Underwater detection device, underwater detection method, and program

Abstract

To provide an underwater detection device (10), an underwater detection method, and a program capable of smoothly and properly estimating a fish catch. The underwater detection device (10) includes a

Description

UNDERWATER DETECTION DEVICE, UNDERWATER DETECTION METHOD, AND PROGRAM

[0001] The present invention relates to an underwater detection device for detecting underwater objects, an underwater detection method for detecting underwater objects, and a program for allowing a computer to perform a function for detecting underwater objects.

[0002] Conventionally, underwater detection devices for detecting underwater objects have been known. Such type of underwater detection devices transmit ultrasonic waves into the water, receives the reflected waves, calculates the echo intensity from each position in the water, and displays the three-dimensional distribution of the echo intensity (echo image) on a screen.

[0003] For example, an underwater detection device transmits an umbrella-like transmission wave along a conical surface from a transducer having a plurality of ultrasonic oscillators, and receives the reflected wave by the transducer. A plurality of reception beams arranged in the circumferential direction on the conical surface are constituted by beamforming from an electrical signal outputted from each ultrasonic oscillator of the transducer by receiving a reflected wave, and a reception signal is generated for each reception beam. From the generated reception signal, an echo image corresponding to the scanning range of the reception beam is generated and displayed.

[0004] The following Patent Literature describes an underwater detection system that generates an echo image by transmitting a plurality of types of transmission waves having different beam widths. In the underwater detection system, a reception signal is generated for each transmission wave having different beam widths and an echo image is generated for each generated reception signal.

[0005] Japanese Patent No. 6722521

[0006] Skilled fishermen may estimate fish catch by referring to echo images. However, it may be difficult for inexperienced fishermen to make this estimation properly. It is also difficult for experienced fishermen to continue making this estimation centrally during steering. This problem may be solved by adding a function to the underwater detection device to estimate and display the total weight of fish in the detection range.

[0007] Further, a calculation formula for the estimation may generally include parameters related to the transmission and reception of the underwater detection device and parameters such as target strength of a single fish. However, it is usually difficult for the fisherman to grasp the parameters. In addition, the target strength of single fish varies depending on fish species and may also vary depending on sea area and season. Therefore, it may be difficult for the fisherman to properly estimate the catch by inputting the parameters into the underwater detection device.

[0008] In view of such problems, an object of the present invention is to provide an underwater detection device, an underwater detection method, and a program capable of smoothly and properly estimating the catch of fish.

[0009] A first aspect of the present invention relates to an underwater detection device. The underwater detection device, according to this first aspect, comprises a fish quantity index calculation module for calculating a fish quantity index based on electrical signals output from a plurality of ultrasonic oscillators, an image generation module for generating a display image containing information on the fish quantity index, and a correction value reception processing module for receiving input of a correction value for correcting the fish quantity index, wherein the fish quantity index calculation module corrects calculation formula of the fish quantity index based on the correction value.

[0010] According to the underwater detection device, according to this first aspect, the calculation formula of the fish quantity index may be corrected based on the correction value input from a user such as a fisherman. In general, since the user may easily estimate the amount of fish caught by himself (e.g., tonnage), the correction value for correcting the displayed fish quantity index to the actual amount of fish may input smoothly and properly. Therefore, the calculation formula for calculating the fish quantity index may be corrected to approach the actual catch quantity based on the correction value. Thus, the fish catch quantity may be smoothly and properly estimated by this correction processing.

[0011] In the underwater detection device, the calculation formula includes a fish quantity correction coefficient, the correction value is a correction magnification, and the fish quantity index calculation module may be configured to calculate the fish quantity index by using the fish quantity correction coefficient multiplied by the correction magnification as a new fish quantity correction coefficient.

[0012] According to this configuration, when the correction magnification is provided by the user, the correction magnification may be integrated and the new fish quantity correction coefficient is set. Thus, by repeating the input of the correction magnification, the user may bring the fish quantity index closer to the fish quantity according to the estimation. Therefore, the fish quantity index according to the fishing ground of the user, fish species and season, may be smoothly and properly displayed.

[0013] In this configuration, the calculation formula may be obtained by replacing the first formula with a formula consisting of an approximate number of the first formula and the fish quantity correction coefficient with respect to an original calculation formula consisting of the first formula including the weight per fish and the target strength of the fish to be caught, the intensity of the transmitted wave and the reception sensitivity of the transducer, and a second formula may not include the parameters that are included in the first formula.

[0014] According to this configuration, the weight and the target strength of the fish to be captured, the intensity of the transmission wave and the reception sensitivity of the transducer are added to the calculation formula, so that the fish quantity index may be accurately calculated by the calculation formula. In addition, since the first formula including the parameters is replaced with a term consisting of the approximate number of the first formula and the fish quantity correction coefficient, the user may smoothly correct the calculation formula by the correction magnification according to the fish quantity estimation without grasping the parameters. Thus, the user may smoothly approach the displayed fish quantity index to the fish quantity estimation. Therefore, the user may appropriately display the fish quantity index close to his / her own catch.

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

[0016] According to this configuration, the user may grasp the fish quantity at the current position from the fish quantity index value.

[0017] The display image may include a graph of the time series of the fish quantity index calculated by the fish quantity index calculation module.

[0018] According to this configuration, the user may grasp the transition of the fish quantity in the route of his / her ship from the graph. Therefore, the user may smoothly grasp the position where the fish may be caught.

[0019] Alternatively, the display image may be configured to include an image in which information indicating the value of the fish quantity index at the position that may be added to a plurality of positions arranged on a track of the ship.

[0020] This configuration also enables the user to grasp the transition of the fish quantity in the route of the ship so far. Therefore, the user may smoothly grasp the position where the fish should be caught.

[0021] The underwater detection device, according to the present embodiment, is further provided with an object area reception processing module for receiving designation of an object area to be the object of calculation of the fish quantity index in the search range, and the fish quantity index calculation module may be configured to calculate the fish quantity index for the designated object area.

[0022] According to this configuration, the user may designate an area to be noticed by himself, an area to be enclosed by a purse seine, and the like as an object area, and may display the fish quantity index in the object area. Therefore, the user may smoothly advance the capture of fish based on the displayed fish quantity index.

[0023] A second aspect of the present invention relates to an underwater detection method performed by an underwater detection device. The underwater detection method, according to this aspect, includes a step of calculating a fish quantity index based on electrical signals output from a plurality of ultrasonic oscillators, a step of generating a display image containing information on the fish quantity index, and a step of receiving 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 calculating the fish quantity index based on the correction value.

[0024] According to the underwater detection method, according to the second aspect, an effect similar to that of the underwater detection device according to the first aspect may be achieved.

[0025] In a third aspect of the present invention, a program executes a computer of an underwater detection device includes a function of calculating a fish quantity index based on electrical signals output from a plurality of ultrasonic oscillators, a function of generating a display image containing information on the fish quantity index, and a function of receiving an input of a correction value for correcting the fish quantity index, wherein the function of calculating the fish quantity index including a function of correcting a calculation formula for calculating the fish quantity index based on the correction value.

[0026] According to the third aspect, an effect similar to that of the underwater detection device according to the first aspect may be achieved.

[0027] As described above, according to the present invention, it may possible to provide an underwater detection device, an underwater detection method, and a program capable of smoothly and properly estimating a fish catch.

[0028] The effect or significance of the present invention may be further clarified by the description of the following embodiments. However, the following embodiments are only examples of the embodiment of the present invention, and the present invention is not limited in any way to those described in the following embodiments.

[0029] FIG. 1 is a diagram schematically showing a state of searching underwater by an underwater detection device according to an embodiment.FIG. 2 is a diagram schematically showing the state of searching underwater by the underwater detection device according to an embodiment.FIG. 3 is a block diagram showing a configuration of the underwater detection device according to an embodiment.FIG. 4 is a diagram schematically showing an example of an echo image displayed on a display unit according to an embodiment.FIG. 5 is a diagram schematically showing a propagation state of a transmission pulse and its reflected wave (reflected pulse) in one beam axis according to an embodiment.FIG. 6(a) and FIG. 6(b) are diagrams schematically showing a rectangular coordinate system having a beam number and a sample number as two axes according to an embodiment, respectively.FIG. 7 is a flowchart showing a reception process of a fish quantity correction magnification according to an embodiment.FIG. 8 is a diagram showing an example of a fish quantity correction magnification reception screen according to an embodiment.FIG. 9 is a flowchart showing a display process of a fish quantity index according to an embodiment.FIG. 10 is a diagram schematically showing an example of a display image of information on the fish quantity index according to an embodiment.FIG. 11 shows an example of a fish quantity calculation area reception screen according to an embodiment.FIG. 12 is a diagram showing an example of the display image including information on the fish quantity index according to a modified example.FIG. 13 is a diagram showing an example of the display image including information on the fish quantity index according to another modification.

[0030] Embodiments of the present invention is described with reference to the drawings. For convenience, XYZ axes orthogonal to each other are optionally indicated in the drawings. The X and Y axis directions are horizontal, and the Z axis direction is vertical. The positive X axis is the direction in which the ship travels.

[0031] FIGS. 1 and 2 are diagrams schematically showing a state in which underwater is searched by an underwater detection device (10).

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

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

[0034] The transducer (13) includes a plurality of ultrasonic oscillators (13a). Each ultrasonic oscillator (13a) converts an input electrical signal into a sound wave and radiates it during transmission, and converts an incident sound wave into an electrical signal and outputs it during reception. Typically, the transducer (13) is cylindrical and with of the plurality of ultrasonic oscillators (13a) regularly arranged on its sides.

[0035] Here, the region targeted by the underwater detection device (10) is a conical surface. The axis of the conical surface coincides with the central axis (here, the Z axis) of the transducer (13). The conical surface is referred to as a scanning plane (SP1), and the apex and axis of the scanning plane (SP1) are referred to as origin and scanning axis, respectively. The origin coincides with the position of the transducer (13) and the scanning axis extends from the origin in the 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 θ described above.

[0036] As shown in FIG. 1, the underwater detection device (10) transmits a transmission beam (TB1) having the maximum intensity on the scanning plane (SP1) over the entire circumference at the time of transmission. The transmission beam (TB1) has an axial intensity distribution with respect to the scanning axis (Z axis in FIG. 1), and its vertical width is relatively narrow.

[0037] As shown in FIG. 2, the underwater detection device (10) forms a large number of reception beams (RB1) having maximum sensitivity on the scanning plane (SP1) when receiving waves. The reception beams (RB1) are formed by applying beamforming processing to electrical signals output from the plurality of ultrasonic oscillators (13a) arranged in the transducer (13).

[0038] Each reception beam (RB1) is a pencil beam having a narrow width in both the vertical and horizontal directions, and has the same directivity. A straight line passing through the origin and pointing in the direction of maximum sensitivity of the reception beam (RB1) is the beam axis of each reception beam (RB1). A plurality of reception beams (RB1) are formed side by side at a fixed angular interval 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 wave received by each reception beam (RB1) into a 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).

[0040] The underwater detection device (10) includes a control unit (11), a storage unit (12), the transducer (13), a transmission processing module (14), a reception processing module (15), a transmission / reception switching unit (16), a display unit (17), a display processing module (18), an input unit (19), and an input processing module (20). The transducer (13) is installed in the bottom of the ship (S1) as described above, and other configurations such as the control unit (11) are installed in a wheelhouse 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 later by a program stored in the storage unit (12). The storage unit (12) includes a storage medium such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a hard disk. The storage unit (12) stores a program for the control unit (11) to execute control processing.

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

[0043] In response to the control from the control unit (11), the transmission processing module (14) outputs a transmission signal for transmitting the ultrasonic wave to the transducer (13) via the transmission / reception switching unit (16). As shown in FIG. 3, the transmission signal is a signal that oscillates with a predetermined amplitude over a certain period. At the time of one transmission of the transmission beam (TB1), the transmission signal may be supplied to each ultrasonic oscillator (13a) of the transducer (13) via the transmission / reception switching unit (16). Thus, as shown in FIG. 3, ultrasonic waves corresponding to the transmission signal are transmitted from each ultrasonic oscillator (13a). The pulse of ultrasonic waves transmitted in a single transmission is called a transmission pulse.

[0044] The reception processing module (15) receives an electrical signal that each ultrasonic oscillator (13a) of the transducer (13) receives a reflected wave of ultrasonic waves and outputs through the transmission / reception switching unit (16), and applies amplification and noise removal (i.e., bandpass filter) processing to the received electrical signal. The reception processing module (15) outputs the electrical signal subjected to these processes to the control unit (11).

[0045] The transmission / reception switching unit (16) outputs the transmission signal output from the transmission processing module (14) to the transducer (13) (ultrasonic oscillator (13a)) at the time of the transmission of the transmission beam (TB1), and outputs the electrical signal from the transducer (13) (ultrasonic oscillator (13a)) to the reception processing module (15) during a certain period from the timing when the transmission of the transmission beam (TB1) is completed.

[0046] Although the transmission processing module (14) and the reception processing module (15) are illustrated one by one in FIG. 3, the above-mentioned processing in the transmission processing module (14) and the reception processing module (15) is performed for each ultrasonic oscillator (13a) arranged in the transducer (13). Accordingly, an electrical signal has been subjected to amplification and noise removal processing to the electrical signal output from each ultrasonic oscillator (13a) as an input to the control unit (11) individually. The electrical signals are converted into digital signals with a predetermined sampling period by an A / D converter when input to the control unit (11).

[0047] The display unit (17) includes a display such as a liquid crystal display. The display processing module (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 an operation key and a mouse. In response to the control from the control unit (11), the input processing module (20) outputs a signal corresponding to the operation to the input unit (19) to the control unit (11). The display unit (17) and the input unit (19) may be composed of a liquid crystal panel on which a touch panel is superimposed on the liquid crystal display.

[0048] In the present embodiment, the functions of a reception signal generation module (11a), an image generation module (11b), a fish quantity index calculation module (11c), a correction value reception processing module (11d), and an object area reception processing module (11e) are assigned to the control unit (11) by the program stored in the storage unit (12).

[0049] The reception signal generation module (11a) forms the reception beam (RB1) shown in FIG. 2 by beamforming the electrical signals (digital signals) output from the ultrasonic oscillators (13a), and generates the reception signals corresponding to the sound waves incident on the transducer (13) from the beam axial direction (the direction of the predetermined azimuth angle φ and tilt angle θ) of the respective reception beams (RB1). Further, the reception signal generation module (11a) applies band limiting and envelope detection processing to the reception signals in the respective beam axial directions, and acquires the envelope signals in the respective beam axial directions.

[0050] The band limiting processing is a process for extracting the frequency components of the transmission signals output from the transmission processing module (14). This processing is performed when the transmission signal outputs from the transmission processing module (14), is a signal having a fixed frequency (CW signal).

[0051] On the other hand, when the transmission signal outputs from the transmission processing module (14), is not a signal having a fixed frequency (CW signal) but a chirp signal having a frequency modulation (FM signal), the reception signal generating module (11a) applies the processing of a matched filter to the reception signal in the respective beam axis directions instead of the processing of band limitation. Then, the reception signal generating module (11a) applies the processing of envelope detection to the signal after the matched filter processing and acquires the envelope signal in the respective beam axis directions.

[0052] The envelope signal thus acquired is a signal indicating an echo intensity (sound wave intensity) which changes in accordance with the elapsed time from the transmission timing of the transmission beam (TB1) (ultrasonic wave). Here, the elapsed time 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 of each distance position in each beam axis direction from the echo signal of each reception beam (RB1) by associating the elapsed time from the transmission timing with the distance. The echo intensity is acquired at a predetermined distance resolution.

[0053] The image generation module (11b) generates an echo image (P10) for displaying the echo intensity at each distance position in each beam axis direction in a predetermined color scale. The image generation module (11b) sequentially outputs the echo images (P10) generated for each ping to the display processing module (18). As a result, the echo images (P10) updated for each ping are displayed on the display unit (17). In addition, the image generation module (11b) generates a display image (110) including information related to the fish quantity index as described later.

[0054] FIG. 4 is a diagram schematically showing an example of the echo image (P10) displayed on the display unit (17).

[0055] In the mode of displaying the echo image (P10), the screen of the display unit (17) is divided into left and right areas A1 and A2. Among them, the echo image (P10) is displayed in the area A1. Here, the echo image (P10) is displayed as an image when the ship (S1) is viewed from directly above. An image (P11) of the ship (S1) is arranged at the center of the echo image (P10), and a previous track (P12) of the ship (S1) is shown. A straight line (P13) showing the bow direction of the ship (S1) is included in the echo image (P10).

[0056] Further, in the echo image (P10), a range of a certain distance from the position of the own ship (image (P11)) is indicated by circular boundary lines (P14), (P15), and (P16). The diameters of the boundary lines (P14), (P15), and (P16) are, for example, 200 m, 400 m, and 600 m, respectively. The echo image (P10) displays the echo intensity described above on a predetermined color scale. In FIG. 4, for convenience, a hatching is attached to a region where the echo intensity is high. For example, a hatched region (P17) is a region where the echo intensity is high. The hatched region (P17) is the region where a fish group may exist.

[0057] The area A2 is divided into a plurality of upper and lower parts, and information (longitude, latitude) indicating the current position of the ship (S1), the water temperature at the current position, and a graph showing the temporal change of the water temperature are displayed in each divided area. In FIG. 4, the display of these images in the area A2 is omitted for convenience.

[0058] A user such as a fisherman may grasp the presence of a fish group around the ship (S1) by referring to the echo image (P10). In the echo image (P10) of FIG. 4, the echo intensity of the so-called stratiform fish group is displayed. That is, the fish group may form a narrow layer in the vertical direction and be widely distributed in the horizontal direction. In addition, individual fish in this group may swim with their heads oriented in approximately the same direction. Such groups are stratiform fish groups.

[0059] When the ship (S1) is located above the stratiform fish group, an echo intensity called "figure 8" as shown in FIG. 4 appears in the echo image (P10). In the example of FIG. 4, it may be assumed that the individual fish constituting the stratiform fish group have their heads oriented approximately parallel to the heading. That is, in this case, on the starboard and port sides of the ship (S1), the ultrasonic waves transmitted from the transducer (13) is incident on the side of the fish perpendicularly, so that the reflected wave (backscattered wave) from the fish is relatively strong. On the other hand, on the bow and stern sides of the ship (S1), the sound wave is incident parallel to the side of the fish, so that the reflected wave from the fish is weak. Therefore, in the echo image (P10) in such a case, as shown in FIG. 4, a clear reaction of the fish group appears in the two regions located in the symmetrical positions with respect to the ship (S1).

[0060] Such events are well known to fisherman. Skilled fisherman may estimate fish catches (tonnage) from the figure 8 responses.

[0061] However, it is difficult for inexperienced fisherman to make this estimation properly. It may also difficult for the experienced fisherman to continue making this estimation centrally during steering. This problem may be eliminated by adding a function to the underwater detection device (10) to not only display the echo image (P10) but also to estimate and display the total weight of the fish present in the detection range.

[0062] The calculation formula for this estimation may generally include parameters related to the transmission and reception of the underwater detection device (10) and parameters such as the target strength of a single fish. However, it is usually difficult for the fisherman to grasp the parameters. In addition, the target strength of single fish varies depending on the fish species and may also vary depending on the sea area and season. Therefore, it is extremely difficult for the fisherman to properly estimate the catch by inputting the parameters into the underwater detection device (10).

[0063] To solve such problems, in this embodiment, the underwater detection device (10) is equipped with a function capable of smoothly and properly estimating the catch of fish. The function is executed by the fish quantity index calculation module (11c), the correction value reception processing module (11d), and the object area reception processing module (11e) shown in FIG. 3. These processes will be described below.

[0064] The fish quantity index calculation module (11c) calculates the fish quantity index which may be an index of the total weight of fish included in the object area based on the electrical signals output from the plurality of ultrasonic oscillators (13a) installed in the transducer (13). The fish quantity index is calculated by a predetermined calculation formula. Hereinafter, the derivation process of the calculation formula may be described with various parameters.

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

[0066] (2) Pseudo target and simulated fish quantity - When the mean value of the weight and the mean value of the target strength of individual fish contributing to the generation of the echo image (P10) are expressed as W and Ts, respectively, a point target whose weight and target strength are equal to the mean values W and Ts, respectively, is called a pseudo target.

[0067] Here, it is assumed that by placing an arbitrary number of pseudo targets at an arbitrary position on the scanning plane (SP1) in FIGS. 1 and 2, it is possible to generate "the same echo as that generated by the fish contributing to the generation of the echo image (P10)." The sum of the weights of the pseudo targets is called the simulated fish quantity corresponding to the sonar reaction.

[0068] (3) Formulation of the simulated fish quantity - (3-1) Formula for target strength Ts- The relationship between the intensity of the sound transmitted by the transducer (13) and the reception signal caused by “one pseudo target located on the beam axis” is described below along with the propagation process of the sound wave. Here, it may be assumed that the distance rtbetween the transducer (13) and the pseudo target is sufficiently large relative to the size of the transducer (13).

[0069] First, consider the sound pressure of the transmission pulse at a position separated from the origin of the scanning plane (SP1) in FIG. 1 by r0. In general, 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 the transmission pulse increases from zero to a maximum value and then decays to zero. Therefore, the maximum intensity of the transmission pulse is proportional to "the square of the effective value of the sound pressure at the time when the amplitude takes its maximum value."

[0070] In the following, the intensity of the acoustic pulse is defined by the squared value, and it is assumed that the acoustic pressure changes as a sinusoidal wave in any one cycle of the transmission pulse. With the definitions and assumptions, the intensity of the transmission pulse I0is expressed by I0=Pmax2 / 2, where Pmaxis the maximum value of the acoustic pressure amplitude. In the following, 1 μPa (micropascal) is used as the unit of acoustic pressure.

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

[0072] The transmission pulse is attenuated by spherical divergence and absorption while propagating from the origin to the pseudo target. If the absorption coefficient (attenuation of sound waves per unit distance) is a [dB / m], the intensity I1of the transmission pulse incident on the pseudo target is expressed by the following equation.

[0073]

[0074] The pulse is reflected by a pseudo target and propagates toward the origin as a reflected pulse. The intensity I2of the reflected pulse at a position separated by a unit distance r0from the pseudo target is expressed by the following equation according to the definition of the target strength Tsdescribed above.

[0075]

[0076] The intensity of the reflected pulse incident on the transducer (13) is expressed by the following equation in the same manner as the above equation (1).

[0077]

[0078] As described above, in the reception processing module (15) of FIG. 3, the underwater detection device (10) amplifies the electrical signal from the ultrasonic oscillator (13a) by an amplifier and limits the bandwidth by an analog filter. The underwater detection device (10) then samples the processed signal by an A / D converter at the time of input to the control unit (11) to generate a digital signal. The underwater detection device (10) then forms a reception beam (RB1) from the digital signal corresponding to the predetermined ultrasonic oscillator group, and generates a signal (reception signal) corresponding to the acoustic wave received by the transducer (13) by each reception beam (RB1). The underwater detection device (10) applies processing such as a band limiting filter or a pulse compression filter to each reception signal, and then generates an envelope signal which is a signal equal to the instantaneous amplitude thereof. Hereinafter, the 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 by the process of being converted into the electrical signal and the subsequent processing. However, since these conversions and processing may be assumed to have linearity and time invariance, the ratio between the maximum instantaneous amplitude of the acoustic pulse signal and the maximum envelope signal is constant regardless of the distance rtto the pseudo target or the target strength Tsof the pseudo target. Hereinafter, this ratio (the latter ÷ the former) is referred to as the reception sensitivity, which is expressed by the parameter k. The unit of reception sensitivity is 1 / μPa.

[0080] The maximum value of the envelope signal of the reflected pulse, Amax, and the intensity of the reflected pulse, I3, when entering the transducer (13) are related by the following equation.

[0081]

[0082] When this is solved for the target strength Ts, the following equation is obtained.

[0083]

[0084] (3-2) Normalized amplitude data - A beam number (j) is assigned to each reception beam (RB1) according to an azimuthal angle φ of the beam axis. For example, the beam number of the reception beam (RB1) facing the stern azimuth in plan view is set to j=0, and the beam numbers j=1, 2, 3, ... are assigned to each reception beam (RB1) in the order that the angle formed by the stern azimuth (reference azimuth) and the beam axis azimuth increases while the clockwise azimuth is set to positive in plan view. In this case, if the total number of reception beams (RB1) is 128, the beam numbers (j) of the reception beams (RB1) facing the port azimuth, the bow azimuth, and the starboard azimuth are 32, 64, and 96, respectively.

[0085] A sample number (n) is given to each sampling time of the envelope signal in the order of time. The transmission start time 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 to n=0.

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

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

[0088]

[0089] Where, rnis the distance from the origin of the position corresponding to the time tnat which the nth data is sampled. That is, when there is a pseudo target at the position where the distance from the origin is rn, the leading edge of the reflected pulse from the pseudo target is sampled as the nth data. When the sampling frequency is fs, tn=n / fs, the speed at which the sound wave propagates is c, and rnis defined by the following equation.

[0090]

[0091] When the time width (pulse width) of the transmission pulse is τ, the time at which the trailing edge of the reflected pulse is sampled is tn+τ, and the distance of the corresponding position from the origin is rn+ (cτ / 2). In the following, it is assumed that the difference between the distances is sufficiently small as compared with the distance from the origin to the pseudo target. That is, the following relationship is assumed.

[0092]

[0093] At this time, as may be seen from equations (5) and (6), the squared value of A′max, the maximum value of the normalized amplitude data A′(j, n), coincides with the target strength Ts.

[0094]

[0095] (3-3) Amplitude Data Space - Here, a rectangular coordinate system with the beam number (j) and the sample number (n) as two axes is defined. FIGS. 6(a) and 6(b) schematically show the rectangular coordinate system. Although 17×17 lattices (cells) are shown in FIGS. 6(a) and 6(b) for convenience, the actual number of lattices (cells) is significantly larger than this.

[0096] The positions of the lattices (cells) on the vertical and horizontal axes indicate the positions of the respective numbers on the vertical and horizontal axes. Because the numbers on the vertical and horizontal axes are incremented by 1 and the width of each cell is 1. Using the coordinate of the horizontal axis as the beam number (j) and the coordinate of the vertical axis as the sample number (n), the normalized amplitude data A′(j, n) described above is given to the cell located at the point (j, n). The set of normalized amplitude data arranged in this manner is called an amplitude data space. On the other hand, an underwater space which is a detection object of the underwater detection device (10) is called a real space.

[0097] (3-4) Point spread coefficient - Assume that there is a pseudo target at the position in real space corresponding to point P1 in FIG. 6(a). At this time, in the amplitude data space, normalized amplitude data originating from the pseudo target is generated behind the point P1 (upper side in FIG. 6(a)). In FIG. 6(a), these cells are hatched. In this way, the region where normalized amplitude data is generated due to the target (the region in the amplitude data space) is called the echo region.

[0098] The longitudinal width of the echo region is determined by the time width of the transmission pulse. The transverse width of the echo region is determined by the beam width of the reception beam (RB1). The value of the normalized amplitude data of each cell in the echo region is generally non-uniform, depending on the envelope waveform of the transmission pulse and the beam pattern of the reception beam (RB1).

[0099] In any cell in the echo region, the squared 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 region is also proportional to the target strength Ts.

[0100] Now, consider a point target whose target strength Tsis 1. By the definition of the normalized amplitude data, the maximum value of the normalized amplitude data attributable to this target is 1. The sum of the squared values of the normalized amplitude data is called the point spread coefficient, which is expressed by Vunit.

[0101] The following relationship may be obtained from the aforementioned proportional relationship and the definition of the point spread coefficient Vunit.

[0102] (Lemma A) - For a single pseudo target, the quotient of the sum of the squared values of its normalized amplitude data divided by the point spread coefficient Vunitis equal to the target strength Tsof the pseudo target.

[0103] (3-5) Total value of target strength Ts- As shown in FIG. 6(b), a case in which two pseudo targets exist in the orthogonal coordinate system defining the amplitude data space, and a part of the echo regions generated from each of the pseudo targets overlap is examined. One cell included in the overlap is noted. In FIG. 6(b), this cell is filled with black.

[0104] In this case, the reception signal is used as a complex envelope signal, and the following considerations are made. When a pseudo target exists only at one of the points P1 and P2, the complex envelopes generated in the black cell are set to A1e+jθ1and A2e+jθ2, respectively. When the instantaneous amplitude when both exist simultaneously is set to A12, the squared value is expressed by the following equation.

[0105]

[0106] The distance between the transducer (13) and the individual single fish changes between the time the underwater detection device (10) transmits the transmission pulse and the time of the next transmission. This amount of change may be assumed to vary randomly over a length of about 1 / 4 of the wavelength of the transmission wave. Therefore, if the average value Aav2of the squared value of the instantaneous amplitude obtained by multiple transmissions is calculated, the value approximately corresponds to A12+A22.

[0107]

[0108] Similarly, when the echo regions of an arbitrary number of pseudo targets overlap, the following relationship is established.

[0109] (Lemma B) - The value obtained by averaging the squared values of the normalized amplitude data at the coordinate where the echoes from the multiple pseudo targets overlap over a number of transmissions is approximately equal to the sum of the squared values of the normalized amplitude data produced by the individual pseudo targets.

[0110] The following relations may be obtained from the above Lemma A and Lemma B.

[0111] Theorem - In a region containing the entire echo from the pseudo target group (a region in the amplitude data space), the value obtained by averaging the quotient of the sum of the squared values of the normalized amplitude data divided by the point spread coefficient Vunitover many transmissions approximately equals the sum of the target strengths Tsof the pseudo target group.

[0112] (3-6) Formula for calculating the simulated fish quantity - As seen from the above definition of the simulated fish quantity and the above theorem, in order to obtain the simulated fish quantity, the Qqdefined by the following equation should be averaged over a number of transmissions of transmission pulses.

[0113]

[0114] The symbol Σ in the equation (12) means the sum of all sets of (j, n) to be processed at 1 ping of the transmission / reception wave.

[0115] (4) Formula for defining fish quantity index - In the above equation (12), the intensity I0of the transmission pulse and the square of the reception sensitivity k2are parameters specific to each underwater detection device (10), and their exact values are difficult to obtain by ordinary fishermen. The value of the target strength Tsis obtained by substituting the body length of the collected fish into an empirical formula, but this calculation is not easy for ordinary fishermen. On the other hand, it is easy for fishermen to estimate the amount of fish caught (tonnage).

[0116] The fish quantity index calculation module (11c) in FIG. 3 calculates the fish quantity index Q defined by the following equation as an approximate value of the simulated fish quantity. Then, the fish quantity index calculation module (11c) outputs the calculated value (111) of the fish quantity index Q or the value obtained by averaging the value (111) of the fish quantity index Q over a plurality of transmissions to the image generation module (11b) and displays it on the display unit (17).

[0117]

[0118] The coefficient C0is an approximate number of W / (2I0k2Ts). The approximate number may be a value obtained by substituting the values of W and Tsfor a representative fish and the design values of I0and k in the underwater detection device (10), or it may be a value determined in advance so that the catch quantity estimated by the fisherman or the actual catch quantity agrees well with the fish quantity index Q.

[0119] The coefficient Ccoris a fish quantity correction coefficient. The fish quantity correction coefficient Ccorreflects a fish quantity correction magnification input from a user such as a fisherman. That is, the fish quantity index calculation module (11c) calculates the fish quantity index Q by setting an initial value of 1 for the fish quantity correction coefficient Ccoruntil the fish quantity correction magnification is the first input. The fish quantity index calculation module (11c) updates the value of the fish quantity correction coefficient Ccorby the following equation whenever the fish quantity correction magnification is inputted.

[0120] “New Ccor” =“ Fish quantity correction magnification ” × “Old Ccor” - That is, the fish quantity index calculation module (11c) calculates the fish quantity index Q by using the value obtained by multiplying the fish quantity correction coefficient Ccorimmediately before the input of the correction magnification by the fish quantity correction magnification as the new fish quantity correction coefficient Ccor.

[0121] Thus, since the fish quantity correction magnification input from the user is reflected in the fish quantity correction coefficient Ccor, the calculation formula of the fish quantity index Q may be corrected to approach the actual catch quantity based on the input fish quantity correction magnification. Therefore, by repeating the input of the fish quantity correction magnification, the user may approach the fish quantity index Q to the fish quantity corresponding to the estimate. Therefore, the fish quantity index Q corresponding to the fishing ground of the user, fish species and season may be smoothly and properly displayed on the display unit (17).

[0122] The above equation (13) is stored in the storage unit (12) of FIG. 3, and the updated fish quantity correction coefficient Ccoris also updated and stored in the storage unit (12) at any time. Using the above equation (13) stored in the storage unit (12) and the updated fish quantity correction coefficient Ccor, the control unit (11) calculates the fish quantity index Q by the function of the fish quantity index calculation module (11c), and displays information about the fish quantity index Q on the display unit (17) by the function of the image generation module (11b). This process will be described with reference to FIG. 9.

[0123] (5) Formula for calculating the point spread coefficient Vunit. The following is an addition to the formula for calculating the point spread coefficient Vunit.

[0124] The pulse width of the transmission pulse, the beam width of the reception beam (RB1), and the tilt angle are denoted by τ, ψ, and θ, respectively. Here, the beam width ψ is defined as "the beam width in the plane tangent to the scanning plane (SP1) at the beam axis," and the beam width ψ is assumed to be independent of the tilt angle θ. The arbitrarily chosen reference values for the sampling frequency fs, the pulse width τ, and the beam width ψ are fs0, τ0, and ψ0, respectively. The value of the point spread coefficient Vunitat the tilt angle θ=0 degrees corresponding to these reference values is denoted by V0.

[0125] At this time, the point spread coefficient Vunitat any fs, τ, ψ, θ is expressed by the following equation.

[0126]

[0127] For example, if the sampling interval (1 / fs) is proportional to the pulse width τ of the transmission pulse and the beam width of the reception beam (RB1) may not have a value other than ψ0, then the point spread coefficient Vunitis expressed as a function of θ by Vunit=V0 / cosθ.

[0128] (6) Setting the fish quantity correction magnification - FIG. 7 is a flowchart showing the acceptance processing of the fish quantity correction magnification. This processing is performed by the control unit (11) according to the function of the correction value reception processing module (11d) shown in FIG. 3.

[0129] When the value (111) of the fish quantity index calculated by the above equation (13) is different from the total weight of the fish actually captured by the user, the user inputs an input instruction of the fish quantity correction magnification through the input unit (19) in order to correct the difference. In response to the input instruction, the control unit (11) displays a correction magnification reception screen for inputting the fish quantity correction magnification on the display unit (17), and receives an input of the fish quantity correction magnification from the user (S11).

[0130] FIG. 8 is a diagram showing an example of a fish quantity correction magnification reception screen (100).

[0131] 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 the magnification input area (101) through the input unit (19), selection candidates for magnification are displayed vertically in a drop-down display below the magnification input area (101). The selection candidates are arranged in 0.1 steps from 0.1 to 2.0, for example. The user selects a desired magnification from the displayed selection candidates. Thus, the selected magnification is displayed in the magnification input area (101). In the example of FIG. 8, a magnification of 1.1 is selected.

[0132] The user may change the fish quantity correction magnification by clicking the magnification input area (101) again. Thus, after inputting the fish quantity correction magnification, the user may click the button (102). Thus, the input of the fish quantity correction magnification is determined. When the user clicks the button (103) without clicking the button (102), the input operation of the fish quantity correction magnification is canceled.

[0133] Returning to FIG. 7, when the user determines the input of the fish quantity correction magnification (S12: YES), the control unit (11) sets the new fish quantity correction coefficient Ccoras the value obtained by multiplying the fish quantity correction coefficient Ccorbefore the input by the input fish quantity correction magnification (S13). As a result, the fish quantity correction coefficient Ccoris updated. On the other hand, if the user cancels the input operation without determining the input of the fish quantity correction magnification (S12: NO), the control unit (11) terminates the processing shown in FIG. 7 without updating the fish quantity correction coefficient Ccor.

[0134] Display of fish quantity index - FIG. 9 is a flowchart showing the display processing of the fish quantity index. This processing is performed by the control unit (11) according to the functions of the image generation module (11b) and the fish quantity index calculation module (11c) shown in FIG. 3.

[0135] When the fish quantity index display process is started, the control unit (11) determines whether or not the fish quantity correction coefficient Ccormay be updated according to the processing shown in FIG. 7 (S21). When the fish quantity correction coefficient Ccormay be updated (S21: YES), the control unit (11) sets the updated fish quantity correction coefficient Ccorto the above equation (13) (S22). When the fish quantity correction coefficient Ccormay not updated (S21: NO), the control unit (11) skips step S22 and proceeds to step S23.

[0136] After that, when the transmission / reception period (1 ping) ends and the data necessary for the calculation of the fish quantity index Q is prepared (S23: YES), the control unit (11) calculates the fish quantity index Q by the function of the fish quantity index calculation module (11c) according to the above equation (13) (S24). Then, the control unit (11) may be configured to generate a display image (110) including information on the calculated fish quantity index Q by the function of the image generation module (11b) (S25), and operate the display unit (17) to display the generated display image (110) (S26).

[0137] When the processing for the present ping is completed, the control unit (11) may be configured to determine whether the operation for displaying information on the fish quantity index Q may be completed by an operation from the user (S27). If the display operation may not completed (S27: NO), the control unit (11) may be configured to return the process to step S21 and executes the same process. If the process shown in FIG. 8 is executed in parallel with the process shown in FIG. 9 and the fish quantity correction coefficient Ccormay be updated (S21: YES), the updated fish quantity correction coefficient Ccoris applied to the above equation (13) (S22) and the processing from step S23 onwards is executed.

[0138] Thus, the control unit (11) repeatedly executes the processing in steps S21 to S26 until the display operation of the information on the fish quantity index Q is completed (S27: NO). As a result, the display of the information on the fish quantity index Q is updated for each ping. After that, when the display operation is finished (S27: YES), the control unit (11) terminates the processing shown in FIG. 9.

[0139] FIG. 10 is a diagram showing an example of the display image (110) of information on the fish quantity index Q.

[0140] The display image (110) includes the value (111) of the current fish quantity index Q calculated by the function of the fish quantity index calculation module (11c) in step S24 of FIG. 9 and the graph (112) of the time series of the previously calculated fish quantity index Q. The value (111) of the current fish quantity index Q may be the value (111) of the current fish quantity index Q itself, or it may be the average value of the value (111) of the fish quantity index Q calculated between the present and the past fixed period. The value (111) of the fish quantity index Q at each time in the graph (112) is the same.

[0141] The horizontal and vertical axes of the graph (112) are the time (in minutes) and the fish quantity index (in tons), respectively. On the horizontal axis, the current time is set to the rightmost position, and the further to the left the time goes back to the past. Here, the transition of the value (111) of the fish quantity index in the period from the present to 20 minutes ago is displayed as the graph (112).

[0142] The user may grasp the amount of fish at the present position from the value (111) of the fish quantity index included in the display image (110), and furthermore, the transition of the amount of fish in the route of the ship (S1) so far may be grasped from the graph (112). Therefore, the user may smoothly grasp the situation of the fish group and the position where the fish should be caught.

[0143] The display image (110) of FIG. 10 may be arranged in any of the divided areas of the area A2 in the screen of FIG. 4. Alternatively, in the screen of FIG. 4, the display image (110) of FIG. 10 may be superimposed in such a way not to cover the echo image (P10) as much as possible. In this case, the display and erasure of the display image (110) may be switched in response to an operation from the user.

[0144] Setting of fish quantity calculation area - The range for calculating the fish quantity index according to equation (13) may be limited to a predetermined range by the user from the entire range scanned at 1 ping. For example, in the case, where the user carries out purse seining, the range for calculating the fish quantity index may be limited to the range that may be enclosed by the purse seine (for example, a radius of 200 m around the ship (S1)).

[0145] FIG. 11 is a diagram showing an example of a fish quantity calculation area reception screen (120).

[0146] The reception processing of the fish quantity calculation area is performed by the control unit (11) according to the function of the object area reception processing module (11e) shown in FIG. 3. According to this function, the control unit (11) displays the fish quantity calculation area reception screen (120) shown in FIG. 11 in response to the setting operation of the calculation area from the user.

[0147] 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 the screen, and a button (124) for performing manual setting. The range input area (121) is an area for inputting the radius of the circle centered on the own ship when viewed from directly above the own ship.

[0148] When the user clicks the range input area (121) through the input unit (19), a selection candidate of the range is tickled below the range input area (121). The selection candidates are arranged in steps of 50 m from 200 m to 800 m, for example. 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 (121). In the example shown in FIG. 11, a range having a radius of 200 m centered on the ship (S1) is selected.

[0149] The user may change the calculation range of the fish quantity by clicking the range input area (121) again. After inputting the calculation range of the fish quantity, the user clicks the button (122). Thus, the input of the fish quantity calculation range is determined. When the user clicks the button (123) without clicking the button (122), the input operation of the fish quantity calculation range is canceled.

[0150] When setting an arbitrary range, the user operates the button (124). Thus, for example, an image including boundary lines (P14) to (P16) similar to the echo image (P10) of FIG. 4 is displayed. The user draws a line surrounding the desired range on the image via the input unit (19) and operates the confirmation button. As a result, the range surrounded by the line is confirmed as the fish quantity calculation range.

[0151] The control unit (11) (fish quantity index calculation module (11c)) executes the processing in step S24 of FIG. 9 using the range set by the user as the calculation object range. That is, the processing in step S24 is executed using the 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, when the range of radius 200 m centered on the ship (S1) is set in the fish quantity calculation range, the processing in step S24 is executed using the data included in the range of the sample number of the vertical axis corresponding to 0~200 m.

[0152] By limiting the fish quantity calculation range as described above, the user may display information about the fish quantity index Q in the range where the user intends to capture fish. Thus, the user may smoothly advance the fishing.

[0153] Effect of Embodiment - According to the above embodiment, the following effects may be achieved.

[0154] As shown in FIG. 3, the underwater detection device (10) includes a fish quantity index calculation module (11c) that calculates a fish quantity index Q based on electrical signals output from a plurality of ultrasonic oscillators (13a), an image generation module (11b) that generates the display image (110) containing information about the fish quantity index Q, and a correction value reception processing module (11d) that receives input of a correction value (correction magnification) for correcting the fish quantity index Q, and the fish quantity index calculation module (11c) corrects the above equation (13), which is a calculation formula for the fish quantity index Q, based on the input correction value.

[0155] According to this configuration, the fish quantity correction coefficient Ccorof the above equation (13) is corrected based on the correction value (correction magnification) input from a user such as a fisherman. In general, since the user may easily estimate the amount of fish caught by himself (e.g., tonnage), the correction value for correcting the displayed fish quantity index Q to the actual amount of fish may be input smoothly and appropriately. Therefore, the calculation formula of the fish quantity index Q may be corrected to approach the actual amount of fish caught based on the input correction value. Therefore, the amount of fish caught may be smoothly and properly estimated by this correction processing.

[0156] As described above, the equation (13) for calculating the fish quantity index Q includes the fish quantity correction coefficient Ccor, and the correction value for correcting the equation (13) is the correction magnification. The fish quantity index calculation module (11c) calculates the fish quantity index Q by using the value obtained by multiplying the immediately preceding fish quantity correction coefficient Ccorby the correction magnification as the new fish quantity correction coefficient Ccor.

[0157] Thus, by repeating the input of the correction magnification, the user may approach the fish quantity index Q to the fish quantity corresponding to his / her estimate. Therefore, the fish quantity index Q according to the fishing ground of the user, fish species and season may be smoothly and properly displayed.

[0158] Here, the equation (13) for calculating the fish quantity index Q is obtained by replacing the first formula with a formula consisting of an approximate number (coefficient C0) of the first formula and a fish quantity correction coefficient Ccor, in contrast to the original equation (12) consisting of a first formula including the weight W and the target strength Tsof the fish to be captured, the intensity I0of the transmitted wave and the reception sensitivity k of the transducer (13), and a second formula not including these parameters including in the first formula.

[0159] As described above, since the weight W and the target strength Tsof the fish to be captured, the intensity I0of the transmission wave and the reception sensitivity k of the transducer (13) are added to the equation (13), which is a formula for calculating the fish quantity index Q, the fish quantity index may be accurately calculated by the equation (13). In addition, since the first formula including these parameters is replaced with a term consisting of the approximate number (coefficient C0) of the first formula and the fish quantity correction coefficient Ccoras described above, the user may smoothly correct the formula by the correction magnification according to his / her fish quantity estimation without grasping these parameters. Thus, the user may smoothly bring the displayed fish quantity index Q close to his / her fish quantity estimation. Therefore, the user may properly display the fish quantity index Q close to his / her own catch.

[0160] As shown in FIG. 10, the display image (110) includes the value (111) of the current fish quantity index Q calculated by the fish quantity index calculation module (11c). Thus, the user may grasp the fish quantity at the current position from the value (111) of the fish quantity index.

[0161] The display image (110) also includes a graph (112) of the time series of the fish quantity index Q calculated by the fish quantity index calculation module (11c). As a result, the user may grasp the transition of the fish quantity in the route of the ship (S1) so far from the graph (112). Therefore, the user may smoothly grasp the position where the fish should be caught.

[0162] As shown in FIG. 3, the underwater detection device (10) further includes the object area reception processing module (11e) for receiving the designation of an object area to be used for calculating the fish amount index Q in the search range, and as described with reference to FIG. 11, the fish amount index calculation module (11c) calculates the fish amount index Q for the designated object area.

[0163] As a result, the user may designate an area to be noticed by himself or herself, an area that may be enclosed by a purse seine, or the like as the object area, and display the fish amount index Q in the object area. Therefore, the user may smoothly advance the capture of fish based on the displayed fish amount index Q.

[0164] Modified Example - In the above embodiment, the display image (110) shown in FIG. 10 is exemplified as the display image (110) including information on the fish quantity index Q, but the display image (110) is not limited thereto.

[0165] For example, as shown in FIG. 12, in the echo image (P10), a plot (P18) may be attached to the track (P12) of the ship (S1) at regular intervals, and the value (in tons) (111) of the fish quantity index Q at the position (time) of each plot (P18) may be added to the right of the plot (P18). Alternatively, as shown in FIG. 13, a circular mark (P19) having a diameter corresponding to the value (111) of the fish quantity index Q at the position may be superimposed on the track (P12) of the ship (S1) at regular intervals. In this case, the value (111) of the fish quantity index Q at the position may be further added near each circle.

[0166] With the display image (110), the user may also grasp the transition of the fish quantity in the route of the ship (S1). Therefore, the user may smoothly grasp the position where the fish should be caught.

[0167] Alternatively, the graph (112) of a time series in which the horizontal axis of FIG. 10 is corrected to the rhumb distance (cumulative rhumb distance) may be displayed. The speed of the ship (S1) during a fish group search is not necessarily constant. On the other hand, if the horizontal axis of the graph (112) of the time series is the rhumb distance (cumulative rhumb distance), the user may easily estimate the point by the rhumb distance (cumulative rhumb distance) of the graph (112) horizontal axis when he / she wants to return to the point where a promising fish quantity index value has occurred by referring to the graph (112).

[0168] In the above embodiment, the fish quantity correction coefficient Ccoris corrected by the 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 Ccormay be used as the correction value of the fish quantity correction coefficient Ccor.

[0169] The screen for receiving the fish quantity correction magnification is not limited to the fish quantity correction magnification reception screen (100) shown in FIG. 8, and may be a reception 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 reception screen (120) shown in FIG. 11, and may be a reception screen of another configuration.

[0170] The control unit (11) may further include a function that enables the user to set a plurality of fish quantity correction coefficients Ccoraccording to, for example, a fish species or a fishing ground. In this case, the control unit (11) connects the fish quantity correction coefficients Ccorset by the user to a fish species or a fishing ground and stores them in the storage unit (12). In the application processing of the fish quantity correction coefficients Ccor, the control unit (11) displays the selection candidates of the fish species or the fishing ground on the display unit (17), and calculates the fish quantity index Q by applying the fish quantity correction coefficients Ccorconnected to the fish species or the fishing ground selected by the user through the input unit (19) to the calculation formula of equation (13). Thus, the user may acquire a fish quantity index Q adapted to the fish species he / she intends to capture and the fishing ground, and the fishing may proceed more smoothly. In this case, each fish quantity correction coefficient Ccoris corrected by a fish quantity correction magnification (correction value).

[0171] In the above embodiment, the fish quantity index calculation module (11c) and the like are realized as functions of the control unit (11) assigned by the program stored in the storage unit (12), but they need not be realized as functions assigned by the program stored in the storage unit (12). For example, one or more of these functions may be composed of a field-programmable gate array (FPGA) or hardware with integrated logic circuits.

[0172] In addition, although the above embodiment shows an underwater detection device (10) that transmits and receives along the scanning plane (SP1) of a cone, the present invention may be applied to an underwater detection device (10) that transmits and receives in another manner. In addition, the transducer (13) for transmitting and the transducer (13) for receiving may be individually arranged. In addition, a calculation formula other than equation (13) may be used for calculating the fish quantity index Q. In this case, the calculation formula may also include a fish quantity correction coefficient corrected by a correction value input from the user.

[0173] In addition, embodiments of the present invention may be suitably modified as described in the claims.Terminology

[0174] It is to be understood that not necessarily all objects or advantages may be achieved in accordance with any particular embodiment described herein. Thus, for example, those skilled in the art will recognize that certain embodiments may be configured to operate in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0175] All of the processes described herein may be embodied in, and fully automated via, software code modules executed by a computing system that includes one or more computers or processors. The code modules may be stored in any type of non-transitory computer-readable medium or other computer storage device. Some or all the methods may be embodied in specialized computer hardware.

[0176] Many other variations than those described herein will be apparent from this disclosure. For example, depending on the embodiment, certain acts, events, or functions of any of the algorithms described herein can be performed in a different sequence, can be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the algorithms). Moreover, in certain embodiments, acts or events can be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors or processor cores or on other parallel architectures, rather than sequentially. In addition, different tasks or processes can be performed by different machines and / or computing systems that can function together.

[0177] The various illustrative logical blocks and modules described in connection with the embodiments disclosed herein can be implemented or performed by a machine, such as a processor. A processor can be a microprocessor, but in the alternative, the processor can be a controller, microcontroller, or state machine, combinations of the same, or the like. A processor can include electrical circuitry configured to process computer-executable instructions. In another embodiment, a processor includes an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable device that performs logic operations without processing computer-executable instructions. A processor can also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor (DSP) and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Although described herein primarily with respect to digital technology, a processor may also include primarily analog components. For example, some or all of the signal processing algorithms described herein may be implemented in analog circuitry or mixed analog and digital circuitry. A computing environment can include any type of computer system, including, but not limited to, a computer system based on a microprocessor, a mainframe computer, a digital signal processor, a portable computing device, a device controller, or a computational engine within an appliance, to name a few.

[0178] Conditional language such as, among others, "can," "could," "might" or "may," unless specifically stated otherwise, are otherwise understood within the context as used in general to convey that certain embodiments include, while other embodiments do not include, certain features, elements and / or steps. Thus, such conditional language is not generally intended to imply that features, elements and / or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and / or steps are included or are to be performed in any particular embodiment.

[0179] Disjunctive language such as the phrase "at least one of X, Y, or Z," unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and / or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain embodiments require at least one of X, at least one of Y, or at least one of Z to each be present.

[0180] Any process descriptions, elements or blocks in the flow diagrams described herein and / or depicted in the attached figures should be understood as potentially representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or elements in the process. Alternate implementations are included within the scope of the embodiments described herein in which elements or functions may be deleted, executed out of order from that shown, or discussed, including substantially concurrently or in reverse order, depending on the functionality involved as would be understood by those skilled in the art.

[0181] Unless otherwise explicitly stated, articles such as "a" or "an" should generally be interpreted to include one or more described items. Accordingly, phrases such as "a device configured to" are intended to include one or more recited devices. Such one or more recited devices can also be collectively configured to carry out the stated recitations. For example, "a processor configured to carry out recitations A, B and C" can include a first processor configured to carry out recitation A working in conjunction with a second processor configured to carry out recitations B and C. The same holds true for the use of definite articles used to introduce embodiment recitations. In addition, even if a specific number of an introduced embodiment recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations).

[0182] It will be understood by those within the art that, in general, terms used herein, are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.).

[0183] For expository purposes, the term "horizontal" as used herein is defined as a plane parallel to the plane or surface of the floor of the area in which the system being described is used or the method being described is performed, regardless of its orientation. The term "floor" can be interchanged with the term "ground" or "water surface." The term "vertical" refers to a direction perpendicular to the horizontal as just defined. Terms such as "above," "below," "bottom," "top," "side," "higher," "lower," "upper," "over," and "under," are defined with respect to the horizontal plane.

[0184] As used herein, the terms "attached," "connected," "mated" and other such relational terms should be construed, unless otherwise noted, to include removable, moveable, fixed, adjustable, and / or releasable connections or attachments. The connections / attachments can include direct connections and / or connections having intermediate structure between the two components discussed.

[0185] Numbers preceded by a term such as "approximately," "about," and "substantially" as used herein include the recited numbers, and also represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms "approximately," "about," and "substantially" may refer to an amount that is within less than 10% of the stated amount. Features of embodiments disclosed herein preceded by a term such as "approximately," "about," and "substantially" as used herein represent the feature with some variability that still performs a desired function or achieves a desired result for that feature.

[0186] It should be emphasized that many variations and modifications may be made to the above-described embodiments, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.List of Reference Numerals

[0187] 10 Underwater detection device 11 Control unit 11a Reception signal generation module 11b Image generation module 11c Fish quantity index calculation module 11d Correction value reception processing module 11e Object area reception processing module 12 Storage unit 13 Transducer 13a Ultrasonic Oscillator 14 Transmission processing module 15 Reception processing module 16 Transmission / reception switching unit 17 Display unit 18 Display processing module 19 Input unit 20 Input processing module 100 Fish quantity correction magnification reception screen 101 Magnification input area 102 Button 103 Button 110 Display Image 111 Value of fish quantity index 112 Graph 120 Fish quantity calculation area reception screen 121 Range input area 122 Button for confirming the input 123 Button for returning the screen 124 Button for performing manual setting P10 Echo image P12 Track P13 Straight line P14-P16 Boundary lines P17 Hatched region P18 Plot P19 Circular Mark S1 Ship SP1 Scanning plane TB1 Transmission beam RB1 Reception beams

Claims

1. An underwater detection device (10) comprising: a fish quantity index calculation module (11c) configured to calculate a fish quantity index based on electrical signals output from a plurality of ultrasonic oscillators (13a); an image generation module (11b) configured to generate a display image (110) including information on the fish quantity index; and a correction value reception processing module (11d) configured to receive an input of a correction value for correcting the fish quantity index, wherein the fish quantity index calculation module (11c) corrects a calculation formula of the fish quantity index based on the correction value.

2. The underwater detection device (10) according to claim 1, wherein the calculation formula includes a fish quantity correction coefficient, the correction value is a correction magnification, and the fish quantity index calculation module (11c) calculates the fish quantity index using the fish quantity correction coefficient multiplied by the correction magnification as the new fish quantity correction coefficient.

3. The underwater detection device (10) according to claim 2, wherein the calculation formula is obtained by replacing a first formula with a formula consisting of an approximate number of the first formula and the fish quantity correction coefficient with respect to an original calculation formula consisting of the first formula including a weight of a fish and a target strength per catch, an intensity of a transmitted wave and a reception sensitivity of a transducer (13), and a second formula not including these parameters including in the first formula.

4. The underwater detection device (10) according to claim 1, wherein the display image (110) includes a current value of the fish quantity index calculated by the fish quantity index calculation module (11c).

5. The underwater detection device (10) according to claim 1, wherein the display image (110) includes a graph (112) of a time series of the fish quantity index calculated by the fish quantity index calculation module (11c).

6. The underwater detection device (10) according to claim 1, wherein the display image (110) includes an image in which a plurality of positions aligned on a track (P12) of a ship (S1) are appended with information indicating a value (111) of the fish quantity index at the position.

7. The underwater detection device (10) according to claim 1, further comprising: an object area reception processing module (11e) configured to receive designation of a object area to be calculated for the fish quantity index in a search range, wherein the fish quantity index calculation module (11c) calculates the fish quantity index for the designated object area.

8. An underwater detection method executed by the underwater detection device (10), comprising: calculating, by a fish quantity index calculation module (11c), a fish quantity index based on electrical signals output from a plurality of ultrasonic oscillators (13a); generating, by an image generation module (11b), a display image (110) including information on the fish quantity index; and receiving, by a correction value reception processing module (11d), an input of a correction value for correcting the fish quantity index, wherein the fish quantity index calculation module (11c) corrects a calculation formula of the fish quantity index based on the correction value.

9. A program that makes perform to a computer of an underwater detection device (10): a function to calculate a fish quantity index based on electrical signals output from a plurality of ultrasonic oscillators (13a); a function to generate a display image (110) including information on the fish quantity index; and a function to receive an input of a correction value for correcting the fish quantity index, wherein the function to calculate the fish quantity index includes a function to correct a calculation formula of the fish quantity index based on the correction value.

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