Fish quantity information display system and fish quantity information display method

Abstract

To provide a fish quantity information display system (10) and a fish quantity information display method capable of displaying an image and allowing a user to accurately and easily grasp the fish qua

Description

Technical Field

[0001] The present invention relates to a fish quantity information display system and fish quantity information display method for displaying information on the quantity of fish on track together with the position of own ship and the track. Background

[0002] Conventionally, fish finder for detecting fish group in underwater is known. In this type of fish finder, ultrasonic wave is transmitted vertically downward from the bottom of the ship and its reflected wave is received. Echo data corresponding to the intensity of the reflected wave is generated and an echo image is displayed based on the generated echo data.

[0003] In this type of fish finder, by integrating the acoustic intensity of the echo reflected from a fish group, a value proportional to the amount of fish group existing in a certain area of the sea may be obtained. If the fish finder has a GPS (Global Positioning System) function, an image in which a circle or the like having a size proportional to the size of the integrated value is superimposed may be displayed on the track of the own ship. The following Patent Document 1 describes a fish finder with such a configuration.

[0004] Patent Document 1- Japanese Patent Application Laid-Open No. Hl0-197622 Summary Technical Problem

[0005] However, since fish finder transmits and receives ultrasonic waves in a narrow range directly under own ship, it is not possible to obtain fish quantity information in a range of several hundred meters in diameter, which is the target range of purse seining, by a single transmission and reception.

[0006] In addition, since the fish finder transmits ultrasonic waves directly under own ship, it may not normally receive echoes from the depth range corresponding to the ultrasonic wave transmission period, that is, the depth range near the sea surface. Therefore, the fish quantity information of fish distributed near the sea surface may not be properly obtained.

[0007] In addition, the noise emitted by own ship may cause fish directly under own ship to escape. Therefore, it is difficult to accurately obtain fish quantity information in the fish finder which detects fish directly under own ship.

[0008] Furthermore, in order to estimate the weight (i.e., tonnage) of fish from the integrated value of acoustic intensity, it is necessary to obtain parameters related to transmission and reception of fish finder, target strength of fish etc., and apply an appropriate calculation formula. This work is extremely difficult for an ordinary fisherman.

[0009] In view of such problems, it is an object of the present invention to provide a fish quantity information display system and a fish quantity information display method capable of displaying an image capable of allowing a user to accurately and simply grasp the quantity of fish existing on a track of own ship. Solution to Problem

[0010] A first aspect of the present invention relates to a fish quantity information display system. The fish quantity information display system, according to this aspect, includes: underwater detection device for detecting fish group by scanning reception beam along a conical scanning plane; and a plotter device for displaying the present position of own ship and track up to the present position. The underwater detection device includes: a fish quantity index calculation module for calculating a fish quantity index based on electric signals outputted from a plurality of ultrasonic oscillator; and a communication module for transmitting the fish quantity index to plotter device. The plotter device includes: a communication module for receiving the fish quantity index; and a fish quantity display superposition module for displaying fish quantity information based on the fish quantity index in association with the track.

[0011] According to the fish quantity information display system, according to this embodiment, since fish group is detected by scanning reception beam along the conical scanning plane, it is possible to acquire fish quantity information in a wide range as large as the target range of purse seining, and also to acquire fish quantity information from fish distributed near the sea surface. Moreover, since the fish quantity information of fish distributed in the conical scanning plane rather than directly under the own ship is acquired, it is possible to mitigate the influence of the escape of fish due to noise from the own ship on the fish quantity information. Furthermore, since the fish quantity index is calculated based on the electric signals outputted from the plurality of ultrasonic oscillator, and the fish quantity information based on the calculated fish quantity index is displayed in association with track, the user may easily grasp the fish quantity without applying parameters or calculation formulas of underwater detection device. Therefore, according to the fish quantity display system according to this embodiment, the user may accurately and simply grasp the fish quantity existing on track of the own ship.

[0012] In the fish quantity information display system, according to this embodiment, the fish quantity information includes a fish quantity image according to the value of the fish quantity index, and the fish quantity display superposition module may be configured to display the fish quantity image at a predetermined position on the track.

[0013] According to this configuration, the user may smoothly grasp the fish quantity at each position on track.

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

[0015] According to this configuration, the user may intuitively grasp the fish quantity at each position on track.

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

[0017] With this configuration, the user may intuitively grasp the quantity of fish at each position on track.

[0018] In the fish quantity information display system, according to this configuration, the fish quantity information includes the value of the fish quantity index, and the fish quantity display superposition module may be configured to display the value of the fish quantity index at a predetermined position on the track.

[0019] With this configuration, the user may accurately grasp the quantity of fish at a position on track as a numerical value.

[0020] In addition, the fish quantity display superposition module 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.

[0021] With this configuration, since the display of the fish quantity information where the fish quantity index is less than the threshold is omitted, the user may smoothly grasp the position on the track where a large quantity of fish larger than the threshold occurs.

[0022] The fish quantity information display system, according to this configuration, further includes a correction value reception processing module for receiving the input of a correction value for correcting the fish quantity index, and the fish quantity index calculation module may be configured to correct a calculation formula of the fish quantity index based on the correction value.

[0023] With this configuration, the calculation formula of the fish quantity index is corrected based on the correction value input from the user. In general, since a user such as fisherman may easily estimate the quantity of fish (for example, tonnage) actually captured by himself / herself, the user may smoothly and properly input a correction value for correcting the displayed fish quantity index to the actual quantity of fish. Thus, calculation formula of the fish quantity index may be corrected so as to approach the actual quantity of catch based on the input correction value. Therefore, the fish quantity index may be more accurately acquired by this correction processing, and more accurate fish quantity information may be displayed.

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

[0025] According to this configuration, every time correction magnification is input from the user, correction magnification is accumulated and a new fish quantity correction coefficient is set. Thus, the user may make the fish quantity index close to the fish quantity according to his / her rough estimate by repeating the input of correction magnification. Thus, the fish quantity index may be smoothly and properly acquired according to the fishing ground of the user, fish species and season, and the fish quantity information may be properly displayed.

[0026] In this case, calculation formula may be assumed that the first formula is replaced by a formula consisting of the approximate number of the first formula and fish quantity correction coefficient for the original calculation formula consisting of the first formula including the weight per fish and target strength of the fish to be captured, the intensity of the transmission wave and reception sensitivity of transducer, and the second formula not including these.

[0027] According to this configuration, since the weight and target strength of the fish to be captured, the intensity of the transmission wave and reception sensitivity of transducer are added to calculation formula, the fish quantity index may be accurately calculated by this calculation formula. In addition, since the first formula including these parameters is replaced by a term consisting of the approximate number of the first formula and fish quantity correction coefficient, the user may smoothly correct calculation formula by correction magnification corresponding to his own approximate fish quantity without grasping these parameters. Thus, the user may smoothly approach the calculated fish quantity index to his own approximate fish quantity. Thus, more appropriate fish quantity information may be provided to the user.

[0028] A fish quantity information display system, according to this aspect, is further provided with an object area reception processing module for receiving designation of an object area to be an object of calculation of the fish quantity index in a search range, and fish quantity index calculation module may be configured to calculate the fish quantity index for the designated object area.

[0029] According to this configuration, the user may designate a range to be noticed by the user or a range which may be enclosed by purse seine in the object area, and the fish quantity index in the object area may be displayed. Therefore, the user may smoothly proceed to catch fish based on the displayed fish quantity information.

[0030] The fish quantity information display system, according to this embodiment, is further provided with a radar device for detecting the surrounding target by receiving the reflected wave of the transmitting wave transmitted in the air, and a plotter device may be further provided with target display superposition module for displaying target existing near track together with track and the fish quantity information based on the detection result of radar device. [0031 ] According to this configuration, other ship and flocks of birds existing near track of the own ship may be further displayed together with the fish quantity information of each position on track. Thus, the user may determine which position on track of the own ship to return to for fishing.

[0032] According to a second aspect of the present invention, a fish quantity information display method for displaying an image on a plotter device for displaying the present position of its own ship and track up to the present position by using a underwater detection device for detecting fish group by scanning reception beam along a conical scanning plane, includes calculating, by a fish quantity index calculation module, a fish quantity index based on electric signals output from a plurality of ultrasonic oscillator, and displaying, by a fish quantity superposition module, a fish quantity information based on the fish quantity index in association with track.

[0033] According to fish quantity information display method, according to this aspect, the same effect as that of fish quantity information display system according to the first aspect may be achieved. Advantageous Effects of Invention

[0034] As described above, according to the present invention, it is possible to provide fish quantity information display system and fish quantity information display method capable of displaying an image capable of allowing the user to accurately and easily grasp the fish quantity existing on track of the own ship.

[0035] The effect or significance of the present invention will be further clarified by the description of the following embodiments. However, the following embodiments are merely examples of the present invention, and the present invention is not limited in any way to those described in the following embodiments. Brief Description of Drawings

[0036] FIG. 1 is a diagram schematically showing how underwater is searched by underwater detection device according to an embodiment 1 of the present invention. FIG. 2 is a diagram schematically showing how underwater is searched by underwater detection device according to the embodiment 1 of the present invention. FIG. 3 is a block diagram showing the configuration of fish quantity information display system according to the embodiment 1 of the present invention. FIG. 4 is a block diagram showing the configuration of underwater detection device according to the embodiment 1 of the present invention. FIG. 5 is a diagram schematically showing an example of an echo image displayed on display unit of underwater detection device according to the embodiment 1 of the present invention. FIG. 6 is a diagram schematically showing propagation state of transmission pulse and its reflected wave (reflected pulse) on one beam axis according to the embodiment 1 of the present invention. FIGS. 7A and 7B are diagrams schematically showing a rectangular coordinate system in which the beam number and the sample number are two axes according to the embodiment 1 of the present invention. FIG. 8 is a flowchart showing reception process in fish quantity correction magnification according to the embodiment 1 of the present invention. FIG. 9 is a diagram showing an example of fish quantity correction magnification reception screen according to the embodiment 1 of the present invention. FIG. 10 is a flowchart showing transmission processing of a fish quantity index according to the embodiment 1 of the present invention. FIG. 11 is a block diagram showing the configuration of plotter device according to the embodiment 1 of the present invention. FIG. 12 is a flowchart showing display processing of a fish quantity index according to the embodiment 1 of the present invention. FIG. 13 is a diagram schematically showing an example of a plotter image including fish quantity information based on a fish quantity index according to the embodiment 1 of the present invention. FIG. 14 is a diagram schematically showing an example of a fish quantity calculation area reception screen according to the embodiment 1 of the present invention. FIG. 15 is a diagram schematically showing an example of a plotter image including fish quantity information based on a fish quantity index according to a modification example 1 of the embodiment 1 of the present invention. 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 a modification example 2 of the embodiment 1 of the present invention. 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 a modification Example 3 of the embodiment 1 of the present invention. FIG. 18 is a block diagram showing the configuration of a fish quantity information display system according to an embodiment 2 of the present invention. FIG. 19 is a block diagram showing the configuration of a plotter device according to the embodiment 2 of the present invention. FIG. 20 is a diagram schematically showing an example of a plotter image including fish quantity information based on a fish quantity index and a target image based on radar information according to the embodiment 2 of the present invention. Description of Embodiments

[0037] Embodiments of the present invention will be described below with reference to the drawings. For convenience, XYZ axes orthogonal to each other are appropriately added to the drawings. The X-axis and Y-axis directions are horizontal, and the Z-axis direction is vertical. The X-axis positive direction is the direction in which ship travels. Embodiment 1

[0038] FIGS. 1 and 2 are diagram schematically showing how underwater is searched by an underwater detection device 100, according to an embodiment 1 of the present invention.

[0039] In FIGS. 1 and 2, (p is the azimuth angle about a transducer 103 installed on a bottom of ship SI, and 0 is the tilt angle of scanning plane SP1 to be described later with respect to a horizontal plane (X-Y plane).

[0040] The underwater detection device 100 includes the transducer 103 installed on the bottom of a ship SI such as a fishing boat. The underwater detection device 100 transmits a pulse (i.e., transmission pulse) of sound waves from the transducer 103, and receives sound waves (i.e., echo) reflected (i.e., backscattered) by objects such as fish existing in underwater by the transducer 103. The underwater detection device 100 detects objects in underwater based on sound waves (i.e., echoes) received by the transducer 103.

[0041] The transducer 103 includes a plurality of ultrasonic oscillator 103a (i.e., number of ultrasonic oscillator / hundreds of ultrasonic oscillator). When transmitting a wave, each ultrasonic oscillator converts an input electric signal into an acoustic wave and radiates it, and when receiving a wave, converts an incident acoustic wave into an electric signal and outputs it. Typically, the transducer 103 has a cylindrical shape, and the plurality of ultrasonic oscillator 103a are regularly arranged on its side.

[0042] Here, 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 (i.e., Z axis) of the transducer 103. The conical surface is referred to as scanning plane SP1, and the apex and axis of scanning plane SP1 are referred to as the origin and the scanning axis, respectively. The origin coincides with the position of the transducer 103, and the scanning axis extends from this origin to direction just below. Here, the scanning axis coincides with the Z-axis. The angle formed by the scanning plane SP1 with the horizontal plane (X-Y plane) is the tilt angle 9 described above.

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

[0044] As shown in FIG. 2, the underwater detection device 100 forms a large number of reception beams RBI having the maximum sensitivity on the scanning plane SP1 during reception. The reception beam RBI is formed by beamforming the electric signals (i.e., digital signals) output from the plurality of ultrasonic oscillator 103a disposed in the transducer 103.

[0045] Each reception beam RBI is a pencil beam having a narrow width both vertically and horizontally, and has the same directivity. A straight line passing through the origin and facing the direction in which sensitivity of the reception beam RBI is maximum is the beam axis of each reception beam RBI. A plurality of reception beam RBI are formed side by side at a fixed angular interval in the direction of azimuth angle (p over the entire circumference of the scanning plane SP1. The underwater detection device 100 converts the intensity of sound waves received by each reception beam RBI into a color and displays it as an image (i.e., echo image).

[0046] FIG. 3 is a block diagram showing the configuration of fish quantity information display system 10, according to the embodiment 1 of the present invention.

[0047] In embodiment 1, the fish quantity information display system 10 is configured by the underwater detection device 100 and a plotter device 200.

[0048] As described above, the underwater detection device 100 detects fish group by scanning the reception beam RBI along the conical scanning plane SP1. The underwater detection device 100 calculates a fish quantity index based on the electric signals output from the plurality of ultrasonic oscillator 103a arranged in the transducer 103, and transmits the calculated fish quantity index to the plotter device 200.

[0049] The plotter device 200 has a GPS antenna 200a, and receives radio waves transmitted from the GPS satellite by the GPS antenna 200a to obtain the position of own ship on the earth. The plotter device 200 superimposes the present position of the own ship and track up to the present position on the chart and map near the own ship. Furthermore, the plotter device 200 displays the fish quantity information corresponding to the fish quantity index received from the underwater detection device 100 in association with track of the own ship.

[0050] The calculation method of the fish quantity index in the underwater detection device 100 will be described later with reference to FIGS. 6 to 9. The display method of the fish quantity information in the plotter device 200 will be described later with reference to FIGS. 12 and 13.

[0051] FIG. 4 is a block diagram showing the configuration of underwater detection device 100, according to the embodiment 1 of the present invention.

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

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

[0054] The transducer 103 includes the plurality of ultrasonic oscillator 103a as described above. During each ping (i.e., transmission / reception period), the transducer 103 transmits an ultrasonic wave as the transmission beam TB1 shown in FIG. 1, and receives the reflected wave at each ultrasonic oscillator.

[0055] In response to the control from the control unit 101, the transmission processing module 104 outputs a transmission signal for transmitting the ultrasonic wave to the transducer 103 via the transmission / reception switching unit 106. As shown in FIG. 4, the transmission signal is a signal vibrating at a predetermined amplitude for a fixed period. During one transmission of the transmission beam TB1, this transmission signal is supplied to each ultrasonic oscillator 103a of the transducer 103 via the transmission / reception switching unit 106. Thus, as shown in FIG. 4, the ultrasonic wave corresponding to the transmission signal is transmitted from each ultrasonic oscillator 103a. The pulse of the ultrasonic wave transmitted during one transmission is called transmission pulse.

[0056] The reception processing module 105 receives, via the transmission / reception switching unit 106, the electric signals output by each ultrasonic oscillator 103a of the transducer 103 after receiving the ultrasonic reflected waves, and applies amplification and noise removal (i.e., bandpass filter) processing to the received electric signals. The reception processing module 105 outputs these processed electric signals to control unit 101.

[0057] When transmitting the transmission beam TB1, the transmission / reception switching unit 106 outputs the transmission signals output from the transmission processing module 104 to the transducer 103 (i.e., ultrasonic oscillator 103a), and outputs the electric signals output from the transducer 103 (i.e., ultrasonic oscillator 103a) to the reception processing module 105 within a certain period of time after the transmission of the transmission beam TB1 is completed.

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

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

[0060] In this embodiment, the functions of a reception signal generation module 101a, image generation module 101b, fish quantity index calculation module 101c, correction value reception processing module 101 d, and object area reception processing module lOle are assigned to the control unit 101 by the program stored in the storage unit 102.

[0061] The reception signal generation module 101a beamforms the electric signals output from each ultrasonic oscillator 103a to form the reception beam RBI shown in FIG. 2, and generates reception signal corresponding to the sound waves incident on the transducer 103 from the beam axis direction (the direction of a predetermined azimuth angle (p and tilt angle 0) of each reception beam RBI. Furthermore, the reception signal generation module 101a applies band limitation and envelope detection processing to the reception signal in each beam axis direction to obtain envelope signals in each beam axis direction.

[0062] Here, a band limitation processing is processing for extracting the frequency components of the transmission signal output from the transmission processing module 104. This processing is performed when the transmission signal output from the transmission processing module 104 is a constant frequency signal (i.e., CW signal).

[0063] On the other hand, if the transmission signal output from the transmission processing module 104 is not a constant frequency signal (i.e., CW signal) but a frequency-modulated chirp signal (FM signal), the reception signal generation module 101a applies matched filter processing to the reception signal in each beam axis direction instead of the band limitation processing. Then, the reception signal generation module 101a applies envelope detection processing to the signal after the matched filter processing to obtain envelope signals in each beam axis direction.

[0064] The envelope signal thus obtained is a signal indicating an echo intensity (i.e., sound wave intensity) that changes according to the elapsed time from the transmission timing of the transmission beam TB1 (i.e., ultrasonic wave). Here, the elapsed time from the transmission timing corresponds to the distance from the transducer 103 in each beam axis direction. The control unit 101 acquires the echo intensity at each distance position in each beam axis direction from the echo signal of each reception beam RBI by associating the elapsed time from the transmission timing with the distance. The echo intensity is acquired at a predetermined distance resolution.

[0065] The image generation module 101b generates an echo image for displaying the echo intensity at each distance position in each beam axis direction with a predetermined color scale. The image generation module 101b sequentially outputs the echo image generated for each ping to the display processing module 108. Thus, the echo image updated for each ping is displayed on display unit 107.

[0066] FIG. 5 is a diagram schematically showing an example of the echo image displayed on display unit 107 of the underwater detection device 100, according to the embodiment 1 of the present invention.

[0067] In the mode for displaying the echo image, the screen of display unit 107 is divided into area Al and A2. Among them, an echo image P10 is displayed on the area Al. Here, the echo image P10 is displayed as an image when the ship SI is viewed from directly above. An image Pl 1 of the ship SI is placed at the center of the echo image P10, and a track P12 of the ship SI so far is shown. A straight line P13 showing the bow direction of the ship SI is included in the echo image P10.

[0068] In the echo image P10, a certain distance range from the position of the own ship (image Pl 1) is shown by circular boundary lines Pl 4, Pl 5, andP16. The diameters of the boundary lines P14, Pl5, andP16 are, for example, 200 m, 400 m, and 600 m. In the echo image P10, the above-mentioned echo intensity is displayed in the predetermined color scale. In FIG. 5, the area where the echo intensity is high is hatched for convenience. For example, a hatched area P17 is the area where the echo intensity is high. The hatched area P17 is the area where fish group may exist.

[0069] The area A2 is divided into a plurality of upper and lower sections, and the water temperature at the present position and a graph showing the temporal change of the water temperature are displayed in each divided area. In FIG. 5, the display of these images in the area A2 is omitted for convenience.

[0070] Users such as fisherman may understand the presence of fish group around the ship SI by referring to the echo image P10. The echo image P10 in FIG. 5 shows the echo intensity of the so-called stratiform fish group. That is, the fish group may be distributed widely in the horizontal direction in a narrow vertical layer. Furthermore, the individual fish in this group may swim with their heads pointing in almost the same direction. Such a group is stratiform fish group.

[0071] When the ship SI is located above stratiform fish group, the echo intensity called "figure 8" appears in the echo image P10 as shown in Fig. 5. In the example shown in Fig. 5, it may be estimated that the individual fish constituting stratiform fish group have their heads pointing almost parallel to the heading. That is, in this case, on the starboard and port sides of the ship SI, the ultrasonic wave transmitted from the transducer 103 is incident perpendicularly to the side of the fish, so the reflected wave (i.e., backscattered wave) from the fish is relatively strong. On the other hand, on the bow and stern sides of the ship SI, the ultrasonic wave is incident parallel to the side of the fish, so the reflected wave from the fish is weak. Therefore, in the echo image P10 in such a case, as shown in Fig. 5, a clear fish group reaction appears in the two area located symmetrically with respect to own ship.

[0072] Such events are well known in fisherman. An experienced fisherman may estimate the amount of fish caught (tonnage) from such figure 8 reaction.

[0073] For inexperienced fisherman, however, this estimation is difficult to make properly. Even for an experienced fisherman, it is difficult to make this estimation intensively during steering. Such a problem may be solved by not only displays the echo image P10 to the underwater detection device 100 but also adding a function that estimates the total weight of fish in the detection range and displays it on the plotter device 200.

[0074] The calculation formula for this estimation may generally include parameters related to the transmission and reception of the underwater detection device 100 and parameters such as the target strength of a single fish. However, it is usually difficult for fisherman to grasp these parameters. In addition, the target strength of a single fish differs depending on the species of fish and may change depending on the sea area and season. Therefore, it is extremely difficult for fisherman to properly estimate the catch by properly inputting these parameters into the underwater detection device 100.

[0075] In order to solve such problems, in this embodiment, the underwater detection device 100 is equipped with a function capable of smoothly and properly estimating the catch of fish. This function is executed by the fish quantity index calculation module 101c, the correction value reception processing module lOld and the object area reception processing module lOle shown in FIG. 4. These processes will be described below.

[0076] Fish quantity index calculation module

[0077] The fish quantity index calculation module 101c calculates the fish quantity index which may be an index of the total weight of fish contained in the object area based on the electric signals output from the plurality of ultrasonic oscillator 103a installed in the transducer 103. The fish quantity index is calculated by a predetermined calculation formula. The derivation process of this calculation formula will be described below, showing various parameters.

[0078] (1) Target strength

[0079] The strength at which a fish reflects sound waves is expressed by the target strength. The target strength is defined by the ratio of "the strength of the reflected wave at a unit distance from the object" to "the strength of the sound incident on the object" (former latter). In the following, unit distance is expressed as ro, which is defined as 1 m.

[0080] (2) pseudo target and simulated fish quantity

[0081] When the average value of the weight and the average value of the target strength of each fish contributing to the generation of the echo image P10 are expressed by W and Ts, respectively, a point target whose weight and target strength are equal to the average values W and Ts is called pseudo target.

[0082] Here, it is assumed that it is possible to generate "the same echo generated by the fish contributing to the generation of the echo image P10" by placing any number of the pseudo target at any position on the scanning plane SP1 of FIGS. 1 and 2. The sum of the weights of these pseudo targets is called simulated fish quantity corresponding to the sonar reaction.

[0083] (3) Formulation of simulated fish quantity

[0084] (3-1) Expression of target strength Ts

[0085] The relationship between the sound intensity transmitted by the transducer 103 and the reception signal due to "one pseudo target on the beam axis" will be explained below along the propagation process of sound waves. Here, it is assumed that the distance rt between the transducer 103 and the pseudo target is sufficiently large for the size of transducer 103.

[0086] First, consider the sound pressure of transmission pulse at a position ro away from the origin of scanning plane SP1 in FIG. 1. Generally, the sound intensity is defined by 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 transmission pulse increases from zero to reach its maximum value, and then decays to zero. Therefore, the maximum intensity of transmission pulse is proportional to "Squared value of the effective sound pressure at the time when the amplitude reaches its maximum value."

[0087] In the following, the intensity of an acoustic pulse is defined by this square value, and it is assumed that the sound pressure changes as a sinusoidal wave in any one cycle of transmission pulse. By these definitions and assumptions, a transmission pulse intensity Io is expressed by Io=Pmax2 / 2, where Pmax is the maximum value of the sound pressure amplitude. In the following, lpPa (micropascal) is used as the unit of sound pressure.

[0088] FIG. 6 is a diagram schematically showing propagation state of transmission pulse and its reflected wave (reflected pulse) on one beam axis, according to the embodiment 1 of the present invention.

[0089] The transmission pulse is attenuated by spherical divergence and absorption while propagating from the origin to pseudo target. Assuming that the absorption coefficient (attenuation of sound wave per unit distance) is a[dB / m], the intensity Ii of transmission pulse incident on the pseudo target is expressed by the following equation. / \ 2 / 1 = Zop) i0"°-lctrt -(1)

[0090] This pulse is reflected by the pseudo target and propagates toward the origin as a reflected pulse. The intensity b of the reflected pulse at a position away from the pseudo target by unit distance ro is expressed by the following equation based on the definition of the target strength Ts described above. I2 = I1-Ts = Io io-olart Ts --(2) \rt7

[0091] The intensity of the reflected pulse incident on the transducer 103 is expressed by the following equation similar to the above equation (1).

[0092] As described above, in the reception processing module 105 shown in FIG. 4, the underwater detection device 100 amplifies the electric signal from the ultrasonic oscillator 103a by an amplifier and band-limits it by an analog filter. Next, the underwater detection device 100 samples the processed signal by the A / D converter at the time of input to the control unit 101 to generate the digital signal. Then, the underwater detection device 100 forms the reception beam RBI from the digital signal corresponding to a predetermined ultrasonic oscillator group, and generates a signal (i.e., reception signal) corresponding to the sound wave received by the transducer 103 by each reception beam RBI. The underwater detection device 100 applies a band-limiting filter, a pulse compression filter, or the like to each reception signal, and then generates the envelope signal which is a signal equal to its instantaneous amplitude. Hereinafter, this envelope signal is treated as a dimensionless quantity.

[0093] The sound pressure waveform of the acoustic pulse signal incident on the transducer 103 is distorted by the process of converting it into an electric signal and the subsequent processing. However, since these transformations and processes may generally be assumed to have linearity and time-invariant properties, the ratio of the maximum instantaneous amplitude of the acoustic pulse signal to the maximum envelope signal is constant regardless of the distance rt to the pseudo target or the target strength Ts of the pseudo target. Hereinafter, this ratio (latter former) is referred to as reception sensitivity, and is expressed by the parameter k. The unit of reception sensitivity is 1 / pPa.

[0094] The maximum value Amax of the envelope signal of the reflected pulse when it is incident on the transducer 103 is related to the intensity I3 of the reflected pulse by the following equation.

[0095] When this is solved for the target strength Ts, the following equation is obtained. S max

[0096] (3-2) Normalized amplitude data

[0097] A beam number] is assigned to each reception beam RBI according to the azimuth angle (p of its beam axis. For example, in the plan view, the beam number] of the reception beam RB1 facing the stern direction is assumed to be j=0, and in the plan view, the clockwise direction is assumed to be positive, and beam numbers j=l, 2, 3, ... are assigned to each reception beam RBI in the order of increasing angle between the stern direction (i.e., reference direction) and the beam axis direction. In this case, if the total number of reception beam RBI is 128, the beam numbers] of reception beam RBI facing port, bow, and starboard directions are 32, 64, and 96, respectively.

[0098] Furthermore, a sample number n is assigned to each sampling time of the envelope signal in the order of time. The transmission start time of the transmission beam TB1, that is, the moment when the leading edge of transmission pulse is radiated from the transducer 103, is taken as a reference time, and the sample number at this time is set to n=0.

[0099] The envelope signal obtained in one transmission is composed of a plurality of digital data by the above-described sampling. The sampling period in this sampling may be the same as or different from the sampling period of the above-described A / D converter.

[0100] When data generated by the reception beam RBI with beam number] and sample number n is expressed by A(j,n), A '(j,n) defined by the following equation is called normalized amplitude data.

[0101] Here, rn is the distance from the origin of the position corresponding to the time tn at which the nth data is sampled. That is, when the pseudo target is located at the position rn, the leading edge of the reflected pulse from this pseudo target is sampled as the nth data. When the sampling frequency is fs, tn=n / fs, and the speed at which sound waves propagate is c, rn is defined by the following equation.

[0102] If transmission pulse's time width (pulse width) is t, the time at which the trailing edge of the reflected pulse is sampled is tn+r, and the distance from the origin of the corresponding position is rn+ (ct / 2). In the following, it is assumed that the difference between these distances is sufficiently small compared with the distance from the origin to the pseudo target. Namely, the following relation is assumed.

[0103] In this case, as may be seen from Equations (5) and (6), the square value of the maximum value A' max of the normalized amplitude data A' (j,n) coincides with the target strength Ts. -(9)

[0104] (3-3) Amplitude data space

[0105] Here, a rectangular coordinate system with the beam number] and the sample number n as two axes is defined. FIGS. 7A and 7B are diagrams schematically showing the rectangular coordinate system in which the beam number and the sample number are two axes, according to the embodiment 1 of the present invention. In FIGS. 7A and 7B, 17x17 gratings (i.e., cells) are shown for convenience, but the actual number of gratings (i.e., cells) is significantly larger than this.

[0106] The positions of the gratings (i.e., cells) on the vertical axis and the horizontal axis indicate the positions of the numbers on the vertical axis and the horizontal axis. Since the numbers on the vertical axis and the horizontal axis increase by 1, the vertical and horizontal widths of each cell are both 1. With the coordinates on the horizontal axis as the beam number] and the coordinates on the vertical axis as the sample number n, the normalized amplitude data A '(j,n) described above is applied to a cell located at a point (j,n). The set of normalized amplitude data arranged in this way is called an amplitude data space. On the other hand, the space of underwater, which is the detection target of underwater detection device 100, is called a real space.

[0107] (3-4) Point spread coefficient

[0108] It is assumed that there is one pseudo target at the position of the real space corresponding to a point Pl in FIG. 7A. At this time, in the amplitude data space, normalized amplitude data due to this pseudo target occurs at the rear of point Pl (upper side in FIG. 7A). In FIG. 7A, these gratings are shown by hatching. The area (area in the amplitude data space) in which normalized amplitude data is generated due to the target is called an echo area.

[0109] The longitudinal width of the echo area is determined by the time width of transmission pulse. The transverse width of the echo area is determined by the beam width of reception beam RB1. The normalized amplitude data values of each cell in the echo area generally take non-uniform values depending on the envelope waveform of transmission pulse and the beam pattern of reception beam RBI.

[0110] In any cell in the echo area, the square value of the normalized amplitude data is proportional to the target strength Ts. Therefore, the sum of the squared values of the normalized amplitude data in the echo area is also proportional to the target strength Ts.

[0111] Here, considers the point target whose target strength Ts is 1. According to the definition of normalized amplitude data, the maximum value of normalized amplitude data attributable to this target is 1. The sum of the squared values of the normalized amplitude data is called point spread coefficient, which is expressed by Vunit.

[0112] The following relation may be obtained from the aforementioned proportionality relation and the definition of point spread coefficient Vunit.

[0113] (Lemma A)

[0114] For a single pseudo target, the quotient obtained by dividing the sum of the squared values of the normalized amplitude data by point spread coefficient Vunit is equal to the target strength Ts of pseudo target.

[0115] (3-5) Sum value of target strength Ts

[0116] As shown in Fig. 7B, we consider the case where two pseudo target exist in the rectangular coordinate system that defines the amplitude data space, and a portion of the echo area generated by these pseudo target overlap. We focus on one cell included in this overlap. In Fig. 7B, this cell is filled with black.

[0117] Here, we consider reception signal as a complex envelope signal. When the pseudo target exists at only one of points Pl and P2, the complex envelopes generated in this black cell are Aie+jei and A2e+je2, respectively. Assuming that the instantaneous amplitude when both exist at the same time is A12, the squared value is expressed by the following equation. ^12 = {Aie+^1 + A2e+i02>) ■ (Are~^e± + A2e~^02') = A2 + A2 + 2ArA2 cos(01 — 02) --(10)

[0118] The distance between the transducer 103 and each individual fish changes from the time the underwater detection device 100 transmits transmission pulse to the time of the next transmission. It may be assumed that the amount of change randomly varies over a length of about 1 / 4 of the wavelength of the transmission wave. Therefore, if the average value of the squared instantaneous amplitudes A2av obtained by multiple transmissions is calculated, the value approximately agrees with Ai2+A22. 41v + ---(1 1 )

[0119] Similarly, if an arbitrary number of pseudo target echo area overlap, the following relationship is also established.

[0120] (Lemma B)

[0121] The value obtained by averaging the squared normalized amplitude data at the coordinates where the echoes from multiple pseudo target overlap over multiple transmissions is approximately equal to the sum of the squared normalized amplitude data generated by individual pseudo target.

[0122] The following relationship may be obtained from the above Lemmas A and B.

[0123] (Theorem)

[0124] In area (area in the amplitude data space) including the entire echo from a pseudo target group, the value obtained by averaging the quotient of the sum of the squared normalized amplitude data divided by point spread coefficient Vunit over multiple transmissions is approximately equal to the sum of the target strength Ts of the pseudo target group.

[0125] (3-6) Simulated fish quantity's formula

[0126] As may be seen from simulated fish quantity's definition and the above theorem, in order to obtain simulated fish quantity, Qq defined by the following equation may be averaged over many times of transmission of transmission pulse.

[0127] The symbol S in equation (12) means the sum of all sets of (j,n) to be processed in 1 ping of transmission / reception wave.

[0128] (4) Formula for defining fish quantity index

[0129] In equation (12), transmission pulse's strength Io and reception sensitivity's square k2 are parameters unique to individual the underwater detection device 100, and their accurate values are difficult to obtain in general fisherman. The value of the target strength Ts is obtained by substituting the length of the collected fish into an empirical formula, but this calculation is not easy for ordinary fisherman. On the other hand, it is easy for fisherman to roughly estimate the amount of captured fish (tonnage).

[0130] The fish quantity index calculation module 101c in FIG. 4 calculates a fish quantity index Q defined by the following equation as an approximate value of simulated fish quantity. Then, the fish quantity index calculation module 101c transmits the calculated value of the fish quantity index Q or the average value of the fish quantity index Q over multiple transmissions to the plotter device 200 and displays it on the plotter device 200.

[0131] The coefficient Co is an approximate number of W / (2Io • k2 • Ts). This approximate number may be a value obtained by substituting the values of W and Ts for representative fish and the design values of Io and k in the underwater detection device 100, or may be a value obtained in advance so that the catch estimated by fisherman or the actual catch agrees well with the fish quantity index Q.

[0132] The coefficient Ccor is fish quantity correction coefficient. The fish quantity correction magnification input from the user such as fisherman is reflected in this fish quantity correction coefficient Ccor. That is, until fish quantity correction magnification is first input, the fish quantity index calculation module 101c calculates the fish quantity index Q by setting the initial value of 1 to the fish quantity correction coefficient Ccor. Each time fish quantity correction magnification is input, the fish quantity index calculation module 101c updates the value of the fish quantity correction coefficient Ccor by the following equation.

[0133] "New Ccor" = "fish quantity correction magnification" x "Old Ccor"

[0134] That is, the fish quantity index calculation module 101c calculates the fish quantity index Q by using the value obtained by multiplying the fish quantity correction coefficient Ccor immediately before input of correction magnification by fish quantity correction magnification as a new fish quantity correction coefficient Ccor.

[0135] By reflecting fish quantity correction magnification input from the user to fish quantity correction coefficient Ccor in this way, calculation formula (13) of the fish quantity index Q may be corrected so as to approach the actual catch quantity based on the input fish quantity correction magnification. Therefore, by repeating the input of fish quantity correction magnification, the user may bring the fish quantity index Q closer to the fish quantity according to his own estimate. Therefore, the fish quantity information based on the fish quantity index Q according to the fishing ground of the user, fish species and season may be smoothly and properly displayed on plotter device 200.

[0136] The above equation (13) is stored in the storage unit 102 shown in FIG. 4, and the updated fish quantity correction coefficient Ccor is also updated and stored in the storage unit 102 as needed. Using the above equation (13) and the updated fish quantity correction coefficient Ccor stored in the storage unit 102, the control unit 101 calculates the fish quantity index Q by the function of the fish quantity index calculation module 101c, transmits it to the plotter device 200, and causes the plotter device 200 to display the fish quantity information related to the fish quantity index Q. This process will be described later with reference to FIGS. 10 and 12.

[0137] (5) Calculation formula of point spread coefficient Vunit

[0138] The calculation formula of point spread coefficient Vunit will be supplemented below.

[0139] The pulse width of transmission pulse, the beam width of reception beam and the tilt angle are expressed by t, y and 0, respectively. Here, the beam width y is defined as "the beam width in the plane where the beam axis contacts scanning plane SP1," and the beam width y is assumed to be independent of the tilt angle 9. The arbitrarily selected reference values of sampling frequency fs, pulse width t and beam width y are fso, to and yo, respectively. The value of point spread coefficient Vunit at tilt angle 9=0° corresponding to these reference values is expressed by Vo.

[0140] At this time, the point spread coefficient Vunit at arbitrary fs, t, y and 9 is expressed by the following equation. = -<10) cos 0 Vso r0 / Wo /

[0141] For example, if the sampling interval (l / fs) is proportional to transmission pulse width t and reception beam width may not take a value other than yO, point spread coefficient Vunit is expressed by VUnit=Vo / cos9 as a function of 9.

[0142] (6) Setting of fish quantity correction magnification

[0143] FIG. 8 is a flowchart showing reception process of fish quantity correction magnification, according to the embodiment 1 of the present invention. This processing is performed by the control unit 101 according to the function of the correction value reception processing module 101 d shown in FIG. 4.

[0144] When the fish quantity index calculated by the above equation (13) differs from the total weight of the fish caught by the user, the user inputs an input instruction of fish quantity correction magnification via the input unit 109 in order to correct the difference. In response to the input instruction, the control unit 101 causes the display unit 107 to display correction magnification reception screen for inputting fish quantity correction magnification and receives the input of fish quantity correction magnification from the user (SI 1).

[0145] FIG. 9 is a diagram showing an example of a fish quantity correction magnification reception screen 300, according to the embodiment 1 of the present invention.

[0146] 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 the screen. When the user clicks the magnification input area 301 via the input unit 109, magnification selection candidates are vertically arranged and dropped down below the magnification input area 301. The selection candidates are, for example, values arranged from 0.1 to 2.0 in increments of 0.1. The user selects a desired magnification from the displayed selection candidates. Thus, the selected magnification is displayed in the magnification input area 301. In the example shown in FIG. 9, the magnification of 1.1 is selected.

[0147] The user may change fish quantity correction magnification by clicking the magnification input area 301 again. Thus, after inputting fish quantity correction magnification, the user clicks the button 302. Thus, the input of fish quantity correction magnification is confirmed. If the user clicks the button 303 without clicking the button 302, the input operation of fish quantity correction magnification is canceled.

[0148] Referring back to FIG. 8, when the user confirms the input of fish quantity correction magnification (YES in S12), the control unit 101 sets the value obtained by multiplying the fish quantity correction coefficient Ccor before input by the input fish quantity correction magnification as the new fish quantity correction coefficient Ccor (SI3). As a result, the fish quantity correction coefficient Ccor is updated. On the other hand, when the user cancels the input operation without confirming the input of fish quantity correction magnification (NO in S12), the control unit 101 terminates the process in FIG. 8 without updating the fish quantity correction coefficient Ccor. Display of fish quantity index

[0149] FIG. 10 is a flowchart showing the transmission processing of the fish quantity index, according to the embodiment 1 of the present invention. This process is performed by control unit 101 using the function of the fish quantity index calculation module 101c and the communication module 111 in FIG. 4.

[0150] When the display process of the fish quantity index starts, the control unit 101 determines whether or not fish quantity correction coefficient Ccor has been updated by the process shown in FIG. 8 (S21). If fish quantity correction coefficient Ccorhas been updated (S21: YES), the control unit 101 sets the updated fish quantity correction coefficient Ccor to the above equation (13) (S22). If fish quantity correction coefficient Ccor has not been updated (S21: NO), the control unit 101 skips step S22 and advances the process to step S23.

[0151] After that, when the transmission / reception period (1 ping) ends and the data necessary for the calculation of the fish quantity index Q has been completed (S23: YES), the control unit 101 calculates the fish quantity index Q according to the above equation (13) by the function of the fish quantity index calculation module 101c (S24). Then, the control unit 101 transmits the calculated fish quantity index Q to the plotter device 200 via the communication module 111 (S25).

[0152] When the process for the current ping is thus completed, the control unit 101 determines whether or not the operation for displaying the fish quantity information related to the fish quantity index Q on the plotter device 200 has been completed by the user operation (S26). If the display operation has not been completed (S26: NO), the control unit 101 returns the process to step S21 and executes the same process. If the process of FIG. 8 is executed in parallel with the process of FIG. 10 and the fish quantity correction coefficient Ccor is updated (S21: YES), the updated fish quantity correction coefficient Ccoris applied to the above equation (13) (S22), and the process from step S23 is executed.

[0153] Thus, until the display operation of the fish quantity information related to the fish quantity index Q is completed (S26: NO), the control unit 101 repeatedly executes the processes of steps S21 to S25. Thus, the display of the fish quantity information related to the fish quantity index Q is updated for each ping. After that, when the display operation is completed (S26: YES), the control unit 101 terminates the process of FIG. 10.

[0154] Next, the configuration and operation of the plotter device 200 will be described.

[0155] FIG. 11 is a block diagram showing the configuration of the plotter device 200, according to the embodiment 1 of the present invention.

[0156] The plotter device 200 includes a GPS antenna 200a, control unit 201, storage unit 202, GPS receiver 203, display unit 204, display processing module 205, input unit 206, input processing module 207, and communication module 208. The main configuration of the plotter device 200 is installed in the wheelhouse or the like of ship SI and communicates with the underwater detection device 100 via the communication module 208.

[0157] The control unit 201 includes an arithmetic processing circuit such as a CPU, and executes the control processing described later by a program stored in the storage unit 202. The storage unit 202 includes a storage medium such as a ROM, a RAM, and a hard disk. The storage unit 202 stores a program for the control unit 201 to execute the control processing, and also stores data for displaying a chart and a map.

[0158] The GPS receiver 203 calculates the position of own ship on the earth (i.e., Latitude, Longitude) based on radio waves received from a GPS satellite via the GPS antenna 200a, and outputs the calculated position of own ship to the control unit 201.

[0159] The display unit 204 includes a display device such as a liquid crystal display. The display processing module 205 causes the display unit 204 to display a predetermined image in response to the control from the control unit 201. The input unit 206 includes input means such as an operation key or a track ball. In response to the control from the control unit 201, the input processing module 207 outputs a signal corresponding to the operation of the input unit 206 to the control unit 201. The display unit 204 and the input unit 206 may comprise a liquid crystal panel in which a touch panel is superimposed on a liquid crystal display. The communication module 208 communicates with the underwater detection device 100 in response to control from the control unit 201.

[0160] In this embodiment, the functions of a fish quantity display superposition module 201a are given to the control unit 201 by the program stored in the storage unit 202. The control unit 201 generates a plotter image in which the position of own ship and track are superimposed on the surrounding chart and map based on the position of own ship successively inputted from the GPS receiver 203 and the data of the chart and map stored in the storage unit 202, and causes the display unit 204 to display the plotter image. The fish quantity display superposition module 201a displays the fish quantity information based on the fish quantity index received from the underwater detection device 100 via the communication module 208 in association with track on the plotter image.

[0161] FIG. 12 is a flowchart showing the display processing of the fish quantity index, according to the embodiment 1 of the present invention. This processing is performed by the control unit 201 in accordance with the function of the fish quantity display superposition module 201a in FIG. 11.

[0162] When the control unit 201 receives the fish quantity index transmitted in step S25 of FIG. 10 (S3L YES), the received fish quantity index is associated with the present position of the own ship input from the GPS receiver 203 and stored in the storage unit 202 (S32). When a new display position to display the fish quantity information occurs due to the progress of the own ship (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 present position on track (S34).

[0163] Here, the display position is set at a fixed distance interval, for example, on track of the own ship. The distance interval may be changed according to the magnification (i.e., scale) of the plotter image. The display positions may be set on track of the own ship at fixed time intervals. In this case, the time intervals may also be changed according to the magnification of the plotter image. The distance intervals and time intervals may be adjusted so that the fish quantity information is displayed at intervals that are easy to see on the plotter image.

[0164] The fish quantity information displayed at each display position is generated so as to reflect the value of the fish quantity index stored associated at each display position in the storage unit 202. Alternatively, the fish quantity information may be generated from the value of the fish quantity index associated and stored at each display position and the position on track in the vicinity thereof.

[0165] In this case, for example, from the value of the fish quantity index at the target display position and the values of a plurality of fish quantity indexes associated with positions on track included in a distance range smaller than the distance interval in the longitudinal direction of track relative to the target display position, a representative value (i.e., Mean, median, mode, etc.) of these values is calculated, and the fish quantity information at the target display position is generated so as to reflect the representative value. Here, the above distance range may be set to, for example, about half of the distance interval.

[0166] Alternatively, instead of this method, for example, from the value of the fish quantity index at the target display position and the values of the fish quantity index associated with a position on track between the target display position and the immediately preceding display position, a representative value (i.e., mean, median, mode, etc.) of these values is calculated, and the fish quantity information at the target display position may be generated so as to reflect the representative value.

[0167] In these two methods of generating the fish quantity information, the integrated value of the fish quantity index values may be calculated instead of the representative value, and the fish quantity information at the target display position may be generated so as to reflect the integrated value.

[0168] The control unit 201 repeatedly executes the processes of steps S31 to S34 until the plotter device 200 finishes the display operation of the fish quantity information (S3 5: NO). Thus, while the position of the own ship and track are updated, the fish quantity information is displayed in association with each updated display position on track.

[0169] The start and end of the fish quantity information display operation are instructed by the user via the input unit 206, for example. The control unit 201 starts the process shown in FIG. 12 in response to the start instruction of the fish quantity information display operation, and ends the process shown in FIG. 12 in response to the end instruction of the fish quantity information display operation (step S35: YES). The start and end instructions of the fish quantity information display operation are transmitted to the underwater detection device 100 via the communication module 208. The control unit 101 of the underwater detection device 100 starts the process shown in FIG. 10 in response to the reception of the start instruction, and ends the process shown in FIG. 10 in response to the reception of the end instruction (step S26: YES).

[0170] Alternatively, the start and end of the plotter device 200 may be the start and end of the fish quantity information display operation, and the start and end of the underwater detection device 100 may be the start and end of the fish quantity information display operation.

[0171] FIG. 13 is a diagram schematically showing an example of a plotter image 400 including fish quantity information based on a fish quantity index, according to the embodiment 1 of the present invention.

[0172] The image of area designated 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 may change the magnification (i.e., scale) of the plotter image 400 via the input unit 206. According to the change in magnification, area displayed on the display unit 204 changes.

[0173] The plotter image 400 includes a land image 410 corresponding to the land and a sea image 420 corresponding to the sea area. Although the land image 410 and the sea image 420 are displayed in different colors, the land image 410 is hatched to distinguish the land image 410 and the sea image 420. The sea image 420 includes an isobath line 421 indicated by a broken line and a description of the water depth added to the isobath line 421.

[0174] Furthermore, the plotter image 400 includes a plot 431 indicating the present position of the own ship and a track 432 up to the present position. When the processing of FIG. 12 is executed, the fish quantity information based on the fish quantity index is sequentially displayed at each display position on the track 432. Here, as the fish quantity information, the fish quantity images 433a to 433c are displayed superimposed on each display position. As described above, the interval of each display position may be changed according to the magnification of the plotter image 400.

[0175] In the example of FIG. 13, fish quantity images 433a to 433c are composed of a circle whose diameter and color correspond to the value of the fish quantity index. The larger the value of the fish quantity index, the larger the diameter of the circle. In FIG. 13, for convenience, the difference in color of the fish quantity images 433a to 433c is indicated by the difference in hatching. For example, the fish quantity image 433a is colored red, the fish quantity image 433b is colored yellow, and the fish quantity image 433c is colored blue.

[0176] For example, the diameter of the circle is set in three stages using three thresholds Thl to Th3 (Thl<Th2<Th3). When the value of the fish quantity index is above the threshold Thl and below the threshold Th2, the diameter DI is used, when the value of the fish quantity index is above the threshold Th2 and below the threshold Th3, the diameter D2 is used, and when the value of the fish quantity index is above the threshold Th3, the diameter D3 is used (D1<D2<D3). The threshold Thl to Th3 may be arbitrarily set by the user.

[0177] However, the method of setting the diameter is not limited to this, and for example, the diameter may be set in four stages or more, and the diameter may change linearly according to the change of the value of the fish quantity index. In such a case where the diameter changes linearly, the color of the fish quantity image may change by a color scale in which the hue continuously changes according to the change of the value of the fish quantity index.

[0178] From the fish quantity images 433a to 433c included in the plotter image 400, the user may grasp the fish quantity at each position on the track 432 of own ship until now. Therefore, the user may smoothly grasp the situation of fish group and the position to catch the fish, and may proceed to catch the fish by returning to the position on the track 432 as appropriate.

[0179] In the example of FIG. 13, the fish quantity images 433a to 433c are circular images differing in diameter and color from each other, but the fish quantity images 433a to 433c may be circular images differing only in diameter from each other, or may be circular images differing only in color from each other. The user may grasp the fish quantity on track 432 of own ship from the fish quantity images 433a to 433c by these display forms. Setting of the fish quantity calculation area

[0180] The range in which the fish quantity index is calculated by equation (13) may be limited to a predetermined range by the user from the entire range scanned in 1 ping. For example, when the user performs purse seining, the range in which the fish quantity index is calculated may be limited to the range that may be enclosed by purse seine (For example, a radius of 200 m around own ship).

[0181] FIG. 14 is a diagram schematically showing an example of the fish quantity calculation area reception screen 310, according to the embodiment 1 of the present invention.

[0182] Reception process of the fish quantity calculation area is performed by the control unit 101 by the function of the object area reception processing module lOle shown in FIG. 4. With this function, the control unit 101 displays the fish quantity calculation area reception screen 310 shown in FIG. 14 in response to the setting operation of the calculation area by the user.

[0183] 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 the screen, and a button 314 for manually 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.

[0184] When the user clicks the range input area 311 via input unit 109, range selection candidates are displayed under the range input area 311. The selection candidates are, for example, values arranged in 50 m increments from 200 m to 800 m. The user selects a desired range from the displayed selection candidates. As a result, the value of the selected range is displayed in the range input area 311. In the example shown in FIG. 11, the range with a radius of 200 m centered on the own ship is selected.

[0185] The user may change the calculation range of the fish quantity by clicking the range input area 311 again. After inputting the calculation range of the fish quantity, the user clicks the button 312. Thus, the input of the fish quantity calculation range is confirmed. If the user clicks the button 313 without clicking the button 312, the input operation of the fish quantity calculation range is canceled.

[0186] To set an arbitrary range, the user operates the button 314. Thus, for example, an image including boundary lines P14 to P16 similar to the echo image P10 in FIG. 5 is displayed. The user draws a line surrounding the desired range on the image via the input unit 109 and operates the confirm button. Thus, the range surrounded by the line is determined as the fish quantity calculation range.

[0187] The control unit 101 (fish quantity index calculation module 101c) executes the process of step S24 in FIG. 10 with the range set by the user as the calculation target range. That is, the process of step S24 is executed using the data in the range set by the user in the amplitude data space shown in FIG. 7A. For example, as shown in FIG. 14, if the range with a radius of 200 m centered on the own ship is set as the fish quantity calculation range, the process of step S24 is executed using the data included in the range of the sample number on the vertical axis corresponding to 0-200 m.

[0188] By limiting the fish quantity calculation range in this way, the user may have the plotter device 200 which displays the fish quantity information based on the fish quantity index Q in the range where the user intends to catch fish. Thus, the user may smoothly proceed fishing.

[0189] The fish quantity calculation range may be displayed along with the plotter image 400 on the plotter device 200. For example, the current fish quantity calculation range (the distance of the radius around the own ship) may be displayed on the lower left corner of the plotter image 400 or on the display area provided in the margin. Alternatively, when the user specifies an arbitrary fish quantity image 433a to 433c, the fish quantity calculation range in which the value of the fish quantity index corresponding to the fish quantity image is calculated may be displayed on the side of the fish quantity image. Thus, the user may generally grasp the fish quantity that may be captured by own ship. Effect of Embodiment 1

[0190] According to Embodiment 1, the following effects may be achieved.

[0191] As shown in FIG. 3, the fish quantity information display system 10 includes the underwater detection device 100 and the plotter device 200. As shown in FIGS. 1 and 2, the underwater detection device 100 detects fish group by scanning reception beam RB1 along the conical scanning plane SP1. As shown in FIG. 13, the plotter device 200 displays the present position of own ship (plot 431) and track 432 up to the present position. As shown in FIG. 4, the underwater detection device 100 includes the fish quantity index calculation module 101c for calculating the fish quantity index based on the electric signals output from the plurality of ultrasonic oscillator 103a, and the communication module 111 for transmitting the fish quantity index to the plotter device 200. As shown in FIG. 11, the plotter device 200 includes the communication module 208 for receiving the fish quantity index, and the fish quantity display superposition module 201a for displaying the fish quantity information based on the fish quantity index in association with track.

[0192] As shown in FIGS. 10 and 12, fish quantity information display method executed by the fish quantity information display system 10 includes a step for calculating the fish quantity index based on the electric signals output from the plurality of ultrasonic oscillator 103a (S24), and a step for displaying the fish quantity information based on the fish quantity index in association with track (S34).

[0193] According to this configuration, since fish group is detected by scanning reception beam RBI along the conical scanning plane SP1, it is possible to obtain the fish quantity information in a wide range as the target range of purse seining, and also to obtain the fish quantity information from the fish distributed near the sea surface. In addition, since the fish quantity information of the fish distributed in the cone-shaped scanning plane SP1, not directly under the own ship, is acquired, it is possible to mitigate the influence of the escape of the fish due to noise from the own ship (i.e., ship SI) on the fish quantity information. Furthermore, the fish quantity index is calculated based on the electric signals output from the plurality of ultrasonic oscillator 103a, and the fish quantity information based on the calculated fish quantity index is displayed in association with the track 432 as shown in FIG. 13, so that the user may easily grasp the fish quantity without applying the parameters of the underwater detection device 100 or calculation formula. Thus, the user may accurately and easily grasp the fish quantity existing on the track 432 of the own ship.

[0194] As shown in FIG. 13, the fish quantity information includes the fish quantity images 433a to 433c corresponding to the values of the fish quantity index, and the fish quantity display superposition module 201a displays the fish quantity images 433a to 433c at predetermined positions (i.e., display positions) on the track 432.

[0195] With this configuration, the user may smoothly grasp the fish quantity at each position on the track 432.

[0196] As shown in FIG. 13, the fish quantity images 433a to 433c are circles composed of at least one of the diameters and colors (Here, both) corresponding to the values of the fish quantity index.

[0197] With this configuration, the user may intuitively grasp the fish quantity at each position on track 432.

[0198] As shown in FIG. 4, the underwater detection device 100 is provided with the correction value reception processing module 101 d which accepts the input of a correction value (i.e., correction magnification) for correcting the fish quantity index Q, and the fish quantity index calculation module 101c corrects the above equation (13) which is calculation formula of the fish quantity index Q based on the input correction value.

[0199] With this configuration, the fish quantity correction coefficient Ccor of the above equation (13) is corrected based on the correction value (i.e., correction magnification) input from the user such as fisherman. In general, since the user may easily estimate the fish quantity (for example, tonnage) captured by the user, the user may smoothly and properly input the correction value for correcting the displayed fish quantity index Q to the actual fish quantity. Therefore, calculation formula of the fish quantity index Q may be corrected so as to approach the actual catch based on the input correction value. Therefore, the fish catch may be smoothly and appropriately estimated by this correction processing.

[0200] As described above, the equation (13) that is calculation formula of the fish quantity index Q includes the fish quantity correction coefficient Ccor, and the correction value for correcting the equation (13) is correction magnification. The fish quantity index calculation module 101c calculates the fish quantity index Q by using the value obtained by multiplying the previous fish quantity correction coefficient Ccor by correction magnification as the new fish quantity correction coefficient Ccor-

[0201] Thus, the user may make the fish quantity index Q close to the fish quantity according to his / her rough estimate by repeating the input of correction magnification. Thus, the fish quantity index Q according to the user's fishing ground, fish species and season may be smoothly and properly displayed.

[0202] Here, the equation (13) for calculating the fish quantity index Q is obtained by replacing the first equation with an equation consisting of the approximate number of the first equation (coefficient Co) and the fish quantity correction coefficient Ccor, with respect to the original equation (12) consisting of the first equation including the weight W and target strength Ts of the fish to be captured, the intensity Io of the transmission wave and reception sensitivity k of transducer 103, and the second equation not including these.

[0203] Thus, since the weight W and target strength Ts of the fish to be captured, the intensity Io of the transmission wave and reception sensitivity k of the transducer 103 are added to the equation (13) as calculation formula of the fish quantity index Q, the fish quantity index may be accurately calculated by the equation (13). Moreover, since the first equation including these parameters is replaced by a term consisting of the approximate number of the first equation (coefficient Co) and the fish quantity correction coefficient Ccor as described above, the user may smoothly correct calculation formula by correction magnification according to his / her own approximate fish quantity without grasping these parameters. Thus, the user may smoothly approximate the displayed fish quantity index Q to his / her own approximate fish quantity. Therefore, the user may properly display the fish quantity index Q close to his / her own catch.

[0204] As shown in FIG. 4, the underwater detection device 100 is further provided with the object area reception processing module lOle which accepts the designation of an object area to be the object of calculation of the fish quantity index Q in the search range, and as explained with reference to FIG. 11, the fish quantity index calculation module 101c calculates the fish quantity index Q for the designated object area.

[0205] Thus, the user may designate an area to be noticed by the user or an area which may be enclosed by purse seine in the object area, and the fish quantity index Q in the object area may be displayed. Therefore, the user may smoothly capture fish based on the displayed fish quantity index Q Modification Example

[0206] In the plotter image 400 of FIG. 13, fish quantity information at each display position on the track 432 is displayed by the fish quantity images 433a to 433c, but the method of displaying the fish quantity information is not limited to this.

[0207] For example, as shown in Modification Example 1 of FIG. 15, the fish quantity images 433d to 433f may be composed of bands having width (i.e., width in the direction perpendicular to track 432) and color corresponding to the value of the fish quantity index. In FIG. 15, as in FIG. 13, the difference in color is indicated by the difference in hatching.

[0208] In the example of FIG. 15, as in the example of FIG. 13, the width of the fish quantity images 433d to 433f is set to three stages according to the relationship between the value of the fish quantity index and the threshold values Thl to Th3. In the example of FIG. 15, the fish quantity images of a series of display positions having the same width are integrated and displayed as one band. As in the example of FIG. 13, the width of the fish quantity image does not have to be 3 stages, and may change linearly according to the change in the value of the fish quantity index.

[0209] With the plotter image 400 of FIG. 15, the fish quantity at each position on track 432 of the own ship may be grasped from the fish quantity images 433d to 433f included in the plotter image 400. Therefore, the user may smoothly grasp the situation of fish group and the position to capture fish, and may proceed to capture fish by returning to the position on track 432 as appropriate.

[0210] In the example of FIG. 15, the fish quantity images 433d to 433f are images of bands whose width and color differ from each other, but the fish quantity images 433d to 433f may be images of bands whose width only differs from each other, or may be images of bands whose color only differs from each other. The user may grasp the fish quantity on the track 432 of own ship from the fish quantity images 433d to 433f by these display forms.

[0211] In addition, as shown in modified example 2 of FIG. 16, a value 434 of the fish quantity index may be displayed at the position on track 432 (Here, the display position). Here, for the position on track 432 specified by the user (indicated by X in FIG. 16), the value 434 of the fish quantity index at that position (unit: ton) is appended. In addition, the circular fish quantity image 433a corresponding to this position is highlighted.

[0212] With this configuration, the user may accurately grasp the fish quantity at the position on track as a numerical value.

[0213] In the example of FIG. 16, when the user designates an arbitrary display position on track 432, the value 434 of the fish quantity index at that position is displayed. However, the value 434 of the fish quantity index may be displayed in response to the user designating an arbitrary position on the track 432 without being limited to the display position.

[0214] The value of the fish quantity index does not necessarily have to be displayed according to the user's designation. For example, the control unit 201 (fish quantity display superposition module 201a) may display the value of the fish quantity index 434 at a display position where the value of the fish quantity index is equal to or greater than a predetermined threshold (For example, the above threshold Th3). In addition, instead of the fish quantity images 433a to 433c, the value of the fish quantity index 434 may be displayed at each display position.

[0215] Alternatively, in a state where the fish quantity images 433a to 433c are omitted from the plotter image 400 of FIG. 13, when the user designates a desired position on the track 432, the value of the fish quantity index 434 at that position may be displayed. Similarly, in a state where the fish quantity images 433a to 433c are omitted from the plotter image 400 of FIG. 13, when the user designates a desired position on the track 432, the fish quantity images 433a to 433c or fish quantity images 433d to 433f corresponding to the value of the fish quantity index at that position may be displayed, and the value of the fish quantity index 434 at that position may be displayed together with this fish quantity image.

[0216] In addition, as shown in modified example 3 of FIG. 17, the fish quantity information may be displayed when the value of the fish quantity index is equal to or greater than a predetermined threshold value. Here, the fish quantity images 433a and 433b (fish quantity information) are displayed at the display position on track 432 where the value of the fish quantity index is equal to or greater than the threshold value Th2.

[0217] According to this configuration, the display of the fish quantity information where the fish quantity index is less than the predetermined threshold value is omitted from the plotter image 400. Therefore, the user may smoothly grasp the position on the track 432 where a large fish quantity exceeding the threshold value occurs.

[0218] In the configuration of modified example 3, the threshold value for displaying the fish quantity information may be arbitrarily set by the user. Also in modified example 3, as in the case of modified example 2, the fish quantity index value 434 may be displayed together with the fish quantity images 433a and 433b, or the fish quantity index value 434 may be displayed instead of the fish quantity images 433a and 433b. Embodiment 2

[0219] FIG. 18 is a block diagram showing the configuration of the fish quantity information display system 10. according to the embodiment 2 of the present invention.

[0220] As shown in FIG. 18, the fish quantity information display system 10 according to embodiment 2 includes a radar device 500 compared with the configuration shown in FIG. 3. The radar device 500 includes a radar antenna 500a, and transmits a transmission wave (i.e., microwave) from the radar antenna 500a to the surroundings (i.e., air) of own ship. The radar device 500 receives the reflected wave of the transmitted transmission wave by the radar antenna 500a, and detects target (i.e., ship, land, birds, etc.) existing around own ship.

[0221] The radar antenna 500a is installed, for example, on the top surface of the wheelhouse, and rotates in the horizontal direction. The traveling direction of the transmission wave traveling straight from the radar antenna 500a in the horizontal direction rotates with the turning of the radar antenna 500a. By receiving the reflected wave at each turning position (bearing), the presence or absence of target at each turning position (bearing), the distance to target, and the intensity (echo intensity) of the reflected wave from target are detected. The radar device 500 is the radar device of a well-known configuration used for ships. The radar device 500 transmits the distance to target and the echo intensity at each bearing to the plotter device 200.

[0222] FIG. 19 is a block diagram showing the configuration of the plotter device 200, according to the embodiment 2 of the present invention.

[0223] As shown in FIG. 19, in the plotter device 200 according to embodiment 2, compared with the configuration shown in FIG. 11, the functions of a target display superposition module 201b are added to the control unit 201. The target display superposition module 201b superimposes the display of the current target on the plotter image 400 based on the azimuth, the distance to target, and the echo intensity received from the radar device 500 via the communication module 208.

[0224] FIG. 20 is a diagram schematically showing an example of the plotter image 400 including fish quantity information based on a fish quantity index and a target image based on radar information, according to the embodiment 2 of the present invention.

[0225] Compared with the plotter image 400 shown in FIG. 13, the plotter image 400 shown in FIG. 20 includes a target image 435 based on information from the radar device 500. Here, two target images 435 correspond to other ship. From these target images 435, the user may grasp that other ship is currently in the vicinity of the track 432 of own ship. Thus, the user may return to the position of the fish quantity image 433a showing a large fish quantity on track 432, which is further away from the other ship, and smoothly proceed fishing.

[0226] Alternatively, when target image showing a flock of birds is included, the user may estimate the position where more fish may be expected to be caught based on target image of the flock of birds and the fish quantity information on the track 432. Thus, the user may return to the position and smoothly proceed fishing.

[0227] The plotter image 400 displayed according to the configuration of embodiment 2 may also be changed in the same manner as in the modification example 1~3. Effect of Embodiment 2

[0228] As shown in FIG. 18, the fish quantity information display system 10 further includes the radar device 500 for detecting the surrounding target by receiving the reflected wave of the transmitted wave transmitted into the air, and as shown in FIG. 19, the plotter device 200 further includes the target display superposition module 201b for displaying target existing near track together with track 432 and the fish quantity information (fish quantity images 433a to 433c) based on the detection result of the radar device 500.

[0229] According to this configuration, as shown in FIG. 20, the target image 435 of another ship existing near the track 432 of the own ship may be displayed together with the fish quantity information (i.e., fish quantity images 433a to 433c) of each position on track 432, and target image of the flock of birds or the like existing near the track 432 may also be displayed. Thus, the user may more smoothly determine which position on track of the own ship to return to for fishing. Other Modification Examples

[0230] In embodiments 1 and 2, the fish quantity correction coefficient Ccor is corrected by correction magnification, but the correction value for correcting the fish quantity correction coefficient Ccoris not limited thereto. For example, a numerical value added to or subtracted from the fish quantity correction coefficient Ccor may be used as the correction value for the fish quantity correction coefficient Ccor.

[0231] The screen for receiving fish quantity correction magnification is not limited to the fish quantity correction magnification reception screen 300 shown in FIG. 9, and may be a reception screen of another configuration. Similarly, the screen for receiving designation of fish quantity calculation area is not limited to the fish quantity calculation area reception screen 310 shown in FIG. 14, and may be a reception screen of another configuration.

[0232] In addition, the control unit 101 may further include a function that allows the user to set a plurality of fish quantity correction coefficient Ccors according to, for example, fish species and fishing grounds. In this case, the control unit 101 associates fish quantity correction coefficient Ccor set by the user with the fish species and fishing grounds and stores it in the storage unit 102. In the application processing of the fish quantity correction coefficient Ccor, the control unit 101 causes the display unit 107 to display the selection candidates of the fish species or fishing grounds, and applies the fish quantity correction coefficient Ccor associated with the fish species or fishing grounds selected by the user via the input unit 109 to calculation formula of equation (13) to calculate the fish quantity index Q. Thus, the user may obtain the fish quantity index Q suitable for the fish species he / she intends to catch and the fishing grounds, and may proceed fishing more smoothly. In this case, the correction using fish quantity correction magnification (i.e., correction value) is performed for each fish quantity correction coefficient Ccor.

[0233] In embodiments 1 and 2, the fish quantity index calculation module 101c or the like is realized as a function of the control unit 101 provided by the program stored in the storage unit 102, and the fish quantity display superposition module 201a or the like is realized as a function of the control unit 201 provided by the program stored in the storage unit 202, but these functions need not necessarily be realized as functions provided by the program stored in the storage unit 102 and 202. For example, one or more of these functions may consist of a field-programmable gate array (FPGA) or hardware with integrated logic circuits.

[0234] In embodiments 1 and 2, the fish quantity index value is calculated by calculation formula of equation (13), but a calculation formula other than equation (13) may be used to calculate the fish quantity index Q. In this case as well, this calculation formula may include a fish quantity correction coefficient that is corrected by the correction value input from the user.

[0235] The plotter images 400 shown in Embodiments 1 and 2 and modification examples 1~3 are only examples, and may be plotter images of other configurations. For example, in the plotter image 400 of FIG. 13, the fish quantity images 433a to 433c may be changed to ellipses, diamonds, or the like. In addition, the fish quantity information (i.e., Fish quantity images and fish quantity index 5 values) may not be displayed only when the threshold value Thl is set near 0 and there is practically no fish.

[0236] In addition, various modifications can be made to the embodiment of the present invention as required within the scope of the claims. Reference Signs List 10 Fish quantity information display system 100 Underwater detection device 101 Control unit 101a Reception signal generation module 101b Image generation module 101c Fish quantity index calculation module 101 d Correction value reception processing module lOle Object area reception processing module 102 Storage unit 103 Transducer 103a Plurality of ultrasonic oscillator / ultrasonic oscillator 104 Transmission processing module 105 Reception processing module 106 Transmission / reception switching unit 107 Display unit 108 Display processing module 109 Input unit 110 Input processing module 111 Communication module SI Ship SP1 Scanning plane TB1 Transmission beam RBI Reception beam Al, A2 Area P10 Echo image Pll Image P12 Track P13 Straight line P14, P15, andP16 Circular boundary lines P17 Hatched area 200 Plotter device 200a GPS antenna 201 Control unit 201a Fish quantity display superposition module 201b Target display superposition module 202 Storage unit 203 GPS receiver 204 Display unit 205 Display processing module 206 Input unit 207 Input processing module 208 Communication module 300 Fish quantity correction magnification reception screen 301 Magnification input area 302, 303 Button 310 Fish quantity calculation area reception screen 311 Range input area 312, 313, 314 Button 400 Plotter image 410 Land image 420 Sea image 421 Isobath line 431 Plot 432 Track 433a, 433b, 433c, 433d, 433e, 433f Fish quantity images 434 Value 435 Target images 500 Radar device 500a Radar antenna

Claims

1. A fish quantity information display system (10), comprising:an underwater detection device (100) configured to detect fish group by scanning reception beam along a conical scanning plane (SP1); anda plotter device (200) configured to display a present position of an own ship and a track up to the present position; whereinthe underwater detection device (100) comprising:a fish quantity index calculation module (101c) configured to calculate a fish quantity index based on electric signals output from a plurality of ultrasonic oscillator (103a); anda communication module (111) configured to transmit the fish quantity index to the plotter device (200);the plotter device (200) comprising:a communication module (111) configured to receive the fish quantity index; anda fish quantity display superposition module (201a) configured to display a fish quantity information based on the fish quantity index in association with the track.

2. The fish quantity information display system (10) according to claim 1, whereinthe fish quantity information includes a fish quantity image according to a value of the fish quantity index, andthe fish quantity display superposition module (201a) displays the fish quantity image at a predetermined position on the track.

3. The fish quantity information display system (10) according to claim 2, wherein the fish quantity image is a circle composed of at least one of a diameter and a color corresponding to the value of the fish quantity index.

4. The fish quantity information display system (10) according to claim 2, wherein the fish quantity image is a band composed of at least one of a width and a color corresponding to the value of the fish quantity index.

5. The fish quantity information display system (10) according to claim 1, wherein the fish quantity information includes the value of the fish quantity index, andthe fish quantity display superposition module (201a) displays the value of the fish quantity index at a predetermined position on the track.

6. The fish quantity information display system (10) according to any one of claims 1 to 5, wherein the fish quantity display superposition module (201a) displays the fish quantity information when the value of the fish quantity index is equal to or greater than a predetermined threshold value.

7. The fish quantity information display system (10) according to claim 1, further comprising:a correction value reception processing module (10Id) configured to receive an input of a correction value for correcting the fish quantity index; whereinthe fish quantity index calculation module (101c) corrects a calculation formula of the fish quantity index based on the correction value.

8. The fish quantity information display system (10) according to claim 7, whereinthe calculation formula includes a fish quantity correction coefficient,the correction value is a correction magnification, andthe fish quantity index calculation module (101c) calculates the fish quantity index by using a value obtained by multiplying the fish quantity correction coefficient by the correction magnification as a new fish quantity correction coefficient.

9. The fish quantity information display system (10) according to claim 8, whereinthe calculation formula is obtained by replacing a first equation with an equation consisting of an approximate number of the first equation and the fish quantity correction coefficient, with respect to a prototype calculation formula consisting of the first equation including a weight and a target strength of a fish to be captured, an intensity of a transmission wave and a reception sensitivity of a transducer (103), and a second equation not including these parameters including in the first equation.

10. The fish quantity information display system (10) according to claim 1, further comprising:an object area reception processing module (101 e) configured to receive designation of an object area to be an object of calculation of the fish quantity index in a search range; whereinthe fish quantity index calculation module (101c) calculates the fish quantity index for the designated object area.

11. The fish quantity information display system (10) according to claim 1, further comprising:a radar device (500) configured to detect a surrounding target by receiving a reflected wave of a transmission wave transmitted in the air; whereinthe plotter device (200) further comprising a target display superposition module (201b) 5 configured to display a target existing in a vicinity of the track together with the track and the fish quantity information based on a detection result of the radar device.

12. A fish quantity information display method for displaying an image on a plotter device (200) for displaying a present position of own ship and a track up to the present position by using an 10 underwater detection device (100) for detecting fish group by scanning reception beam (RBI) along a conical scanning plane (SP1), comprising:calculating, by a fish quantity index calculation module (101c), a fish quantity index based on electric signals outputted from a plurality of ultrasonic oscillator (103a); anddisplaying, by a fish quantity superposition module (201a), a fish quantity information based 15 on the fish quantity index in association with the track.

Images