommodated in the cylindrical member in a state where the cover member is mounted in the opening of the cylindrical member. The frequency shift means and the recording device are provided on one surface of the mounting plate. The recording means further includes a power unit fixed on one surface of the mounting plate and supplying power to the frequency shift means and the recording device.

  A mounting plate is mounted on the back surface of the cover member, and a recording device is mounted on one surface thereof. Therefore, when the cover member is removed from the cylindrical member, the recording apparatus can be pulled out together with the cover member. The device can be easily routed when taking out the recorded underwater sound.

  More preferably, the aquatic organism monitoring device further includes a handle provided on the surface of the cover member opposite to the opening.

  The cylindrical member is more preferably made of metal.

  Preferably, the recording means further includes an interface for outputting the signals of the first and second channels recorded in the recording device to the outside.

  The method for monitoring aquatic organisms according to the second aspect of the present invention comprises preparing three or more of the above-mentioned aquatic organism monitoring devices, connecting the first and second underwater microphones to each, In each of the step of installing with a microphone on the bottom of the water, the step of recording the position and sound collection direction of each of the underwater microphones installed on the bottom of the water, and the monitoring device installed on the bottom of the water, the first connected to the monitoring device. Among the underwater sounds collected by the second underwater microphone, a step of recording underwater sounds in a predetermined band by a recording means for a predetermined period, a step of recovering the monitoring device after the end of the predetermined period, For each of the monitored devices, the underwater sound data recorded by the first and second underwater microphones recorded in the recording device is read and read. Estimating the arrival directions of the pinger sounds arriving at the first and second underwater microphones based on the temporal difference between the detected pinger sounds in the underwater sound data and the position information of each microphone, and , Measuring the position of the pinger by examining the crossing position of the arrival direction of the pinger sound to the underwater microphone connected to each monitoring apparatus obtained by each of the plurality of monitoring apparatuses.

It is a schematic diagram for demonstrating the method of the conventional biotelemetry and biologging. It is a figure showing typically a schematic structure of a monitoring system concerning an embodiment of the invention. It is a figure which shows the general view of the logger main body used with the monitoring system shown in FIG. It is a top view which shows the state which removed the cover of the logger shown in FIG. 3, and pulled out the internal mounting plate. It is a hardware block diagram which shows the circuit structure of the electronic circuit mounted in the attachment board shown in FIG. It is a schematic diagram for demonstrating the frequency shift of the signal by the heterodyne detection system performed with the electronic circuit shown in FIG. FIG. 4 is a block diagram of a high-precision positioning device for aquatic organisms for positioning a pinger from underwater sound data recorded by the logger shown in FIG. 3. It is a flowchart which shows the procedure of aquatic organism monitoring. It is a flowchart which shows the control structure of the program for positioning performed with the highly accurate positioning apparatus of the aquatic organism shown in FIG. It is a schematic diagram for demonstrating the principle of the method of calculating the arrival direction of the pinger sound to a logger. It is a schematic diagram for demonstrating the principle of the process which measures a pinger position based on the arrival direction of the pinger sound to each logger.

  In the following description and drawings, the same parts are denoted by the same reference numerals. Therefore, detailed description thereof will not be repeated.

[Constitution]
Referring to FIG. 2, the aquatic organism monitoring system 50 according to the present embodiment is attached to at least two (three in FIG. 2) loggers 60, 62 and 64, target individuals 72, 76, and the like. Transmitters 70, 74, etc., each transmitting an ultrasonic signal (Pinger signal) at a specific frequency. In the present embodiment, transmitters 70 and 74 generate pinger signals at different frequencies. In the present embodiment, the Pinger signal further includes identification information of the Pinger and time information when the Pinger signal is generated (the time itself or the Pinger signal is output intermittently at a predetermined time interval. , Etc.) are superimposed.

  The loggers 60, 62 and 64 have the same configuration in this embodiment. Hereinafter, the configuration of the logger 60 will be described on behalf of these.

  The logger 60 is connected to the main body 100 by a pair of cables 108 and 118, and receives a pinger signal from the transmitter 70, etc., converts it into an electrical signal, and transmits it to the main body 100 for transmission to the main body 100. 104 and 114. The underwater microphones 104 and 114 are fixed to the sea floor by poles 102 and 112, respectively. The positions of the underwater microphones 104 and 114 need to be determined (or measured) as accurately as possible in order to maintain measurement accuracy. The distance between the underwater microphones 104 and 114 and the main body 100 is not particularly limited, but it is preferable that the distance between the underwater microphones 104 and 114 is large. In the present embodiment, the distance between the underwater microphone 104 and the underwater microphone 114 is 20 meters. If the heights of the poles 102 and 112 cannot be aligned due to the topography, the height of both can be as high as possible by fixing the underwater microphone in the higher position to a position in the middle of the pole (ie, lower position). It is necessary to align.

  If possible, it is desirable to measure the position of the microphone after installation again.

  Referring to FIG. 3, the main body 100 of the logger 60 includes a metallic casing 120 that is a cylindrical member having a hollow cylindrical shape with one end closed and an opening at the other end, and an opening of the casing 120. A cover 122 made of metal, which is attached to the housing 120 so as to cover it, and a fixture 124 for fixing the cover 122 to the housing 120 in a watertight manner are included. Each part of the logger 60 is designed to withstand a constant water pressure even when the cover 122 is fixed to the housing 120 with the fixture 124.

  A handle 126 that is used when the cover 122 is removed from the housing 120 is provided at the center of the fixture 124. The fixture 124 is further provided with a pair of underwater connectors 128 and 130 to which cables for a pair of underwater microphones are connected as will be described later.

  With reference to FIG. 4, the cover 122 can be removed from the housing 120 by removing the fixture 124 and pulling the handle 126. A mounting plate 140 is fixed to the surface of the cover 122 opposite to the handle 126. On one surface of the mounting plate 140, an electronic circuit 144 for recording the pinger sound collected by the underwater microphones 104 and 114, and a switch for the user to set various conditions for recording the pinger sound by the electronic circuit 144 142 and a power unit 146 containing a plurality of dry batteries for supplying power to the electronic circuit 144 are fixed. By fixing the mounting plate 140 to the cover 122 and fixing various components on the mounting plate 140 in this way, it is possible to remove the cover 122 from the housing 120 and simultaneously take out the internal components. There is an effect that handling and maintenance become easy. It is a design matter which surface of the mounting plate 140 should be attached to. Both sides of the mounting plate 140 may be used.

  The switch 142 is for setting the operation by the electronic circuit 144, and the operation condition of the electronic circuit 144 is set by a push button switch. What the operating conditions are will be described later. In the following description, in order to make the description easy to understand, details of the circuit configuration for directly recording the sound from the underwater microphones 104 and 114 will not be described. A circuit configuration for recording will be described.

  Referring to FIG. 5, the electronic circuit 144 is converted to a low frequency by amplifying, band limiting, and heterodyne detection with respect to the pinger signal received from the underwater microphones 104 and 114 via the underwater connectors 128 and 130 and digitized. A signal processing circuit 160 for outputting a Pinger signal, a controller 162 for processing the Pinger signal in accordance with the setting from the switch 142, connected to receive the output of the signal processing circuit 160, and processed by the controller 162 A hard disk drive 164 for recording a Pinger signal and an interface (IF) 166 connected to the controller 162 and used when the controller 162 performs data communication with an external computer are included.

  The signal processing circuit 160 includes a first signal processing circuit 180 that processes a signal from the underwater connector 128 side, a second signal processing circuit 182 that processes a signal from the underwater connector 130 side, and a first signal processing circuit. 180, and an analog / digital (A / D) conversion circuit 184 that converts an analog pinger signal output from the second signal processing circuit 182 into a digital signal and supplies the digital signal to the controller 162.

  The first signal processing circuit 180 and the second signal processing circuit 182 have the same configuration. Therefore, only the configuration of the first signal processing circuit 180 will be described below. Note that the settings of all the circuits described below are changed by the switch 142.

  The first signal processing circuit 180 includes an amplifier 200 that amplifies a signal given from the underwater connector 128, a high-pass filter (HPF) 202 having an input connected to receive the output of the amplifier 200, and an output of the HPF 202. A low-pass filter (LPF) 204 connected to receive the signal and an input connected to receive the output of the LPF 204, and the frequency domain of the input signal is a low-frequency domain by a predetermined frequency by the heterodyne detection method. And a detector 206 that shifts the signal to output.

  Similar to the first signal processing circuit 180, the second signal processing circuit 182 includes an amplifier 220, an HPF 222, an LPF 224, and a detector 226.

  Each component of the first signal processing circuit 180 and the second signal processing circuit 182 is connected so as to receive a corresponding setting signal from the switch 142.

  The operating conditions that can be switched by the switch 142 include the following.

  Referring to FIG. 6, detectors 206 and 208 shift the frequency of the input signal (signal 240 in FIG. 6) to a low frequency region (signal 242 in FIG. 6) (frequency conversion) by the heterodyne detection method. To do. In the example shown in FIG. 6, an input signal (for example, 65 kHz, 69 kHz, and 75 kHz) is converted into an output signal (5 kHz, 9 kHz, and 15 kHz) with a fundamental frequency of 60 kHz.

  The logger 60 and the like shown in FIGS. 1 to 6 are collected after the data collection period elapses, and the signals recorded on them are extracted and processed, thereby positioning the individual to which the pinger is attached. FIG. 7 shows a hardware structure of a high-precision positioning device for aquatic organisms that performs processing for positioning an individual by processing a signal collected from the logger 60 or the like.

  Referring to FIG. 7, a high-precision positioning device 260 for aquatic organisms includes a calculation unit 272 including a CPU (Central Processing Unit) and a clock circuit, and a bus 270 connected to the calculation unit 272. It should be noted that each component of the high-precision positioning device 260 for aquatic organisms described below is connected to the bus 270, although it will not be described each time.

  The high-precision positioning device 260 for aquatic organisms is further provided in the main body 100 of the logger 60 and the data input / output unit 274 for receiving basic data and the like for positioning from an external device and giving them to the calculation unit 272. It includes an IF 288 for communicating under the control of the IF 166 and the calculation unit 272, and a data display unit 276 made up of a liquid crystal display device for displaying calculation results and the like by the calculation unit 272.

  The high-precision positioning device 260 for aquatic organisms further includes an underwater sound data memory 278 for storing underwater sound data received from the IF 166 of the main body 100 of the logger 60 via the IF 288, an installation position of the logger 60, and an observation start. Sound data of a portion of a pinger sound extracted from the underwater sound data stored in the underwater sound data memory 278, and the environmental data memory 280 for storing environment data such as time and representative values of the sound velocity field in the observation sea area For each underwater microphone, and the azimuth of each underwater microphone such as the logger 60 with respect to the earth coordinate system (hereinafter referred to as “true direction”) with true north as 0 degree. A true orientation data memory 284, a pinger data stored in the pinger data memory 282, and an environment data memory 280. And a pinger position data memory 286 for storing a series of positioning data (pinger position data) calculated for each individual by the arithmetic unit 272 based on the data and the true direction data stored in the true direction data memory 284 .

  The pinger sound is an ultrasonic band of 20 kHz or higher. Humans cannot hear signals in this band. On the other hand, in order to sample a high-frequency signal so that it can be restored, sampling must be performed at a frequency more than twice as high. In general, the amount of data after sampling increases as the sampling frequency increases. Even if a large-capacity storage device such as an HDD is prepared, it is inevitable that the recording time will be shortened if the storage capacity is constant.

  On the other hand, it is known that no pinger sound is present in the band of 60 kHz or less under the condition that the frequency of the pinger signal is higher than 60 kHz. Therefore, in the present embodiment, in the main body 100 of the logger 60, the pinger signal in the ultrasonic band is shifted to the audible range by a heterodyne method (a superheterodyne method may be used). As a result, even if the sampling frequency is kept low, it is possible to record underwater sound for a long time without degrading the waveform of the pinger signal.

[Program structure]
The actual monitoring procedure will be described with reference to FIG. 8, and the control structure of the program executed by the calculation unit 272 in this procedure will be further described with reference to FIG.

  Referring to FIG. 8, at the beginning of monitoring (step 300), loggers 60, 62, etc. are installed at predetermined positions. At this time, the installation position and orientation of each logger's underwater microphone are recorded accurately. For each logger, start recording underwater sound with a predetermined setting.

  Subsequently, in step 302, as described above, recording of underwater sound at each logger is continued for a predetermined time. When the predetermined time has elapsed, all the loggers are collected (step 304).

  The recorded audio signal is input from the collected logger to the high-precision positioning device 260 for aquatic organisms, and each pinger is positioned (step 306). Output the positioning results in some form. For example, it is displayed on the data display unit 276 together with the individual number corresponding to each pinger. When the desired data is displayed and confirmed, the monitor is finished.

  Referring to FIG. 9, the control structure of the program executed by operation unit 272 at step 306 in FIG. 8 is shown in flowchart form. Prior to executing this program, the computing unit 272 stores the environmental data in the environmental data memory 280.

  The environmental data includes logger index information for specifying the position and orientation of each logger, the logger's underwater microphone interval d ', and a representative value C of the sound field in the observation sea area.

Logger index information, installation position information p _i for each _logger, observation starting time information Ts _i, and 2 channels of water microphone, orientation relative to the earth coordinate system with 0 degrees true north (hereinafter, true bearing) and [theta] r _i Including. The logger index data of the i-th logger is expressed as I (p _i , Ts _i , θr _i ) = I (p, Ts, θr) _i . Hereinafter, the subscript “i” indicates that the data is obtained from the i-th logger.

  Referring to FIG. 9 again, this program includes step 320 for performing the processing of step 322 described below for all loggers. In step 322, the underwater sound data of the two channels of the target logger is read from the logger body 100 via the IF 166 and the data input / output unit 274 and stored in the underwater sound data memory 278. In the underwater sound data, the time is recorded as a relative time integrated from the observation interval, starting from the recording start.

  Subsequently, step 336 described below is performed on all underwater sound data (step 334).

  In step 336, the relative time of all the underwater sounds of interest is converted into an absolute time using the observation start time Ts. From the underwater sound data of both channels, a portion exceeding a predetermined level is detected as a pinger sound. And step 352 for storing the data in the Pinger data memory 282. At this time, if the operating frequency is different for each pinger, this processing is performed for each frequency band.

  The process of step 336 further includes a step 354 of executing the following process of step 356 for each of the pinger sounds obtained from the target logger stored in the pinger data memory 282 by the processes of steps 350 and 352. Including.

In step 356, the relative arrival direction of the pinger sound relative to the logger is calculated based on the read out pinger sound, and the true direction of the logger is added to the relative arrival direction calculated in step 360 relative to the logger. By doing so, the true azimuth (true azimuth) at which the pinger sound arrives at the logger is calculated and stored in the true azimuth data memory 284 as true azimuth data.

  The calculation method of the pinger sound arrival direction performed in step 360 will be described with reference to FIG. The computing unit 272 calculates the pinger data stored in the pinger data memory 282, the logger index data stored in the environment data memory 280, the underwater microphone interval d ′ of the logger, and the representative value C of the sound velocity field in the observation sea area. Read.

  Here, the geometry for finding the direction of sound arrival from the sound that reaches the two-channel (left and right) underwater microphones installed in the logger is shown. Referring to FIG. 10, the distance d ′ between the two underwater microphones h1 and h2, the arrival time difference Δτ of the same sound S between the underwater microphones h1 and h2, and the typical value of the sound velocity field in the observation sea area. When C is used and the incident angle to the underwater microphones h1 and h2 is an angle θ shown in FIG. 10, the angle θ is obtained by the following equation.

ここで，Δτは水中マイクｈ１とｈ２とに入射した音波の位相差，又は相関を取ることによって求められる。図９のステップ３６０では，この式によりロガー６０等に対するピンガー音の到来方向を算出する。

Here, Δτ is obtained by obtaining a phase difference or correlation between sound waves incident on the underwater microphones h1 and h2. In step 360 of FIG. 9, the arrival direction of the pinger sound with respect to the logger 60 etc. is calculated by this equation.

Further, in step 362, the true bearing [theta] r _i of 2 channels of water microphone is added to the arrival direction θ of sounding for logger obtained itself, determine the true orientation data [theta] s _i of arrival direction of ringing, i th Are stored in the true direction data memory 284 as true direction data of the pinger sound.

  In step 354, the processing in step 356 described above is executed for all the pinger sounds.

  By performing the above step 336 for all underwater sound data, the true direction data memory 284 stores the arrival direction (true direction data) of each pinger sound for each logger.

  This program further includes a step 338 of performing the processing of step 340 described below for all the pinger using all the true orientation data stored in the true orientation data memory 284 by the processing of step 334.

  Step 340 includes a step 370 of performing the following step 372 on the pinger sounds at all times obtained for the processing target pinger.

  In step 370, for all pairs of loggers, step 380 for measuring the position of the pinger based on the true direction data calculated by the same pinger sound obtained at the same time, and for all pairs of loggers in step 380. A step 382 of determining the position of the pinger by determining the barycentric position of the positioning data of the obtained pinger and storing it in the pinger position data memory 286 as the pinger position data.

  When there are two loggers, there is only one pair formed by the loggers. Therefore, the result may be a positioning result obtained from true orientation data. However, if there are three loggers, for example, there will be three pairs. In step 370, since each of these pairs is used to perform the positioning calculation of Pinger, three positioning results are also obtained. In step 382, the center of gravity of those positioning results is corrected as positioning data in such a case.

  The pinger positioning calculation in step 380 will be described. Referring to FIG. 11, it is assumed that true orientation data memory 284 stores true orientation data sets for all pinger sounds, and environment data memory 280 stores information on the installation positions of each logger in advance. .

Referring to FIG. 11, it is assumed that two loggers are installed at two points A and B separated by a distance d. The coordinates of the logger B are the origin (0, 0), and the coordinates of the logger A are (0, d). When the sound source position is S (x, y) and θ ₁ and θ ₂ are the arrival directions of the singing sound with respect to the logger A and the logger B, respectively, the following equations are established.

By combining these, the coordinates (x, y) of the S position can be obtained by the following equation.

[Operation]
As described above, by using the monitoring system 50 described in the configuration, a desired aquatic organism individual in the sea area is monitored by the following processing. Note that a transmitter is attached to each individual aquatic organism in advance so that each individual can be identified by an ultrasonic signal transmitted from the transmitter. In some cases, the frequency of the transmitter may be different depending on the individual.

  Referring to FIG. 8, first, at least two loggers 60, 62, etc. are installed (fixed) on the bottom of a desired sea area (step 300). At that time, the installation position and the true direction of the underwater microphone of each logger are recorded. It is assumed that the logger is set in advance by a predetermined operation setting. Both the underwater microphone and the logger body should be firmly fixed on the seabed. By fixing the underwater microphone and logger to the seabed in this way, highly accurate positioning can be performed without being affected by ocean currents. Although it is desirable to install the microphones at the same height as accurately as possible (both are on a horizontal plane), even if there is a slight error, the accuracy will be reduced if the position between the microphones is large. is not.

  In the following description, it is assumed that each logger is set so that each logger records two channels of sound over a long period of time due to a frequency shift by the heterodyne method.

  When the logger is installed, each logger starts recording for a predetermined period by starting recording of each logger (step 302).

  During this period, each logger (for example, logger 60) operates as follows. Referring to FIG. 5, each part of first signal processing circuit 180 and second signal processing circuit 182 is preset by switch 142. The sound collected by the underwater microphones 104 and 114 is converted into an electrical signal, which is supplied to the amplifiers 200 and 220 via the underwater connectors 128 and 130, respectively. The amplifiers 200 and 220 amplify this signal at a preset amplification factor and supply the amplified signal to the HPFs 202 and 222, respectively. By the HPFs 202 and 222 and the LPFs 204 and 224, only signals in a predetermined band of each channel are supplied to the detector 206 and the detector 226.

  As already described, the detectors 206 and 226 output signals having a fundamental frequency of 60 kHz and shifted input signals to the low frequency side by 60 kHz.

  The A / D conversion circuit 184 converts the signals output from the detectors 206 and 226 into digital signals by sampling at a predetermined sampling frequency, and supplies the digital signals to the controller 162.

  When the measurement time comes, the controller 162 records these signals in the HDD 164 for each channel. The measurement may be intermittent or continuous. The controller 162 has a clock inside, and records each measurement value together with the relative time obtained by integrating the measurement interval, starting from the recording start time.

  Loggers are collected after a certain period of time (step 304).

  Subsequently, the underwater sound signals are read from the loggers, and the positioning process described above is performed on the signals, thereby positioning each pinger (and hence each individual). Specifically, the following procedure is executed.

  It is assumed that the environment data memory 280 stores the environment data described above in advance.

  Here, the program of the pinger positioning process whose control structure is shown in FIG. 9 is started, and its execution by the arithmetic unit 272 is started.

  First, in step 320, underwater sound data of each logger is transferred to the underwater sound data memory 278 by the following processing.

  As shown in FIG. 4, the cover 122 of each logger is removed from the housing 120, and the internal mounting plate 140 is taken out. The electronic circuit 144 on the mounting plate 140 is provided with an IF 166 as shown in FIG. This IF 166 is connected to the IF 288 of the high-precision positioning apparatus 260 for aquatic organisms shown in FIG. The computing unit 272 controls the data display unit 276 to read out the underwater sound recorded in the HDD 164 of FIG. 5 and store it in the underwater sound data memory 278 (step 322). By performing this for all loggers in step 320, the underwater sound data memory 278 stores the underwater sound data for all channels of all loggers.

  Subsequently, the following processing is executed for all the underwater sound data stored in the underwater sound data memory 278. First, the time of the underwater sound data is converted to an absolute time (step 350). Subsequently, for both the first channel and the second channel of the underwater sound data, the underwater sound part having a level equal to or higher than a predetermined threshold is cut out as a part of the pinger sound. The data is stored in the Pinger data memory 282. At this time, the pinger sound may be detected for each frequency, or each pinger sound may be distinguished based on the identification data of the pinger included in the pinger sound.

  By performing the processing of steps 350 and 352 on the underwater sound data of the two channels of the target logger, the pinger data memory 282 stores the pinger data related to all the pinger sounds arriving at the logger. It will be stored with the time.

  Subsequently, in step 338, the processing in step 340 described below is executed on all the pinger data obtained from the logger to be processed, which is stored in the pinger data memory 282. In step 340, specifically, the calculation unit 272 stores the pinger data obtained from the processing logger stored in the pinger data memory 282, the logger index data stored in the environment data memory 280, and the logger underwater microphone. Read the interval and the representative value of the sound velocity field in the sea area. And the direction (relative azimuth | direction with respect to a logger) which each pinger sound arrived at the logger of a process target is calculated with the calculation method shown in FIG. Further, in step 362, the true direction of the underwater microphone of the logger to be processed is added to this relative direction, and true direction data is obtained. Subsequently, this true orientation data is stored in the true orientation data memory 284.

  By executing the processing of the above step 336 for all loggers, the arrival directions (true direction data) of all the pinger sounds arriving at the logger are stored in the true direction data memory 284 for each logger. It will be.

  After the true orientation data is obtained in this way, in step 338, the true orientation data of all the pingers obtained in the process of step 334 is used, and the following step 340 is executed for each of the pingers. To do.

  In step 340, the following processing in step 372 is executed for the pinger sounds at all times obtained for the target pinger.

  In step 372, first, in step 380, the pinger positioning process is performed for all of the logger pairs. This process is as described with reference to FIG. When the Pinger positioning results are obtained for all pairs of loggers in step 380, the center of gravity is calculated in step 382, so that the position of the pinger at that time (from the target logger pair ( That is, the position of the individual to which this pinger is attached is calculated. This value is stored in the pinger position data memory 286 at step 382.

  Thus, the position of the pinger is specified for all the pinger sounds of all the pinger.

  The position of the pinger thus obtained may be displayed on the data display unit 276, for example, or may be output to another device via the data input / output unit 274.

  According to the above embodiment, since the logger including the underwater microphone is fixed to the seabed, it is not subject to installation restrictions by the land device, and there is no fear that the positioning accuracy will be affected by the influence of the ocean current. Each logger records all sounds in a predetermined band among the underwater sounds arriving at the logger. Since underwater sound is not recorded while switching the frequency, there is little risk of losing the recording of the pinger sound in the target frequency band. As a result, the position of the individual can be determined with high reliability.

  In addition, the logger according to the above embodiment shifts and records ultrasonic waves into a relatively low band signal by the heterodyne method. Therefore, the sampling frequency can be kept low, and a pinger sound can be recorded for a long time without causing deterioration of the signal waveform. Also, since the pinger sound is recorded as underwater sound data for a long time and the underwater sound data is collected, the reception status of the logger can be monitored. As already described, it is needless to say that the superheterodyne system may be used without being limited to the heterodyne system.

  In the above embodiment, it is assumed that the individual to be measured lives in a relatively shallow sea area. Therefore, it is considered that the individual exists in a substantially constant plane, and the positioning of the pinger sound can be performed with two loggers. However, the present invention is not limited to such an embodiment. It will be apparent to those skilled in the art from the principle that the positioning of an individual in three dimensions can be performed by using three loggers.

  In the above embodiment, a single dry battery is used for the power unit 146. The power source is not limited to the one using a dry battery as described above, and a lithium battery may be used. However, since lithium batteries are dangerous when used in the sea, batteries are used in the above embodiment.

  Various modifications can be made to the above embodiment. For example, the HDD 164 can be replaced with an SSD (Solid State Drive) if the device is allowed to be somewhat expensive. When SSD is used, the power consumption is further suppressed as compared with HDD, and as a result, the recording time can be made longer.

  If a large-capacity memory that can be attached to and detached from a predetermined memory port is available, a memory port may be provided on the mounting plate 140 instead of the HDD 164. Installed underwater with the memory installed in the memory port to record underwater sound in the memory, and when recovered, remove the memory from the port and install it in the high-precision positioning device 260 for aquatic organisms without going through the IF 166. It may be.

  In the above embodiment, each logger can record two channels of underwater sound. However, in principle, it is clear that each logger has three or more recording channels. However, in practice, it seems that the one that records two channels with one logger is the easiest to use.

  Note that the logger according to the above embodiment uses a metal casing 120. By using a metallic housing, even if a certain level of water pressure is applied in the water or a large impact is applied to the logger for some reason, it will not be broken, and the risk of data recording failure can be reduced. The casing 120 need not have a circular cross section, but a circular shape is considered to have the highest impact resistance, and is more desirable than other shapes in terms of durability.

  In the above embodiment, the underwater microphone is separated from the logger body 100 and connected to the logger body 100 with a wire and an underwater connector. With this configuration, the position of the underwater microphone is not restricted by the installation position of the logger body 100, and the underwater microphone can be installed at an appropriate position. However, the present invention is not limited to such an embodiment. For example, a pair of underwater microphones may be fixed to the main body. In that case, for example, a pair of arms protruding from the main body may be provided so that the distance between the underwater microphones is as large as possible, and the underwater microphones may be installed there. Or you may make it provide a microphone in the front-end | tip and rear end of a cylindrical main body. By doing so, there is no need to install the microphone separately from the main body, so that the effect of facilitating the installation of the logger can be obtained.

  In the above embodiment, the case where the pinga positioning is performed by the dedicated hydrosphere high-precision positioning device 260 has been described. However, the high-precision positioning device 260 for aquatic organisms can also be realized by general-purpose computer hardware and software whose control structure is illustrated in FIG.

  The embodiment disclosed herein is merely an example, and the present invention is not limited to the above-described embodiment. The scope of the present invention is indicated by each claim in the claims after taking into account the description of the detailed description of the invention, and all modifications within the meaning and scope equivalent to the wording described therein are included. Including.

50 Monitoring system 60, 62, 64 Logger 70, 74 Transmitter 100 Logger body 102, 112 Pole 104, 114 Underwater microphone 108, 118 Cable 120 Case 122 Cover 124 Fixing tool 126 Handle 128, 130 Underwater connector 140 Mounting plate 142 Switch 144 Electronic circuit 146 Power unit 160 Signal processing circuit 162 Controller 164 HDD
166,288 interface (IF)
180, 182 Signal processing circuit 184 A / D conversion circuit 200, 220 Amplifier 202, 222 High-pass filter 204, 224 Low-pass filter 206, 226 Detector 260 High-precision positioning device 274 for aquatic organisms Data input / output unit 272 Operation Part

Claims (8)

A watertight housing;
Recording means provided in the housing, for recording the first and second signals output from the first and second underwater microphones in the first and second channels, respectively;
The recording means is
Frequency shifting means for shifting the frequency bands of the first and second signals to a lower frequency side by a predetermined frequency;
A monitoring device for aquatic organisms, comprising: a recording device that digitizes the first and second signals output by the frequency shift means and records the signals as signals of the first and second channels, respectively. The housing is
A hollow cylindrical member having an opening at one end;
A cover member covering the opening of the cylindrical member;
A fixture for watertightly fixing the cover member to the opening of the tubular member;
2. The aquatic organism monitoring according to claim 1, further comprising: a first and a second underwater connector provided on the cover member for guiding an external electrical signal to an input of the frequency shift means inside the cylindrical member. apparatus. The monitoring apparatus for aquatic organisms according to claim 2, wherein the recording means can be pulled out from the inside of the tubular member in a state where the cover member is removed from the tubular member. The recording means is
A mounting plate that is fixed at one end to the back surface of the cover member, and that is completely accommodated inside the cylindrical member in a state where the cover member is mounted in the opening of the cylindrical member;
The frequency shift means and the recording device are provided on one surface of the mounting plate;
The aquatic organism according to any one of claims 2 to 4, wherein the recording means further includes a power unit fixed on one surface of the mounting plate and supplying power to the frequency shift means and the recording device. Monitoring device. The aquatic organism monitoring apparatus according to any one of claims 2 to 4, further comprising a handle provided on a surface of the cover member opposite to the opening. The aquatic organism monitoring apparatus according to any one of claims 2 to 5, wherein the cylindrical member is made of metal. The aquatic organism monitoring according to any one of claims 1 to 6, wherein the recording means further includes an interface for outputting the first and second channel signals recorded in the recording device to the outside. apparatus. Preparing at least three monitoring devices for aquatic organisms according to claim 1, connecting the first and second underwater microphones to each, and installing the monitoring devices together with the microphones in a predetermined water area;
Recording the position and sound collection direction of each underwater microphone installed on the bottom of the water;
In each of the monitoring devices installed on the bottom of the water, among the underwater sounds collected by the first and second underwater microphones connected to the monitoring device, underwater sounds in a predetermined band are transmitted over the predetermined period. Recording with the recording means;
Collecting the monitoring device after completion of the predetermined period;
For each of the collected monitoring devices, the temporal difference of the pinger sound in the underwater sound recorded by the first and second underwater microphones recorded in the recording device, and each underwater microphone is installed. Estimating the arrival direction of the pinger sound arriving at the first and second underwater microphones based on the position and the sound collection direction that have been performed;
Monitoring aquatic organisms, including the step of positioning the pinger by examining the crossing position of the arrival direction of the pinger sound to the underwater microphone connected to each monitoring device obtained by each of the plurality of monitoring devices Method.

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