Fish quantity information display system and fish quantity information display method

Abstract

To provide a fish quantity information display system and a fish quantity information display method that are capable of displaying an image that allows a user to accurately and easily grasp the quantity of fish present on the wake of its own ship.SOLUTION: A fish quantity information display system 10 includes: an underwater detection device 100 that detects a fish school by scanning a receiving beam along a conical scanning surface; and a plotter device 200 that displays its own ship's current position and a track to the current position. The underwater detection device 100 includes: a fish quantity index calculation unit that calculates a fish quantity index based on electrical signals output from multiple ultrasonic vibrators; and a communication unit that transmits the fish quantity index to the plotter device 200. The plotter device 200 includes: a communication unit for receiving the fish quantity index; and a fish quantity display superimposition unit that displays fish quantity information based on the fish quantity index in association with the track.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a fish quantity information display system and a fish quantity information display method that display information about the position and track of a ship as well as the quantity of fish on the track. [Background technology]

[0002] Conventionally, fish finders that detect schools of fish in water are known. In this type of fish finder, ultrasonic waves are transmitted vertically downward from the bottom of a ship and the reflected waves are received. Echo data corresponding to the intensity of the reflected waves is generated, and an echo image is displayed based on the generated echo data.

[0003] This type of fish finder can obtain a value proportional to the number of fish present in a certain area of ​​the ocean by integrating the acoustic intensity of echoes reflected from the schools of fish. If the fish finder is equipped with a GPS (Global Positioning System) function, it can display an image in which a circle or the like of a size proportional to the magnitude of the integrated value is superimposed on the ship's wake. Patent Document 1 listed below describes a fish finder with such a configuration. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-197622 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because fish finders transmit and receive ultrasonic waves in a narrow area directly below the vessel, they cannot obtain information on fish abundance over an area of ​​several hundred meters in diameter, which is the target area of ​​purse seine fishing, in a single transmission and reception.

[0006] Furthermore, because fish finders transmit ultrasonic waves directly below the ship, they cannot properly receive echoes from the depth range corresponding to the ultrasonic transmission period, i.e., the depth range near the sea surface, making it impossible to properly obtain information on the quantity of fish distributed near the sea surface.

[0007] Furthermore, noise emitted by the ship can cause fish directly below the ship to flee, making it difficult for fish finders that detect fish directly below the ship to accurately obtain information on fish abundance.

[0008] Furthermore, to estimate the weight (tonnage) of fish from the integrated acoustic intensity, it is necessary to obtain parameters related to the fish finder's transmitting and receiving waves, as well as parameters such as the fish's target strength, and apply the appropriate calculation formula. This task is extremely difficult for ordinary fishermen.

[0009] In view of such problems, the present invention aims to provide a fish quantity information display system and a fish quantity information display method that can display an image that allows the user to accurately and easily grasp the amount of fish present along the ship's wake. [Means for solving the problem]

[0010] A first aspect of the present invention relates to a fish quantity information display system. This fish quantity information display system includes an underwater detection device that detects schools of fish by scanning a receiving beam along a conical scanning surface, and a plotter device that displays the ship's current position and the track to the current position. The underwater detection device includes a fish quantity index calculation unit that calculates a fish quantity index based on electrical signals output from multiple ultrasonic transducers, and a communication unit that transmits the fish quantity index to the plotter device. The plotter device includes a communication unit that receives the fish quantity index, and a fish quantity display superimposition unit that displays fish quantity information based on the fish quantity index in association with the track.

[0011] According to the fish quantity information display system of this embodiment, schools of fish are detected by scanning a receiving beam along a conical scanning surface, allowing for acquisition of fish quantity information over a wide area, comparable to the target area of ​​purse seine fishing, and also for acquisition of fish quantity information from fish distributed near the sea surface. Furthermore, since fish quantity information is acquired for fish distributed on the conical scanning surface rather than directly below the ship, the impact of fish escape due to noise from the ship on the fish quantity information can be reduced. Furthermore, fish quantity indices are calculated based on electrical signals output from multiple ultrasonic transducers, and fish quantity information based on the calculated fish quantity indices is displayed in association with the ship's wake, allowing users to easily grasp the fish quantity without applying parameters or calculation formulas from an underwater detection device. Therefore, the fish quantity display system of this embodiment allows users to accurately and easily grasp the quantity of fish present along the ship's wake.

[0012] In the fish quantity information display system of this embodiment, the fish quantity information includes a fish quantity image corresponding to the value of the fish quantity index, and the fish quantity display overlay unit can be configured to display the fish quantity image at a predetermined position on the track.

[0013] This configuration allows the user to easily grasp the amount of fish at each position on the track.

[0014] In this configuration, the fish quantity image may be a circle configured with at least one of a diameter and a color according to the value of the fish quantity index.

[0015] This configuration allows the user to intuitively grasp the amount of fish at each position on the track.

[0016] Alternatively, the fish quantity image may be a band configured with at least one of a width and a color according to the value of the fish quantity index.

[0017] This configuration also allows the user to intuitively grasp the amount of fish at each position on the track.

[0018] In the fish quantity information display system of this aspect, the fish quantity information includes the value of the fish quantity index, and the fish quantity display overlay unit can be configured to display the value of the fish quantity index at a predetermined position on the track.

[0019] With this configuration, the user can accurately grasp the amount of fish at each position on the wake as a numerical value.

[0020] The fish quantity display superimposition unit may be configured to display the fish quantity information when the value of the fish quantity index is equal to or greater than a predetermined threshold value.

[0021] According to this configuration, the display of fish quantity information where the fish quantity index is below the threshold is omitted, so the user can easily grasp the positions on the wake where a large amount of fish equal to or greater than the threshold has occurred.

[0022] In the fish quantity information display system of this embodiment, a correction value reception processing unit is further provided that receives input of a correction value for correcting the fish quantity index, and the fish quantity index calculation unit may be configured to correct the calculation formula for the fish quantity index based on the correction value.

[0023] With this configuration, the calculation formula for the fish quantity index is corrected based on the correction value input by the user. Generally, users, such as fishermen, can easily estimate the amount of fish they have actually caught (e.g., tons), and can therefore smoothly and appropriately input a correction value for correcting the displayed fish quantity index to the actual amount of fish. This allows the calculation formula for the fish quantity index to be corrected based on the input correction value so that it approaches the actual amount of fish caught. Therefore, this correction process allows the fish quantity index to be obtained more accurately, and more accurate fish quantity information to be displayed.

[0024] In this configuration, the calculation formula includes a fish quantity correction coefficient, the correction value is a correction magnification, and the fish quantity index calculation unit can be configured to calculate the fish quantity index by multiplying the fish quantity correction coefficient by the correction magnification as the new fish quantity correction coefficient.

[0025] With this configuration, each time the user inputs a correction factor, the correction factor is added up and a new fish quantity correction coefficient is set. By repeatedly inputting the correction factor, the user can bring the fish quantity index closer to the fish quantity that corresponds to their own rough estimate. This allows the fish quantity index to be obtained smoothly and appropriately according to the user's fishing ground, fish species, and season, and fish quantity information to be displayed appropriately.

[0026] In this case, the calculation formula may be an original calculation formula consisting of a first formula that includes the weight of each fish to be caught, the target strength, the intensity of the transmitted wave, and the receiving sensitivity of the transducer, and a second formula that does not include these, in which the first formula is replaced with a formula consisting of an approximate value of the first formula and the fish quantity correction coefficient.

[0027] With this configuration, the calculation formula takes into account the weight and target strength of the fish to be caught, the strength of the transmitted waves, and the receiving sensitivity of the transducer, allowing the fish quantity index to be calculated with high accuracy. Furthermore, because the first formula, which includes these parameters, is replaced with a term consisting of the first formula's approximate value and a fish quantity correction coefficient, the user can smoothly correct the calculation formula using a correction multiplier according to their own fish quantity estimate, without needing to know these parameters. This allows the user to smoothly bring the calculated fish quantity index closer to their own fish quantity estimate. This allows the user to be provided with more accurate fish quantity information.

[0028] The fish quantity information display system of this embodiment further includes a target area reception processing unit that receives a designation of a target area within the search range for which the fish quantity index is to be calculated, and the fish quantity index calculation unit can be configured to calculate the fish quantity index for the designated target area.

[0029] With this configuration, the user can specify a target area, such as an area that the user wants to focus on or an area that can be enclosed by a purse seine net, and the fish quantity indicator for that target area can be displayed. Therefore, the user can smoothly proceed with catching fish based on the displayed fish quantity information.

[0030] The fish quantity information display system of this embodiment may further include a radar device that receives reflected waves of transmitted waves sent into the air and detects surrounding targets, and the plotter device may be configured to further include a target display superimposition unit that displays targets present near the wake together with the wake and the fish quantity information based on the detection results of the radar device.

[0031] This configuration allows other ships or flocks of birds near the ship's wake to be displayed along with information on the quantity of fish at each location on the wake, allowing the user to determine which location on the ship's wake they should return to to continue fishing.

[0032] A second aspect of the present invention is a fish quantity information display method that uses an underwater detection device that detects schools of fish by scanning a receiving beam along a conical scanning surface to display an image on a plotter device that displays the current position of the ship and the track to the current position, calculates a fish quantity index based on electrical signals output from multiple ultrasonic transducers, and displays fish quantity information based on the fish quantity index in association with the track.

[0033] The fish quantity information display method according to this aspect can achieve the same effects as the fish quantity information display system according to the first aspect. [Effects of the Invention]

[0034] As described above, according to the present invention, it is possible to provide a fish quantity information display system and a fish quantity information display method that can display an image that allows the user to accurately and easily grasp the amount of fish present along the ship's wake.

[0035] The effects and significance of the present invention will become more apparent from the following description of the embodiments, however, the embodiments shown below are merely examples of how the present invention can be implemented, and the present invention is not limited to the embodiments described below. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a diagram showing a schematic view of an underwater detection device according to a first embodiment, which is used to search underwater. [Figure 2] FIG. 2 is a diagram schematically showing how underwater is searched by the underwater detection device according to the first embodiment. [Figure 3] FIG. 3 is a block diagram showing the configuration of the fish quantity information display system according to the first embodiment. [Figure 4] FIG. 4 is a block diagram showing the configuration of the underwater detection device according to the first embodiment. [Figure 5] FIG. 5 is a diagram schematically showing an example of an echo image displayed on the display unit of the underwater detection device according to the first embodiment. [Figure 6] FIG. 6 is a diagram schematically illustrating the propagation state of a transmission pulse and its reflected wave (reflected pulse) along one beam axis according to the first embodiment. [Figure 7] 7(a) and 7(b) are diagrams schematically showing an orthogonal coordinate system with two axes representing the beam number and the sample number according to the first embodiment. [Figure 8] FIG. 8 is a flowchart showing the process of receiving the fish quantity correction magnification according to the first embodiment. [Figure 9] FIG. 9 is a diagram showing an example of a fish quantity correction magnification acceptance screen according to the first embodiment. [Figure 10] FIG. 10 is a flowchart showing the fish quantity index transmission process according to the first embodiment. [Figure 11] FIG. 11 is a block diagram showing the configuration of a plotter device according to the first embodiment. [Figure 12] FIG. 12 is a flowchart showing the fish quantity index display process according to the first embodiment. [Figure 13] FIG. 13 is a diagram schematically illustrating an example of a plotter image including fish quantity information based on fish quantity indices according to the first embodiment. [Figure 14] FIG. 14 is a diagram showing an example of a fish quantity calculation region reception screen according to the first embodiment. [Figure 15]FIG. 15 is a diagram schematically showing an example of a plotter image including fish quantity information based on fish quantity indices, according to the first modification of the first embodiment. [Figure 16] FIG. 16 is a diagram schematically showing an example of a plotter image including fish quantity information based on a fish quantity index, according to the second modification of the first embodiment. [Figure 17] FIG. 17 is a diagram schematically showing an example of a plotter image including fish quantity information based on a fish quantity index, according to the third modification of the first embodiment. [Figure 18] FIG. 18 is a block diagram showing the configuration of a fish quantity information display system according to the second embodiment. [Figure 19] FIG. 19 is a block diagram showing the configuration of a plotter device according to the second embodiment. [Figure 20] FIG. 20 is a diagram showing an example of a plotter image including fish quantity information based on fish quantity indices and target images based on radar information according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For convenience, mutually orthogonal X, Y, and Z axes are indicated in the drawings as appropriate. The X-axis and Y-axis directions are horizontal, and the Z-axis direction is vertical. The positive X-axis direction is the direction in which the ship moves.

[0038] <Embodiment 1> 1 and 2 are diagrams that schematically show how underwater detection is performed by an underwater detection device 100. FIG.

[0039] In FIGS. 1 and 2, φ is the azimuth angle centered on the transducer 103 installed on the bottom of the ship S1, and θ is the tilt angle of a scanning plane SP1 (to be described later) relative to the horizontal plane (XY plane).

[0040] The underwater detection device 100 includes a transducer 103 installed on the bottom of a vessel S1 such as a fishing boat. The underwater detection device 100 transmits a pulse of sound waves (transmission pulse) from the transducer 103, and receives sound waves (echoes) reflected (backscattered) by objects such as fish present in the water with the same transducer 103. The underwater detection device 100 detects objects present in the water based on the echoes received by the transducer 103.

[0041] The transducer 103 is equipped with a large number of ultrasonic transducers. When transmitting, each ultrasonic transducer converts an input electrical signal into a sound wave and emits it, and when receiving, it converts the incident sound wave into an electrical signal and outputs it. Typically, the transducer 103 is cylindrical, with several hundred ultrasonic transducers regularly arranged on its side.

[0042] Here, the area to be detected by the underwater detection device 100 is a conical surface. The axis of this conical surface coincides with the central axis (here, the Z axis) of the transducer 103. This conical surface is called the scanning surface SP1, and the apex and axis of this scanning surface SP1 are called the origin and the scanning axis, respectively. The origin coincides with the position of the transducer 103, and the scanning axis extends vertically downward from this origin. Here, the scanning axis coincides with the Z axis. The angle that the scanning surface SP1 makes with the horizontal plane (XY plane) is the tilt angle θ described above.

[0043] As shown in Fig. 1, the underwater sounding device 100 transmits a transmission beam TB1 having the maximum intensity on the scanning plane SP1 over the entire circumference during transmission. This transmission beam TB1 has an intensity distribution that is symmetrical with respect to the scanning axis (Z-axis in Fig. 1), and its width in the vertical direction is relatively narrow.

[0044] 2, the underwater detection device 100 forms multiple reception beams RB1 with maximum sensitivity on the scanning plane SP1 during wave reception. The reception beams RB1 are formed by applying beamforming processing to the electrical signals output from multiple ultrasonic transducers arranged in the transducer 103.

[0045] Each receive beam RB1 is a pencil beam with a narrow width in both the vertical and horizontal directions, and has the same directivity. The beam axis of each receive beam RB1 is a straight line that passes through the origin and points in the direction where the sensitivity of the receive beam RB1 is maximum. Multiple receive beams RB1 are formed in a line at regular angular intervals in the direction of the azimuth angle φ around the entire circumference of the scan plane SP1. The underwater sounding device 100 converts the intensity of the sound waves received by each receive beam RB1 into color and displays it as an image (echo image).

[0046] FIG. 3 is a block diagram showing the configuration of the fish quantity information display system 10.

[0047] In the first embodiment, the fish quantity information display system 10 is configured by the underwater detection device 100 and the plotter device 200 described above.

[0048] As described above, the underwater detection device 100 detects schools of fish by scanning the receiving beam RB1 along the conical scanning surface SP1. The underwater detection device 100 calculates a fish abundance index based on the electrical signals output from the multiple ultrasonic transducers arranged in the transducer 103, and transmits the calculated fish abundance index to the plotter device 200.

[0049] The plotter device 200 is equipped with a GPS antenna 200a, which receives radio waves transmitted from GPS satellites to obtain the ship's position on Earth. The plotter device 200 displays the ship's current position and the track to the current position superimposed on a nautical chart and map of the area around the ship. Furthermore, the plotter device 200 displays fish quantity information corresponding to the fish quantity index received from the underwater detection device 100 in association with the ship's track.

[0050] A method for calculating fish quantity indices in the underwater detection device 100 will be explained later with reference to Figures 6 to 9. A method for displaying fish quantity information in the plotter device 200 will be explained later with reference to Figures 12 and 13.

[0051] FIG. 4 is a block diagram showing the configuration of the underwater detection device 100.

[0052] The underwater detection device 100 comprises a control unit 101, a memory unit 102, a transducer 103, a transmission processing unit 104, a reception processing unit 105, a transmission / reception switching unit 106, a display unit 107, a display processing unit 108, an input unit 109, an input processing unit 110, and a communication unit 111. The transducer 103 is installed on the bottom of the ship S1 as described above, and the other components such as the control unit 101 are installed in the wheelhouse or the like of the ship S1.

[0053] The control unit 101 includes an arithmetic processing circuit such as a CPU (Central Processing Unit), and executes the control processing described below using programs stored in the storage unit 102. The storage unit 102 includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a hard disk. The storage unit 102 stores programs for the control unit 101 to execute the control processing.

[0054] As described above, the transducer 103 includes a plurality of ultrasonic transducers 103a. In each transmission and reception period (ping), the transducer 103 transmits an ultrasonic wave as the transmission beam TB1 in FIG. 1, and receives the reflected wave at each ultrasonic transducer.

[0055] The transmission processing unit 104 outputs a transmission signal for transmitting ultrasonic waves to the transducer 103 via the transmission / reception switching unit 106 in accordance with control from the control unit 101. The transmission signal is a signal that vibrates at a predetermined amplitude for a fixed period of time, as shown in FIG. 4. During one transmission of the transmission beam TB1, this transmission signal is supplied to each ultrasonic transducer 103a of the transducer 103 via the transmission / reception switching unit 106. As a result, as shown in FIG. 4, ultrasonic waves corresponding to the transmission signal are transmitted from each ultrasonic transducer 103a. The ultrasonic pulse transmitted during one transmission is called a transmission pulse.

[0056] The reception processing unit 105 receives, via the transmission / reception switching unit 106, the electrical signals output by each ultrasonic transducer 103a of the transmitter / receiver 103 after receiving reflected ultrasonic waves, and performs amplification and noise removal (bandpass filter) processing on the received electrical signals. The reception processing unit 105 outputs the electrical signals that have undergone these processes to the control unit 101.

[0057] When transmitting the transmission beam TB1, the transmission / reception switching unit 106 outputs the transmission signal output from the transmission processing unit 104 to the transmitter / receiver 103 (ultrasonic vibrator 103a), and outputs the electrical signal output from the transmitter / receiver 103 (ultrasonic vibrator 103a) to the reception processing unit 105 for a certain period of time from the timing when the transmission of the transmission beam TB1 is completed.

[0058] 4 shows one transmission processing unit 104 and one reception processing unit 105, the above-described processing in the transmission processing unit 104 and the reception processing unit 105 is performed for each ultrasonic transducer 103a arranged in the transducer 103. Therefore, the electrical signals output from each ultrasonic transducer 103a are amplified and subjected to noise removal processing, and the resulting electrical signals are individually input to the control unit 101. When these electrical signals are input to the control unit 101, they are converted by an A / D converter into digital signals with a predetermined sampling period.

[0059] The display unit 107 includes a display device such as a liquid crystal display. The display processing unit 108 displays a predetermined image on the display unit 107 in response to control from the control unit 101. The input unit 109 includes input means such as operation keys and a mouse. The input processing unit 110 outputs a signal corresponding to an operation on the input unit 109 to the control unit 101 in response to control from the control unit 101. The display unit 107 and the input unit 109 may be configured as a liquid crystal panel in which a touch panel is superimposed on a liquid crystal display. The communication unit 111 communicates with the plotter device 200 in response to control from the control unit 101.

[0060] In this embodiment, the functions of a received signal generating unit 101a, an image generating unit 101b, a fish quantity index calculating unit 101c, a correction value receiving processing unit 101d, and a target area receiving processing unit 101e are given to the control unit 101 by a program stored in the memory unit 102.

[0061] The reception signal generation unit 101a performs beamforming on the electrical signals (digital signals) output from each ultrasonic transducer 103a to form the reception beam RB1 shown in Fig. 2, and generates reception signals corresponding to sound waves incident on the transducer 103 from the beam axis direction of each reception beam RB1 (the direction of a predetermined azimuth angle φ and tilt angle θ). Furthermore, the reception signal generation unit 101a performs band limitation and envelope detection processing on the reception signals in each beam axis direction to acquire envelope signals in each beam axis direction.

[0062] Here, the band limiting process is a process for extracting frequency components of the transmission signal output from the transmission processing unit 104. This process is performed when the transmission signal output from the transmission processing unit 104 is a signal with a constant frequency (CW signal).

[0063] On the other hand, when the transmission signal output from the transmission processing unit 104 is not a signal with a constant frequency (CW signal) but a frequency-modulated chirp signal (FM signal), the reception signal generation unit 101a performs matched filter processing on the reception signal in each beam axis direction instead of band-limiting processing.The reception signal generation unit 101a then performs envelope detection processing on the signal after matched filter processing to obtain an envelope signal in each beam axis direction.

[0064] The envelope signal thus acquired is a signal indicating echo intensity (sound wave strength) that changes according to the time elapsed since the transmission timing of the transmission beam TB1 (ultrasound wave). Here, the time elapsed since the transmission timing corresponds to the distance from the transducer 103 in each beam axis direction. The control unit 101 associates the time elapsed since the transmission timing with the distance, thereby acquiring the echo intensity at each distance position in each beam axis direction from the echo signal of each reception beam. The echo intensity is acquired with a predetermined distance resolution.

[0065] The image generator 101b generates an echo image that displays the echo intensity at each distance position in each beam axis direction on a predetermined color scale. The image generator 101b sequentially outputs the echo images generated for each ping to the display processor 108. As a result, the echo images updated for each ping are displayed on the display unit 107.

[0066] FIG. 5 is a diagram schematically showing an example of an echo image displayed on the display unit 107. As shown in FIG.

[0067] In the mode for displaying an echo image, the screen of the display unit 107 is divided into left and right areas A1 and A2. Of these, an echo image P10 is displayed in area A1. Here, the echo image P10 is displayed as an image of the ship S1 as seen from directly above. An image P11 of the ship S1 is placed in the center of the echo image P10, and furthermore, a track P12 of the ship S1 thus far is shown. Also included in the echo image P10 is a straight line P13 indicating the direction of the ship's bow.

[0068] Furthermore, in the echo image P10, a range within a certain distance from the position of the ship (image P11) is indicated by circular boundary lines P14, P15, and P16. The diameters of the boundary lines P14, P15, and P16 are, for example, 200 m, 400 m, and 600 m. In the echo image P10, the above-mentioned echo intensity is displayed using a predetermined color scale. For convenience, in FIG. 5, ranges with high echo intensity are hatched. For example, the hatched range P17 is a range with high echo intensity. The hatched range is a range where a school of fish may be present.

[0069] Area A2 is divided vertically into multiple sections, and each section displays the water temperature at the current location and a graph showing changes in water temperature over time. For convenience, these images are omitted from Figure 5 in area A2.

[0070] By referring to the echo image P10, users such as fishermen can ascertain the presence of a school of fish around the vessel S1. The echo image P10 in FIG. 5 displays the echo intensity of a so-called layered school of fish. That is, a school of fish may form a narrow layer in the vertical direction and be widely distributed horizontally. Furthermore, individual fish in this school may swim with their heads facing in roughly the same direction. Such a school is called a layered school of fish.

[0071] When the vessel S1 is positioned above the layered fish school, the echo image P10 shows an echo intensity pattern known as an "eight pattern," as shown in Figure 5. In the example of Figure 5, it can be estimated that the individual fish making up the layered fish school are pointing their heads almost parallel to the vessel's heading. That is, in this case, on the starboard and port sides of the vessel S1, the ultrasonic waves transmitted from the transducer 103 strike the sides of the fish perpendicularly, so the reflected waves (backscattered waves) from the fish are relatively strong. On the other hand, on the bow and stern sides of the vessel S1, the sound waves strike the fish parallel to their sides, so the reflected waves from the fish are weaker. Therefore, in this case, the echo image P10 shows clear responses from the fish school in two regions symmetrically positioned on the left and right of the vessel, as shown in Figure 5.

[0072] This phenomenon is well known to fishermen, who can estimate the amount of fish caught (in tons) from such figure-eight responses.

[0073] However, it is difficult for inexperienced fishermen to make this estimation properly. Even experienced fishermen find it difficult to concentrate on this estimation while steering. These problems can be solved by adding a function to the underwater detection device 100 that not only displays the echo image P10 but also estimates the total weight of fish present within the detection range and displays it on the plotter device 200.

[0074] The calculation formula for this estimation generally includes parameters related to the transmission and reception of waves by the underwater detection device 100, as well as parameters such as the target strength of a single fish. However, it is usually difficult for fishermen to grasp these parameters. Furthermore, the target strength of a single fish varies depending on the fish species, and may also change depending on the sea area and season. Therefore, it is extremely difficult for fishermen to appropriately input these parameters into the underwater detection device 100 to accurately estimate the catch.

[0075] To solve this problem, in this embodiment, the underwater detection device 100 is equipped with a function that enables smooth and accurate estimation of the fish catch. This function is executed by the fish quantity index calculation unit 101c, correction value reception processing unit 101d, and target area reception processing unit 101e shown in Figure 4. These processes will be described below.

[0076] <Fish quantity index calculation part> The fish quantity index calculation unit 101c calculates a fish quantity index that can be used as an index of the total weight of fish contained in the target area based on the electrical signals output from the multiple ultrasonic transducers 103a installed in the transducer 103. The fish quantity index is calculated using a predetermined calculation formula. The process of deriving this calculation formula will be explained below, showing various parameters.

[0077] (1) Target Strength The strength of the sound waves reflected by a fish is expressed as target strength. Target strength is defined as the ratio of the strength of the reflected wave at a unit distance from the object to the strength of the sound wave incident on the object (the former divided by the latter). In the following, unit distance is represented by r0, which is defined as 1 m.

[0078] (2) False targets and false fish quantities The average weight and target strength of each individual fish contributing to the generation of the echo image P10 are denoted as W and T, respectively. sWhen the weight and target strength are expressed as average values ​​W and T, respectively, s A point target equal to is called a false target.

[0079] Here, we assume that it is possible to generate "echoes identical to those generated by the fish that contribute to generating the echo image P10" by placing any number of pseudo targets at any position on the scanning plane SP1 in Figures 1 and 2. The sum of the weights of these pseudo targets is called the pseudo fish volume corresponding to the sonar response.

[0080] (3) Formulation of pseudo fish quantity (3-1) Target Strength T s Formula The relationship between the intensity of the sound transmitted by the transducer 103 and the received signal resulting from a "dummy target located on the beam axis" will be explained below along the propagation process of the sound waves. Here, the distance r between the transducer 103 and the dummy target is t is assumed to be sufficiently large compared to the size of the transducer 103.

[0081] First, consider the sound pressure of the transmitted pulse at a position r0 away from the origin of the scanning plane SP1 in Figure 1. Generally, sound intensity is defined as the energy passing through a unit area per unit time, and is proportional to the square of the effective value of the sound pressure. The amplitude of the sound pressure of the transmitted pulse increases from zero, reaches a maximum, and then decays back to zero. Therefore, the maximum intensity of the transmitted pulse is proportional to the square of the effective value of the sound pressure at the time when the amplitude reaches its maximum.

[0082] In the following, we define the intensity of the acoustic pulse as this square value, and assume that the sound pressure varies as a sine wave in any one cycle of the transmitted pulse. With these definitions and assumptions, the intensity I0 of the transmitted pulse is determined by the maximum value of its sound pressure amplitude P max As a result, I0=P 2 max / 2. In the following, 1 μPa (micropascal) will be used as the unit of sound pressure.

[0083] FIG. 6 is a diagram schematically showing the propagation state of a transmission pulse and its reflected wave (reflected pulse) along one beam axis.

[0084] The transmitted pulse is attenuated by spherical divergence and absorption while propagating from the origin to the pseudo target. If the absorption coefficient (the degree of attenuation of sound waves per unit distance) is α [dB / m], the intensity I1 of the transmitted pulse incident on the pseudo target is expressed by the following equation:

[0085]

number

[0086] This pulse is reflected by the false target and propagates toward the origin as a reflected pulse. The intensity I2 of the reflected pulse at a position a unit distance r0 away from the false target is calculated as the target strength T s By the definition of

[0087]

number

[0088] The intensity of the reflected pulse incident on the transducer 103 is expressed by the following equation, similar to the above equation (1).

[0089]

number

[0090] As described above, in the underwater detection device 100, the receiving processing unit 105 in FIG. 4 amplifies the electrical signal from the ultrasonic transducer 103a using an amplifier and band-limits it using an analog filter. Next, the underwater detection device 100 samples this processed signal using an A / D converter when it is input to the control unit 101 to generate a digital signal. The underwater detection device 100 then forms a receiving beam RB1 from the digital signal corresponding to a predetermined group of ultrasonic transducers, and generates a signal (received signal) corresponding to the sound waves received by the transducer 103 via each receiving beam RB1. After processing each received signal using a band-limiting filter, pulse compression filter, etc., the underwater detection device 100 generates an envelope signal, which is a signal equal to the instantaneous amplitude of the received signal. Hereinafter, this envelope signal will be treated as a dimensionless quantity.

[0091] The sound pressure waveform of the acoustic pulse signal incident on the transducer 103 is distorted during the process of conversion into an electric signal and subsequent processing. However, since these conversions and processing can generally be assumed to be linear and time-invariant, the ratio of the maximum value of the instantaneous amplitude of the acoustic pulse signal to the maximum value of the envelope signal is proportional to the distance r to the pseudo target. t and target strength T of the pseudo target s Hereinafter, this ratio (latter divided by former) will be referred to as receiver sensitivity, and will be represented by the parameter k. The unit of receiver sensitivity is 1 / μPa.

[0092] The maximum value A of the envelope signal of the reflected pulse when it enters the transducer 103 max and the reflected pulse intensity I3 are related by the following equation:

[0093]

number

[0094] This is called Target Strength T s Solving for, we obtain the following equation:

[0095]

number

[0096] (3-2) Normalized amplitude data Each receive beam RB1 is assigned a beam number j according to the azimuth angle φ of its beam axis. For example, the beam number j of the receive beam RB1 pointing toward the stern in a planar view is set to j=0, and further, with the clockwise direction in a planar view being positive, each receive beam RB1 is assigned a beam number j=1, 2, 3, ... in order of increasing angle between the stern direction (reference direction) and the beam axis direction. In this case, if the total number of receive beams RB1 is 128, the beam numbers j of the receive beams RB1 pointing toward the port direction, bow direction, and starboard direction are 32, 64, and 96, respectively.

[0097] Furthermore, a sample number n is assigned to each sampling time of the envelope signal in chronological order. The time when transmission of the transmission beam TB1 starts, i.e., the moment when the leading edge of the transmission pulse is emitted from the transducer 103, is set as the reference time, and the sample number at this time is set as n=0.

[0098] The envelope signal obtained by one wave transmission is composed of a plurality of digital data pieces obtained by the above sampling. The sampling period for this sampling may be the same as the sampling period of the A / D converter described above, or may be different from this sampling period.

[0099] When data generated by receiving beam RB1 with beam number j and sample number n is represented by A(j,n), A'(j,n) defined by the following equation is referred to as normalized amplitude data.

[0100]

number

[0101] where r n is the time t when the nth data is sampled. n is the distance from the origin to the position corresponding to rn When there is a false target at the position of , the leading edge of the reflected pulse from this false target is sampled as the nth data. Let the sampling frequency be f s Then, t n =n / f s Therefore, if the speed of sound wave propagation is c, then r n is defined as follows:

[0102]

number

[0103] If the time width (pulse width) of the transmitted pulse is τ, the time when the trailing edge of the reflected pulse is sampled is t n +τ, and the distance from the origin of the corresponding position is r n +(cτ / 2). In the following, we assume that the difference between these distances is sufficiently small compared to the distance from the origin to the pseudo target. That is, we assume the following relationship:

[0104]

number

[0105] At this time, as can be seen from equations (5) and (6), the maximum value A' of the normalized amplitude data A'(j,n) max The squared value of is the target strength T s matches.

[0106]

number

[0107] (3-3) Amplitude data space Here, we define an orthogonal coordinate system with the beam number j and sample number n as its two axes. Figures 7(a) and 7(b) are diagrams that schematically show this orthogonal coordinate system. For convenience, Figures 7(a) and 7(b) show a 17 × 17 grid (cells), but the actual number of grids (cells) is significantly greater than this.

[0108] The position of each grid (cell) on the vertical and horizontal axes indicates the position of the respective numbers on the vertical and horizontal axes. Since the numbers on the vertical and horizontal axes increase by one, the vertical and horizontal widths of each cell are both 1. With the horizontal axis coordinate representing the beam number j and the vertical axis coordinate representing the sample number n, the cell located at point (j,n) is assigned the normalized amplitude data A'(j,n) described above. The set of normalized amplitude data arranged in this manner is called the amplitude data space. In contrast, the underwater space that is the detection target of the underwater detection device 100 is called the real space.

[0109] (3-4) Point spread coefficient Assume that there is a false target at a position in real space corresponding to point P1 in Figure 7(a). In this case, normalized amplitude data resulting from this false target (target) occurs behind point P1 in the amplitude data space (upper side in Figure 7(a)). In Figure 7(a), these cells are indicated by hatching. This region (region in the amplitude data space) where normalized amplitude data resulting from the target occurs is called the echo region.

[0110] The vertical width of the echo region is determined by the time width of the transmit pulse. The horizontal width of the echo region is determined by the beam width of the receive beam. The normalized amplitude data value of each cell in the echo region generally takes a non-uniform value depending on the envelope waveform of the transmit pulse and the beam pattern of the receive beam.

[0111] For any cell in the echo region, the squared value of the normalized amplitude data is the target strength T s Therefore, the sum of the squared values ​​of the normalized amplitude data in the echo region is also proportional to the target strength T s is proportional to.

[0112] Here, the target strength T sConsider a point target where V is 1. By the definition of normalized amplitude data, the maximum value of normalized amplitude data resulting from this target is 1. The sum of the squared values ​​of this normalized amplitude data is called the point spread coefficient, and is defined as V unit It is expressed as:

[0113] The proportional relationship mentioned above and the point spread coefficient V unit From the definition of

[0114] (Lemma A) For a single false target, the sum of the squared values ​​of its normalized amplitude data is taken as the point spread coefficient V unit The quotient obtained by dividing by is the target strength T of the pseudo target. s is equal to.

[0115] (3-5) Target Strength T s The sum of As shown in Figure 7(b), we consider the case where two false targets exist in the Cartesian coordinate system that defines the amplitude data space, and the echo areas generated by these false targets partially overlap. We focus on one cell included in this overlap. In Figure 7(b), this cell is filled in black.

[0116] In addition, the following discussion will be made with the received signal as a complex envelope signal. When a false target exists at only one of points P1 and P2, the complex envelope generated in this black cell is defined as A1e +jθ1 , A2e +jθ2 The instantaneous amplitude when both exist simultaneously is A 12 Then, the squared value is expressed by the following equation:

[0117]

number

[0118] The distance between the transducer 103 and each individual fish changes between the time when the underwater detection device 100 transmits a transmission pulse and the time when it transmits the next pulse. The amount of this change can be assumed to vary randomly, exceeding approximately 1 / 4 of the wavelength of the transmitted wave. Therefore, the average value A of the squared value of the instantaneous amplitude obtained by multiple transmissions is 2 av If we calculate the value, it will be approximately A1 2 +A2 2 Matches.

[0119]

number

[0120] Similarly, when the echo areas of any number of false targets overlap, the following relationship holds:

[0121] (Lemma B) The squared values ​​of normalized amplitude data at coordinates where echoes from multiple false targets overlap, averaged over multiple transmissions, is approximately equal to the sum of the squared values ​​of normalized amplitude data generated by each false target.

[0122] From the above Lemma A and Lemma B, the following relationship can be obtained:

[0123] (theorem) In the region that includes all echoes from the false target group (the region in the amplitude data space), the sum of the squared values ​​of the normalized amplitude data is calculated as the point spread coefficient V unit The quotient is divided by , and averaged over multiple transmissions, and is approximately equal to the total target strength Ts of the group of pseudo targets.

[0124] (3-6) Calculation formula for pseudo fish quantity As can be seen from the definition of the pseudo fish quantity and the above theorem, in order to obtain the pseudo fish quantity, Q defined by the following equation q may be averaged over multiple transmissions of the transmit pulse.

[0125]

number

[0126] The symbol Σ in equation (12) means the sum of all pairs of (j, n) that are the processing targets in one ping of transmitted and received waves.

[0127] (4) Definition formula for fish abundance index In the above equation (12), the strength of the transmitted pulse I0 and the square of the receiving sensitivity k 2 is a parameter specific to each underwater detection device 100, and its accurate value is difficult for ordinary fishermen to obtain. s The value of is calculated by substituting the body length of the fish caught into an empirical formula, but this calculation is not easy for ordinary fishermen. On the other hand, it is easy for fishermen to roughly estimate the amount of fish caught (in tons).

[0128] 4 calculates the fish quantity index Q, defined by the following equation, as an approximation of the pseudo fish quantity: Then, the fish quantity index calculation unit 101c transmits the calculated value of fish quantity index Q, or a value obtained by averaging the values ​​of fish quantity index Q over multiple transmissions, to the plotter device 200, and causes the plotter device 200 to display it.

[0129]

number

[0130] The coefficient C0 is W / (2I0·k 2 T s ) are approximate values ​​for W and T for representative fish. s The value may be a value obtained by substituting the value of I0 and k for the underwater detection device 100 and the design values ​​of I0 and k, or a value determined in advance so that the fish quantity index Q closely matches the catch amount estimated by the fisherman or the actual catch amount.

[0131] Coefficient C cor is the fish abundance correction coefficient. This fish abundance correction coefficient C corThe fish quantity correction factor C is reflected in the fish quantity index calculation unit 101c until the fish quantity correction factor is first input. cor is set to an initial value of 1, and the fish quantity index Q is calculated. In addition, the fish quantity index calculation unit 101c calculates the fish quantity correction coefficient C cor The value of is updated using the following formula:

[0132] “New C cor ” = “Fish amount correction magnification” × “Old C cor " That is, the fish quantity index calculation unit 101c calculates the fish quantity correction coefficient C immediately before the correction magnification is input. cor The new fish quantity correction coefficient C is calculated by multiplying this by the fish quantity correction factor. cor The fish abundance index Q is calculated as follows.

[0133] In this way, the fish quantity correction factor input by the user is the fish quantity correction coefficient C cor By reflecting this in the calculation formula (13) for the fish quantity index Q, the formula (13) can be corrected to approach the actual catch amount based on the input fish quantity correction factor. Therefore, by repeatedly inputting the fish quantity correction factor, the user can bring the fish quantity index Q closer to the fish quantity that corresponds to their own rough estimate. Therefore, fish quantity information based on the fish quantity index Q that corresponds to the user's fishing ground, fish species, and season can be displayed smoothly and appropriately on the plotter device 200.

[0134] The above formula (13) is stored in the storage unit 102 of FIG. 4, and the updated fish quantity correction coefficient C cor The control unit 101 updates and stores the above equation (13) and the updated fish quantity correction coefficient C cor The fish quantity index calculation unit 101c uses the above to calculate the fish quantity index Q and transmits it to the plotter device 200, and causes the plotter device 200 to display fish quantity information related to the fish quantity index Q. This process will be described later with reference to FIGS. 10 and 12.

[0135] (5) Point spread coefficient V unitFormula for Below, the point spread coefficient V unit We will provide additional information on the calculation formula.

[0136] The pulse width of the transmission pulse, the beam width of the reception beam, and the tilt angle are represented by τ, ψ, and θ, respectively. Here, the beam width ψ is defined as "the beam width in the plane tangent to the scanning plane SP1 on the beam axis," and it is assumed that the beam width ψ does not depend on the tilt angle θ. The sampling frequency f s , the pulse width τ and the beam width ψ are arbitrarily chosen as reference values, respectively. s0 , τ0 and ψ0. The point spread coefficient V at the tilt angle θ = 0° corresponding to these reference values ​​is unit The value of is represented as V0.

[0137] In this case, any f s , τ, ψ, θ, the point spread coefficient V unit is expressed by the following equation:

[0138]

number

[0139] For example, the sampling interval (1 / f s ) is proportional to the pulse width τ of the transmitted pulse, and the beam width of the received beam can only take on values ​​of ψ0, then the point spread coefficient V unit is a function of θ, V unit =V0 / cosθ.

[0140] (6) Setting the fish quantity correction factor 8 is a flowchart showing the process of receiving the fish quantity correction factor. This process is performed by the control unit 101 using the function of the correction value reception processing unit 101d in FIG.

[0141] If the fish quantity index calculated by the above formula (13) differs from the total weight of the fish that the user actually caught, the user inputs an instruction to input a fish quantity correction factor via the input unit 109 in order to correct this discrepancy. In response to this instruction, the control unit 101 displays a correction factor acceptance screen on the display unit 107 for inputting the fish quantity correction factor, and accepts the input of the fish quantity correction factor from the user (S11).

[0142] FIG. 9 is a diagram showing an example of the fish quantity correction magnification reception screen 300.

[0143] The fish quantity correction magnification reception screen 300 includes a rectangular magnification input area 301, a button 302 for confirming the input, and a button 303 for returning to the previous screen. When the user clicks on the magnification input area 301 via the input unit 109, a drop-down display of magnification selection options is displayed below the magnification input area 301, arranged vertically. The selection options are, for example, values ​​ranging from 0.1 to 2.0 in increments of 0.1. The user selects the desired magnification from the displayed selection options. The selected magnification is then displayed in the magnification input area 301. In the example of FIG. 9, a magnification of 1.1 has been selected.

[0144] The user can change the fish quantity correction magnification by clicking magnification input area 301 again. After inputting the fish quantity correction magnification in this way, the user clicks button 302. This confirms the input of the fish quantity correction magnification. If the user clicks button 303 without clicking button 302, the input operation of the fish quantity correction magnification is canceled.

[0145] Returning to FIG. 8, when the user confirms the input of the fish quantity correction factor (S12: YES), the control unit 101 resets the fish quantity correction factor C cor The value obtained by multiplying this by the input fish quantity correction factor is the new fish quantity correction coefficient C cor (S13). As a result, the fish quantity correction coefficient C cor On the other hand, if the user cancels the input operation without finalizing the input of the fish quantity correction factor (S12: NO), the control unit 101 updates the fish quantity correction factor Ccor The process of FIG. 8 ends without updating.

[0146] <Display of fish abundance index> 10 is a flowchart showing the process of transmitting the fish quantity index. This process is performed by the control unit 101 using the functions of the fish quantity index calculation unit 101c and the communication unit 111 in FIG.

[0147] When the display process of the fish quantity index is started, the control unit 101 calculates the fish quantity correction coefficient C cor It is determined whether the fish quantity correction coefficient C has been updated (S21). cor If the fish quantity correction coefficient C is updated (S21: YES), the control unit 101 cor is set in the above equation (13) (S22). cor If the value has not been updated (S21: NO), the control unit 101 skips step S22 and advances the process to step S23.

[0148] After that, when the wave transmission / reception period (one ping) ends and the data necessary for calculating the fish quantity index Q is collected (S23: YES), the control unit 101 uses the function of the fish quantity index calculation unit 101c to calculate the fish quantity index Q using the above formula (13) (S24).The control unit 101 then transmits the calculated fish quantity index Q to the plotter device 200 via the communication unit 111 (S25).

[0149] When the processing for this ping is thus completed, the control unit 101 determines whether the operation for displaying fish quantity information related to the fish quantity index Q on the plotter device 200 has been completed by a user operation (S26). If this display operation has not been completed (S26: NO), the control unit 101 returns the process to step S21 and executes the same process. In parallel with the process of FIG. 10, the process of FIG. 8 is executed to calculate the fish quantity correction coefficient C cor If updated (S21: YES), the updated fish quantity correction coefficient C cor is applied to the above equation (13) (S22), and the processes from step S23 onwards are executed.

[0150] In this way, the control unit 101 repeatedly executes the processes of steps S21 to S25 until the display operation of the fish quantity information related to the fish quantity index Q is completed (S26: NO). This causes the display of the fish quantity information related to the fish quantity index Q to be updated for each ping. Thereafter, when this display operation is completed (S26: YES), the control unit 101 ends the process of FIG. 10.

[0151] Next, the configuration and operation of the plotter device 200 will be described.

[0152] FIG. 11 is a block diagram showing the configuration of the plotter device 200.

[0153] In addition to the GPS antenna 200a, the plotter device 200 includes a control unit 201, a memory unit 202, a GPS receiver 203, a display unit 204, a display processing unit 205, an input unit 206, an input processing unit 207, and a communication unit 208. The main components of the plotter device 200 are installed in the wheelhouse or the like of the ship S1, and communicate with the underwater detection device 100 via the communication unit 208.

[0154] The control unit 201 includes a processing circuit such as a CPU, and executes the control processing described below using programs stored in the storage unit 202. The storage unit 202 includes storage media such as a ROM, a RAM, and a hard disk. The storage unit 202 stores programs for the control unit 201 to execute the control processing, and also stores data for displaying nautical charts and maps.

[0155] The GPS receiver 203 calculates the ship's position (latitude, longitude) on the earth based on radio waves received from GPS satellites via the GPS antenna 200 a, and outputs the calculated ship's position to the control unit 201.

[0156] The display unit 204 includes a display device such as a liquid crystal display. The display processing unit 205 displays a predetermined image on the display unit 204 in response to control from the control unit 201. The input unit 206 includes input means such as operation keys or a trackball. The input processing unit 207 outputs a signal corresponding to an operation on the input unit 206 to the control unit 201 in response to control from the control unit 201. The display unit 204 and the input unit 206 may be configured as a liquid crystal panel in which a touch panel is superimposed on a liquid crystal display. The communication unit 208 communicates with the underwater detection device 100 in response to control from the control unit 201.

[0157] In this embodiment, the function of the fish quantity display superimposition unit 201a is imparted to the control unit 201 by a program stored in the memory unit 202. The control unit 201 generates a plotter image in which the position and track of the ship are superimposed on the surrounding nautical charts and maps based on the ship's position sequentially input from the GPS receiver 203 and the nautical chart and map data stored in the memory unit 202, and displays the plotter image on the display unit 204. The fish quantity display superimposition unit 201a displays fish quantity information based on the fish quantity index received from the underwater detection device 100 via the communication unit 208 in association with the track on the plotter image.

[0158] 12 is a flowchart showing the process of displaying the fish quantity indicator. This process is performed by the control unit 201 using the function of the fish quantity display superimposition unit 201a in FIG.

[0159] 10 (S31: YES), the control unit 201 associates the received fish quantity index with the ship's current position input from the GPS receiver 203 and stores the associated fish quantity index in the memory unit 202 (S32). If a new display position where fish quantity information should be displayed arises due to the ship's progress (S33: YES), the control unit 201 displays the fish quantity information based on the fish quantity index of the new display position in association with the ship's current position on the track (S34).

[0160] Here, the display positions are set, for example, at regular distance intervals on the ship's wake. These distance intervals may be changed depending on the magnification (scale) of the plotter image. The display positions may also be set at regular time intervals on the ship's wake. In this case, the time intervals may also be changed depending on the magnification of the plotter image. The distance intervals and time intervals can be adjusted so that the fish quantity information is displayed at intervals that are easy to see on the plotter image.

[0161] The fish quantity information displayed at each display position is generated to reflect the value of the fish quantity index associated with each display position and stored in the storage unit 202. Alternatively, the fish quantity information may be generated from the value of the fish quantity index associated with each display position and a nearby position on the ship track.

[0162] In this case, for example, a representative value (such as the average, median, or mode) of the fish quantity index value at the target display position and the values ​​of multiple fish quantity indexes linked to positions on the wake that are within a distance range smaller than the distance interval in the forward and backward directions of the wake relative to the target display position is calculated, and fish quantity information for the display position is generated to reflect this representative value. Here, the distance range can be set to, for example, about half the distance interval.

[0163] Alternatively, instead of this method, for example, a representative value (such as the average, median, or mode) of the fish quantity index value at the display position of the target and the fish quantity index value linked to a position on the track between the display position of the target and its immediately preceding display position may be calculated, and fish quantity information for the display position may be generated to reflect this representative value.

[0164] Furthermore, in these two methods of generating fish quantity information, an integrated value of the fish quantity index values ​​may be calculated instead of the representative value, and the fish quantity information for the display position may be generated to reflect this integrated value.

[0165] The control unit 201 repeatedly executes the processes of steps S31 to S34 until the plotter device 200 finishes displaying the fish quantity information (S35: NO). As a result, the position and track of the ship are updated, and the fish quantity information is displayed in association with each display position on the updated track.

[0166] The start and end of the fish quantity information display operation is instructed, for example, by the user via the input unit 206. The control unit 201 starts the processing of Figure 12 in response to an instruction to start the fish quantity information display operation, and ends the processing of Figure 12 in response to an instruction to end the fish quantity information display operation (step S35: YES). Instructions to start and end the fish quantity information display operation are transmitted to the underwater detection device 100 via the communication unit 208. The control unit 101 of the underwater detection device 100 starts the processing of Figure 10 in response to receiving a start instruction, and ends the processing of Figure 10 in response to receiving an end instruction (step S26: YES).

[0167] Alternatively, the start and end of the plotter device 200 may be the start and end of the operation of displaying fish quantity information, and the start and end of the underwater detection device 100 may be the start and end of the operation of displaying fish quantity information.

[0168] FIG. 13 is a diagram showing an example of a plotter image 400 including fish quantity information based on fish quantity indices.

[0169] An image of an area specified by the user via the input unit 206 is displayed as a plotter image 400 on the display unit 204 of the plotter device 200. The user can change the magnification (scale) of the plotter image 400 via the input unit 206. The area displayed on the display unit 204 changes in response to the change in magnification.

[0170] The plotter image 400 includes a land image 410 corresponding to land and a sea image 420 corresponding to sea areas. The land image 410 and the sea image 420 are displayed in different colors. Here, in order to distinguish the land image 410 from the sea image 420, the land image 410 is hatched. The sea image 420 includes a contour line 421 indicated by a dashed line and a notation of water depth appended to the contour line 421.

[0171] Furthermore, the plotter image 400 includes a plot 431 indicating the current position of the own ship and a track 432 to the current position. When the process of FIG. 12 is executed, fish amount information based on the fish amount index is sequentially displayed at each display position on the track 432. Here, as the fish amount information, fish amount images 433a to 433c are superimposed and displayed at each display position. As described above, the interval between each display position can be changed according to the magnification of the plotter image 400.

[0172] In the example of FIG. 13, the fish amount images 433a to 433c are constituted by circles having diameters and colors corresponding to the values of the fish amount index. The larger the value of the fish amount index, the larger the diameter of the circle. In FIG. 13, for the sake of convenience, the difference in color of the fish amount images 433a to 433c is shown by the difference in hatching. For example, the fish amount image 433a is colored red, the fish amount image 433b is colored yellow, and the fish amount image 433c is colored blue.

[0173] For example, the diameter of the circle is set in three steps using three threshold values Th1 to Th3 (Th1 < Th2 < Th3). When the value of the fish amount index is equal to or greater than the threshold value Th1 and less than the threshold value Th2, the diameter D1 is used. When the value of the fish amount index is equal to or greater than the threshold value Th2 and less than the threshold value Th3, the diameter D2 is used. When the value of the fish amount index is equal to or greater than the threshold value Th3, the diameter D3 is used (D1 < D2 < D3). The threshold values Th1 to Th3 may be arbitrarily set by the user.

[0174] However, the method for setting the diameter is not limited to this, and for example, the diameter may be set to four or more levels, or the diameter may change linearly in response to changes in the value of the fish quantity index. When the diameter changes linearly in this way, the color of the fish quantity image may change according to a color scale in which the hue changes continuously in response to changes in the value of the fish quantity index.

[0175] The user can understand the amount of fish at each position on the ship's wake 432 up to this point from the fish amount images 433a to 433c included in the plotter image 400. This allows the user to smoothly understand the state of the school of fish and the positions where fish should be caught, and allows the user to return to positions on the wake 432 as appropriate to continue catching fish.

[0176] 13, the fish quantity images 433a to 433c are circular images that differ from one another in diameter and color, but the fish quantity images 433a to 433c may be circular images that differ from one another only in diameter, or may be circular images that differ from one another only in color. With these display formats, the user can grasp the fish quantity along the ship's wake 432 from the fish quantity images 433a to 433c.

[0177] <Setting the fish abundance calculation area> The range in which the fish abundance index is calculated using equation (13) may be limited by the user from the entire range scanned in one ping to a predetermined range. For example, if the user is engaged in purse seine fishing, the range in which the fish abundance index is calculated may be limited to the range that can be enclosed by the purse seine (for example, a range with a radius of 200 m from the user's ship).

[0178] FIG. 14 is a diagram showing an example of the fish quantity calculation area reception screen 310.

[0179] The fish quantity calculation area reception process is performed by the control unit 101 using the function of the target area reception processing unit 101e in Fig. 4. With this function, the control unit 101 displays the fish quantity calculation area reception screen 310 in Fig. 14 in response to the calculation area setting operation from the user.

[0180] The fish quantity calculation area reception screen 310 includes a rectangular range input area 311, a button 312 for confirming the input, a button 313 for returning to the previous screen, and a button 314 for manual setting. The range input area 311 is an area for inputting the radius of a circle centered on the own ship when viewed from directly above the own ship.

[0181] When the user clicks on the range input area 311 via the input unit 109, range selection candidates are displayed in a caption below the range input area 311. The selection candidates are, for example, values ​​ranging from 200 m to 800 m in 50 m increments. The user selects the desired range from the displayed selection candidates. As a result, the selected range value is displayed in the range input area 311. In the example of FIG. 11, a range with a radius of 200 m centered on the ship is selected.

[0182] The user can change the fish quantity calculation range by clicking range input area 311 again. After inputting the fish quantity calculation range in this way, the user clicks button 312. This confirms the input of the fish quantity calculation range. If the user clicks button 313 without clicking button 312, the input operation of the fish quantity calculation range is canceled.

[0183] To set an arbitrary range, the user operates button 314. This causes an image including boundary lines P14 to P16, similar to the echo image P10 in FIG. 5, to be displayed. The user then draws a line enclosing the desired range on this image via input unit 109 and operates the confirm button. This confirms the range enclosed by this line as the fish quantity calculation range.

[0184] The control unit 101 (fish quantity index calculation unit 101c) performs the process of step S24 in Fig. 10 using the range set by the user as the calculation target range. That is, it performs the process of step S24 using data in the range set by the user from the amplitude data space shown in Fig. 7(a). For example, as shown in Fig. 14, if the fish quantity calculation range is set to a range with a radius of 200 m from the ship, the process of step S24 is performed using data included in the range of sample numbers on the vertical axis corresponding to 0 to 200 m.

[0185] By limiting the fish quantity calculation range in this way, the user can have the plotter device 200 display fish quantity information based on the fish quantity index Q for the range in which the user intends to catch fish. This allows the user to smoothly proceed with fishing.

[0186] The fish quantity calculation range may be displayed on the plotter device 200 together with the plotter image 400. For example, the current fish quantity calculation range (radius distance from the vessel's center) may be displayed in the lower left corner of the plotter image 400 or in a display area provided outside the margin. Alternatively, when the user selects any of the fish quantity images 433a to 433c, the fish quantity calculation range for which the fish quantity index value corresponding to that fish quantity image has been calculated may be displayed to the side of that fish quantity image. This allows the user to roughly grasp the quantity of fish that can be caught by the vessel's boat.

[0187] <Effects of the First Embodiment> According to the first embodiment, the following effects can be achieved.

[0188] As shown in FIG. 3, the fish quantity information display system 10 includes an underwater detection device 100 and a plotter device 200. As shown in FIGS. 1 and 2, the underwater detection device 100 detects a school of fish by scanning a receiving beam RB1 along a conical scanning surface SP1. As shown in FIG. 13, the plotter device 200 displays the ship's current position (plot 431) and a track 432 to the current position. As shown in FIG. 4, the underwater detection device 100 includes a fish quantity index calculation unit 101c that calculates a fish quantity index based on electrical signals output from multiple ultrasonic transducers 103a, and a communication unit 111 that transmits the fish quantity index to the plotter device 200. As shown in FIG. 11, the plotter device 200 includes a communication unit 208 that receives the fish quantity index and a fish quantity display superimposition unit 201a that displays fish quantity information based on the fish quantity index in association with the track.

[0189] As shown in Figures 10 and 12, the fish quantity information display method executed by the fish quantity information display system 10 includes a step (S24) of calculating a fish quantity index based on electrical signals output from multiple ultrasonic transducers, and a step (S34) of displaying fish quantity information based on the fish quantity index in association with the wake.

[0190] With this configuration, schools of fish are detected by scanning the receiving beam RB1 along the conical scanning surface SP1. This allows for the acquisition of fish quantity information over a wide area, comparable to the target area of ​​purse seine fishing, and also allows for the acquisition of fish quantity information from fish distributed near the sea surface. Furthermore, since fish quantity information is acquired for fish distributed on the conical scanning surface SP1 rather than directly below the ship, the influence of fish escape due to noise from the ship (ship S1) on the fish quantity information can be reduced. Furthermore, fish quantity indices are calculated based on electrical signals output from multiple ultrasonic transducers 103a, and fish quantity information based on the calculated fish quantity indices is displayed in association with the ship wake 432, as shown in Figure 13. This allows the user to easily grasp the fish quantity without applying parameters or calculation formulas of the underwater detection device 100. This allows the user to accurately and easily grasp the quantity of fish present along the ship wake 432.

[0191] As shown in FIG. 13, the fish quantity information includes fish quantity images 433a to 433c corresponding to the values ​​of the fish quantity index, and the fish quantity display superimposition unit 201a displays the fish quantity images 433a to 433c at predetermined positions (display positions) on the wake 432.

[0192] This configuration allows the user to easily grasp the amount of fish at each position on the wake 432.

[0193] As shown in FIG. 13, the fish quantity images 433a to 433c are circles configured with at least one of a diameter and a color (here, both) according to the value of the fish quantity index.

[0194] This configuration allows the user to intuitively grasp the amount of fish at each position on the wake 432.

[0195] As shown in Figure 4, the underwater detection device 100 is equipped with a correction value reception processing unit 101d that receives input of a correction value (correction multiplier) for correcting the fish quantity index Q, and the fish quantity index calculation unit 101c corrects the above equation (13), which is the calculation formula for the fish quantity index Q, based on the input correction value.

[0196] According to this configuration, the fish quantity correction coefficient C in the above formula (13) is calculated based on the correction value (correction magnification) input by a user such as a fisherman. cor is corrected. Generally, a user can easily estimate the amount of fish they have caught (e.g., tons), and therefore can smoothly and accurately input a correction value for correcting the displayed fish quantity index Q to the actual amount of fish. Therefore, the calculation formula for the fish quantity index Q can be corrected based on the input correction value so that it approaches the actual amount of fish caught. Therefore, this correction process allows the amount of fish caught to be smoothly and accurately estimated.

[0197] As mentioned above, the fish abundance index Q is calculated using equation (13) with the fish abundance correction coefficient C cor The correction value for correcting this equation (13) is a correction magnification. The fish quantity index calculation unit 101c calculates the fish quantity index by using the immediately preceding fish quantity correction coefficient C cor The value obtained by multiplying this by the correction factor is the new fish quantity correction coefficient C corThe fish abundance index Q is calculated as follows.

[0198] This allows the user to repeatedly input the correction factor to bring the fish quantity index Q closer to the fish quantity that corresponds to their own rough estimate. Therefore, the fish quantity index Q can be displayed smoothly and appropriately according to the user's fishing grounds, fish species, and season.

[0199] Here, the equation (13) for calculating the fish quantity index Q is the weight W of the fish to be caught and the target strength T s The original equation (12) is made up of a first equation including the intensity I0 of the transmitted wave and the receiving sensitivity k of the transducer 103, and a second equation not including these, and the first equation is calculated by adding the approximate coefficient (coefficient C0) of the first equation and the fish quantity correction coefficient C cor This is replaced by a mathematical formula consisting of:

[0200] Thus, the fish quantity index Q is calculated using equation (13), which includes the weight W of the target fish and the target strength T s Since the intensity I0 of the transmitted wave and the receiving sensitivity k of the transducer 103 are taken into account, the fish quantity index can be calculated with high accuracy using equation (13). In addition, the first equation containing these parameters is calculated by using the approximate coefficient C0 of the first equation and the fish quantity correction coefficient C cor Since the equation is replaced with a term consisting of the above, the user can smoothly correct the calculation formula using a correction factor that corresponds to their own fish quantity estimate, without needing to understand these parameters. This allows the user to smoothly bring the displayed fish quantity index Q closer to their own fish quantity estimate. Therefore, the user can properly display a fish quantity index Q that is close to their own catch.

[0201] As shown in Figure 4, the underwater detection device 100 further includes a target area reception processing unit 101e that receives the designation of a target area within the search range for which the fish quantity index Q is to be calculated, and as explained with reference to Figure 11, the fish quantity index calculation unit 101c calculates the fish quantity index Q for the designated target area.

[0202] This allows the user to specify a target area such as an area that the user should pay attention to or an area that can be enclosed by a purse seine net, and display the fish quantity index Q for that target area. Therefore, the user can smoothly proceed with catching fish based on the displayed fish quantity index Q.

[0203] <Example of change> In the plotter image 400 of FIG. 13, fish quantity information at each display position on the wake 432 is displayed using fish quantity images 433a to 433c, but the method for displaying fish quantity information is not limited to this.

[0204] For example, as shown in Modification 1 in Figure 15, fish quantity images 433d to 433f may be configured with bands having widths (widths in the direction perpendicular to the wake 432) and colors according to the values ​​of the fish quantity index. In Figure 15, as in Figure 13, differences in color are indicated by differences in hatching.

[0205] In the example of Fig. 15, as in the example of Fig. 13, the width of fish quantity images 433d-433f is set to three levels according to the relationship between the value of the fish quantity index and the threshold values ​​Th1-Th3. Also, in the example of Fig. 15, fish quantity images at a series of display positions to which the same width is set are integrated and displayed as a single band. As in the example of Fig. 13, the width of the fish quantity images does not have to be three levels, and may change linearly according to changes in the value of the fish quantity index.

[0206] 15, the fish quantity images 433d to 433f included in the plotter image 400 allow the user to grasp the fish quantity at each position on the ship's wake 432 up to that point. This allows the user to smoothly grasp the state of the school of fish and the positions where fish should be caught, and allows the user to return to positions on the wake 432 as appropriate to continue catching fish.

[0207] 15, the fish quantity images 433d-433f are images of bands that differ from one another in width and color, but the fish quantity images 433d-433f may be images of bands that differ from one another only in width, or may be images of bands that differ from one another only in color. With these display formats, the user can grasp the amount of fish along the ship's wake 432 from the fish quantity images 433d-433f.

[0208] Furthermore, as shown in a second modification in Fig. 16, a fish quantity index value 434 may be displayed at a position (here, the display position) on the ship track 432. Here, the fish quantity index value 434 (unit: tons) for a position specified by the user on the ship track 432 (indicated by an x ​​in Fig. 16) is added. Also, a circular fish quantity image 433a corresponding to this position is highlighted.

[0209] With this configuration, the user can accurately grasp the amount of fish at each position on the wake as a numerical value.

[0210] In the example of Figure 16, the user can specify any display position on the track 432, and the fish quantity index value 434 for that position can be displayed. However, the fish quantity index value 434 for a position can also be displayed when the user specifies any position on the track 432, regardless of the display position.

[0211] Furthermore, the fish quantity index value does not necessarily have to be displayed according to the user's specification, and for example, the control unit 201 (fish quantity display superimposition unit 201a) may display the fish quantity index value 434 at a display position where the fish quantity index value is equal to or greater than a predetermined threshold value (for example, the above-mentioned threshold value Th3). Furthermore, instead of the fish quantity images 433a to 433c, the fish quantity index value 434 may be displayed at each display position.

[0212] Alternatively, when fish quantity images 433a-433c are omitted from plotter image 400 in Fig. 13, the user may specify a desired position on wake 432, and fish quantity index value 434 for that position may be displayed. Similarly, when fish quantity images 433a-433c are omitted from plotter image 400 in Fig. 13, the user may specify a desired position on wake 432, and fish quantity images 433a-433c or fish quantity images 433d-433f may be displayed according to the value of the fish quantity index for that position, and fish quantity index value 434 for that position may be displayed together with this fish quantity image.

[0213] 17, fish quantity information may be displayed when the value of the fish quantity index is equal to or greater than a predetermined threshold. Here, fish quantity images 433a and 433b (fish quantity information) are displayed at display positions on the wake 432 where the value of the fish quantity index is equal to or greater than threshold Th2.

[0214] According to this configuration, display of fish quantity information for which the fish quantity index is less than a predetermined threshold is omitted from the plotter image 400. This allows the user to easily grasp the positions on the wake 432 where a large amount of fish equal to or greater than the threshold has occurred.

[0215] In the configuration of Modification Example 3, the threshold value for displaying fish quantity information may be set arbitrarily by the user. Also, in Modification Example 3, as in Modification Example 2, fish quantity index value 434 may be displayed together with fish quantity images 433a, 433b, or fish quantity index value 434 may be displayed instead of fish quantity images 433a, 433b.

[0216] <Embodiment 2> FIG. 18 is a block diagram showing the configuration of a fish quantity information display system 10 according to the second embodiment.

[0217] As shown in Fig. 18, the fish quantity information display system 10 according to the second embodiment includes a radar device 500, as compared to the configuration shown in Fig. 3. The radar device 500 includes a radar antenna 500a, and transmits transmission waves (microwaves) from the radar antenna 500a into the vicinity (air) of the ship. The radar device 500 receives reflected waves of the transmitted transmission waves with the radar antenna 500a, and detects targets (ships, land, birds, etc.) present around the ship.

[0218] The radar antenna 500a is installed, for example, on the ceiling of a wheelhouse and rotates horizontally. The direction of the transmitted wave traveling straight horizontally from the radar antenna 500a rotates as the radar antenna 500a rotates. By receiving the reflected wave at each rotation position (azimuth), the presence or absence of a target at each rotation position (azimuth), the distance to the target, and the strength of the reflected wave from the target (echo strength) are detected. The radar device 500 is a radar device with a well-known configuration used on ships. The radar device 500 transmits the distance to the target and the echo strength at each azimuth to the plotter device 200.

[0219] FIG. 19 is a block diagram showing the configuration of a plotter device 200 according to the second embodiment.

[0220] 19, in the plotter device 200 according to the second embodiment, the function of a target display superimposition unit 201b is added to the control unit 201, compared to the configuration in Fig. 11. The target display superimposition unit 201b superimposes a display of the current target on the plotter image 400 based on the direction, distance to the target, and echo intensity received from the radar device 500 via the communication unit 208.

[0221] FIG. 20 is a diagram showing an example of a plotter image 400 according to the second embodiment.

[0222] Compared to the plotter image 400 in FIG. 13, the plotter image 400 in FIG. 20 includes target object images 435 based on information from the radar device 500. Here, two target object images 435 correspond to other ships. From these target object images 435, the user can understand that other ships are currently near the wake 432 of the user's ship. This allows the user to return to a position on the wake 432 that is farther away from the other ships, among the positions of the fish quantity image 433a that indicates a large amount of fish, and smoothly continue fishing.

[0223] Alternatively, if a target image showing a flock of birds is included, the user can estimate a location where they can expect to catch more fish by using the target image of the flock of birds and the fish quantity information on the wake 432. This allows the user to return to that location and continue fishing smoothly.

[0224] The plotter image 400 displayed by the configuration of the second embodiment can also be modified in the same manner as the first to third modifications.

[0225] <Effects of the Second Embodiment> As shown in FIG. 18, the fish quantity information display system 10 further includes a radar device 500 that receives reflected waves of transmitted waves sent into the air and detects surrounding targets, and as shown in FIG. 19, the plotter device 200 further includes a target display superimposition unit 201b that displays targets present near the wake together with the wake 432 and fish quantity information (fish quantity images 433a to 433c) based on the detection results of the radar device 500.

[0226] 20, this configuration makes it possible to display target images 435 of other ships that exist near the ship's wake 432 together with fish quantity information (fish quantity images 433a to 433c) at each position on the wake 432, and also to display target images such as flocks of birds that exist near the wake 432. This allows the user to more smoothly determine which position on the ship's wake they should return to and continue fishing.

[0227] <Other change examples> In the above-mentioned first and second embodiments, the fish quantity correction coefficient C corwas corrected by the correction factor, but the fish abundance correction coefficient C cor The correction value for correcting is not limited to this. For example, the fish quantity correction coefficient C cor The value added or subtracted from is the fish abundance correction coefficient C cor may be used as a correction value for

[0228] Furthermore, the screen for receiving the fish quantity correction multiplier is not limited to the fish quantity correction multiplier receiving screen 300 shown in Fig. 9, but may be a receiving screen with a different configuration. Similarly, the screen for receiving the designation of the fish quantity calculation area is not limited to the fish quantity calculation area receiving screen 310 shown in Fig. 14, but may be a receiving screen with a different configuration.

[0229] The control unit 101 may also allow the user to set multiple fish quantity correction coefficients C according to the fish species, fishing grounds, etc. cor In this case, the control unit 101 can set the fish quantity correction coefficient C cor The control unit 101 stores the fish quantity correction coefficient C cor In the application process of the fish quantity correction coefficient C cor is applied to the calculation formula (13) to calculate the fish quantity index Q. This allows the user to obtain the fish quantity index Q that is suited to the fish species and fishing grounds that the user is trying to catch, allowing for smoother fishing. In this case, the fish quantity correction coefficient C cor A correction is made using the fish quantity correction multiplier (correction value) for each fish catch.

[0230] Furthermore, in the above-described first and second embodiments, the fish quantity index calculation unit 101c and the like are realized as functions of the control unit 101 provided by the program stored in the storage unit 102, and the fish quantity display superimposition unit 201a and the like are realized as functions of the control unit 201 provided by the program stored in the storage unit 202, but these do not necessarily have to be realized as functions provided by the program stored in the storage units 102 and 202. For example, one or more of these functions may be configured by hardware that integrates an FPGA (field-programmable gate array) or logic circuits.

[0231] Furthermore, in the above first and second embodiments, the fish quantity index value is calculated using equation (13), but a calculation formula other than equation (13) may be used to calculate the fish quantity index Q. In this case, too, the calculation formula only needs to include a fish quantity correction coefficient that is corrected by a correction value input by the user.

[0232] Furthermore, the plotter image 400 shown in the above-described first and second embodiments and modifications 1 to 3 is merely an example, and other configurations of plotter images may be used. For example, in the plotter image 400 of Fig. 13, the fish quantity images 433a to 433c may be changed to ovals, diamonds, or other shapes. Furthermore, the threshold value Th1 may be set near zero, and fish quantity information (fish quantity images, fish quantity index values) may not be displayed only when there are substantially no fish.

[0233] In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the claims. [Explanation of symbols]

[0234] 10 Fish quantity information display system 100 Underwater detection equipment 101 Control section 101c Fish quantity index calculation section 101d Correction value reception processing unit 101e Target area reception processing unit 102 Storage section 103 Transmitter / Receiver 103a Ultrasonic transducer 111 Communications Department 200 Plotter Device 201 Control Unit 201a Fish quantity display superimposition section 201b Target display superimposition section 202 Storage section 208 Communications Department 400 plotter images 431 Plot (current location) 432 Wake 433a~433f Fish quantity image 434 Fish abundance index value 435 Target Image 500 radar equipment

Claims

1. an underwater detection device that detects schools of fish by scanning a receiving beam along a conical scanning surface; a plotter device that displays the current position of the ship and the course of the ship to the current position; The underwater detection device a fish quantity index calculation unit that calculates a fish quantity index based on the electrical signals output from the plurality of ultrasonic transducers; a communication unit for transmitting the fish quantity index to the plotter device, The plotter device a communication unit for receiving the fish quantity index; a fish quantity display superimposition unit that displays fish quantity information based on the fish quantity index in association with the wake, A fish quantity information display system characterized by:

2. 2. The fish quantity information display system according to claim 1, the fish quantity information includes a fish quantity image corresponding to the value of the fish quantity index, the fish quantity display superimposing unit displays the fish quantity image at a predetermined position on the wake; A fish quantity information display system characterized by:

3. 3. The fish quantity information display system according to claim 2, The fish quantity image is a circle configured with at least one of a diameter and a color according to the value of the fish quantity index. A fish quantity information display system characterized by:

4. 3. The fish quantity information display system according to claim 2, The fish quantity image is a band configured with at least one of a width and a color according to the value of the fish quantity index. A fish quantity information display system characterized by:

5. 2. The fish quantity information display system according to claim 1, the fish quantity information includes the value of the fish quantity index, the fish quantity display superimposition unit displays the value of the fish quantity index at a predetermined position on the wake, A fish quantity information display system characterized by:

6. 6. The fish quantity information display system according to claim 1, the fish quantity display superimposition unit displays the fish quantity information when the value of the fish quantity index is equal to or greater than a predetermined threshold value; A fish quantity information display system characterized by:

7. 2. The fish quantity information display system according to claim 1, a correction value reception processing unit that receives an input of a correction value for correcting the fish quantity index; The fish quantity index calculation unit corrects the calculation formula for the fish quantity index based on the correction value. A fish quantity information display system characterized by:

8. 8. The fish quantity information display system according to claim 7, The calculation formula includes a fish quantity correction coefficient, the correction value is a correction magnification, The fish quantity index calculation unit calculates the fish quantity index by multiplying the fish quantity correction coefficient by the correction magnification as the new fish quantity correction coefficient. A fish quantity information display system characterized by:

9. 9. The fish quantity information display system according to claim 8, The calculation formula is an original calculation formula consisting of a first formula including the weight of each fish to be caught, the target strength, the intensity of the transmitted wave, and the receiving sensitivity of the transducer, and a second formula not including these, in which the first formula is replaced with a formula consisting of an approximate value of the first formula and the fish quantity correction coefficient. A fish quantity information display system characterized by:

10. 2. The fish quantity information display system according to claim 1, a target area reception processing unit that receives a designation of a target area within the search range that is to be used to calculate the fish quantity index; The fish quantity index calculation unit calculates the fish quantity index for the specified target area. A fish quantity information display system characterized by:

11. 2. The fish quantity information display system according to claim 1, The radar device further includes a radar unit that receives reflected waves of transmitted waves into the air and detects surrounding targets. The plotter device further includes a target display superimposition unit that displays targets present near the wake together with the wake and the fish quantity information based on the detection results of the radar device. A fish quantity information display system characterized by:

12. A fish quantity information display method using an underwater detection device that detects schools of fish by scanning a receiving beam along a conical scanning surface, and displaying an image on a plotter device that displays the current position of the ship and the track to the current position, comprising: Calculating a fish abundance index based on the electrical signals output from the plurality of ultrasonic transducers; and displaying fish quantity information based on the fish quantity index in association with the wake. A fish quantity information display method characterized by:

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