Underwater detection device, method for underwater detection, and program

Abstract

To provide an underwater detection device, a method for underwater detection, and a program which can smoothly and properly estimate fish catches.SOLUTION: An underwater detection device 10 includes: a fish quantity index calculation unit 11c for calculating a fish quantity index on the basis of an electrical signal output from plural ultrasonic transducers; an image generation unit 11b for generating a display image including information related to the fish quantity index; and a corrected value reception processing unit 11d for receiving the input of a corrected value for correcting the fish quantity index. The fish quantity index calculation unit 11c corrects the calculation formula of the fish quantity index on the basis of the input corrected value.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an underwater detection device for detecting underwater targets, an underwater detection method for detecting underwater targets, and a program for causing a computer to execute a function for detecting underwater targets. [Background technology]

[0002] Underwater detection devices that detect underwater targets are known in the art. These types of underwater detection devices transmit ultrasonic waves into the water, receive the reflected waves, calculate the echo intensity from each position in the water, and display a three-dimensional distribution of the echo intensity (echo image) on a screen.

[0003] For example, an underwater detection device transmits umbrella-shaped transmission waves along a conical surface from a transducer having multiple ultrasonic transducers, and receives the reflected waves with the transducer. From the electrical signals output from each ultrasonic transducer of the transducer upon receiving the reflected waves, multiple reception beams are formed by beamforming that are arranged in the circumferential direction on the conical surface, and a reception signal is generated for each reception beam. From the reception signals thus generated, an echo image according to the scanning range of the reception beam is generated and displayed.

[0004] The following Patent Document 1 describes an underwater detection system that generates an echo image by transmitting multiple types of transmission waves with different beam widths. In this underwater detection system, a reception signal is generated for each transmission wave with a different beam width, and an echo image is generated for each generated reception signal. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6722521 Summary of the Invention [Problem to be solved by the invention]

[0006] Experienced fishermen can estimate the amount of fish caught by referring to the echo images. However, it is difficult for inexperienced fishermen to make this estimation properly. Moreover, even experienced fishermen find it difficult to concentrate on this estimation while steering. Such problems can be solved by adding a function to the underwater detection device that estimates and displays the total weight of fish present within the detection range.

[0007] The calculation formula for this estimation may generally include parameters related to the transmission and reception of waves from the underwater detection device, parameters such as the target strength of a single fish, etc. However, it is usually difficult for fishermen to grasp these parameters. In addition, the target strength of a single fish differs depending on the fish species, and may also change depending on the sea area and season. Therefore, it is difficult for fishermen to input these parameters appropriately into the underwater detection device to properly estimate the catch amount.

[0008] In view of the above problems, an object of the present invention is to provide an underwater detection device, an underwater detection method, and a program that are capable of smoothly and appropriately estimating the amount of fish caught. [Means for solving the problem]

[0009] A first aspect of the present invention relates to an underwater detection device, which includes a fish quantity index calculation unit that calculates a fish quantity index based on electrical signals output from a plurality of ultrasonic transducers, an image generation unit that generates a display image including information related to the fish quantity index, and a correction value reception processing unit that receives an input of a correction value for correcting the fish quantity index, and the fish quantity index calculation unit corrects a calculation formula for the fish quantity index based on the correction value.

[0010] According to the underwater detection device of this embodiment, the calculation formula for the fish quantity index is corrected based on a correction value input by a user such as a fisherman. Generally, a user can easily estimate the amount of fish (e.g., tons) that he or she has caught, and therefore can smoothly and appropriately input a correction value for correcting the displayed fish quantity index to the actual amount of fish. Therefore, the calculation formula for the fish quantity index can be corrected based on the input correction value so as to approach the actual amount of fish caught. This correction process therefore allows the amount of fish caught to be smoothly and appropriately estimated.

[0011] In the underwater detection device of this embodiment, the calculation formula includes a fish quantity correction coefficient, the correction value is a correction multiplier, and the fish quantity index calculation unit may be configured to calculate the fish quantity index by multiplying the fish quantity correction coefficient by the correction multiplier as the new fish quantity correction coefficient.

[0012] According to this configuration, each time a correction factor is input by the user, the correction factor is accumulated to set a new fish quantity correction coefficient. This allows the user to repeatedly input the correction factor, thereby bringing the fish quantity index closer to the fish quantity that corresponds to the user's rough estimate. Therefore, the fish quantity index that corresponds to the user's fishing ground, fish species, and season can be displayed smoothly and appropriately.

[0013] In this configuration, the calculation formula may be an original calculation formula consisting of a first formula including the weight per fish to be caught and the target strength, the intensity of the transmitted wave, and the receiving sensitivity of the transducer, and a second formula that does not include these, in which the first formula is replaced with a formula consisting of an approximate value of the first formula and the fish quantity correction coefficient.

[0014] According to this configuration, the calculation formula takes into account the weight and target strength of the fish to be caught, the strength of the transmitted waves, and the receiving sensitivity of the transducer, so that the fish quantity index can be calculated with high accuracy. Furthermore, the first formula including these parameters is replaced with a term consisting of the approximate number of the first formula and the fish quantity correction coefficient, so that the user can smoothly correct the calculation formula with a correction factor according to their own fish quantity estimate without knowing these parameters. This allows the user to smoothly bring the displayed fish quantity index closer to their own fish quantity estimate. Therefore, the user can properly display a fish quantity index that is close to their own catch.

[0015] In the underwater detection device of this aspect, the display image may be configured to include the current value of the fish quantity index calculated by the fish quantity index calculation unit.

[0016] With this configuration, the user can ascertain the amount of fish at the current location from the fish amount index value.

[0017] The display image may also be configured to include a time-series graph of the fish quantity index calculated by the fish quantity index calculation unit.

[0018] According to this configuration, the user can grasp the change in the amount of fish on the route of the ship so far from the graph, and can smoothly grasp the location where fish should be caught.

[0019] Alternatively, the display image may be configured to include an image of a number of positions along the ship's wake, with information indicating the value of the fish abundance index at each position added.

[0020] This configuration also allows the user to grasp the change in the amount of fish on the route of the ship so far, and therefore the user can smoothly grasp the location where fish should be caught.

[0021] The underwater detection device of this embodiment further includes a target area reception processing unit that accepts a designation of a target area within the search range for which the fish quantity index is to be calculated, and the fish quantity index calculation unit may be configured to calculate the fish quantity index for the specified target area.

[0022] According to this configuration, the user can specify an area to which the user should pay attention, an area that can be enclosed by a purse seine net, etc., as a target area, and the fish quantity index for the target area can be displayed. Therefore, the user can smoothly proceed with catching fish based on the displayed fish quantity index.

[0023] A second aspect of the present invention relates to an underwater detection method executed by an underwater detection device, the underwater detection method according to this aspect includes the steps of calculating a fish quantity index based on electrical signals output from a plurality of ultrasonic transducers, generating a display image including information related to the fish quantity index, and accepting an input of a correction value for correcting the fish quantity index, wherein the step of calculating the fish quantity index corrects a calculation formula for the fish quantity index based on the correction value.

[0024] According to the underwater detection method of this aspect, the same effects as those of the underwater detection device of the first aspect can be achieved.

[0025] A third aspect of the present invention is a program that causes a computer of an underwater detection device to perform the following functions: calculate a fish quantity index based on electrical signals output from a plurality of ultrasonic transducers; generate a display image including information related to the fish quantity index; and accept input of a correction value for correcting the fish quantity index, wherein the function of calculating the fish quantity index includes a function of correcting a calculation formula for the fish quantity index based on the correction value.

[0026] According to the program of this aspect, the same effects as those of the underwater detection device of the first aspect can be achieved. Effect of the Invention

[0027] As described above, according to the present invention, it is possible to provide an underwater detection device, an underwater detection method, and a program that are capable of smoothly and appropriately estimating the amount of fish caught.

[0028] The effects and significance of the present invention will become clearer from the following description of the embodiment. However, the embodiment described below is merely an example of how the present invention can be put into practice, and the present invention is not limited to the embodiment described below. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing a schematic view of underwater exploration by an underwater detection device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing a schematic view of underwater exploration by an underwater detection device according to an embodiment. [Diagram 3] FIG. 3 is a block diagram showing the configuration of an underwater detection device according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of an echo image displayed on a display unit according to the embodiment. [Diagram 5] FIG. 5 is a diagram illustrating a schematic diagram of a propagation state of a transmission pulse and its reflected wave (reflected pulse) on one beam axis according to an embodiment. [Figure 6] 6(a) and 6(b) are diagrams illustrating a schematic diagram of an orthogonal coordinate system having two axes representing the beam number and the sample number according to the embodiment. [Figure 7] FIG. 7 is a flowchart showing the process of receiving a fish quantity correction factor according to the embodiment. [Figure 8] FIG. 8 is a diagram showing an example of a fish quantity correction magnification acceptance screen according to the embodiment. [Figure 9] FIG. 9 is a flowchart showing the fish quantity index display process according to the embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a display image of information relating to fish quantity index according to the embodiment. [Figure 11]FIG. 11 is a diagram showing an example of a fish quantity calculation region receiving screen according to the embodiment. [Figure 12] FIG. 12 is a diagram showing an example of a display image including information related to the fish quantity index according to the modified example. [Figure 13] FIG. 13 is a diagram showing an example of a display image including information related to the fish quantity index according to another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For convenience, the drawings appropriately include X, Y, and Z axes that are perpendicular to each other. The X-axis and Y-axis directions are horizontal, and the Z-axis direction is vertical. The positive X-axis direction is the direction in which the ship advances.

[0031] 1 and 2 are diagrams that show a schematic diagram of underwater searching by an underwater detection device 10. FIG.

[0032] In FIG. 1 and FIG. 2, φ is the azimuth angle centered on the transducer 13 installed on the bottom of the ship S1, and θ is the tilt angle of a scanning plane SP1 (to be described later) with respect to the horizontal plane (XY plane).

[0033] The underwater detection device 10 includes a transducer 13 installed on the bottom of a ship S1 such as a fishing boat. The underwater detection device 10 transmits a pulse of sound waves (transmission pulse) from the transducer 13, and receives sound waves (echoes) reflected (backscattered) by objects such as fish present in the water by the same transducer 13. The underwater detection device 10 detects objects present in the water based on the echoes received by the transducer 13.

[0034] The transducer 13 is equipped with a large number of ultrasonic transducers. When transmitting, each ultrasonic transducer converts an input electrical signal into a sound wave and emits it, and when receiving, it converts the incident sound wave into an electrical signal and outputs it. Typically, the transducer 13 is cylindrical, with several hundred ultrasonic transducers regularly arranged on its side.

[0035] Here, the area to be detected by the underwater detection device 10 is a conical surface. The axis of this conical surface coincides with the central axis (here, the Z-axis) of the transducer 13. This conical surface is called the scanning surface SP1, and the apex and axis of this scanning surface SP1 are called the origin and the scanning axis, respectively. The origin coincides with the position of the transducer 13, and the scanning axis extends vertically downward from this origin. Here, the scanning axis coincides with the Z-axis. The angle that the scanning surface SP1 makes with the horizontal plane (XY plane) is the tilt angle θ described above.

[0036] As shown in Fig. 1, the underwater sounding device 10 transmits a transmission beam TB1 having maximum intensity on the scanning plane SP1 over the entire circumference during transmission. This transmission beam TB1 has an intensity distribution symmetrical with respect to the scanning axis (Z-axis in Fig. 1), and its width in the vertical direction is relatively narrow.

[0037] 2, the underwater detection device 10 forms multiple reception beams RB1 with maximum sensitivity on the scanning plane SP1 during wave reception. The reception beam RB1 is formed by performing beamforming processing on the electrical signals output from multiple ultrasonic transducers arranged in the transducer 13.

[0038] Each receiving beam RB1 is a pencil beam that is narrow in both the vertical and horizontal directions and has the same directivity. A straight line that passes through the origin and faces the direction in which the sensitivity of the receiving beam RB1 is maximum is the beam axis of each receiving beam RB1. Multiple receiving beams RB1 are formed in a line at regular angular intervals in the direction of the azimuth angle φ over the entire circumference of the scanning plane SP1. The underwater detection device 10 converts the intensity of the sound waves received by each receiving beam RB1 into color and displays it as an image (echo image).

[0039] FIG. 3 is a block diagram showing the configuration of the underwater detection device 10. As shown in FIG.

[0040] The underwater detection device 10 comprises a control unit 11, a memory unit 12, a transducer 13, a transmission processing unit 14, a reception processing unit 15, a transmission / reception switching unit 16, a display unit 17, a display processing unit 18, an input unit 19, and an input processing unit 20. The transducer 13 is installed on the bottom of the ship S1 as described above, and the other components such as the control unit 11 are installed in the wheelhouse or the like of the ship S1.

[0041] The control unit 11 includes an arithmetic processing circuit such as a CPU (Central Processing Unit) and executes the control processing described below according to a program stored in the storage unit 12. The storage unit 12 includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk, etc. The storage unit 12 stores programs for the control unit 11 to execute the control processing.

[0042] As described above, the transducer 13 includes a plurality of ultrasonic transducers 13a. In each transmission and reception period (ping), the transducer 13 transmits an ultrasonic wave as the transmission beam TB1 in FIG. 1, and receives the reflected wave by each ultrasonic transducer.

[0043] The transmission processing unit 14 outputs a transmission signal for transmitting ultrasonic waves to the transducer 13 via the transmission / reception switching unit 16 in response to control from the control unit 11. The transmission signal is a signal that vibrates at a predetermined amplitude for a fixed period of time, as shown in FIG. 3. During one transmission of the transmission beam TB1, this transmission signal is supplied to each ultrasonic transducer 13a of the transducer 13 via the transmission / reception switching unit 16. As a result, ultrasonic waves corresponding to the transmission signal are transmitted from each ultrasonic transducer 13a, as shown in FIG. 3. The ultrasonic pulse transmitted during one transmission is called a transmission pulse.

[0044] The reception processing unit 15 receives the electrical signals output by the ultrasonic transducers 13a of the transducer 13 upon receiving the reflected ultrasonic waves via the transmission / reception switching unit 16, and performs amplification and noise removal (band pass filter) processing on the received electrical signals. The reception processing unit 15 outputs the electrical signals that have been subjected to these processes to the control unit 11.

[0045] When transmitting the transmission beam TB1, the transmit / receive switching unit 16 outputs the transmission signal output from the transmission processing unit 14 to the transmitter / receiver 13 (ultrasonic transducer 13a), and outputs the electrical signal output from the transmitter / receiver 13 (ultrasonic transducer 13a) to the reception processing unit 15 for a certain period of time from the timing when the transmission of the transmission beam TB1 is completed.

[0046] 3, one each of the transmission processing unit 14 and the reception processing unit 15 is illustrated, but the above-mentioned processing in the transmission processing unit 14 and the reception processing unit 15 is performed for each individual ultrasonic transducer 13a arranged in the transducer 13. Therefore, the electrical signals output from each ultrasonic transducer 13a are amplified and subjected to noise removal processing, and the electrical signals are individually input to the control unit 11. When these electrical signals are input to the control unit 11, they are converted by an A / D converter into digital signals with a predetermined sampling period.

[0047] The display unit 17 includes a display such as a liquid crystal display. The display processing unit 18 causes the display unit 17 to display a predetermined image in response to control from the control unit 11. The input unit 19 includes input means such as operation keys and a mouse. The input processing unit 20 outputs a signal corresponding to an operation on the input unit 19 to the control unit 11 in response to control from the control unit 11. The display unit 17 and the input unit 19 may be configured by a liquid crystal panel in which a touch panel is superimposed on a liquid crystal display.

[0048] In this embodiment, the functions of a received signal generating unit 11a, an image generating unit 11b, a fish quantity index calculating unit 11c, a correction value receiving processing unit 11d and a target area receiving processing unit 11e are provided to the control unit 11 by a program stored in the memory unit 12.

[0049] The reception signal generating unit 11a performs beamforming on the electric signals (digital signals) output from each ultrasonic transducer 13a to form the reception beam RB1 in Fig. 2, and generates reception signals corresponding to sound waves incident on the transducer 13 from the beam axis direction (the direction of a predetermined azimuth angle φ and tilt angle θ) of each reception beam RB1. Furthermore, the reception signal generating unit 11a performs band limitation and envelope detection processing on the reception signals in each beam axis direction to obtain envelope signals in each beam axis direction.

[0050] Here, the band limiting process is a process for extracting frequency components of the transmission signal output from the transmission processing unit 14. This process is performed when the transmission signal output from the transmission processing unit 14 is a signal with a constant frequency (CW signal).

[0051] On the other hand, when the transmission signal output from the transmission processing unit 14 is not a constant frequency signal (CW signal) but a frequency modulated chirp signal (FM signal), the reception signal generating unit 11a performs matched filter processing on the reception signal in each beam axis direction instead of band limiting processing. Then, the reception signal generating unit 11a performs envelope detection processing on the signal after the matched filter processing to obtain the envelope signal in each beam axis direction.

[0052] The envelope signal thus acquired is a signal indicating echo intensity (sound wave strength) that changes according to the time elapsed from the transmission timing of the transmission beam TB1 (ultrasound wave). Here, the time elapsed from the transmission timing corresponds to the distance from the transducer 13 in each beam axis direction. The control unit 11 acquires the echo intensity at each distance position in each beam axis direction from the echo signal of each reception beam by associating the time elapsed from the transmission timing with the distance. The echo intensity is acquired with a predetermined distance resolution.

[0053] The image generator 11b generates an echo image that displays the echo intensity at each distance position in each beam axis direction on a predetermined color scale. The image generator 11b sequentially outputs the echo images generated for each ping to the display processor 18. As a result, the echo images updated for each ping are displayed on the display unit 17. In addition, the image generator 11b generates a display image including information on the fish quantity index, as described below.

[0054] FIG. 4 is a diagram showing a schematic example of an echo image displayed on the display unit 17. As shown in FIG.

[0055] In the mode for displaying an echo image, the screen of the display unit 17 is divided into regions A1 and A2 on the left and right. Of these, an echo image P10 is displayed in region A1. Here, the echo image P10 is displayed as an image of the ship S1 as viewed from directly above. An image P11 of the ship S1 is placed in the center of the echo image P10, and further, a track P12 of the ship S1 thus far is shown. Also, a straight line P13 indicating the bow direction of the ship is included in the echo image P10.

[0056] Furthermore, in the echo image P10, a range at a certain distance from the position of the ship (image P11) is indicated by circular boundaries P14, P15, and P16. The diameters of the boundaries P14, P15, and P16 are, for example, 200 m, 400 m, and 600 m. In the echo image P10, the above-mentioned echo intensity is displayed using a predetermined color scale. For convenience, the range where the echo intensity is high is hatched in FIG. 4. For example, the hatched range P17 is the range where the echo intensity is high. The hatched range is the range where a school of fish may exist.

[0057] Area A2 is divided vertically into multiple areas, and each divided area displays information (longitude, latitude) indicating the current position of ship S1, the water temperature at the current position, a graph showing the change in water temperature over time, etc. For the sake of convenience, the display of these images in area A2 is omitted in Fig. 4.

[0058] Users such as fishermen can understand the presence of a school of fish around the vessel S1 by referring to the echo image P10. The echo image P10 in FIG. 4 displays the echo intensity of a so-called layered school of fish. That is, a school of fish may form a narrow layer in the vertical direction and be widely distributed in the horizontal direction. Furthermore, each fish in the school may swim with their heads facing in almost the same direction. Such a school is a layered school of fish.

[0059] When the ship S1 is located above the layered fish school, the echo intensity appears in the echo image P10 in a shape called an "eight-shape" as shown in FIG. 4. In the example of FIG. 4, it can be estimated that each fish constituting the layered fish school is pointing its head almost parallel to the bow direction. That is, in this case, on the starboard and port sides of the ship S1, the ultrasonic waves transmitted from the transducer 13 are incident perpendicularly to the sides of the fish, so the reflected waves (backscattered waves) from the fish are relatively strong. On the other hand, on the bow and stern sides of the ship S1, the sound waves are incident parallel to the sides of the fish, so the reflected waves from the fish are weak. Therefore, in the echo image P10 in such a case, as shown in FIG. 4, clear responses from the fish school appear in two areas symmetrically positioned to the left and right of the ship.

[0060] This phenomenon is well known to fishermen, and experienced fishermen can estimate the tonnage of fish caught from such figure-of-eight responses.

[0061] However, it is difficult for inexperienced fishermen to make this estimation properly. Even for experienced fishermen, it is difficult to concentrate on this estimation while steering. This problem can be solved by adding a function to the underwater detection device 10 that not only displays the echo image P10, but also estimates and displays the total weight of fish present within the detection range.

[0062] The calculation formula for this estimation may generally include parameters related to the transmission and reception of waves from the underwater detection device 10, the target strength of a single fish, and other parameters. However, it is usually difficult for fishermen to grasp these parameters. In addition, the target strength of a single fish differs depending on the fish species, and may also change depending on the sea area and season. Therefore, it is extremely difficult for fishermen to input these parameters appropriately into the underwater detection device 10 to properly estimate the catch amount.

[0063] To solve such problems, in this embodiment, the underwater detection device 10 is equipped with a function that enables smooth and proper estimation of the fish catch amount. This function is executed by the fish quantity index calculation unit 11c, the correction value reception processing unit 11d, and the target area reception processing unit 11e shown in Fig. 3. These processes will be described below.

[0064] <Fish quantity index calculation part> The fish quantity index calculation unit 11c calculates a fish quantity index that can be an index of the total weight of fish contained in the target area based on the electrical signals output from the multiple ultrasonic transducers 13a installed in the transducer 13. The fish quantity index is calculated using a predetermined calculation formula. The process of deriving this calculation formula will be explained below while showing various parameters.

[0065] (1) Target Strength The strength of the sound waves reflected by fish is expressed as target strength. Target strength is defined as the ratio of the strength of the reflected wave at a unit distance from the object to the strength of the sound wave incident on the object (the former divided by the latter). In the following, the unit distance is represented by r0, which is defined as 1m.

[0066] (2) False targets and false fish quantities The average weight and the average target strength of each fish that contribute to the generation of the echo image P10 are denoted as W and T, respectively. s If the weight and target strength are expressed as average values ​​W and T, respectively, s A point target equal to is called a false target.

[0067] Here, we assume that it is possible to generate "echoes identical to those generated by the fish that contribute to the generation of the echo image P10" by placing any number of pseudo targets at any positions on the scanning plane SP1 in Figures 1 and 2. The sum of the weights of these pseudo targets is called the amount of pseudo fish corresponding to the sonar response.

[0068] (3) Formulation of artificial fish volume (3-1) Target Strength T s Formula The relationship between the intensity of the sound transmitted by the transducer 13 and the received signal caused by a "dummy target located on the beam axis" will be explained below along the propagation process of the sound waves. t is assumed to be sufficiently large with respect to the size of the transducer 13.

[0069] First, consider the sound pressure of the transmitted pulse at a position r0 away from the origin of the scanning plane SP1 in Fig. 1. Generally, sound intensity is defined as the energy passing through a unit area per unit time, and is proportional to the square of the effective value of the sound pressure. The amplitude of the sound pressure of the transmitted pulse increases from zero, reaches a maximum value, and then attenuates to zero. Therefore, the maximum intensity of the transmitted pulse is proportional to "the square of the effective value of the sound pressure at the time when the amplitude reaches a maximum value."

[0070] In the following, we define the intensity of the acoustic pulse as this square value, and assume that the sound pressure changes as a sine wave in any one cycle of the transmission pulse. With these definitions and assumptions, the intensity I0 of the transmission pulse is expressed as the maximum value of the sound pressure amplitude P max Then, I0=P 2 max / 2. In what follows, the unit of sound pressure will be 1 μPa (micropascal).

[0071] FIG. 5 is a diagram showing a schematic diagram of the propagation state of a transmission pulse and its reflected wave (reflected pulse) on one beam axis.

[0072] The transmitted pulse is attenuated by spherical divergence and absorption while propagating from the origin to the pseudo target. If the absorption coefficient (the degree of attenuation of sound waves per unit distance) is a [dB / m], the intensity I1 of the transmitted pulse incident on the pseudo target is expressed by the following equation.

[0073]

number

[0074] This pulse is reflected by the pseudo target and propagates toward the origin as a reflected pulse. The strength I2 of the reflected pulse at a position a unit distance r0 away from the pseudo target is the target strength T s By the definition of

[0075]

number

[0076] The intensity of the reflected pulse incident on the transducer 13 is expressed by the following equation, similar to the above equation (1).

[0077]

number

[0078] As described above, in the underwater detection device 10, the electric signal from the ultrasonic transducer 13a is amplified by an amplifier and band-limited by an analog filter in the reception processing unit 15 of FIG. 3. Next, the underwater detection device 10 samples this processed signal by an A / D converter when it is input to the control unit 11 to generate a digital signal. Then, the underwater detection device 10 forms a reception beam RB1 from the digital signal corresponding to a predetermined group of ultrasonic transducers, and generates a signal (reception signal) corresponding to the sound wave received by the transducer 13 by each reception beam RB1. The underwater detection device 10 processes each reception signal with a band-limiting filter, a pulse compression filter, etc., and then generates an envelope signal that is a signal equal to the instantaneous amplitude of the signal. Hereinafter, this envelope signal is treated as a dimensionless quantity.

[0079] The sound pressure waveform of the acoustic pulse signal incident on the transducer 13 is distorted during the process of converting it into an electric signal and the subsequent processing. However, since these conversions and processing can generally be assumed to be linear and time-invariant, the ratio of the maximum instantaneous amplitude of the acoustic pulse signal to the maximum instantaneous amplitude of the envelope signal can be calculated as the distance r to the pseudo target. t and the target strength T of the pseudo target s In the following, this ratio (latter divided by former) is called receiver sensitivity and is represented by the parameter k. The unit of receiver sensitivity is 1 / μPa.

[0080] The maximum value A of the envelope signal of the reflected pulse when it enters the transducer 13 max and the reflected pulse strength I3 are related by the following equation:

[0081]

number

[0082] This is called Target Strength T s By solving for , we obtain the following equation:

[0083]

number

[0084] (3-2) Normalized Amplitude Data Each receiving beam RB1 is assigned a beam number j according to the azimuth angle φ of its beam axis. For example, the beam number j of the receiving beam RB1 facing the stern direction in a plan view is set to j=0, and further, the beam numbers j=1, 2, 3, ... are assigned to each receiving beam RB1 in order of increasing angle between the stern direction (reference direction) and the beam axis direction, with the clockwise direction in a plan view being positive. In this case, if the total number of receiving beams RB1 is 128, the beam numbers j of the receiving beams RB1 facing the port direction, bow direction, and starboard direction are 32, 64, and 96, respectively.

[0085] Furthermore, a sample number n is assigned to each sampling time of the envelope signal in chronological order. The start time of transmission of the transmission beam TB1, i.e., the moment when the leading edge of the transmission pulse is emitted from the transducer 13, is set as the reference time, and the sample number at this time is set as n=0.

[0086] The envelope signal obtained by one transmission is composed of a plurality of digital data by the above sampling. The sampling period in this sampling may be the same as the sampling period of the A / D converter described above, or may be different from this sampling period.

[0087] When data generated by receiving beam RB1 with beam number j and sample number n is represented as A(j,n), A'(j,n) defined by the following equation is called normalized amplitude data.

[0088]

number

[0089] where r n is the time t when the nth data is sampled. n is the distance from the origin to the position corresponding to r n When there is a false target at the position of , the leading edge of the reflected pulse from this false target is sampled as the nth data. Let the sampling frequency be f s Then, t n =n / f s Therefore, the speed at which sound waves propagate is c, and r n is defined as follows:

[0090]

number

[0091] If the time width (pulse width) of the transmitted pulse is τ, the time when the trailing edge of the reflected pulse is sampled is t n+τ, and the distance of the corresponding position from the origin is r n +(cτ / 2). In the following, we assume that the difference between these distances is sufficiently small compared to the distance from the origin to the pseudo target. That is, we assume the following relationship:

[0092]

number

[0093] In this case, as can be seen from equations (5) and (6), the maximum value A' of the normalized amplitude data A'(j,n) max The squared value of is the target strength T s Matches.

[0094]

number

[0095] (3-3) Amplitude data space Here, we define an orthogonal coordinate system with the beam number j and sample number n as its two axes. Figures 6(a) and (b) are schematic diagrams showing this orthogonal coordinate system. For convenience, a 17 x 17 grid (cell) is shown in Figures 6(a) and (b), but the actual number of grids (cells) is significantly greater than this.

[0096] The position of each grid (cell) on the vertical and horizontal axes indicates the position of the respective numbers on the vertical and horizontal axes. The numbers on the vertical and horizontal axes increase by 1, so the vertical and horizontal widths of each cell are both 1. With the horizontal coordinate being the beam number j and the vertical coordinate being the sample number n, the above-mentioned normalized amplitude data A'(j,n) is assigned to the cell located at point (j,n). A collection of normalized amplitude data arranged in this manner is referred to as an amplitude data space. In contrast, the underwater space that is the target of detection by the underwater detection device 10 is referred to as a real space.

[0097] (3-4) Point spread coefficient Assume that there is a false target at a position in real space corresponding to point P1 in Fig. 6(a). In this case, in the amplitude data space, normalized amplitude data caused by this false target (target) is generated behind point P1 (upper side in Fig. 6(a)). In Fig. 6(a), these cells are shown by hatching. In this way, the region (region in the amplitude data space) where normalized amplitude data is generated due to the target is called the echo region.

[0098] The vertical width of the echo region is determined by the time width of the transmit pulse. The horizontal width of the echo region is determined by the beam width of the receive beam. The normalized amplitude data value of each cell in the echo region generally has a non-uniform value depending on the envelope waveform of the transmit pulse and the beam pattern of the receive beam.

[0099] For any cell in the echo region, the squared value of the normalized amplitude data is equal to the target strength T s Therefore, the sum of the squared values ​​of the normalized amplitude data in the echo region is also proportional to the target strength T s is proportional to.

[0100] Here, the target strength T s Consider a point target with V = 1. By the definition of normalized amplitude data, the maximum value of normalized amplitude data caused by this target is 1. The sum of the squared values ​​of this normalized amplitude data is called the point spread coefficient, and this is V unit It is expressed as:

[0101] The proportional relationship mentioned above and the point spread coefficient V unit From the definition of

[0102] (Lemma A) For a single pseudo target, the sum of the squared values ​​of the normalized amplitude data is taken as the point spread coefficient V unit The quotient is the target strength T of the pseudo target. s is equal to.

[0103] (3-5) Target Strength T s The sum of As shown in Fig. 6(b), we consider the case where there are two false targets in the orthogonal coordinate system that defines the amplitude data space, and the echo areas generated by these false targets overlap in part. We focus on one cell included in this overlap. In Fig. 6(b), this cell is filled in black.

[0104] In addition, the following discussion will be made with the received signal as a complex envelope signal. When a false target exists at only one of points P1 and P2, the complex envelope generated in this black cell is defined as A1e +jθ1 , A2e +jθ2 The instantaneous amplitude when both exist simultaneously is A 12 Then, the squared value is expressed by the following equation.

[0105]

number

[0106] The distance between the transducer 13 and each individual fish changes between the time when the underwater detection device 10 transmits a transmission pulse and the time when it transmits the next pulse. The amount of this change can be assumed to vary randomly beyond about 1 / 4 of the wavelength of the transmission wave. Therefore, the average value A of the squared value of the instantaneous amplitude obtained by multiple transmissions is 2 av If we calculate the value, it will be approximately A1 2 +A2 2 Matches.

[0107]

number

[0108] Similarly, when the echo areas of any number of pseudo targets overlap, the following relationship holds:

[0109] (Lemma B) The squared values ​​of normalized amplitude data at coordinates where echoes from multiple false targets overlap are averaged over multiple transmissions and are approximately equal to the sum of the squared values ​​of normalized amplitude data generated by each false target.

[0110] From the above Lemma A and Lemma B, we obtain the following relationship.

[0111] (theorem) In the region that includes all echoes from the false target group (region in the amplitude data space), the sum of the squared values ​​of the normalized amplitude data is calculated as the point spread coefficient V unit The quotient is then averaged over multiple transmissions and is approximately equal to the sum of the target strengths Ts of the pseudo targets.

[0112] (3-6) Calculation formula for artificial fish volume As can be seen from the above definition of the pseudo fish quantity and the above theorem, in order to obtain the pseudo fish quantity, Q q may be averaged over multiple transmissions of the transmit pulse.

[0113]

number

[0114] The symbol Σ in equation (12) denotes the sum over all pairs of (j, n) that are the subject of processing in one ping of transmitted and received waves.

[0115] (4) Definition of fish abundance index In the above equation (12), the strength of the transmitted pulse I0 and the square of the receiving sensitivity k 2 is a parameter specific to each underwater detection device 10, and its accurate value is difficult for ordinary fishermen to obtain. s The value of is calculated by substituting the body length of the fish caught into an empirical formula, but this calculation is not easy for ordinary fishermen. On the other hand, it is easy for fishermen to roughly estimate the amount of fish caught (in tons).

[0116] 3 calculates a fish quantity index Q defined by the following formula as an approximation value of the pseudo fish quantity. Then, fish quantity index calculation unit 11c outputs the calculated value of fish quantity index Q or a value obtained by averaging the values ​​of fish quantity index Q over multiple transmissions to image generation unit 11b, which then displays it on display unit 17.

[0117]

number

[0118] The coefficient C0 is W / (2I0 k 2 T s ) for representative fish. s and the design values ​​of I0 and k for the underwater detection device 10, or it may be a value calculated in advance so that the fish abundance index Q closely matches the catch amount estimated by the fishermen or the actual catch amount.

[0119] Coefficient C cor is the fish volume correction coefficient. This fish volume correction coefficient C cor The fish quantity correction factor C is reflected by a fish quantity correction factor input by a user such as a fisherman. That is, until the fish quantity correction factor is input for the first time, the fish quantity index calculation unit 11c uses the fish quantity correction factor C cor The fish quantity index calculation unit 11c sets the initial value of 1 to the fish quantity correction coefficient C cor The value of is updated according to the following formula: “New C cor ” = “Fish amount correction magnification” × “Old C cor " That is, the fish quantity index calculation unit 11c calculates the fish quantity correction coefficient C immediately before the correction magnification is input. cor The new fish volume correction coefficient C is calculated by multiplying the fish volume correction factor by cor The fish abundance index Q is calculated as follows.

[0120] In this way, the fish quantity correction factor input by the user is the fish quantity correction coefficient C corBy reflecting the fish quantity index Q in the calculation formula (13), the fish quantity index Q can be corrected to approach the actual catch amount based on the input fish quantity correction factor. Therefore, by repeatedly inputting the fish quantity correction factor, the user can bring the fish quantity index Q closer to the fish quantity according to the user's rough estimate. Therefore, the fish quantity index Q according to the user's fishing ground, fish species, and season can be displayed smoothly and appropriately on the display unit 17.

[0121] The above formula (13) is stored in the memory unit 12 of FIG. 3, and the updated fish quantity correction coefficient C cor The control unit 11 updates and stores the above formula (13) and the updated fish quantity correction coefficient C cor Using the function of fish quantity index calculation unit 11c, fish quantity index Q is calculated, and using the function of image generation unit 11b, information related to fish quantity index Q is displayed on display unit 17. This process will be described later with reference to FIG.

[0122] (5) Point spread coefficient V unit Formula The point spread coefficient V unit The following provides additional information about the calculation formula.

[0123] The pulse width of the transmission pulse, the beam width of the reception beam, and the tilt angle are represented by τ, ψ, and θ, respectively. Here, the beam width ψ is defined as "the beam width in the plane that is tangent to the scanning plane SP1 on the beam axis," and it is assumed that the beam width ψ does not depend on the tilt angle θ. The sampling frequency f s Let us assume that arbitrarily chosen reference values ​​for the pulse width τ and the beam width ψ are f s0 , τ0 and ψ0. The point spread coefficient V at the tilt angle θ = 0° corresponding to these reference values ​​is unit The value of is represented as V0.

[0124] In this case, any f s , the point spread coefficient V at τ, ψ, and θ unit is expressed by the following equation.

[0125]

number

[0126] For example, the sampling interval (1 / f s ) is proportional to the pulse width τ of the transmitted pulse, and the beam width of the receiving beam can only take values ​​of ψ0, then the point spread coefficient V unit is a function of θ, V unit =V0 / cosθ.

[0127] (6) Setting the fish quantity correction factor 7 is a flow chart showing the process of receiving the fish quantity correction factor. This process is performed by the control unit 11 using the function of the correction value reception processing unit 11d in FIG.

[0128] When the fish quantity index calculated by the above formula (13) differs from the total weight of the fish that the user actually caught, in order to correct this difference, the user inputs an instruction to input a fish quantity correction factor via the input unit 19. In response to this input instruction, the control unit 11 causes the display unit 17 to display a correction factor acceptance screen for inputting the fish quantity correction factor, and accepts the input of the fish quantity correction factor from the user (S11).

[0129] FIG. 8 is a diagram showing an example of the fish quantity correction magnification acceptance screen 100.

[0130] The fish quantity correction magnification reception screen 100 includes a rectangular magnification input area 101, a button 102 for confirming the input, and a button 103 for returning the screen. When the user clicks on the magnification input area 101 via the input unit 19, a drop-down display of magnification options is displayed below the magnification input area 101, arranged vertically. The options are, for example, values ​​ranging from 0.1 to 2.0 in increments of 0.1. The user selects the desired magnification from the displayed options. The selected magnification is then displayed in the magnification input area 101. In the example of FIG. 8, a magnification of 1.1 has been selected.

[0131] The user can change the fish quantity correction magnification by clicking magnification input area 101 again. After inputting the fish quantity correction magnification in this way, the user clicks button 102. This confirms the input of the fish quantity correction magnification. If the user clicks button 103 without clicking button 102, the input operation of the fish quantity correction magnification is cancelled.

[0132] Returning to FIG. 7, when the user confirms the input of the fish quantity correction factor (S12: YES), the control unit 11 resets the fish quantity correction factor C cor The new fish volume correction coefficient C is calculated by multiplying the input fish volume correction factor by cor (S13). This sets the fish quantity correction coefficient C cor On the other hand, if the user cancels the input operation without finalizing the input of the fish quantity correction factor (S12: NO), the control unit 11 updates the fish quantity correction factor C cor The process of FIG. 7 ends without updating.

[0133] <Display of fish abundance index> 9 is a flowchart showing the fish quantity index display process, which is performed by the control unit 11 using the functions of the image generation unit 11b and the fish quantity index calculation unit 11c in FIG.

[0134] When the display process of the fish quantity index is started, the control unit 11 calculates the fish quantity correction coefficient C cor It is determined whether the fish quantity correction coefficient C has been updated (S21). cor If the fish quantity correction coefficient C is updated (S21: YES), the control unit 11 cor is set in the above formula (13) (S22). Fish quantity correction coefficient C cor If the control unit 11 has not updated the value (S21: NO), the control unit 11 skips step S22 and advances the process to step S23.

[0135] Thereafter, when the wave transmission / reception period (one ping) ends and data necessary for calculating fish quantity index Q is collected (S23: YES), control unit 11 uses the function of fish quantity index calculation unit 11c to calculate fish quantity index Q using equation (13) above (S24). Then control unit 11 uses the function of image generation unit 11b to generate a display image including information related to the calculated fish quantity index Q (S25), and causes display unit 17 to display the generated display image (S26).

[0136] When the process for the current ping is thus completed, the control unit 11 judges whether or not the operation for displaying information regarding the fish quantity index Q has been completed by the user's operation (S27). If this display operation has not been completed (S27: NO), the control unit 11 returns the process to step S21 and executes the same process. In parallel with the process of FIG. 9, the process of FIG. 8 is executed to calculate the fish quantity correction coefficient C cor If updated (S21: YES), the updated fish quantity correction coefficient C cor is applied to the above equation (13) (S22), and the processes from step S23 onwards are executed.

[0137] In this manner, the control unit 11 repeatedly executes the processes of steps S21 to S26 until the display operation of the information related to the fish quantity index Q is ended (S27: NO). This causes the display of the information related to the fish quantity index Q to be updated for each ping. Thereafter, when this display operation is ended (S27: YES), the control unit 11 ends the process of FIG.

[0138] FIG. 10 is a diagram showing an example of a display image 110 of information related to the fish quantity index Q. As shown in FIG.

[0139] Display image 110 includes current fish quantity index Q value 111 calculated by the function of fish quantity index calculation unit 11c in step S24 of Fig. 9, and a time series graph 112 of fish quantity index Q calculated up to now. Current fish quantity index Q value 111 may be the current fish quantity index Q value itself, or may be the average value of the fish quantity index Q values ​​calculated over a fixed period of time from the present. The same is true for the fish quantity index Q value at each time on graph 112.

[0140] The horizontal and vertical axes of graph 112 are time (units: minutes) and fish quantity index (units: tons), respectively. The current time is set at the right end of the horizontal axis, and the further to the left the time goes back in time. Here, graph 112 shows the transition of the value of the fish quantity index from the present up to 20 minutes ago.

[0141] The user can grasp the fish quantity at the current position from the fish quantity index value 111 included in the display image 110, and can further grasp the transition of the fish quantity on the ship's route so far from the graph 112. Thus, the user can smoothly grasp the state of the school of fish and the position where the fish should be caught.

[0142] The display image 110 of Fig. 10 may be arranged in any of the divided areas of the area A2 on the screen of Fig. 4. Alternatively, the display image 110 of Fig. 10 may be displayed overlapping the echo image P10 on the screen of Fig. 4 so as not to overlap the echo image P10 as much as possible. In this case, the display image 110 may be switched between display and erasure in response to an operation from the user.

[0143] <Setting the fish quantity calculation area> The range in which the fish quantity index is calculated using formula (13) may be limited by the user from the entire range scanned in one ping to a predetermined range. For example, when the user is engaged in purse seine fishing, the range in which the fish quantity index is calculated may be limited to the range that can be enclosed by the purse seine (for example, a range with a radius of 200 m from the user's ship).

[0144] FIG. 11 is a diagram showing an example of the fish quantity calculation region reception screen 120. As shown in FIG.

[0145] The control unit 11 performs the process of receiving the fish quantity calculation area using the function of the target area reception processing unit 11e in Fig. 3. Using this function, the control unit 11 displays the fish quantity calculation area reception screen 120 in Fig. 11 in response to the user's operation to set the calculation area.

[0146] The fish quantity calculation area reception screen 120 includes a rectangular range input area 121, a button 122 for confirming the input, a button 123 for returning to the screen, and a button 124 for manual setting. The range input area 121 is an area for inputting the radius of a circle centered on the ship when viewed from directly above the ship.

[0147] When the user clicks on the range input area 121 via the input unit 19, range selection candidates are displayed in a caption below the range input area 121. The selection candidates are, for example, values ​​ranging from 200 m to 800 m in increments of 50 m. The user selects the desired range from the displayed selection candidates. The selected range value is then displayed in the range input area 121. In the example of FIG. 11, a range with a radius of 200 m centered on the ship is selected.

[0148] The user can change the fish quantity calculation range by clicking range input area 121 again. After inputting the fish quantity calculation range in this way, the user clicks button 122. This confirms the input of the fish quantity calculation range. If the user clicks button 123 without clicking button 122, the input operation of the fish quantity calculation range is canceled.

[0149] To set an arbitrary range, the user operates button 124. This causes an image including boundary lines P14 to P16, similar to the echo image P10 in FIG. 4, to be displayed. The user draws a line enclosing the desired range on this image via input unit 19 and operates the confirm button. This causes the range enclosed by this line to be confirmed as the fish quantity calculation range.

[0150] The control unit 11 (fish quantity index calculation unit 11c) executes the process of step S24 in Fig. 9, using the range set by the user as the calculation target range. That is, the process of step S24 is executed using data in the range set by the user in the amplitude data space shown in Fig. 6(a). For example, as shown in Fig. 11, if a range of 200 m radius from the ship is set as the fish quantity calculation range, the process of step S24 is executed using data included in the range of sample numbers on the vertical axis corresponding to 0 to 200 m.

[0151] In this way, by limiting the fish quantity calculation range, the user can display information about the fish quantity index Q for the range in which the user intends to catch fish. This allows the user to smoothly proceed with fishing.

[0152] <Effects of the embodiment> According to the above embodiment, the following effects can be achieved.

[0153] As shown in Figure 3, the underwater detection device 10 includes a fish quantity index calculation unit 11c that calculates the fish quantity index Q based on electrical signals output from multiple ultrasonic transducers 13a, an image generation unit 11b that generates a display image including information related to the fish quantity index Q, and a correction value reception processing unit 11d that receives input of a correction value (correction multiplier) for correcting the fish quantity index Q, and the fish quantity index calculation unit 11c corrects the above equation (13), which is the calculation formula for the fish quantity index Q, based on the input correction value.

[0154] According to this configuration, the fish quantity correction coefficient C in the above formula (13) is calculated based on the correction value (correction factor) input by a user such as a fisherman. cor is corrected. Generally, a user can easily estimate the amount of fish caught (e.g., tons) and therefore can smoothly and appropriately input a correction value for correcting the displayed fish amount index Q to the actual amount of fish. Therefore, the calculation formula for the fish amount index Q can be corrected based on the input correction value so as to approach the actual amount of fish caught. This correction process therefore allows the amount of fish caught to be smoothly and appropriately estimated.

[0155] As described above, the fish abundance index Q can be calculated using the fish abundance correction coefficient C cor The correction value for correcting this formula (13) is a correction magnification. The fish quantity index calculation unit 11c calculates the fish quantity correction coefficient C cor The new fish quantity correction coefficient C is calculated by multiplying the correction factor by cor The fish abundance index Q is calculated as follows.

[0156] This allows the user to repeatedly input the correction factor to bring the fish quantity index Q closer to the fish quantity that corresponds to the user's rough estimate. Therefore, the fish quantity index Q can be displayed smoothly and appropriately according to the user's fishing ground, fish species, and season.

[0157] Here, the equation (13) for calculating the fish quantity index Q is expressed as the weight W of the fish to be caught and the target strength T s The original equation (12) is made up of a first equation including the intensity I0 of the transmission wave and the receiving sensitivity k of the transducer 13, and a second equation not including these, and the first equation is recalculated by subtracting the approximate coefficient (coefficient C0) of the first equation and the fish quantity correction coefficient C cor This is replaced by the mathematical formula:

[0158] Thus, the fish quantity index Q is calculated using equation (13), which includes the weight W of the target fish and the target strength T s Since the intensity I0 of the transmitted wave and the receiving sensitivity k of the transducer 13 are taken into account, the fish quantity index can be calculated with high accuracy by the formula (13). In addition, the first formula including these parameters is calculated by using the approximate coefficient C0 of the first formula and the fish quantity correction coefficient C cor Since the term Q is replaced with a term consisting of Q and Q, the user can smoothly correct the calculation formula with a correction factor according to his / her own fish quantity estimate without knowing these parameters. This allows the user to smoothly bring the displayed fish quantity index Q closer to his / her own fish quantity estimate. Therefore, the user can properly display the fish quantity index Q that is close to his / her own catch.

[0159] 10, the display image 110 includes a current fish quantity index Q value 111 calculated by the fish quantity index calculation unit 11c. This allows the user to know the amount of fish at the current location from the fish quantity index value 111.

[0160] The display image 110 also includes a time-series graph 112 of the fish quantity index Q calculated by the fish quantity index calculation unit 11c. This allows the user to understand the transition of the fish quantity on the ship's route so far from the graph 112. This allows the user to smoothly understand the position where the fish should be caught.

[0161] As shown in Figure 3, the underwater detection device 10 further includes a target area reception processing unit 11e that accepts a designation of a target area within the search range for which the fish quantity index Q is to be calculated, and as described with reference to Figure 11, the fish quantity index calculation unit 11c calculates the fish quantity index Q for the specified target area.

[0162] This allows the user to specify an area that the user should pay attention to, an area that can be enclosed by a purse seine net, etc., as a target area, and displays the fish quantity index Q in that target area. Therefore, the user can smoothly proceed with catching fish based on the displayed fish quantity index Q.

[0163] <Example of change> In the above embodiment, the display image 110 in FIG. 10 is shown as an example of a display image including information related to the fish quantity index Q, but the display image is not limited to this.

[0164] For example, as shown in Fig. 12, plots P18 may be added at regular intervals on the ship's wake P12 in an echo image P10, and the value of the fish quantity index Q (unit: tons) at the position (time) of each plot P18 may be added to the right of the plot P18. Alternatively, as shown in Fig. 13, circular marks P19 with a diameter according to the value of the fish quantity index Q at each position may be superimposed and displayed at regular intervals on the ship's wake P12. In this case, the value of the fish quantity index Q at each point may also be added near each circle.

[0165] These display images also allow the user to understand the changes in the amount of fish on the route the ship has taken so far, and therefore the user can smoothly understand the locations where fish should be caught.

[0166] Alternatively, a time series graph may be displayed in which the horizontal axis of FIG. 10 is corrected to the distance traveled (accumulated distance traveled). The speed of a boat during fish search is not necessarily constant. In contrast, if the horizontal axis of the time series graph is the distance traveled (accumulated distance traveled), when a user refers to this graph and wants to return to a location where a promising fish quantity index value was generated, the user can easily estimate that location based on the distance traveled (accumulated distance traveled) on the horizontal axis of the graph.

[0167] In the above embodiment, the fish quantity correction coefficient C cor was corrected by the correction factor, but the fish abundance correction coefficient C cor The correction value for correcting is not limited to this. For example, the fish quantity correction coefficient C cor The value added or subtracted from is the fish abundance correction coefficient C cor may be used as a correction value for

[0168] Furthermore, the screen for receiving the fish quantity correction magnification is not limited to the fish quantity correction magnification receiving screen 100 shown in Fig. 8, but may be a receiving screen of another configuration. Similarly, the screen for receiving the designation of the fish quantity calculation area is not limited to the fish quantity calculation area receiving screen 120 shown in Fig. 11, but may be a receiving screen of another configuration.

[0169] In addition, the control unit 11 may allow the user to set a number of fish quantity correction coefficients C according to the fish species, fishing grounds, etc. cor In this case, the control unit 11 may further have a function of setting the fish quantity correction coefficient C cor The control unit 11 stores the fish quantity correction coefficient C cor In the application process of the fish quantity correction coefficient C corThe fish quantity index Q is calculated by applying the above to the formula (13). This allows the user to obtain the fish quantity index Q suitable for the fish species he or she is trying to catch and the fishing ground, and allows the user to proceed with fishing more smoothly. In this case, the fish quantity correction coefficient C cor A correction is made using the fish quantity correction multiplier (correction value) for each fishery.

[0170] In addition, in the above embodiment, the fish quantity index calculation unit 11c and the like are realized as functions of the control unit 11 provided by the program stored in the storage unit 12, but these do not necessarily have to be realized as functions provided by the program stored in the storage unit 12. For example, one or more of these functions may be configured by hardware such as an FPGA (field-programmable gate array) or an integrated logic circuit.

[0171] In addition, in the above embodiment, the underwater detection device 10 that transmits and receives waves along the conical scanning surface SP1 is shown, but the present invention may be applied to an underwater detection device 10 that transmits and receives waves in other ways. Also, the transmitter for transmitting waves and the receiver for receiving waves may be arranged separately. Also, a calculation formula other than equation (13) may be used to calculate the fish quantity index Q. In this case, the calculation formula only needs to include a fish quantity correction coefficient that is corrected by a correction value input by the user.

[0172] In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the claims. [Explanation of symbols]

[0173] 10 Underwater detection equipment 11 Control section 11b Image generation section 11c Fish quantity index calculation part 11d Correction value reception processing unit 11e Target area reception processing unit 12 Storage section 13 Transmitter / Receiver 13a Ultrasonic transducer 110 Display images 111 Fish abundance index value 112 Graphs P12 Wake P18 Plot P19 Mark

Claims

1. a fish quantity index calculation unit that calculates a fish quantity index based on electrical signals output from a plurality of ultrasonic transducers; an image generating unit that generates a display image including information about the fish quantity index; a correction value reception processing unit that receives an input of a correction value for correcting the fish quantity index, The fish quantity index calculation unit corrects the calculation formula for the fish quantity index based on the correction value. An underwater detection device characterized by:

2. 2. The underwater detection device according to claim 1, The calculation formula includes a fish quantity correction coefficient, the correction value is a correction magnification, The fish quantity index calculation unit calculates the fish quantity index by multiplying the fish quantity correction coefficient by the correction magnification as the new fish quantity correction coefficient. An underwater detection device characterized by:

3. 3. The underwater detection device according to claim 2, The calculation formula is a formula obtained by replacing an original formula consisting of a first formula including the weight of each fish to be caught, the target strength, the intensity of the transmitted wave, and the receiving sensitivity of the transducer, with a second formula not including these, by a formula consisting of an approximate value of the first formula and the fish quantity correction coefficient. An underwater detection device characterized by:

4. 2. The underwater detection device according to claim 1, The display image includes the current value of the fish quantity index calculated by the fish quantity index calculation unit. An underwater detection device characterized by:

5. 2. The underwater detection device according to claim 1, The display image includes a time series graph of the fish quantity index calculated by the fish quantity index calculation unit. An underwater detection device characterized by:

6. 2. The underwater detection device according to claim 1, The display image includes an image in which information indicating the value of the fish quantity index at a plurality of positions aligned on the ship's wake is added to each of the positions. An underwater detection device characterized by:

7. 2. The underwater detection device according to claim 1, A target area reception processing unit is further provided for receiving a designation of a target area within the search range that is to be used for calculating the fish quantity index, The fish quantity index calculation unit calculates the fish quantity index for the specified target area. An underwater detection device characterized by:

8. An underwater detection method performed by an underwater detection device, comprising: Calculating a fish quantity index based on electrical signals output from the plurality of ultrasonic transducers; generating a display image including information about the fish abundance index; and receiving an input of a correction value for correcting the fish quantity index; The step of calculating the fish quantity index includes correcting a calculation formula for the fish quantity index based on the correction value. An underwater detection method comprising:

9. The underwater detection device's computer A function of calculating a fish quantity index based on electrical signals output from a plurality of ultrasonic transducers; generating a display image including information about the fish abundance index; and receiving an input of a correction value for correcting the fish quantity index. A program, wherein the function of calculating the fish quantity index includes a function of correcting a calculation formula for the fish quantity index based on the correction value.

Images