Echo image display device, echo image display control method, and program

Abstract

This invention provides an echo image display device, an echo image display control method, and a program that enable users to clearly understand the echo distribution for both the outward and return journeys when a vessel returns to its previous route. [Solution] The underwater detection device 10 includes an echo intensity acquisition unit 11b that acquires the echo intensity of each point on the latitude and longitude plane over time, a time division setting unit 11e that sets time divisions, a storage unit 12 that stores values ​​based on the echo intensity of each point acquired over time, associating each point with a time division, a time range reception unit 11f that receives a specification of a desired time range from the user from among the time ranges divided by the time divisions, and an image generation unit 11g that generates an echo image at each point based on the above values ​​for each point corresponding to the specified time range.

Description

Technical Field

[0001] The present invention relates to a display device, a display control method, and a program for displaying an echo image obtained by underwater detection.

Background Art

[0002] Conventionally, an underwater detection device for detecting underwater targets has been known. This type of underwater detection device transmits ultrasonic waves into the water, receives the reflected waves, calculates the echo intensity from each position in the water, and displays an echo image.

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

[0004] In this type of underwater detection device, each position on the conical surface is converted into a position in an L (latitude) / L (longitude) / D (depth) coordinate system consisting of latitude, longitude, and depth. The echo intensity at each position after conversion is obtained as the echo intensity for a point on the L (latitude) / L (longitude) coordinate plane that overlaps in the depth direction at each position. An echo image in which these obtained echo intensities are distributed two-dimensionally is displayed.

[0005] Such an echo image may include a noise image based on echoes from, among other things, fish schools and floating substances in the water. As a method for suppressing this noise image, there is a method of obtaining the average value of the echo intensity for each point on the L / L coordinate plane and using this average value as the echo intensity at that point.

[0006] In other words, as the ship moves, the cone surface moves, and at each point on the L / L coordinate plane, echo intensities for different depths are sequentially acquired for each ping (ultrasonic transmission / reception period). By averaging these series of echo intensities, the average value mentioned above is obtained. Here, since the depth range of floating objects is narrow, the number of pings for which echoes of floating objects can be obtained at each point is small. Therefore, the echoes of floating objects have less influence on the average value at each point. This makes it possible to effectively suppress noise images such as floating objects from the echo image.

[0007] However, in this configuration, at each location, the echo intensity from the fish school, along with the noise echo intensity, is weakened by averaging. As a result, the echoes from the fish school become less clearly visible in the echo image.

[0008] In contrast, Patent Document 1 describes an echo image display device that can display echo images of fish schools more clearly. In this display device, multiple layers are set in the depth direction. For each point, the display device calculates the average value of the echo intensity for each layer and displays the echo image at that point based on the highest average value among these average values.

[0009] This method allows for the suppression of noise effects through averaging. Furthermore, because fish schools tend to be distributed over a relatively wide area of ​​one of the layers, the average echo intensity in that layer can be increased according to the fish school. Therefore, as described above, by displaying the echo image of a given location based on the maximum average value obtained from each layer, the echo image of the fish school can be displayed more clearly. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Patent No. 4781240 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] As described above, echo images can be displayed in various ways. Here, the echo image displays not only the current distribution of echo intensity but also the past distribution of echo intensity. This allows the user to understand the situation of fish schools near their ship's past route over time from the echo image, and to return their ship to the location of past fish schools as needed to continue fishing.

[0012] However, when a vessel returns to its previous route, the echo image shows a mixture of the echo intensity distribution before and after the return. As a result, it becomes difficult for users to distinguish which echo intensity distribution corresponds to which period before or after the return, making it difficult to accurately determine the location of the fish school.

[0013] In view of these problems, the present invention aims to provide an echo image display device, an echo image display control method, and a program that enable a user to clearly understand the echo images before and after a ship returns to the position of its past course. [Means for solving the problem]

[0014] A first aspect of the present invention relates to a display device that displays an image of an echo obtained by underwater detection using ultrasonic waves. The display device according to this aspect includes: an echo intensity acquisition unit that acquires the echo intensity of each point on a latitude-longitude plane over time; a time division setting unit that sets time divisions; a storage unit that stores values ​​based on the echo intensity of each point acquired over time, associating each point with the time divisions; a time range receiving unit that receives a specification from the user for a desired time range from among the time ranges divided by the time divisions; and an image generation unit that generates an echo image at each point based on the values ​​of each point corresponding to the specified time range.

[0015] According to the display device of this embodiment, since echo images for a time range specified by the user are displayed, echo images from other time ranges do not overlap with the displayed echo images. Therefore, the user can clearly understand each echo image by specifying the time range before and after the ship turns back.

[0016] In the display device according to this embodiment, the time interval setting unit may be configured to set the time intervals through user operation.

[0017] With this configuration, users can arbitrarily set time divisions. For example, when a user is using echo images to return their ship to the location of a school of fish, they can set time divisions to separate the echo intensity acquired before steering the ship back from the echo intensity acquired after steering the ship back. This allows the echo images before and after the return to be displayed separately.

[0018] In the display device according to this embodiment, the time division setting unit may be configured to acquire information regarding the movement of the ship on which the display device is installed over time, estimate whether the ship will return to its previous route based on the information, and set the time division according to the estimation that the ship will return.

[0019] With this configuration, the time range before and after the point in time when the ship turns back is automatically set. Therefore, user convenience can be improved.

[0020] In the display device according to this embodiment, the time range receiving unit may be configured to include a button on the echo image display screen for receiving a selection of the time range from the user.

[0021] With this configuration, users can switch the displayed time range and change the displayed echo image at any time by operating buttons while referring to the echo image. Therefore, user convenience can be enhanced.

[0022] In this configuration, the time range reception unit is configured to be able to select a plurality of the buttons simultaneously, and the image generation unit may be configured to generate an echo image at each of the points corresponding to the time ranges of the plurality of the buttons that are selected simultaneously, based on the values at the respective points corresponding to the time ranges of the plurality of the buttons that are selected simultaneously.

[0023] According to this configuration, the user can display echo images of a plurality of time ranges simultaneously, in addition to each time range. For example, when the echo images before and after the steering to return the own ship do not overlap so much, the user can select this display form to grasp the movement of the fish school, etc. in the periods before and after the turning back.

[0024] In the display device according to this aspect, until the time range reception unit receives the designation of the time range, the image generation unit generates an echo image at each of the points corresponding to all the time ranges, based on the values at the respective points corresponding to all the time ranges, and in response to the time range reception unit receiving the designation of the time range, the image generation unit may be configured to generate an echo image at each of the points corresponding to the designated time range, based on the values at the respective points corresponding to the designated time range.

[0025] According to this configuration, the user can arbitrarily switch to the echo image of the designated time range by appropriately designating the desired time range while referring to the normal echo images corresponding to all the time ranges.

[0026] The display device according to this aspect further includes a communication unit capable of acquiring the echo intensity at each point on the latitude-longitude plane from the underwater detection device of another ship over time, the storage unit stores, for each other ship, the values based on the echo intensity at each point acquired from the other ship over time in association with the time intervals for each point, and the image generation unit may be configured to generate an echo image at each of the points of the other ship corresponding to the time range designated via the time range reception unit, based on the values at the respective points of the other ship corresponding to the time range designated, based on the reception of the display instruction of the echo image of the other ship from the user.

[0027] According to this configuration, the user can appropriately display echo images based on echo intensities obtained not only on their own ship but also on other ships. As a result, for example, fish schools that cannot be grasped from the echo image of their own ship can be grasped from the echo image of other ships.

[0028] The second aspect of the present invention relates to a control method in an apparatus for displaying an echo image obtained by underwater detection by transmitting and receiving ultrasonic waves. The control method according to this aspect acquires the echo intensity at each point on the latitude-longitude plane over time, sets a time interval, associates a value based on the echo intensity at each point acquired over time with the time interval for each point, stores the value in a memory, accepts from the user a designation of a desired time range among the time ranges divided by the time interval, and generates an echo image at the point based on the value at each point corresponding to the designated time range.

[0029] According to the control method according to this aspect, the same effect as that of the echo image display apparatus according to the first aspect can be achieved.

[0030] The third aspect of the present invention relates to a program for causing a control unit of an apparatus for displaying an echo image obtained by underwater detection by transmitting and receiving ultrasonic waves to execute a predetermined function. The program according to this aspect causes the control unit to execute a function of acquiring the echo intensity at each point on the latitude-longitude plane over time, a function of setting a time interval, a function of storing, in a storage unit, by associating with the time interval for each point, a value based on the echo intensity at each point acquired over time, a function of accepting from the user a designation of a desired time range among the time ranges divided by the time interval, and a function of generating an echo image at the point based on the value at each point corresponding to the designated time range.

[0031] According to the program according to this aspect, the same effect as that of the echo image display apparatus according to the first aspect can be achieved.

Advantages of the Invention

[0032] As described above, the present invention provides an echo image display device, an echo image display control method, and a program that enable a user to clearly understand the echo images before and after a ship returns to the position of its past course.

[0033] The effects and significance of the present invention will become even clearer from the description of the embodiments shown below. However, the embodiments shown below are merely examples of how to implement the present invention, and the present invention is not limited in any way to those described in the embodiments below. [Brief explanation of the drawing]

[0034] [Figure 1] Figure 1 is a schematic diagram showing how the underwater area is searched by an underwater detection device according to an embodiment. [Figure 2] Figure 2 is a schematic diagram showing how the underwater area is searched by an underwater detection device according to an embodiment. [Figure 3] Figure 3 is a block diagram showing the configuration of an underwater detection device according to an embodiment. [Figure 4] Figure 4 shows a method for obtaining the average echo intensity for each layer according to the embodiment. [Figure 5] Figure 5 is a schematic diagram illustrating the acquisition of the echo intensity of a school of fish as the school moves, according to the embodiment. [Figure 6] Figure 6 is a flowchart showing the process of generating and displaying echo images according to an embodiment. [Figure 7] Figure 7 is a flowchart showing the process of labeling each point (coordinate position) in the L / L / D coordinate system to indicate whether or not it corresponds to a school of fish, according to the embodiment. [Figure 8] Figures 8(a) and 8(b) show examples of echo image displays according to the respective embodiments. [Figure 9] Figure 9 is a diagram showing the configuration of information stored in the storage unit for displaying an echo image, according to the embodiment. [Figure 10]Figure 10 is a flowchart showing the display process of an echo image according to an embodiment. [Figure 11] Figure 11 shows an example of displaying an echo image based on echo intensity over the entire time range, according to the embodiment. [Figure 12] Figure 12 shows an example of displaying an echo image based on echo intensity over a specified time range, according to the embodiment. [Figure 13] Figure 13 shows an example of displaying an echo image based on echo intensity over a specified time range, according to the embodiment. [Figure 14] Figure 14 is a flowchart showing the time interval setting process related to Change Example 1. [Figure 15] Figure 15 is a block diagram showing the configuration of the underwater detection device according to modification example 2. [Figure 16] Figure 16 shows an example of displaying echo images based on echo intensity for all time ranges when the echo image of the own ship is designated as the display target, according to Modification Example 2. [Figure 17] Figure 17 shows the configuration of a system including a display device, relating to another example of modification. [Modes for carrying out the invention]

[0035] Embodiments of the present invention will be described below with reference to the drawings. For convenience, mutually orthogonal X, Y, and Z axes are indicated in the drawings as appropriate. The X and Y axes are horizontal, and the Z axis is vertical. The positive X direction is the direction in which the ship moves.

[0036] In the following embodiments, the underwater detection device 10 corresponds to the "echo image display device" described in the claims. However, the following embodiments are merely examples of realization of the present invention and do not limit the present invention in any way.

[0037] Figures 1 and 2 schematically illustrate how the underwater area is searched by the underwater detection device 10.

[0038] In Figures 1 and 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 the scanning plane SP1, described later, with respect to the horizontal plane (XY plane).

[0039] The underwater detection device 10 includes a transducer 13 installed on the bottom of a vessel S1, such as a fishing boat. The underwater detection device 10 transmits sound wave pulses (transmit pulses) from the transducer 13 and receives sound waves (echoes) reflected (backscattered) by objects such as fish in the water using the same transducer 13. Based on the echoes received by the transducer 13, the underwater detection device 10 detects objects in the water.

[0040] The transducer 13 is equipped with numerous ultrasonic transducers. Each ultrasonic transducer 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, with hundreds of ultrasonic transducers regularly arranged on its side.

[0041] Here, the area to be detected by the underwater detection device 10 is a conical surface. The axis of this conical surface is parallel to the vertical direction (Z-axis direction). This conical surface is called the scanning surface SP1, and its vertex and axis are called the origin and 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.

[0042] As shown in Figure 1, the underwater detection device 10 transmits a transmission beam TB1 with maximum intensity on the scanning surface SP1 over its entire circumference during transmission. This transmission beam TB1 has an intensity distribution axially symmetric with respect to the scanning axis (Z-axis in Figure 1), and its vertical width is relatively narrow.

[0043] As shown in Figure 2, the underwater detection device 10 forms a number of receiving beams RB1 with maximum sensitivity on the scanning surface SP1 during wave reception. The receiving beams RB1 are formed by applying beamforming processing to the electrical signals output from a plurality of ultrasonic transducers arranged in the transducer 13.

[0044] Each receiving beam RB1 is a pencil beam with a narrow width in both the vertical and horizontal directions and has the same directivity. The beam axis of each receiving beam RB1 is a straight line passing through the origin and pointing in the direction in which the sensitivity of the receiving beam RB1 is maximized. Multiple receiving beams RB1 are formed by arranging them at constant angular intervals in the direction of the azimuth angle φ around 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 echo image. The method for generating the echo image will be described in detail later.

[0045] Figure 3 is a block diagram showing the configuration of the underwater detection device 10.

[0046] The underwater detection device 10 comprises a control unit 11, a storage 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, while the control unit 11 and other components are installed in the wheelhouse or other location on the ship S1. The underwater detection device 10 acquires information such as the position, heading, and speed of the ship S1 from a navigation device 100 equipped with GPS functionality as needed.

[0047] The control unit 11 is equipped with an arithmetic processing circuit such as a CPU (Central Processing Unit) and executes the control processing described later using a program stored in the memory unit 12. The memory unit 12 is equipped with a storage medium such as ROM (Read Only Memory), RAM (Random Access Memory), or hard disk. The memory unit 12 stores a program for the control unit 11 to execute the control processing.

[0048] The transducer 13 is equipped with multiple ultrasonic transducers 13a, as described above. During each transmission / reception period (ping), the transducer 13 transmits ultrasonic waves as the transmission beam TB1 shown in Figure 1, and the reflected waves are received by each ultrasonic transducer.

[0049] The transmission processing unit 14 outputs a transmission signal for transmitting ultrasonic waves to the transducer 13 via the transmit / receive 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 certain period of time, as shown in Figure 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 transmit / receive switching unit 16. As a result, ultrasonic waves corresponding to the transmission signal are transmitted from each ultrasonic transducer 13a, as shown in Figure 3. The ultrasonic pulse transmitted during one transmission is called a transmission pulse.

[0050] The receiving processing unit 15 receives the electrical signals output by each ultrasonic transducer 13a of the transmitter / receiver 13 after receiving the reflected ultrasonic waves, via the transmit / receive switching unit 16, and applies amplification and noise reduction (bandpass filtering) to the received electrical signals. The receiving processing unit 15 outputs these processed electrical signals to the control unit 11.

[0051] The transmit / receive switching unit 16 outputs the transmit signal output from the transmit processing unit 14 to the transducer 13 (ultrasonic transducer 13a) when the transmit beam TB1 is being transmitted, and outputs the electrical signal output from the transducer 13 (ultrasonic transducer 13a) to the receive processing unit 15 for a certain period of time from the moment when the transmission of the transmit beam TB1 is completed.

[0052] Although Figure 3 shows one transmission processing unit 14 and one reception processing unit 15, the processing described above in the transmission processing unit 14 and reception processing unit 15 is performed for each individual ultrasonic transducer 13a located in the transducer 13. Therefore, the control unit 11 receives individually amplified and noise-reduced electrical signals from each ultrasonic transducer 13a. These electrical signals are converted into digital signals with a predetermined sampling period by an A / D converter when input to the control unit 11.

[0053] The display unit 17 includes a display device such as a liquid crystal display. The display processing unit 18 displays a predetermined image on the display unit 17 in response to control from the control unit 11. The input unit 19 includes input means such as operation keys or a mouse. The input processing unit 20 outputs a signal to the control unit 11 corresponding to the operation on the input unit 19 in response to control from the control unit 11. The display unit 17 and the input unit 19 may be composed of a liquid crystal panel in which a touch panel is superimposed on a liquid crystal display.

[0054] In this embodiment, the functions of the received signal generation unit 11a, the echo intensity acquisition unit 11b, the fish school echo estimation unit 11c, the average value calculation unit 11d, the time interval setting unit 11e, the time range reception unit 11f, and the image generation unit 11g are assigned to the control unit 11 by a program stored in the memory unit 12.

[0055] The receiving signal generation unit 11a performs beamforming on the electrical signals (digital signals) output from each ultrasonic transducer 13a to form the receiving beam RB1 shown in Figure 2, and generates a received signal corresponding to the sound wave incident on the transducer 13 from the beam axis direction (direction of a predetermined azimuth angle φ and tilt angle θ) of each receiving beam RB1. Furthermore, the receiving signal generation unit 11a performs band limiting and envelope detection processing on the received signal in each beam axis direction to obtain an envelope signal in each beam axis direction.

[0056] Here, the bandwidth limiting process is a process for extracting the 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 constant frequency signal (CW signal).

[0057] On the other hand, if 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 received signal generation unit 11a applies matched filtering to the received signal in each beam axis direction instead of bandwidth limiting. Then, the received signal generation unit 11a applies envelope detection to the signal after matched filtering to obtain the envelope signal in each beam axis direction.

[0058] The envelope signal thus obtained is a signal that indicates the echo intensity (sound wave strength) which changes according to the elapsed time since the transmission timing of the transmitting beam TB1 (ultrasound). Here, the elapsed time since the transmission timing corresponds to the distance from the transducer 13 in each beam axis direction.

[0059] The echo intensity acquisition unit 11b acquires the echo intensity at each distance position in each beam axis direction from the envelope signal by associating the elapsed time from the transmission timing with distance. The echo intensity is acquired with a predetermined distance resolution. Furthermore, the echo intensity acquisition unit 11b converts each distance position into a position in the L(latitude) / L(longitude) / D(depth) coordinate system consisting of latitude, longitude, and depth, and acquires the echo intensity for a point on the L(latitude) / L(longitude) coordinate plane that overlaps each position in the depth direction.

[0060] The echo intensity acquisition unit 11b then acquires the echo intensity for each point over time for each of the multiple layers obtained by dividing the search range in the depth direction in the depth direction. This process will be explained later with reference to Figure 4.

[0061] The fish school echo estimation unit 11c estimates the echo intensity of a fish school based on the echo intensity acquired by the echo intensity acquisition unit 11b. More specifically, the fish school echo estimation unit 11c labels the positions in the L / L / D coordinate system that correspond to the fish school based on the echo intensity acquired for each ping. This labeling identifies whether the echo intensity at each position corresponds to the echo intensity of a fish school. The labeling process will be explained later with reference to Figure 7.

[0062] The average value calculation unit 11d assigns weights to the echo intensity and calculates the average value of the echo intensity at each point for each layer. More specifically, the average value calculation unit 11d sets the weight of the echo intensity of fish schools to be greater than the weight of other echo intensities, and calculates the average value at each point for each layer by applying the respective weights to the echo intensity in a weighted averaging process. In this embodiment, a weighted average value is calculated as the average value. The process of calculating the average value will be explained later with reference to Figure 4.

[0063] The time interval setting unit 11e sets the time intervals. In this embodiment, the time interval setting unit 11e sets the time intervals in response to user input.

[0064] The time range reception unit 11f receives a request from the user for a desired time range from among time ranges divided by time intervals.

[0065] The image generation unit 11g generates echo images for each location based on a series of echo intensities acquired over time at each location until the time range receiving unit 11f receives a time range specification from the user. Furthermore, once the time range receiving unit 11f receives a time range specification, the image generation unit 11g generates echo images for each location based on the echo intensities of each location corresponding to the specified time range.

[0066] The storage unit 12 stores values ​​based on the echo intensity of each location acquired over time, associating them with time intervals set by the time interval setting unit 11e, for each location.

[0067] Figure 4 shows a method for obtaining the average echo intensity for each layer divided in the depth direction.

[0068] Figure 4 schematically shows the underwater view from the left side of the ship S1. Therefore, Figure 4 shows a cross-section of the umbrella-shaped scanning plane SP1, cut by a plane containing its vertex (origin) and axis (Z-axis) and the direction of ship S1's movement. Two receiving beams RB1, one in front and one behind, are shown within this cross-section. As ship S1 moves, the two receiving beams RB1 move along with the scanning plane SP1. In Figure 4, the beam axis of the receiving beam RB1 in the current ping is shown by a solid line, and the beam axis of the receiving beam RB1 in the past few pings is shown by short dashed lines. The beam axis of the receiving beam RB1 in the next ping is shown by a long dashed line.

[0069] The underwater search area is divided in the depth direction, and multiple layers are set. Here, three layers L1 to L3 are set. The search area is divided into four in the depth direction. Layer L1 is formed by merging the two upper divisions, Layer L2 is formed by merging the two middle divisions, and Layer L3 is formed by merging the two lower divisions. In other words, the range of each layer partially overlaps with the range of the adjacent layer in the depth direction. Here, adjacent layers overlap by half each.

[0070] A school of fish, F1, is located near the center of the search area in the depth direction. Additionally, three floating objects, N1-N3, are present within the search area. For convenience, the school of fish F1 and floating objects N1-N3 are indicated by hatching to show their echo intensity. Higher hatching density indicates higher echo intensity.

[0071] P1 to P4 are points within the above cross-section where L(latitude) / L(longitude) coordinates are located, and in the depth direction, a portion of the fish school F1 and floating objects N1 to N3 are present. A portion of the fish school F1 is located vertically below point P1, and floating objects N1 to N3 are located at points P2 to P4, respectively.

[0072] For point P1, the echo intensity of fish school F1 (indicated by circles on the dashed line extending from point P1) is obtained by the receiving beam RB1 of the current and past several pings. For points P2 to P4, the echo intensity of floating objects N1 to N3 (indicated by circles on the dashed lines extending from points P2 to P4, respectively) is obtained only by the receiving beam RB1 of the current ping. Pings with echo intensities near zero are not shown on each of these dashed lines, but echo intensities near zero do exist on these dashed lines.

[0073] The lower part of Figure 4 schematically shows echo images of the points (cross-sections) included in the above cross-section when the echo intensity of these points was obtained using different methods. In these echo images as well, the echo intensity is indicated by hatching. The higher the density of the hatching, the higher the echo intensity.

[0074] In the top method (peak hold), the maximum echo intensity from a series of echo intensities acquired at each location is retained as a representative value for the echo intensity at that location. The echo image at each location reflects this retained maximum echo intensity. This method allows for a clear display of the echo image of fish school F1. However, on the other hand, because the echo intensity of floating objects is retained as the maximum echo intensity, the echo image of floating objects remains clearly visible in the echo image.

[0075] In the second method from the top (averaging), the average of a series of echo intensities acquired at each location is calculated as a representative value of the echo intensity at each location. The calculated average value is reflected in the echo image at each location. In this method, the echo intensity of floating objects is weakened by the averaging process, so that the echo intensity of floating objects does not substantially affect the echo image. However, on the other hand, the echo intensity of fish school F1 is also weakened by averaging, so the echo image of fish school F1 becomes unclear.

[0076] In the third method from the top (average peak L1 / L3), a series of echo intensities acquired at each location are averaged for each layer L1 and L3, and the maximum average value is set as the representative value of the echo intensity at the corresponding location. The echo image at each location reflects the set maximum average value. In this method, the averaging process weakens the echo intensity of floating objects, making it less likely for floating object echo intensity to affect the echo image. Also, because a maximum echo intensity is set for each location, the echo image of fish school F1 is clearer compared to the average method in the second stage from the top. In this method, the echo image of fish school F1 can be made even clearer by increasing the number of layers by increasing the number of divisions in the search range in the depth direction.

[0077] In the fourth method from the top (Average Peak L1-L3), a series of echo intensities acquired at each location are averaged for each layer L1, L2, and L3, and the highest average value is set as the representative value of the echo intensity at the corresponding location. This differs from the Average Peak L1 / L3 method (third from the top) in that an additional layer L2 is set, which overlaps with adjacent layers. The echo image at each location reflects the set highest average value.

[0078] This method also weakens the echo intensity of floating objects through averaging, making them less influential on the echo image. Furthermore, because a maximum echo intensity is set for each location, the echo image of fish school F1 is clearer compared to the average method (second from the top). Additionally, the addition of layer L2 makes it more likely that fish school F1 will be predominantly included in one of the layers. Therefore, this method produces a clearer echo image of fish school F1 compared to the average peak L1 / L3 method (third from the top). In this method as well, increasing the number of layers by increasing the number of divisions in the search range in the depth direction can further enhance the clarity of the echo image of fish school F1.

[0079] As described above, by using the average peak L1 / L3 method and the average peak L1-L3 method, it is possible to suppress noise images caused by floating objects and other factors while clearly displaying echo images of fish schools.

[0080] However, with these methods, as shown in Figure 5, once the fish school F1 moves away from directly below point P1, a near-zero echo intensity continues to be applied to the average value at point P1. In the example in Figure 5, the echo intensity of fish school F1 is only obtained for the current ping and the ping immediately preceding it. Therefore, the maximum average value at point P1 is small, and the averaging process for subsequent pings gradually reduces the maximum average value. As a result, as shown in the echo image in the lower panel, the echo image of fish school F1 becomes blurry and then gradually fades over time (as the ping progresses).

[0081] Therefore, in this embodiment, control is implemented that allows for a clearer display of the image of the school of fish even when the school of fish is moving. This control will be described below.

[0082] Figure 6 is a flowchart showing the process of generating and displaying echo images according to an embodiment.

[0083] In this flowchart, steps S101, S106, and S107 are performed by the function of the average value calculation unit 11d in Figure 3, and steps S102 to S104 are performed by the function of the received signal generation unit 11a in Figure 3. Step S105 is performed by the function of the echo intensity acquisition unit 11b in Figure 3. Steps S108 and S109 are performed by the function of the image generation unit 11g in Figure 3. Labeling in step S106 is performed by the function of the fish school echo estimation unit 11c in Figure 3, as shown in Figure 7. In the following explanation, the control unit 11 will execute the corresponding steps using these functions.

[0084] When the display operation of the echo image begins, the control unit 11 initializes the formula for calculating the average value in step S107 (S101). The average value is calculated by the following formula. Here, the average value is obtained by weighted averaging.

[0085]

number

[0086]

number

[0087]

number

[0088] LevelSum is the sum of the echo intensities obtained for each location, corresponding to layers L1, L2, and L3 as shown in Figure 5. Li is the echo intensity obtained for that location during this ping, and Wi is the weight assigned to the echo intensity at that location during this ping.

[0089] The weight is set to either a value when the echo intensity at that location corresponds to a school of fish (e.g., 0.9) or a value when the echo intensity at that location does not correspond to a school of fish (e.g., 0.1). The weight does not have to be one of these two values; it may be varied according to the echo intensity, or determined by a combination of these. Weight is the sum of the weighted average weights obtained for each layer L1, L2, and L3. Average is the weighted average value obtained for each layer L1, L2, and L3.

[0090] In equation (1), the echo intensity Li obtained from the current ping is multiplied by its weight Wi, and this value is added to the LevelSum calculated up to the previous ping to update the LevelSum. In equation (2), the echo intensity Li obtained from the current ping is multiplied by its weight Wi, and this value is added to the Weight calculated up to the previous ping to update the Weight. In equation (3), the LevelSum calculated in equation (1) is multiplied by the Weight calculated in equation (2) to calculate the Average for the current ping.

[0091] In step S101 of Figure 6, the control unit 11 resets the values ​​of each parameter in equations (1) to (3) above to zero for all layers L1, L2, and L3 of all points (L / L coordinate points) included in the search range in a plan view. After that, when the control unit 11 obtains the echo intensity for one ping (S102: YES), it determines whether or not the level conversion process has been set (S103).

[0092] Level conversion processing is a process that reduces the level of echo signals from the seabed based on seabed detection in order to prevent superimposition of seabed echoes. Instead of level conversion processing, filtering processing to remove noise may be performed. Both level conversion processing and filtering processing may be performed. These processing settings are made by the user via the input unit 19. If level conversion processing or the like is set (step S103: YES), the control unit 11 performs the level conversion processing described above in step S104. If level conversion processing or the like is not set (S103: NO), the control unit 11 skips the processing in step S104.

[0093] Next, the control unit 11 converts each position on the conical scanning surface SP1 to a coordinate position in the L (latitude) / L (longitude) / D (depth) coordinate system (3D coordinate system) (S105). The control unit 11 sets a weighted Wi based on the fish school presence / absence labeling for each converted coordinate position (S106). Using the set weighted Wi and the echo intensity Li of each coordinate position, the control unit 11 calculates the average value Average (weighted average) for each layer L1, L2, and L3 of each point (L / L coordinate point) from the above equations (1) to (3) (S107).

[0094] The control unit 11 compares the average values ​​of layers L1, L2, and L3 for each point, obtains the largest average value (representative value), and stores it in the storage unit 12 (S108). Based on the largest average value stored for each point, the control unit 11 performs the echo image display process (S109). If the display operation is not yet complete (S110: NO), the control unit 11 returns to step S102 and performs the same process. The control unit 11 repeatedly executes the processes from steps S102 to S109 until the display operation is complete (S110: NO). As a result, the echo image is updated with each ping. After the display operation is complete (S110: YES), the control unit 11 terminates the process shown in Figure 6.

[0095] Figure 7 is a flowchart showing the process of labeling each point (coordinate position) in the L / L / D coordinate system to indicate whether or not it corresponds to a school of fish.

[0096] As described above, the labeling process in Figure 7 is performed by the control unit 11 using the function of the fish school echo estimation unit 11c in Figure 3. The control unit 11 initializes the labeling process by resetting the echo intensity at each coordinate position in the L / L / D coordinate system to 0 (S201). When the echo intensity for one ping is obtained (S202: YES), the control unit 11 executes the level conversion process (S204) or skips it, depending on whether the level conversion process is set (S203). Subsequently, the control unit 11 performs a threshold-based binarization process on the echo intensity at each position on the scanning plane SP1 (S205). As a result, the echo intensity of strong echoes generated from fish schools and floating objects is set to 1, and the echo intensity of other weak echoes is set to 0.

[0097] Subsequently, the control unit 11 performs a contraction / expansion process on the echo intensity of each position after binarization (S206). This process changes any randomly occurring 0 values ​​within a group of 1 values ​​to 1 values, and any randomly occurring 1 values ​​within a group of 0 values ​​to 0 values. As a result, the echo intensity of each position corresponding to a school of fish becomes 1, and the echo intensity of the positions corresponding to floating objects is replaced with a 0 value.

[0098] The control unit 11 labels positions on the scanning plane SP1 with a value of 1 as fish school positions and positions with a value of 0 as non-fish school positions (S207). Then, the control unit 11 converts these labeled positions into coordinate positions in the L / L / D coordinate system (S208). This adds a label to these coordinate positions indicating whether or not they correspond to a fish school. In step S106 of Figure 6, a weight is set for each coordinate position based on this labeling. For example, a weight of 0.9 is set for coordinate positions corresponding to a fish school, and a weight of 0.1 is set for coordinate positions that do not correspond to a fish school. The control unit 11 performs the process shown in Figure 7 for each ping to label each coordinate position in the L / L / D coordinate system.

[0099] Figure 8(a) shows an example of an echo image displayed by the processing shown in Figure 6. Figure 8(b) shows an echo image generated using the same echo data as in Figure 8(a) but using the average peak L1-L3 method (unweighted) shown in Figure 4.

[0100] In Figure 8(a), as in Figure 5, multiple layers are set up so that adjacent layers partially overlap. The layer setup method in Figure 8(b) is the same as in Figure 8(a). For convenience, the echo images in Figures 8(a) and (b) are shown in grayscale, with higher echo intensity indicated by the color being closer to black.

[0101] As can be seen by comparing Figures 8(a) and (b), the processing in Figure 6 allows for the display of clear and time-lapse-free echo images of fish schools F11, F12, and F13 by changing the weighting depending on whether the location corresponds to a school of fish or not. Therefore, users can more clearly grasp the location and size of the school of fish from the echo images.

[0102] Figure 9 shows the configuration of the information stored in the storage unit 12 in step S108 of Figure 6.

[0103] The control unit 11 associates a representative value of echo intensity with each point included in the scanning plane SP1 in a plan view and stores it in the storage unit 12. The points are the coordinate positions of each point in the L / L / D coordinate system. Here, the maximum weighted average value obtained for each point in step S108 of Figure 6 is associated with each point as the representative value. When the representative value is updated in step S108 for each ping, the representative value of each point stored in the storage unit 12 is also updated. When a point moves out of the scanning plane SP1 in a plan view, the representative value stored in the storage unit 12 for that point is not updated thereafter and is fixed at the value at the time of the last update.

[0104] When a new point overlaps the scanning plane SP1 in a plan view, the control unit 11 registers that point in the table shown in Figure 9 in chronological order. The control unit 11 then updates the representative value of each registered point with each ping as described above, and when a registered point no longer overlaps the scanning plane SP1, it fixes the representative value of that point to the value at the time of the last update.

[0105] Furthermore, each location is associated with a time range. As described above, the time ranges are divided according to the time division setting unit 11e in Figure 3 receiving a time division operation from the user via the input unit 19. In the example in Figure 9, the user has performed two division operations. Here, time range T1 is associated with locations registered before the first division operation, and time range T2 is associated with locations registered between the first and second division operations. Time range T3 is then sequentially associated with locations registered after the second division operation. The association of time range T3 continues until a new division operation is performed.

[0106] Figure 10 is a flowchart showing the echo image display process performed in step S109 of Figure 6.

[0107] As described above, the display processing in Figure 10 is performed by the control unit 11 using the function of the image generation unit 11g in Figure 3. The determination in step S302 is made based on whether or not the time range reception unit 11f in Figure 3 has received the specification.

[0108] The control unit 11 determines whether or not it has received a time range specification from the user via the input unit 19 (S301). If the user has not yet specified a time range (S301: NO), the control unit 11 generates an echo image at each location based on representative values ​​for each location corresponding to all time ranges, and displays the generated echo image on the display unit 17 (S302). Therefore, after starting the display operation of the echo image, the control unit 11 generates and displays an echo image at each location based on representative values ​​for each location corresponding to all time ranges until it receives a time range specification from the user. With this, the control unit 11 terminates the process shown in Figure 10.

[0109] On the other hand, if the user has specified a time range (S301: YES), the control unit 11 generates echo images at each location based on representative values ​​for each location corresponding to the specified time range, and displays the generated echo images on the display unit 17 (S302). With this, the control unit 11 terminates the process shown in Figure 10.

[0110] Thus, the control unit 11 executes the display process in step S109 of Figure 6. Therefore, the echo images displayed in steps S302 and S303 of Figure 10 are updated each time the echo intensity is acquired in step S102 of Figure 6, i.e., with each ping.

[0111] Figures 11 to 13 show examples of echo image displays resulting from the processing shown in Figure 10.

[0112] Here, the user performs the aforementioned delimiter operation when initiating a steering maneuver to return the ship to its previous course position. This sets up two time ranges, one before and one after this delimiter operation.

[0113] Figure 11 shows an example of the echo image displayed on the display unit 17 before this delimiter operation is performed, i.e., the echo image displayed by step S303 in Figure 10. For convenience, the display of the ship's position is omitted in the display examples in Figures 11-13.

[0114] As shown in Figure 11, the echo image is displayed in area A1 of the display screen. Here, area A1 includes the echo image of the outward journey before the ship turned back and the echo image of the return journey after turning back. Area A1 also contains the echo images F21 of the fish schools. Some of these echo images F21 of the fish schools overlap with each other. Therefore, it is difficult for the user to clearly grasp the extent of each fish school from these echo images F21 of the fish schools.

[0115] The bottom of the display screen includes six buttons B1 for specifying a time range and a button B2 for adding a time interval. Buttons B1 are included in the display screen by the function of the time range receiving unit 11f, and buttons B2 are included in the display screen by the function of the time interval setting unit 11e. In the example in Figure 11, the number of time ranges that can be specified is limited to six. That is, the user can specify six time ranges starting from the most recent time range.

[0116] In the example in Figure 11, the time division operation is performed only once, and only two time ranges are set. Therefore, only the leftmost and second-to-left button B1 are enabled, and the remaining four buttons B1 do not display the time range numbers, thus disabling these four buttons B1.

[0117] The button B1 for the most recent time range is displayed on the far right, and the buttons B1 for each time range are arranged to the left in order from most recent to oldest. The number displayed on each button B1 decreases by one as you move from most recent to oldest. Here, echo images are displayed for all time ranges, so the two enabled buttons B1 are colored to indicate that the corresponding time range is selected. For convenience, this coloring is shown with hatching in Figure 11.

[0118] When setting a time interval, the user operates button B2 via input unit 19. As a result, the new time range is associated with the locations subsequently registered in the table in Figure 9. Additionally, the new time range is assigned to button B1, the third button from the left in Figure 11, and this button B1 is activated. In this case, the echo image for the new time range is also displayed in region A1, and the newly added button B1 is colored to indicate that it is selected.

[0119] The user can deselect the time range corresponding to button B1 by interacting with the currently selected button B1. Furthermore, the user can re-select the time range corresponding to button B1 by interacting with the deselected button B1 again. In other words, each button B1 cyclically switches between selected and deselected states with each interaction.

[0120] For example, if the user operates the second button from the left in Figure 11, button B1, via the input unit 19, the time range specified for this button B1 is deselected. In this case, the determination in step S301 in Figure 10 becomes YES, and in step S302, only the echo image for the time range corresponding to the leftmost button B1 is displayed in region A1.

[0121] Figure 12 shows an example of the echo image displayed on the display unit 17 when only button B1 on the far left of Figure 11 is selected, i.e., the echo image displayed by step S302 in Figure 10.

[0122] As described above, button B1 on the far left is assigned to the time range immediately preceding the most recent. Therefore, in this case, the echo image for the time range before the user set the time interval is displayed in area A1. As described above, if the user performs a time interval operation when returning their ship to the position of a past route, only the echo image based on the echo intensity acquired during the outward journey is displayed in area A1. Therefore, compared to the display example in Figure 11, the echo image for the return journey is excluded. As a result, the echo image F21 of the fish school on the return journey does not overlap with the echo image F21 of the fish school on the outward journey. This allows the user to understand the echo image F21 of the fish school on the outward journey more clearly.

[0123] Figure 13 shows an example of the echo image displayed on the display unit 17 when only the second button from the left in Figure 11, B1, is selected, i.e., the echo image displayed by step S302 in Figure 10.

[0124] As described above, the second button from the left, B1, is assigned the latest time range. Therefore, in this case, the echo image for the time range set by the user is displayed in area A1. Consequently, when the user performs the time division operation as described above, only the echo image based on the echo intensity acquired on the return trip is displayed in area A1, and the echo image from the outward trip is excluded compared to the display example in Figure 11. This eliminates the overlap between the echo image F21 of the fish school on the outward trip and the echo image F21 of the fish school on the return trip. As a result, the user can more clearly perceive the echo image F21 of the fish school on the return trip.

[0125] As described above, in the state shown in Figure 13, the user can simultaneously display both the outbound and return echo images shown in Figure 11 by operating the leftmost button B1. Similarly, in the state shown in Figure 12, the user can simultaneously display both the outbound and return echo images shown in Figure 11 by operating the second button from the left, B1. In this way, by operating button B1, the user can switch the display of the echo images to the states shown in Figures 11 and 12, and compare the outbound, return, and both echo images. This allows the user to understand the situation of the fish school over time and to proceed with fishing smoothly.

[0126] In this case, since the time division operation was performed only once, the user was able to switch between displaying the echo images of the outward and return journeys before and after this operation. However, in cases where the user travels back and forth multiple times within a predetermined area of ​​the ocean to search for schools of fish, the time division operation may be performed multiple times within that predetermined area of ​​the ocean. In this case, the user can specify any of the multiple time ranges set in each division operation, and display the echo images of each time range individually or in combination as appropriate.

[0127] <Effects of the Embodiment> According to the above embodiment, the following effects may be achieved.

[0128] As shown in Figures 3 and 9, the underwater detection device 10 (display device) includes an echo intensity acquisition unit 11b that acquires the echo intensity of each point on the latitude and longitude plane over time, a time division setting unit 11e that sets time divisions, a storage unit 12 that stores representative values ​​(values ​​based on echo intensity) of each point acquired over time, associating each point with a time division, a time range reception unit 11f that receives a specification of a desired time range from the user from among the time ranges divided by the time divisions, and an image generation unit 11g that generates an echo image at a point based on the representative values ​​of each point corresponding to the specified time range.

[0129] With this configuration, as shown in Figures 12 and 13, echo images for the time range specified by the user are displayed, so that echo images from other time ranges do not overlap with the displayed echo images. Therefore, by specifying the time range before and after the ship turns back, the user can clearly understand each echo image.

[0130] As shown in Figure 9, the time interval setting unit 11e sets time intervals based on user input.

[0131] With this configuration, users can arbitrarily set time divisions. For example, when a user is using echo images to return their ship to the location of a school of fish, they can set time divisions to separate the echo intensity acquired before steering the ship back from the echo intensity acquired after steering the ship back. This allows the echo images before and after the return to be displayed separately.

[0132] As shown in Figures 11-13, the time range reception unit 11f includes a button B1 on the echo image display screen to receive a time range selection from the user.

[0133] With this configuration, the user can switch the displayed time range and change the displayed echo image at any time by operating button B1 while referring to the echo image. Therefore, user convenience can be improved.

[0134] As shown in Figures 11-13, the time range receiving unit 11f is configured to allow simultaneous selection of multiple buttons B1, and the image generation unit 11g generates an echo image at each location based on the representative values ​​of each location corresponding to the time range of the simultaneously selected buttons B1 when multiple buttons B1 are selected simultaneously.

[0135] With this configuration, the user can simultaneously display echo images for multiple time ranges, not just individual time ranges, as shown in Figure 11. For example, if the echo images before and after turning the ship back do not overlap significantly, the user can select this display mode to understand the movement of fish schools during the period before and after the return trip.

[0136] As shown in Figure 10, the image generation unit 11g generates echo images at each location based on representative values ​​for each location corresponding to all time ranges until the time range reception unit 11f accepts the time range specification (S301: NO), and in response to the time range reception unit 11f accepting the time range specification (S301: YES), it generates echo images at each location based on representative values ​​for each location corresponding to the specified time range (S303).

[0137] With this configuration, the user can refer to normal echo images for all time ranges and, by specifying a desired time range as needed, switch to echo images for a specified time range.

[0138] As shown in Figure 3, the underwater detection device 10 (display device) includes a fish school echo estimation unit 11c that estimates the echo intensity of a fish school based on the echo intensity, and an average value calculation unit 11d that calculates the average value for each location by weighting the echo intensity of the fish school to be greater than the weighting of other echo intensities and applying the respective weights to the echo intensities. The image generation unit 11g generates an echo image at each location based on the average value at each location. The underwater detection device 10 displays the echo image at each location while updating it as the vessel moves.

[0139] More specifically, the echo intensity acquisition unit 11b acquires echo intensity over time for each of the multiple layers (L1 to L3 in Figure 4) obtained by dividing a predetermined range in the water in the depth direction, the average value calculation unit 11 calculates the average value for each point in each layer, and the image generation unit 11g generates an echo image at that point based on the maximum value of the average values ​​for each point.

[0140] With this configuration, as described above, the average value at the location does not decrease easily even after the school of fish has passed, and the echo image of the school of fish does not fade easily. Therefore, even when the school of fish is moving, the echo image of the school of fish can be displayed clearly.

[0141] <Example of change 1> In the above embodiment, time intervals were set by user operation, but in Modification Example 1, time intervals are automatically set by the underwater detection device 10 (display device). That is, the time interval setting unit 11e in Figure 3 acquires information on the ship's movement from the navigation device 100 over time, estimates whether the ship will return to its past course position based on the acquired information, and sets time intervals according to the estimation that it will return.

[0142] Figure 14 is a flowchart showing the time interval setting process related to Change Example 1.

[0143] The process shown in Figure 14 is performed by the control unit 11 through the function of the time interval setting unit 11e. The control unit 11 acquires information regarding the ship's movement from the navigation device 100 (S401). As described above, this information includes the position, heading, and speed of the ship S1. Based on this information, the control unit 11 determines whether the predetermined return conditions have been met (S402).

[0144] The conditions for turning back may be, for example, that the current speed of the vessel is more than a predetermined value lower than the speed of the vessel a few seconds ago, and the current heading of the vessel has changed more than a predetermined value compared to the heading of the vessel a few seconds ago. Alternatively, the conditions for turning back may be that the current heading of the vessel has changed by more than 90° compared to the heading of the vessel several tens of seconds ago. The conditions for turning back should be such that, based on information about the vessel's movement, it can be estimated that the vessel is returning to the position of its past course.

[0145] If the return condition is not met (S401: NO), the control unit 11 returns to step S401 and executes the same process. As long as the return condition is not met (S402: NO), the control unit 11 repeatedly executes the processes in steps S401 and S402 at regular intervals. After that, when the return condition is met (S402: YES), the control unit 11 sets a time interval (S403). As a result, a new time range is associated with the locations that are subsequently registered in the table in Figure 9. Then, if the display operation of the echo image has not finished (S404: NO), the control unit 11 returns to step S401 and executes the same process.

[0146] The control unit 11 repeatedly executes the processes in steps S401 to S403 until the display operation of the echo image is completed (S404: NO). During this time, each time the return condition is met, a time interval is set and a new time range is set. After that, when the display operation of the echo image is completed (S404: YES), the control unit 11 terminates the process shown in Figure 14.

[0147] <Effect of Change Example 1> As shown in Figure 14, the time division setting unit 11e acquires information regarding the movement of the vessel equipped with the underwater detection device 10 from the navigation device 100 over time (S401), estimates whether the vessel will return to its previous course position based on the acquired information (S402), and sets a time division according to the estimation that it will return (S402: YES).

[0148] With this configuration, the time range before and after the point in time when the ship turns back is automatically set. Therefore, user convenience can be improved.

[0149] Furthermore, in the configuration of Modification Example 1, it may also be possible to set time intervals by user operation, similar to the embodiment described above. In this case, the user may be able to accept an operation to stop / restart the automatic setting mode related to Modification Example 1 via the input unit 19.

[0150] <Example of change 2> In modification example 2, the ship's underwater detection device 10 receives echo intensity data acquired by another ship. The underwater detection device 10 is configured to display echo images based on the echo intensity data received from the other ship.

[0151] Figure 15 is a block diagram showing the configuration of the underwater detection device 10 according to modification example 2.

[0152] Compared to the configuration in Figure 3, in Modification Example 2, a wireless communication unit 21 is added. The wireless communication unit 21, under control from the control unit 11, communicates wirelessly with the underwater detection device of another vessel and sequentially receives echo intensity data acquired by the underwater detection device of the other vessel. However, the wireless communication unit 21 is not limited to this and may also sequentially receive echo intensity data from the underwater detection device of another vessel via a relay device on land.

[0153] The underwater detection device of the other vessel has at least the function of acquiring echo intensity in the same manner as the underwater detection device 10 of the own vessel, and the function of communicating wirelessly with the underwater detection device 10 of the own vessel. When communication with the underwater detection device 10 of the own vessel is initiated, the underwater detection device of the other vessel sequentially transmits the echo intensity acquired at each location, along with information about each location, to the underwater detection device 10 of the own vessel.

[0154] The control unit 11 of the underwater detection device 10 performs the same processing as in Figures 6 and 7 (step S109 in Figure 6 is skipped) on the received echo intensity to construct table information similar to that in Figure 9 for each other vessel, and stores the constructed table information in the storage unit 12. At this time, each point and representative value is associated with a time range corresponding to the time division set in the underwater detection device 10 of the own vessel. In this way, table information similar to that in Figure 9 is stored in the storage unit 12 for each other vessel with which communication has taken place.

[0155] Figure 16 shows the configuration of the echo image display screen related to modification example 2.

[0156] In modification example 2, a button B3 is added to select whether to display the echo image of the own ship or another ship in area A1. In Figure 16, the echo image of the own ship is selected as the display target. The user can display the echo image of another ship in area A1 by operating one of the other two buttons B3. Here, the echo images of other ships that can be displayed are limited to two: "Other Ship 1" and "Other Ship 2". Therefore, the number of underwater detection devices of other ships that are targeted for echo intensity reception is also limited to two. In addition, with the addition of button B3, the number of buttons B1 is reduced by one from Embodiment 1 to five.

[0157] The buttons B1 and B3, which are the target of the display, may be configured to be scrollable left and right. This increases the number of selectable time ranges and the number of other ships that can be selected. In this case, the number of underwater detection devices of other ships that are the target of echo intensity reception can be increased to three or more.

[0158] Even if the user selects to display echo images of other ships by operating button B3, they can, as in the above embodiment, restrict the echo images displayed in area A1 to echo images within a desired time range by operating button B1.

[0159] In other words, when the button B3 for displaying the echo image of another ship is operated, the control unit 11 uses the table information of the other ship corresponding to the operated button B3 to execute the process shown in Figure 10 for each ping. As a result, the echo image of the other ship corresponding to the button B1 selected by the user is displayed in area A1.

[0160] <Effect of Change Example 2> As shown in Figure 15, the underwater detection device 10 further includes a wireless communication unit 21 capable of acquiring echo intensity at various points on the latitude-longitude plane from the underwater detection devices of other vessels over time. The storage unit 12 stores representative values ​​based on the echo intensity at various points acquired over time from other vessels, associated with time divisions for each point, in a configuration similar to the table information in Figure 9, for each other vessel. As explained with reference to Figure 16, the image generation unit 11g, upon receiving a user instruction to display echo images of other vessels through operation of button B3, generates echo images at those points based on representative values ​​for each point on other vessels corresponding to the time range specified via the time range reception unit 11f.

[0161] This configuration allows users to display echo images based on echo intensity acquired not only from their own vessel but also from other vessels as needed. This allows, for example, to identify schools of fish that cannot be identified from the echo images of their own vessel by using the echo images of other vessels.

[0162] In the above modification example 2, the time division of the echo intensity at each point received from the underwater detection device of another vessel was performed by the time division setting unit 11e of the underwater detection device 10 of the own vessel. However, if the underwater detection device of another vessel has a time division function, the time division of the echo intensity acquired by the underwater detection device of another vessel may be performed by the underwater detection device of the other vessel. In this case, the underwater detection device of the other vessel sequentially transmits the echo intensity acquired for each point, along with information indicating the time range, to the underwater detection device 10 of the own vessel. The control unit 11 of the underwater detection device 10 of the own vessel can then use this received information to construct table information similar to that in Figure 9 for each other vessel and store it in the storage unit 12.

[0163] However, in this case, the timing and number of time divisions differ between the table information in Figure 9 based on the echo intensity acquired by the ship's own underwater detection device 10 and the table information in Figure 9 based on the echo intensity acquired from the other ship's underwater detection device. As a result, the length and number of time ranges associated with each location may differ. Therefore, if the user selects the echo image based on the echo intensity from the other ship's underwater detection device as the display target on the screen in Figure 16, the number of activated buttons B1 may differ from when the ship's own ship is selected, and the time ranges assigned to each activated button B1 may also differ from when the ship's own ship is selected.

[0164] However, even in this case, the user can individually display the echo images based on the echo intensity acquired by the other vessel's underwater detection device, according to time ranges set by the user of the other vessel. Therefore, even in this case, the user can clearly identify the echoes of fish schools in the echo images of the other vessel.

[0165] <Other examples of changes> In the above embodiment, the underwater detection device 10 constitutes a display device, and the echo image is displayed on the display unit 17 of the underwater detection device 10. However, the embodiment is not limited to this, and a separate display device may be arranged in addition to the underwater detection device 10, and the echo data acquired by the underwater detection device 10 may be provided to the display device, and the above-described processing may be performed in the display device.

[0166] For example, as shown in Figure 17, a personal computer may be used as the echo image display device 30, and echo data may be transmitted from the underwater detection device 10 to the display device 30 via an external communication network 40 such as the Internet. In this case, the display device 30 performs the same processing on the received echo data as in Figures 6, 7, and 10 to display the echo image on the display unit 31. The underwater detection device 10 is further equipped with a wireless communication unit (wireless communication module) for connecting to the external communication network 40.

[0167] The control unit (CPU) of the display device 30 performs the same functions as the received signal generation unit 11a, the echo intensity acquisition unit 11b, the fish school echo estimation unit 11c, the average value calculation unit 11d, the time interval setting unit 11e, the time range reception unit 11f, and the image generation unit 11g, according to the program stored in the memory unit. Step S102 in Figure 6 is replaced by a determination of whether or not an echo intensity of 1 ping has been received from the underwater detection device 10.

[0168] The display device 30 (personal computer) may be installed in the ship S1 (wheelhouse). In this case, the display device 30 only needs to be connected to the underwater detection device 10 by a communication line. Alternatively, instead of sending and receiving echo data online, the data collected by the underwater detection device 10 may be recorded on a recording medium such as a USB memory, and this recording medium may be attached to the display device 30 (personal computer) to transfer the echo data to the display device 30. In this case, the display device 30 should sequentially perform the processing shown in Figures 6, 7, and 10 for each echo data ping to display the echo image on the display unit 31.

[0169] Furthermore, in the above embodiment, in steps S107 and S108 of Figure 6, the weighted average value of each layer is calculated for each location by adding weighting based on the fish school to the average peak L1-L3 method of Figure 4, and the maximum value is obtained as the representative value of the echo intensity at each location. However, the method for obtaining the representative value of the echo intensity at each location is not limited to this. For example, the representative value of the echo intensity at each location may be obtained using the same method as the average peak L1-L3 method of Figure 4 without adding weighting based on the fish school, or the representative value of the echo intensity at each location may be obtained using the same method as the average peak L1-L3 method of Figure 4. In this case as well, the number of layers set in the search range is not limited to the number shown in Figure 4, and a larger number of layers may be set in the search range. Also, the representative value of the echo intensity at each location may be obtained using the same method as the peak hold method of Figure 4.

[0170] Furthermore, in the above embodiment, a representative value of echo intensity is associated with each location in the table information of Figure 9, but the "value based on echo intensity" associated with each location is not limited to this. For example, the weighted average value of each layer calculated in step S107 of Figure 6 may be associated with each location. In this case, step S108 is omitted, and in step S109, the maximum weighted average value is obtained for each location and the echo image is displayed. A series of echo intensities obtained for each location may also be associated with each location. The "value based on echo intensity" associated with each location only needs to be information that allows the display of the echo image for each location.

[0171] Furthermore, the configuration of the echo image display screen is not limited to the configurations shown in Figures 11 to 13 and Figure 16, and various modifications are possible. For example, buttons other than buttons B1 to B3, such as a button for deleting the time range, may be included on the display screen.

[0172] Furthermore, in the above embodiment, the receiving signal generation unit 11a shown in Figure 3 was implemented as a function of a program stored in the storage unit 12, but these do not necessarily have to be implemented by a program stored in the storage unit 12. For example, one or more of these functions may be configured by an FPGA (field-programmable gate array) or hardware integrating logic circuits.

[0173] Furthermore, the processing for generating and displaying echo images is not limited to the processing shown in Figure 6, and can be modified as appropriate. For example, the level conversion processing in steps S103 and S104 may be omitted from the processing in Figure 6, or the cropping processing shown in Patent Document 1 may be added to the processing in Figure 5. The method for estimating the echo intensity from the fish school is also not limited to the labeling method described above, and a well-known method for estimating the range of the fish school from echo data may be used.

[0174] Furthermore, although the above embodiment shows an underwater detection device 10 that transmits and receives waves along a conical scanning surface SP1, the present invention may also be applied to an underwater detection device 10 that transmits and receives waves in other ways. For example, the present invention may be applied to an underwater detection device that transmits and receives waves along a semicircular or arc-shaped scanning surface with a predetermined depression angle to generate and display echo images for each point. In addition, a transmitter for transmitting waves and a receiver for receiving waves may be arranged separately.

[0175] 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]

[0176] 10 Underwater detection equipment 11 Control Unit 11b Echo intensity acquisition unit 11e Time interval setting section 11F Time Range Reception Desk 11g image generation section 12 Storage section 13 Transducer 13a Ultrasonic transducer

Claims

1. A display device that displays images of echoes obtained by underwater detection using ultrasonic transmission and reception, An echo intensity acquisition unit that acquires the echo intensity of each point on the latitude and longitude plane over time, A time interval setting unit for setting time intervals, A storage unit that stores values ​​based on the echo intensity of each point acquired over time, associated with the time intervals for each point, A time range receiving unit that receives a user's specification of a desired time range from among the time ranges divided by the aforementioned time divisions, The system includes an image generation unit that generates an echo image at each of the points corresponding to the specified time range, based on the values ​​of each point. A display device for echo images characterized by the following:

2. In the display device according to claim 1, The time interval setting unit sets the time intervals based on user input. A display device for echo images characterized by the following:

3. In the display device according to claim 1, The aforementioned delimiter setting unit is, Information regarding the movement of the ship equipped with the display device is acquired over time. Based on the above information, we estimate whether the ship will return to its previous route. Based on the estimation that they will turn back, the aforementioned time interval is set. A display device for echo images characterized by the following:

4. In the display device according to claim 1, The time range receiving unit includes a button on the echo image display screen for receiving a selection of the time range from the user. A display device for echo images characterized by the following:

5. In the display device according to claim 4, The aforementioned time range receiving unit is configured to allow simultaneous selection of multiple buttons, When multiple buttons are selected simultaneously, the image generation unit generates an echo image at each location based on the values ​​of each location corresponding to the time range of the multiple buttons selected simultaneously. A display device for echo images characterized by the following:

6. In the display device according to claim 1, The image generation unit, Until the time range receiving unit accepts the specified time range, it generates an echo image at each location based on the values ​​of each location corresponding to all of the time ranges. In response to the time range receiving unit receiving the specified time range, it generates an echo image at each of the points corresponding to the specified time range based on the values ​​of those points. A display device for echo images characterized by the following:

7. In the display device according to claim 1, It is further equipped with a communication unit capable of acquiring the echo intensity of various points on the latitude-longitude plane from the underwater detection equipment of other vessels over time. The memory unit stores values ​​based on the echo intensity of each location acquired over time from the other vessel, associating each location with the time intervals for each of the other vessels. The image generation unit, upon receiving a user's instruction to display an echo image of the other vessel, generates an echo image at that location based on the values ​​of each point on the other vessel corresponding to the time range specified via the time range reception unit. A display device for echo images characterized by the following:

8. A control method for a device that displays an image of an echo obtained by underwater detection using ultrasonic transmission and reception, The echo intensity of each point on the latitude-longitude plane is acquired over time, Set a time interval, The values ​​based on the echo intensity of each point acquired over time are stored for each point, corresponding to the time intervals. The user specifies a desired time range from among the time ranges defined by the aforementioned time divisions. Based on the values ​​of each point corresponding to the specified time range, an echo image is generated at that point. A method for controlling the display of echo images, characterized by the features described above.

9. The control unit of a device that displays images of echoes obtained by underwater detection using ultrasonic transmission and reception, A function to acquire the echo intensity of each point on the latitude and longitude plane over time, A function to set time intervals, A function to store values ​​based on the echo intensity of each point acquired over time in the storage unit, corresponding to the time intervals for each point, A function that accepts the user's specification of a desired time range from among the time ranges divided by the aforementioned time divisions, A function to generate an echo image at a given location based on the values ​​of each location corresponding to the specified time range, A program that executes the command.

Images