JP2014077701A - Fish finding device, signal processing device, fish finder, fish finding method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately locate a fish shoal.SOLUTION: A fish finding device for finding a fish shoal on the basis of an echo signal of the ultrasonic wave that has been transmitted into the water includes: a binarization part 14; a fish shoal candidate specifying part 15; and a fish shoal range extraction part 16. The binarization part 14 binarizes data generated on the basis of the echo signal with reference to a signal level. The fish shoal candidate specifying part 15 detects continuity of data, of the binarized data, having a higher value in the signal level in a prescribed direction, and specifies a data range in which the continuity is observed. The fish shoal range extraction part 16 extracts a range of a fish shoal on the basis of the specified data range.

Description

  The present invention relates to a technique for transmitting an ultrasonic signal and detecting a school of fish based on the echo signal.

  2. Description of the Related Art Conventionally, an ultrasonic detection device that transmits an ultrasonic signal and detects a target from the echo signal is known. A fish finder is an example of the use of an ultrasonic detector. A fish finder generally detects an fish by transmitting an ultrasonic signal into the sea and receiving an echo signal reflected from a target such as a fish school. For example, an apparatus is known that transmits ultrasonic signals of two different frequencies and detects a school of fish having a specific body length by utilizing the difference in the reflectance of ultrasonic waves of two different frequencies (for example, , See Patent Document 1).

Japanese Patent Publication No. 40-25555

  Currently, annual fish catches are determined for each fish species, each country, and each fishing boat in order to protect global marine resources. For example, in TAC (Total Allowance Catch), the annual catch of each country is determined for each fish species. In IVQ (Individual Vessel Quota), the annual catch is determined for each fish type and each fishing boat. When landing over the set catch, various penalties will be imposed, such as reducing the catch of the next year.

  Therefore, it is anxious for each fishing boat to more reliably discriminate fish species before landing.

  On the other hand, in order to discriminate the fish species, the user designates a range where the school of fish is supposed to exist in advance, and performs fish species discrimination for the range. However, there is a problem in that the accuracy of the result of discriminating the fish species decreases because the presence and size of the school of fish varies depending on the size of the range specified by the user.

  An object of the present invention is to accurately extract a school of fish.

  According to one aspect of the present invention, a fish detection device that detects a school of fish based on an ultrasonic echo signal transmitted toward the water, a binarization unit, a fish candidate identification unit, and a fish range extraction unit And comprising. The binarization unit binarizes the data generated based on the echo signal based on the signal level. The fish school candidate specifying unit detects continuity in a predetermined direction of data having a higher signal level among the binarized data, and specifies a data range having the same continuity. The fish school range extraction unit extracts a fish school range based on the specified data range.

  According to the present invention, a school of fish can be extracted with high accuracy.

Schematic configuration diagram of a fish finder according to an embodiment Schematic block diagram of the signal processing device of the fish finder Diagram for explaining labeling by the fish finder Diagram for explaining labeling by the fish finder Flow chart showing processing by the fish finder of the fish finder Flow chart showing an example of labeling processing Flow chart showing an example of labeling processing Flow chart showing an example of fish school range extraction processing The figure which shows the result of processing by the fish finder of the same fish finder The flowchart which shows the example of the process by the fish detection part of the fish finder which concerns on other embodiment.

<1 First Embodiment>
Hereinafter, a fish finder according to an embodiment of the present invention will be described with reference to the drawings.

<1-1 Fish Finder 1>
FIG. 1 is a block diagram showing the configuration of the fish finder 1 according to the embodiment. The fish finder 1 includes a transducer 2, a transmission / reception unit 3 (an example of a transmission / reception device), a signal processing device 10, a display unit 4 (an example of a display device), and an operation unit 5.

  The transmitter / receiver 2 is mounted on the bottom of a ship and is configured by bundling a required number of ultrasonic transducers, which are electromechanical conversion elements, with their transmission surfaces facing one side. The transmitter / receiver 2 transmits ultrasonic waves toward the water based on an ultrasonic signal having a predetermined frequency generated by the transmitter 20 described later. The transmitter / receiver 2 receives a reflected wave generated by reflecting ultrasonic waves having a transmitted frequency on a target such as a school of fish with an ultrasonic transducer. As a result, an echo signal is generated and output to the receiving unit 32 described later.

  The transmission / reception unit 3 transmits and receives signals between the transducer 2 and the signal processing device 10, and includes a transmission / reception switching unit 31, a reception unit 32, and a transmission unit 33.

  The transmission / reception switching unit 31 is a circuit or the like for switching the signal path, and guides the ultrasonic signal from the transmission unit 33 to the transducer 2 while guiding the echo signal from the transducer 2 to the reception unit 32.

  The reception unit 32 samples the echo signal for each PING input from the transmission / reception switching unit 31 at a predetermined sampling timing interval, and generates reception data. This sampling timing interval is set based on the distance resolution in the depth direction, for example. The receiving unit 32 outputs received data for each PING to the signal processing device 10.

  The transmission unit 33 generates an ultrasonic signal having a predetermined frequency and outputs it to the transducer 2.

  The signal processing device 10 converts the received signal into a digital signal and performs predetermined signal processing. The signal processing device 10 is, for example, a device including a processor or a memory, an integrated circuit, or the like, and processes reception data output from an A / D conversion unit described later to generate an image signal. The signal processing device 10 is realized by, for example, a general-purpose DSP or FPGA that executes a program stored in a memory. The signal processing device 10 can also be realized by a digital circuit such as an ASIC (Application Specific Integrated Circuit).

  The display unit 4 has a screen such as an LCD (Liquid Crystal Display). For example, the display device 4 displays an echo image corresponding to the received data with the vertical axis of the screen as the depth direction and the horizontal axis as the time direction (transmission count direction). The display unit 4 also displays data indicating the fish school extraction range by the signal processing device 10 as will be described later. In addition, you may switch and display the echo image display of normal reception data, and the display of the data of a fish school extraction range by operating the operation part 5 by a user.

  The operation unit 5 is a mouse, a touch panel, a keyboard, or the like, and the user inputs information by a predetermined input operation.

<1-2 Signal Processing Device 10>
<1-2-1 Configuration of Signal Processing Device 10>
FIG. 2 schematically shows a functional configuration of the signal processing apparatus 10. The signal processing device 10 includes an A / D conversion unit 11, a reception data storage unit 12, a range selection reception unit 13, a binarization unit 14, a labeling unit 15 (an example of a fish school candidate specifying unit), a fish range An extraction unit 16 and a display control unit 17 are included. The range selection receiving unit 13, the binarizing unit 14, the labeling unit 15, the fish range extracting unit 16, and the display control unit 17 constitute a fish detection unit 9 (an example of a fish detection device).

  The A / D conversion unit 11 converts the received data input from the transmission / reception unit 3 into a digital signal.

  The reception data storage unit 12 sequentially stores the reception data digitized by the A / D conversion unit 11.

  The range selection receiving unit 13 receives a selection of a predetermined range by the user. For example, the user looks at an echo image corresponding to the received data displayed on the display unit 4 and operates the operation unit 5 to set a predetermined range.

  The binarization unit 14 binarizes received data in a predetermined range set by the range selection receiving unit 13. Specifically, in the received data, processing is performed in which sampling points (dots) having a signal level equal to or higher than a predetermined threshold are set to 1 or 0, and other sampling points are set to 0 or 1. The predetermined threshold value may be fixed in advance or may be variable.

  In the labeling unit 15, among the data binarized by the binarizing unit 14, a sampling point having a predetermined threshold value or more is in the depth direction or the PING direction (a direction orthogonal to the depth direction in the displayed reception data). If they are consecutive, labeling is performed by assigning the same label to the consecutive sampling points (sampling point group).

  Note that the PING direction refers to a direction along the time axis when echo signals (received data) received in each sweep are displayed for each time.

  3 and 4 show examples of labeling processing patterns. In the illustrated example, 10 dots are shown as 1 dot for easy viewing.

  FIG. 3A shows a portion in which the data value for each sampling point (dot) is continuously greater than or equal to the threshold value (here, “1” data is continuous) in the set predetermined range of received data. In the illustrated example, from the start depth to the end depth). In this case, the continuous length of “1” is not less than a predetermined depth direction minimum length mindepth (for example, mindepth = 200 dots) and not more than a predetermined depth direction maximum length maxdepth (for example, maxdepth = 1000 dots). In some cases, the same label is allocated (shown in gray in the illustrated example).

  FIG. 3B shows that in the received data in the predetermined range that is set, the data value for each sampling point is continuously “1”, but the continuous portion is less than the minimum depth direction depth mindepth. Show the case. In this case, do not allocate the same label.

  FIG. 3C shows a case where there are a plurality of consecutive data values “1” in the set predetermined range of received data, and less than a predetermined number of “0” is interposed between them (that is, “1”). If the continuity is interrupted within a predetermined minimum length or less), it is considered continuous. In this case, if the number of interrupted sampling points is a predetermined number (for example, 10 dots) or less, it is considered that “1” is continuous, and as a result, the continuous length of “1” is the predetermined minimum depth direction minimum depth mindepth. If it is not less than the predetermined depth direction maximum length maxdepth, the same label is allocated.

  FIG. 4A shows a case where a predetermined number of sampling points “1” continue in the PING direction in the set reception data within a predetermined range. In this case, the continuous length of “1” is equal to or greater than a predetermined PING direction minimum length minping (for example, minping = 20 dots), and a predetermined maximum PING direction length maxping (for example, maxping = PING direction of input data) If it is equal to or less than 80% of the number of sampling points, the same label is allocated (gray portion in the illustrated example).

  FIG. 4B shows that the received data in the predetermined range includes a portion where a predetermined number of “1” sampling points continue in the PING direction, and “1” that is not less than mindepth and not more than maxdepth in the depth direction. An example when there are continuous parts is shown. As shown in the figure, when the respective continuous conditions are satisfied in the depth direction and the PING direction, the same label is attached (gray portion in the illustrated example).

  As described above, if mindepth <length in the depth direction <maxdepth, or if minping <length in the PING direction <maxping, the labeling process is performed.

  By performing the labeling process under the predetermined condition, the data range of the fish school candidate (an example of the fish school candidate depth range) is specified.

  The fish range extraction unit 16 calculates the area of the sampling point group with the same label, and among the ranges selected by the user, the range in which the area is greater than or equal to a predetermined value is determined as the fish range (fish range or fish candidate area). Extract as one example).

  The display control unit 17 performs a process of controlling or visualizing the level of received data in the fish range extracted by the fish range extraction unit 16. That is, the display control unit 17 performs processing such as displaying a sampling point group having the same label and having an area of a predetermined value or more with a predetermined color.

  In addition, although illustration is abbreviate | omitted here, the display control part 17 performs the process which visualizes the received data acquired from the received data storage part 12 as a function of a normal fish finder. That is, the display control unit 17 performs a process for displaying each reception data sequentially recorded on the display unit 4 as an echo image corresponding to the depth according to the elapsed time after outputting the ultrasonic wave.

<1-2-2 Operation of Fish Finder 9>
FIG. 5 is a flowchart of processing by the fish finder 9 according to this embodiment.

  Step S101: It is determined that a range has been selected by the range selection receiving unit 13 through a user operation.

  Step S102: The binarization unit 14 performs binarization processing on the received data in the range selected in Step S101. In the binarization processing, as described above, threshold processing is performed on received data at each sampling point, and binarization is performed based on whether the signal level of the data is equal to or higher than the threshold. By performing such processing, as shown in FIG. 8A, the received data is divided into sampling points that are equal to or higher than the threshold value (white portions in the figure) and other sampling points (black portions in the figure). Sorted. In this embodiment, sampling points equal to or higher than the threshold are set to “1”, and other sampling points are set to “0”.

  Step S103: The data binarized in step S102 is labeled by the labeling unit 15 as described above. By this processing, as shown in FIG. 8B, the same label is assigned to the sampling points having a predetermined number of continuity in the depth direction and the PING direction (gray portion in FIG. 8). A specific example of this labeling process will be described later.

  Step S104: The area of the sampling point group to which the same label is attached is calculated by the fish range extraction unit 16 for the reception data labeled in step S103. A range in which the calculated area is equal to or greater than a predetermined value is extracted as a fish school range. For example, if the area is equal to or greater than mindepth (minimum length in the depth direction) × minping (minimum length in the PING direction), it is extracted as a fish school range, and the others are not extracted. By this processing, as shown in FIG. 8C, the extracted fish school (white portion in the figure) is displayed. As shown in the figure, by the labeling process in step S103 and the fish range extraction process in this step, a so-called fish tailing portion below the school of fish (white spots with low continuity shown below FIG. 8A). Signal parts that are unlikely to be a school of fish are excluded. A specific example of this fish school range extraction process will be described later.

  Step S105: The fish range extracted in step S104 is displayed on the display unit 4 after the display control unit 17 performs processing such as adding a predetermined color.

<< Specific examples of labeling process >>
A specific processing example of the labeling processing in step S103 of FIG. 5 executed mainly by the labeling unit 15 will be described with reference to FIGS. 6A and 6B.

  Step S301: Read a received data string in the depth direction.

  Step S302: It is determined whether or not there is a portion where “1” continues in the data value read in Step S301. If there is a continuous portion, the process proceeds to step S303, and if not, the process proceeds to step S308.

  Step S303: It is determined whether or not the continuity of “1” satisfies a predetermined condition. Here, whether the continuous length of “1” is not less than the minimum depth direction length (for example, mindepth = 200 dots) and not more than a predetermined depth direction maximum length (for example, maxdepth = 1000 dots). judge. If the condition is satisfied, the process proceeds to step S304. If the condition is not satisfied, the process proceeds to step S305.

  Step S304: A predetermined label is attached to the continuous portion of “1” determined in Step S303.

  Step S305: It is determined whether there is any other continuous portion of “1” in the depth direction of the read received data string. If there is a continuous part, the process proceeds to step S306, and if there is no continuous part, the process proceeds to step S308.

  Step S306: When “0” is interposed between the continuous portion of “1” and the previously specified continuous portion of “1”, whether or not the number of the interposed “0” is equal to or less than a predetermined number. Determine. When the intervening “0” is equal to or less than the predetermined number, the process proceeds to step S307. When the intervening “0” exceeds the predetermined number, the process returns to step S303. In addition, when the continuous part of “1” and the previously specified “1” continuous part deviate in the depth direction by a predetermined range or more, there is a possibility that they are another school of fish. The label may be changed to another type.

  Step S307: “0” intervening between the consecutive portions of “1” determined in step S306 is regarded as “1”, and the process returns to step S303 to perform continuity determination processing.

  Step S308: It is determined whether or not the read received data string is the terminal in the PING direction (that is, the last string). If it is not the end in the PING direction, the process proceeds to step S309. If it is the end in the PING direction, the process proceeds to step S310 (FIG. 6B).

  Step S309: Shift in the PING direction to read the next depth direction received data string.

  Step S310: Read the received data string in the PING direction.

  Step S311: It is determined whether or not there is a portion where “1” continues in the data value read in Step S310. If there is a continuous portion, the process proceeds to step S312; otherwise, the process proceeds to step S315.

  Step S312: It is determined whether the continuity of “1” satisfies a predetermined condition. Here, the continuous length of “1” is not less than the minimum length in the PING direction (for example, minping = 20 dots) and the predetermined maximum length in the PING direction (for example, maxping = the number of sampling points in the PING direction of the input data) 80%) or less. If the condition is satisfied, the process proceeds to step S313. If the condition is not satisfied, the process proceeds to step S314.

  Step S313: A predetermined label is attached to the continuous portion of “1” determined in Step S312.

  Step S314: It is determined whether or not there is another continuous portion of “1” in the read received data string PING direction. If there is a continuous part, the process returns to step S312;

  Step S315: It is determined whether or not the read received data string is the end in the depth direction (that is, the last string). If it is not the end in the depth direction, the process proceeds to step S316, and if it is the end in the depth direction, the process ends.

  Step S316: Shift in the depth direction to read the next PING direction reception data string.

<< Specific example of fish range extraction process >>
A specific processing example of the fish range extraction process in step S104 of FIG. 5 executed mainly by the fish range extraction unit 16 will be described with reference to FIG.

  Step S401: The area of the range to which the same label is attached is calculated by the labeling process in step S103.

  Step S402: It is determined whether or not the calculated area is greater than or equal to a predetermined value. The predetermined value is, for example, mindepth (minimum length in the depth direction) × minping (minimum length in the PING direction). If the condition is satisfied, the process proceeds to step S403, and if not, the process proceeds to step S404.

  Step S403: The labeled range is specified as the school of fish range.

  Step S404: If there is another label part, the process returns to step S401, and if not, the process ends.

  In addition, the execution order of the processing method in the said embodiment is not necessarily restrict | limited to description of the said embodiment, The execution order can be changed in the range which does not deviate from the summary of invention.

<1-3 Features of this Embodiment>
According to the fish finder 9 in the fish finder 1 according to the above-described embodiment, it is possible to extract a range where the possibility of the fish school is high from the data range selected by the user, excluding information with a low possibility of the fish school. Therefore, a school of fish can be extracted with high accuracy.

  Also, instead of estimating the fish range based on the data range selected by the user as in the past, it is possible to identify the fish species by extracting the most likely range of the fish school, so that the fish species can be identified. The accuracy can be expected to improve.

<2 Other Embodiments>
<2-1>
In the fish finder 9 in the fish finder 1 according to the above embodiment, for example, when there are a plurality of sampling point groups assigned the same label, the fish range extracting unit 16 selects the sampling point group having the maximum area, May be extracted as a school of fish.

  Alternatively, the fish school range extracting unit 16 may only extract the sampling point group assigned the same label as the fish school without obtaining the area.

  Alternatively, the fish school range extraction unit 16 may replace the area or in addition to the area with the shape of the sampling point group assigned the same label (for example, a predetermined ratio between the length in the depth direction and the length in the transmission direction) and other sizes. You may make it extract a school of fish based on the parameter (depth direction length, transmission direction length, periphery length, etc.) which shows this.

<2-2>
According to the fish finder 9 in the fish finder 1 according to the above embodiment, the labeling unit 15 has sampling points that are equal to or greater than a predetermined threshold in the vertical direction (that is, the depth direction) or the horizontal direction (that is, the PING direction) of the image. When they are continuous, the same label is assigned to the consecutive sampling points. However, the same label may be assigned even when they are continuous in an oblique direction.

<2-3>
According to the fish finder 9 in the fish finder 1 according to the above embodiment, processing is performed on reception data of one frequency, but processing may be performed on reception data of two or more types of frequencies. Good. In this case, for example, the transmission unit 33 is configured to generate an ultrasonic signal having a plurality of frequencies, and generates at least two types of ultrasonic signals having different frequencies. For example, an ultrasonic signal of 60 kHz is generated as the first frequency, and an ultrasonic signal of 200 kHz is generated as the second frequency. The combination of frequencies is not limited to this, and can be set as appropriate depending on the target fish species. The transmitter 33 outputs the first frequency and the second frequency to the transducer 2 at a predetermined timing interval. In the case of a fish finder that can obtain reception data of three or more frequencies, the fish finder 9 may select and process reception data of two or more frequencies. In this case, which frequency is selected may be dynamically set according to the environment.

  In addition, when processing is performed on reception data of two or more types of frequencies, the predetermined threshold regarding the signal level determined by the binarization unit 14 may be set to the same threshold for each frequency, but different values. May be set.

  When extracting the fish range by the fish detection unit 9 using the received data of two frequencies (for example, 60 kHz and 200 kHz), the binarization unit 14 combines the data into one data by the binarization process (see FIG. 5). Step S103). FIG. 9 shows an example.

  Step S2201: Sampling points at the same position in the depth direction and the PING direction are specified in the reception data of each frequency for which a predetermined range is set in step S101 of FIG.

  Step S2202: It is determined whether the signal level at the sampling point in the received data of 60 kHz is equal to or higher than a threshold value. If it is equal to or greater than the threshold value, the process proceeds to step S2203, and if it is less than the threshold value, the process proceeds to step S2205.

  Step S2203: It is determined whether or not the signal level at the sampling point in the received data of 200 kHz is equal to or higher than a threshold value. If it is equal to or greater than the threshold value, the process proceeds to step S2204, and if it is less than the threshold value, the process proceeds to step S2205.

  Step S2204: The data value of the sampling point is set to “1”.

  Step S2205: The data value of the sampling point is set to “0”.

  Step S2206: Steps S2201 to 2205 are repeated at all sampling points to generate one binarized reception data, and the processing of steps S103 to S105 in FIG. 5 is performed on the reception data.

  In the above binarization processing, “1” is set only when the signal levels of both reception data of two frequencies are equal to or higher than the threshold value, but one of the signal levels is equal to or higher than the threshold value. In this case, “1” may be set.

<2-4>
In the above embodiment, the fish detection unit 9 has been described as an apparatus or an integrated circuit, but the present invention can also be realized as a fish detection method or a computer program.

<2-5>
According to the fish finder 9 in the fish finder 1 according to the above embodiment, a predetermined range is selected by the user via the range selection accepting unit 13, but is not limited to being selected by the user. Even if there is no selection of the range by a user, what is necessary is just to be able to set the range at the depth where the school of fish may exist.

<2-6>
In the labeling process in the PING direction according to the embodiment (FIG. 6B), when there are a plurality of “1” continuous portions and “0” is interposed between them, the number of “0” interposed is predetermined. You may perform the process which determines whether it is below a number. In this case, similarly to the labeling process in the depth direction (FIG. 6A), when the intervening “0” is equal to or less than the predetermined number, “0” is regarded as “1” and the labeling process is performed (step S306 in FIG. 6A). To S307).

DESCRIPTION OF SYMBOLS 1 Fish detector 2 Transmitter / receiver 3 Transmission / reception part 4 Display part 5 Operation part 9 Fish detection part 10 Signal processing apparatus 11 A / D conversion part 12 Received data storage part 13 Range selection reception part 14 Binarization part 15 Labeling part 16 Fish range extractor 17 Display controller

Claims (24)

A fish detection device that detects a school of fish based on an ultrasonic echo signal transmitted toward the water,
A binarization unit that binarizes data generated based on the echo signal based on the signal level;
A fish candidate specifying unit for detecting continuity in a predetermined direction of data having a higher signal level among binarized data and specifying the data range having the continuity, and the specified data range A fish finder having a fish range extraction unit for extracting a range of fish based on the above. The data is generated based on ultrasonic echo signals transmitted at a plurality of frequencies,
The binarization unit binarizes based on whether the signal level of data corresponding to at least two frequencies is equal to or higher than a threshold value,
The fish finder according to claim 1. The predetermined direction is at least one of a depth direction when the data is displayed, a direction orthogonal to the depth direction, and an oblique direction with respect to the depth direction and the orthogonal direction.
The fish finder according to claim 1. The fish range extraction unit extracts the range of the fish based on the size of the identified data range;
The fish finder according to claim 1. The fish school range extraction unit, when there are a plurality of the specified data ranges, extracts a data range having a maximum area as the fish school range,
The fish finder according to claim 4. The fish range extracting unit extracts the range of the fish based on the shape of the identified data range;
The fish finder according to claim 1. When the continuity of the data is interrupted in the depth direction, the fish candidate identification unit identifies the data range as having the continuity when the interrupted length is equal to or less than a predetermined minimum length.
The fish finder according to claim 1. A range selection receiving unit that receives a selection of a predetermined range for the data generated based on the echo signal,
The binarization unit binarizes the selected data in the predetermined range.
The fish finder according to claim 1. The fish school candidate specifying unit specifies the data range by assigning the same label to the data range having the continuity.
The fish finder according to claim 1. The fish finder according to claim 1,
An A / D converter that digitally converts the echo signal to generate the data; and a memory that stores the data;
A signal processing apparatus comprising: The signal processing device according to claim 10,
A transmitter / receiver for transmitting the ultrasonic transmission signal toward the water and receiving the echo signal;
The ultrasonic transmission signal is generated and output to the transmitter / receiver, and the transmitter / receiver that receives the echo signal from the transmitter / receiver, and the fish school extracted by the fish detector of the signal processing device A display device for displaying data indicating a range;
With a fish finder. A fish detection method for detecting a school of fish based on an ultrasonic echo signal transmitted toward the water,
The data generated based on the echo signal is binarized based on the signal level,
Detect continuity in a predetermined direction of data having a higher signal level among the binarized data, identify the data range having the continuity as a fish school candidate,
A school detection method for extracting a school range based on a specified data range.   A computer program for causing a computer to execute the fish finder method according to claim 12. A fish detection device that detects a school of fish based on an ultrasonic echo signal transmitted toward the water,
A binarization unit that binarizes a signal level of the echo signal at each sampling point in the transmission direction of the ultrasonic wave by a predetermined threshold, discriminates a sampling point exceeding the threshold, and outputs a discrimination sampling point;
A fish candidate identification unit that identifies a region where consecutive discrimination sampling points output by the binarization unit are output as a fish candidate depth range, and determines whether the fish candidate depth range has a predetermined area or more, A fish finder having a fish range extraction unit that extracts the fish range depth range as a fish range when the area is greater than or equal to the area. A fish detection method for detecting a school of fish based on an ultrasonic echo signal transmitted toward the water,
A sampling point determination process for binarizing a signal level of the echo signal at each sampling point in the transmission direction of the ultrasonic wave by a predetermined threshold, determining a sampling point exceeding the threshold, and outputting a determination sampling point;
A sampling point distribution evaluation process for evaluating the distribution state of the discriminant sampling points for each sampling point;
Based on the distribution state, a fish candidate depth range specifying process for specifying a fish candidate depth range that is a candidate for a fish school;
A method for detecting fish school. The sampling point distribution evaluation process includes:
Including a process of extracting regions where the discriminant sampling points are continuous;
The method for detecting a school of fish according to claim 15. The discriminant sampling point evaluation process includes:
Including a process of extracting a region in which the number of sampling points that are not the discrimination sampling points between two consecutive sampling points of the discrimination sampling points is a predetermined number or less.
The method for detecting a school of fish according to claim 15. A method for detecting a school of fish according to any one of claims 15 to 17,
The ultrasonic waves are ultrasonic waves having two frequencies different from each other,
The sampling point discrimination process binarizes the signal level of the echo signal with respect to the sampling point corresponding to substantially the same position with respect to the ultrasonic signal of each frequency by a predetermined threshold value, and both sampling points exceeding the threshold value are selected. A school of fish detection method that discriminates and outputs discriminant sampling points. A method for detecting a school of fish according to any one of claims 15 to 17,
The ultrasonic signal is transmitted at a predetermined period,
The fish school identification process includes a process of identifying the fish school candidate depth range corresponding to each ultrasonic wave transmitted in the predetermined cycle,
Further, a fish candidate area specifying process for specifying a fish candidate area constituted by the fish candidate depth range for each time at which the ultrasonic wave is transmitted,
Fish school detection method. The fish detection method according to claim 15,
The fish school candidate area identification process
Including a fish candidate area selection process for selecting a fish candidate area having the largest area among the plurality of fish candidate areas specified by the fish candidate area specifying process,
Fish school detection method. The region where the discrimination sampling points are continuous is at least one of a depth direction when the received echo signal is displayed, a direction orthogonal to the depth direction, and an oblique direction with respect to the depth direction and the orthogonal direction. Is a region in which discriminant sampling points are continuous,
The fish school detection method according to claim 16. The fish school candidate depth range identification process extracts the fish school range based on the shape of the distribution range.
The method for detecting a school of fish according to claim 15. A range selection process for receiving a selection of a predetermined range for the data generated based on the echo signal,
The sampling point discrimination process binarizes the data of the predetermined range selected in the range selection process;
The method for detecting a school of fish according to claim 15. The fish candidate depth range specifying process specifies the fish candidate depth range by assigning the same label to an area where the discriminant sampling points are continuous.
The fish school detection method according to claim 16.