Measurement system

Abstract

In a measurement system comprising at least two measurement devices (1a, 1b), each of the two measurement devices 1 comprises: a signal generation unit 101 that generates an acoustic wave signal including transmitter identification information; a transmitter 103 that transmits the acoustic wave signal into the sea; a receiver 106 that receives an acoustic wave from the sea; and a sound source separation unit 108 that, if the transmitter identification information included in the acoustic wave matches transmitter identification information in the host measurement device, outputs the acoustic wave to a biological quantity measurement unit 109 which measures a biological quantity in the sea, and, if the transmitter identification information included in the acoustic wave does not match the transmitter identification information in the host measurement device, outputs the acoustic wave to a spatial structure measurement unit 110 which measures the spatial structure in the sea.

Description

Measurement System

[0001] The present disclosure relates to a measurement system.

[0002] There is a demand for technology that enables remote sensing of underwater spatial structures and underwater biomass to grasp the respective distribution status and the like. In underwater remote sensing, sound waves are mainly used because electromagnetic waves experience severe attenuation (Non-Patent Document 1). Remote sensing using sound waves can be roughly divided into two methods, and frequencies of approximately several hundred kHz or lower with low attenuation are generally used.

[0003] When grasping an underwater spatial structure, a method for measuring the speed of sound in underwater space, such as ocean acoustic tomography (10 kHz to 100 kHz), is used. For example, the following are used: a first measurement device provided with a transmitter for transmitting a sound wave signal at its tip, and a second measurement device positioned forward of the first measurement device and provided with a receiver at its rear end for capturing the speed of sound of the sound wave that has passed through the water.

[0004] When grasping underwater biomass, a method for measuring reflected waves from underwater objects is used, such as sonar (military 20 Hz to 20 kHz), fish finders (50 kHz to 200 kHz), and OAWRS (~1 kHz). For example, a measurement device provided with both a transmitter for transmitting a sound wave signal and a receiver for capturing underwater reflected waves at its tip is used.

[0005] “Wirelessly Operating an Underwater Drone via Underwater Acoustic Communication!”, [online], [Retrieved December 13, Reiwa 6], <URL: https: / / online-umi.osr.or.jp / archives / 89>

[0006] When performing remote sensing on both an underwater spatial structure and underwater biomass, it is necessary to introduce corresponding measurement devices for each, which gives rise to issues such as the cost of preparing measurement devices, the risk of acoustic interference, and inconsistent measurement timing.

[0007] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a technology that enables simultaneous remote sensing of both an underwater spatial structure and underwater biomass with one set of measurement devices.

[0008] A measurement system according to one aspect of the present disclosure is a measurement system comprising at least two measurement devices, wherein each of the two measurement devices includes: a signal generation unit that generates a sound wave signal including identification information of a transmitter; a transmitter that transmits the sound wave signal into the sea; a receiver that receives sound waves from the sea; and a sound source separation unit that, if the identification information of the transmitter included in the sound wave matches the identification information of the transmitter of its own measurement device, outputs the sound wave to a biomass measurement unit that measures the biomass in the sea, and if the identification information of the transmitter included in the sound wave does not match the identification information of the transmitter of its own measurement device, outputs the sound wave to a spatial structure measurement unit that measures the spatial structure in the sea.

[0009] According to this disclosure, a single set of measuring devices can simultaneously remotely sense both the spatial structure and biomass of the ocean.

[0010] Figure 1 shows an example of the configuration of the measurement system. Figure 2 shows an example of the functional configuration 1 of the measurement device. Figure 3 shows an example of the functional configuration 2 of the measurement device. Figure 4 is a flowchart showing an example of the operation of the first and second measurement devices.

[0011] Embodiments of this disclosure will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals and their descriptions are omitted.

[0012] This disclosure describes how each measuring device performs sound source separation, separating sound waves from the ocean into either sound waves between the measuring devices or reflected waves from underwater objects. This allows for simultaneous remote sensing of both the spatial structure and biomass of the ocean by using at least two measuring devices (one set of measuring devices).

[0013] Figure 1 shows an example of the configuration of the measurement system according to this embodiment.

[0014] The measurement system according to this embodiment comprises two measuring devices 1 (1a, 1b).

[0015] The first measuring device 1a transmits a sound wave signal into the sea in front of it. The second measuring device 1b transmits a sound wave signal into the sea behind it. The first measuring device 1a receives sound waves from the sea and separates them into sound waves from the second measuring device 1b located in front of it and reflected waves from underwater objects. The second measuring device 1b also receives sound waves from the sea and performs sound source separation in the same manner.

[0016] The first measuring device 1a and the second measuring device 1b have their respective time zones synchronized, and the time zones of the measurement processes performed by each measuring device 1 are also synchronized. In other words, the first measuring device 1a and the second measuring device 1b perform the measurement process at the same time. The means and method of time synchronization are arbitrary. The time itself may be off from standard time, as long as the measuring devices can perform the measurement process at the same time relative to each other. For example, if the distance between the measuring devices is relatively short, electromagnetic waves can reach each other, so the time between the measuring devices can be synchronized by communication using a green laser. As a periodic calibration, the measuring devices may be brought closer together to synchronize their time.

[0017] The first measuring device 1a and the second measuring device 1b are capable of determining their own and the other's position information. For example, possible methods include obtaining position information from GPS (Global Positioning System), repeatedly updating the current position from the amount of movement using a gyro sensor, performing position correction by triangulation between multiple measuring devices, and receiving the other's position information using electromagnetic waves. However, these are not the only possible means and methods for determining position, and any other means and methods can be used.

[0018] At least two measuring devices 1 are sufficient. Increasing the number of measuring devices 1 to three or more may widen the spatial range of the measurement target or increase the resolution.

[0019] Figure 2 shows an example of the functional configuration 1 of the measuring device 1 according to this embodiment. The first measuring device 1a and the second measuring device 1b shown in Figure 1 each have the functional configuration shown in Figure 2.

[0020] The measuring device 1 (1a, 1b) comprises a signal generation unit 101, a transmission control unit 102, a transmitter 103, a transmitting antenna 104, a receiving antenna 105, a receiver 106, a receiving control unit 107, a sound source separation unit 108, a biomass measurement unit 109, and a spatial structure measurement unit 110.

[0021] The signal generation unit 101 has the function of generating an acoustic wave signal that includes identification information for the transmitter 103.

[0022] The transmission control unit 102 has functions to control the intensity of the sound wave signal, the transmission time, and so on.

[0023] The transmitter 103 has the function of transmitting sound wave signals from the transmitting antenna 104 into the sea.

[0024] The receiver 106 has the function of receiving underwater sound waves captured by the receiving antenna 105.

[0025] The receiving control unit 107 has functions to control the reception time and intensity of sound waves received in the ocean.

[0026] The sound source separation unit 108 has the function of separating sound waves in the sea into sound waves between measuring devices and reflected waves from objects in the sea. Specifically, the sound source separation unit 108 has the function of outputting the sound waves in the sea to the biomass measurement unit 109 if the identification information of the transmitter contained in the sound waves in the sea matches the identification information of the transmitter of its own measuring device 1, and outputting the sound waves in the sea to the spatial structure measurement unit 110 if the identification information of the transmitter contained in the sound waves in the sea does not match the identification information of the transmitter of its own measuring device 1.

[0027] The biomass measurement unit 109 has the function of measuring the biomass in the ocean using sound waves when the other measuring device that receives the sound waves in the ocean uses those sound waves to measure the spatial structure in the ocean.

[0028] The spatial structure measurement unit 110 has the function of measuring the spatial structure of the ocean using sound waves when the other measuring device that receives the sound waves uses those sound waves to measure the biomass in the ocean.

[0029] Figure 3 shows an example of the functional configuration 2 of the measuring device 1 according to this embodiment.

[0030] The measuring device 1 (1a, 1b) comprises a signal generation unit 101, a transmission control unit 102, a reception control unit 107, a sound source separation unit 108, a biomass measurement unit 109, a spatial structure measurement unit 110, a transmit / receive switching unit 111, a transducer 112, and a transmit / receive antenna 113.

[0031] The transmit / receive switching unit 111 has the function of switching between transmitting sound wave signals and receiving underwater sound waves. Specifically, when transmitting sound wave signals from the measuring device 1, the transmit / receive switching unit 111 connects the transmit / receive control unit 102 to the transducer 112, and when receiving underwater sound waves, connects the transducer 112 to the receive control unit 107.

[0032] The transducer 112 incorporates the functions of both the transmitter 103 and the receiver 106 shown in Figure 2.

[0033] The transmitting and receiving antenna 113 functions as both the transmitting antenna 104 and the receiving antenna 105 shown in Figure 2.

[0034] Figure 4 is a flowchart showing an example of the operation of the first measuring device 1a and the second measuring device 1b. The first measuring device 1a and the second measuring device 1b are time-synchronized and mutually know each other's position information.

[0035] Step S1; The signal generation unit 101 of the first measuring device 1a generates an acoustic wave signal. At this time, in order to distinguish the transmitter of the acoustic wave signal source, the signal generation unit 101 multiplexes the identification information of the transmitter 103 of the first measuring device 1a onto the acoustic wave signal.

[0036] The signal generation unit 101 may, if necessary, multiplex information such as the position information of the transmitter 103 of the first measuring device 1a, the current time information, and various information from the previous time the sound wave was received, which is necessary for sound velocity calculation and accuracy improvement measures on the receiving side.

[0037] The multiplexing methods used include, for example, frequency division multiplexing, time division multiplexing, and code division multiplexing.

[0038] Step S2: The transmission control unit 102 of the first measuring device 1a adjusts the intensity of the sound wave signal generated in step S1 and sets the transmission time of the sound wave signal.

[0039] Step S3: The transmitter 103 of the first measuring device 1a transmits the sound wave signal generated and intensity-adjusted in steps S1 and S2 from the transmitting antenna 104 into the sea at the transmission time set in step S2.

[0040] Here, it is assumed that the first sound wave signal SIG1 is transmitted from the first measuring device 1a at time T1. As illustrated in FIG. 1, it is assumed that the first sound wave signal SIG1 becomes a sound wave reflected by some underwater object (reflected wave from the underwater object) and also becomes a sound wave that propagates through the sea as it is without being reflected by the underwater object (sound wave between measuring devices).

[0041] It is also assumed that the second measuring device 1b also executes steps S1 to S3, and the second sound wave signal SIG2 is transmitted from the second measuring device 1b at time T2. As illustrated in FIG. 1, it is assumed that the second sound wave signal SIG2 becomes a sound wave that propagates through the sea as it is without being reflected by the underwater object (sound wave between measuring devices). Note that the underwater object is any object that reflects sound waves, such as living organisms and marine debris.

[0042] Step S4: The receiver 106 of the first measuring device 1a receives sound waves from the sea. It is assumed that the sound wave is a mixed sound wave of a reflected wave from an underwater object (=the first sound wave signal SIG1) and a sound wave from the second measuring device 1b (=the second sound wave signal SIG2).

[0043] The receiver 106 of the second measuring device 1b also receives sound waves from the sea. It is assumed that the sound wave is the sound wave from the first measuring device 1a (=the first sound wave signal SIG1).

[0044] Step S5: Each reception control unit 107 of the first measuring device 1a and the second measuring device 1b adjusts the intensity of the sound wave received in step S4.

[0045] Step S6: Each sound source separation unit 108 of the first measuring device 1a and the second measuring device 1b receives the sound wave that has been received and intensity-adjusted in steps S4 and S5. Each sound source separation unit 108 extracts the identification information of the transmitter from the sound wave according to the multiplexing method used in step S1. Each sound source separation unit 108 determines whether the identification information of the transmitter matches the identification information of the transmitter 103 of its own measuring device 1 (1a, 1b).

[0046] When the extracted transmitter identification information matches the identification information of the transmitter 103 of the own measuring device 1, each sound source separation unit 108 passes the sound wave to the biomass measurement unit 109 as a "reflected wave from an underwater object".

[0047] When the extracted transmitter identification information does not match the identification information of the transmitter 103 of the own measuring device 1, each sound source separation unit 108 passes the sound wave to the spatial structure measurement unit 110 as a "sound wave between measuring devices".

[0048] Specifically, the first measuring device 1a and the second measuring device 1b perform the following processing.

[0049] In the first measuring device 1a, the transmitter identification information included in the reflected wave from an underwater object received from the sea (=the first sound wave signal SIG1) matches the identification information of the transmitter 103 of the first measuring device 1a, so the first measuring device 1a passes the reflected wave to the biomass measurement unit 109 of the first measuring device 1a.

[0050] Furthermore, in the first measuring device 1a, the transmitter identification information included in the sound wave from the second measuring device 1b received from the sea (=the second sound wave signal SIG2) does not match the identification information of the transmitter 103 of the first measuring device 1a, so the first measuring device 1a passes the sound wave to the spatial structure measurement unit 110 of the first measuring device 1a.

[0051] In the second measuring device 1b, the transmitter identification information included in the sound wave from the first measuring device 1a received from the sea (=the first sound wave signal SIG1) does not match the identification information of the transmitter 103 of the second measuring device 1b, so the second measuring device 1b passes the sound wave to the spatial structure measurement unit 110 of the second measuring device 1b.

[0052] Step S7: For the first sound wave signal SIG1, the biomass measurement unit 109 of the first measuring device 1a measures the underwater biomass using the sound wave passed in step S6. At the same timing as the biomass measurement performed by the first measuring device 1a, each spatial structure measurement unit 110 of the second measuring device 1b measures the underwater spatial structure using the sound wave passed in step S6.

[0053] With respect to the second sound wave signal SIG2, the spatial structure measurement unit 110 of the first measuring device 1a measures the spatial structure of the sea using the sound waves transmitted in step S6. In other words, the first measuring device 1a measures the biomass of the sea based on the first sound wave signal SIG1, and then measures the spatial structure of the sea based on the second sound wave signal SIG2.

[0054] Subsequently, the first measuring device 1a and the second measuring device 1b calculate the distribution status of marine biomass (e.g., species, quantity, distribution) and marine spatial structure (e.g., temperature, salinity, current velocity) based on the measured biomass and analyze marine phenomena and biodiversity.

[0055] At this time, if the first sound wave signal SIG1 and the second sound wave signal SIG2 contain information such as the position information of the transmitter 103, the current time information, and information from the previous time the sound wave was received, the first measuring device 1a and the second measuring device 1b will use this information to measure the biomass and spatial structure of the ocean. This makes it possible to improve the accuracy of each measurement.

[0056] According to this embodiment, the first measuring device 1a and the second measuring device 1b separate the sound waves in the ocean into sound waves between the measuring devices and reflected waves from underwater objects, so that both the spatial structure and biomass of the ocean can be simultaneously remotely sensed with a single set of measuring devices 1 (1a, 1b). As a result, the cost of the measuring devices to be prepared and the risk of sound wave interference can be reduced, and advanced underwater analysis can be realized in real time from the temporal changes in both spatial structure and biomass.

[0057] 1. Measuring device 1a. First measuring device 1b. Second measuring device 101. Signal generation unit 102. Transmission control unit 103. Transmitter 104. Transmitting antenna 105. Receiving antenna 106. Transmitter 107. Receiving control unit 108. Sound source separation unit 109. Biomass measurement unit 110. Spatial structure measurement unit 111. Transmit / receive switching unit 112. Transmitter / receiver 113. Transmitting / receiving antenna

Claims

1. A measurement system comprising at least two measuring devices, wherein each of the two measuring devices comprises: a signal generation unit that generates a sound wave signal including identification information of a transmitter; a transmitter that transmits the sound wave signal into the sea; a receiver that receives sound waves from the sea; and a sound source separation unit that, if the identification information of the transmitter included in the sound wave matches the identification information of the transmitter of its own measuring device, outputs the sound wave to a biomass measurement unit that measures the biomass in the sea, and if the identification information of the transmitter included in the sound wave does not match the identification information of the transmitter of its own measuring device, outputs the sound wave to a spatial structure measurement unit that measures the spatial structure in the sea.

2. The measurement system according to claim 1, wherein the signal generation unit includes the identification information of the transmitter in the sound wave signal using one of the following multiplexing methods: frequency division multiplexing, time division multiplexing, or code division multiplexing.

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