JPH0648453Y2 - Fish finder for fish length discrimination - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to an underwater object detection technology using ultrasonic waves, and a cross-fan beam applied in Japanese Patent Application No. 60-123914 (No. Sho 62-32386) is applied. The present invention relates to a technique for improving the accuracy of a fish finder that is used to detect fish length information of the fishes that compose a fish school more accurately.

(Prior Art) When a school of fish is found by a fish finder, it is necessary to determine whether or not it is a target fish species for fishermen by preventing useless operations and by determining the mesh size of the net to be cast. It is important for selection of operational procedures such as selection, and also important from the viewpoint of resource conservation. A powerful clue to such fish species determination is to know the body length of each fish composing the school of fish.

On the other hand, the conventional fish finder has a directivity width of 5 even at high frequencies such as 200 KHz, which has the sharpest directivity.
The detection range is about 60m ² [(t
an2.5 ° × 100) ² × π]. Recently, TVG (Time Variable G
ain: time variable gain) correction has been performed, and devices that faithfully display the intensity of echo signals have been created, but these are mainly for resource surveys, and the beam directivity is widened and logically The superimposed echo signal of is positively used to perform arithmetic processing and display.

However, when a fish school is detected with directivity like a conventional fish finder, echo signals of individual fishes within the range are received in a superimposed state and processed and displayed as one echo signal. , If there are many fish in the same range, it is displayed as a weak level, and if there are few fish, it is displayed as a weak level. When the purpose is simply detection of a school of fish, there is no problem, but it is impossible to estimate the fish length of the fish that compose the school of fish, because only the information of the combined echo level can be obtained.

It is also possible to estimate the fish body length of a swimming fish as a part of the functions of a fish finder for measurement and a scientific fish finder, but the directivity is widened because it gives priority to the measurement accuracy of the whole fish school. Therefore, the target fish whose fish length can be estimated is limited to fish that are far from the school or fish that swim at intervals of several meters or more, and the fish length of the fish that form the school cannot be estimated directly from the display. As described above, there is no fish finder that can directly determine or estimate the fish length of the fish forming the school.

Therefore, in order to solve the above problem, a fish finder capable of directly estimating the fish length of the fishes forming the fish school from a fish school image was devised, and the Japanese Patent Application 60-123914 (Japanese Utility Model Sho 62-3238).
No. 6), the applicant of the present invention is applying. This real application Sho 60
The fish finder proposed in -123914 (Shokai Sho 62-32386) has a fan-shaped transmitting beam pattern in which the fan faces of each beam pattern are arranged or can be arranged so as to be at right angles to each other. A wave transmitter and a wave transmitter having a fan-shaped receiving beam pattern; a transmission circuit for supplying a transmission signal to the wave transmitting device; and an amplifier for amplifying a reception signal from the wave receiver.
A receiver for processing TVG; and a display for displaying a signal from the receiver. Specifically, the fish finder for fish length measurement by a cross fan beam as shown in FIG. The measurements were made in an embodiment as shown in the machine block diagram.

In FIG. 6, reference numeral 1 is a wave transmitter for forming a wave-transmitting fan beam, and 2 is arranged so as to form a wave-receiving fan beam whose fan surface is orthogonal to the wave-transmitting fan beam formed by the wave transmitter 1. It is a receiver that has been 3 is a transmitter that supplies a transmission signal to the transmitter 1, 4 is a receiver with TVG, 5
Is a display for displaying the signal from the receiver 4.

By utilizing the narrow range of the overlapping portion of the beams obtained by making the fan beams orthogonal to each other in the above-mentioned configuration device, stable and substantially narrow directivity can be achieved even for the rotor ring and pitching of the device-equipped ship. Since the same effect as that detected with the beam can be obtained, by using this to measure the fish length, a fish finder that can directly estimate the fish length of the fish forming the fish school from the image of the echo signal is used. It was meant to be offered.

(Problems to be solved by the invention) However, even in the fish finder of the above-mentioned application, if the cross section (intersection plane) of the overlapping portion of the cross fan beam is carefully examined, as shown in FIG. The wave pattern has a side lobe 17 in addition to the main lobe 20. The strength decreases as the distance from the main axis increases (the width (corner) at the position where the strength is halved from the maximum strength is called the nominal directivity width (corner)).

As described above, the directivity of the practically used transmitter / receiver is not an ideal beam, so not only the echo signal within the nominal directivity width (half-width full angle) but also the echo signal from the side of the main lobe or the side lobe is detected at the same time. Will end up. Therefore, even if the echo signals are from fish of the same fish length, the echo signals within the nominal directivity width are large and stable, but the other echo signals are small, and the change in echo level is large,
It shows various levels, and the echo level changes depending on the angle with the reflector with respect to the central axis of the cross fan beam, so displaying the fish length and calculating from only that signal causes a large error. .

The object of the present invention is to solve the above problems and to further improve the detection accuracy of a fish finder using a narrow directional beam by a cross fan beam, in order to further improve the detection accuracy, Further, it is an object of the present invention to provide a fish finder for discriminating fish length, which can detect fish length with high resolution and accuracy by utilizing a limited narrow range.

(Means for Solving Problems) The present invention has the following means configuration in order to achieve the above object. That is, the fish finder for determining the fish length of the present invention is a fish finder that uses a cross-fan beam to detect a fish, and is arranged linearly in a direction perpendicular to the same radiation direction. It consists of multiple oscillators, and the excitation fan beam is formed by exciting these with an ultrasonic electric signal, and the remaining vibrations except one or multiple oscillators near one end of the array at the time of receiving waves. By forming the first received fan beam whose directional axis is separated from the directional axis of the transmitted fan beam by synthesizing the received wave signals of the child, conversely, the number of transducers near the other end of the array is excluded from the above. A transducer which forms a second received fan beam at a symmetrical position with the first received fan beam and the transmitted fan beam sandwiched by synthesizing the received signals of the remaining oscillators except for the same number. ； Transmitting / receiving the wave receiving surface by the wave transmitter The main receiving fan is composed of a plurality of transducers arranged in the same direction as the plane and linearly arranged in a direction orthogonal to the arrangement direction of the transducers of the transducer. The directional axis is separated from the directional axis of the main received fan beam by forming the beam and synthesizing the received signals of the remaining transducers except for one or more transducers near one end of the array. The first received wave is formed by forming a first received fan beam and conversely synthesizing the received signals of the remaining signal elements after removing the same number of transducers near the other end of the array as above. A wave receiver that forms a second wave-receiving fan beam at a symmetrical position with the fan beam and the main wave-receiving fan beam sandwiched; a target signal received by the first wave-receiving fan beam of the transmitter / receiver, and a target signal Phase difference from the target signal received by the two receiving fan beams Detect Y
An axis phase difference detecting section; an X axis for detecting a phase difference between a target signal received by the first receiving fan beam and a target signal received by the second receiving fan beam of the wave receiver. A phase difference detection unit; if the phase difference detected by the X-axis phase difference detection unit and the phase difference detected by the Y-axis phase difference detection unit are within a predetermined phase difference range, the gate is opened and an echo signal is generated. A fish finder for discriminating a fish body length, comprising: a phase gate unit for passing through.

(Operation) The operation of the fish finder for fish length discrimination according to the present invention having the above-mentioned means will be described below. For convenience of description, the measurement principle will be briefly described first. The principle of fish length measurement is that the fish length is known by utilizing a large amount of accumulated experimental data. The relationship between the fish's equivalent cross-sectional area, echo intensity, and fish length differs somewhat depending on the fish species, but the fish's length is generally proportional to the square root of the fish's equivalent cross-section, and the equivalent cross-section has a constant relationship with the target strength, which is the reflection characteristic of the fish Therefore, the fish length can be known by obtaining the echo intensity of the sound wave.

Therefore, since the fish length is obtained from the echo intensity of the fish, the fish length detection accuracy is largely determined by the uniformity and stability of the intensity of the transmitted beam and the intensity of the received beam. .

In the present invention, a predetermined distance (for example, one ultrasonic transducer element interval)
Depending on the narrow directional range formed by the overlapping part of the fan beam made by the receiver and the fan surface of the transmitting fan beam made by the transmitter, which are connected so as to have two or three directional axes at a distance. The echo signal from the obtained fish is detected and used. However, when the cross-section of the cross-fan beam is viewed in detail, the strength decreases as it moves away from the center of the cross-section as shown in the intensity distribution diagram of the cross-fan beam section shown in FIG. In FIG. 5, the range surrounded by thick lines, which is indicated as “0 to −6”, indicates the vicinity of the center of the cross fan beam (nominal pointing width), and “0 to −6” indicates the transmitted fan beam. In the directional characteristics of the receiving fan beam, the beam intensity at the beam crossing surface formed by the beam in the range of 0 to 3 dB attenuation from the maximum intensity is shown. Therefore, the attenuation of the transmitting fan beam is "0 to -3" dB. It is shown that the attenuation of "0 to -3" dB of the received fan beam acts in a superimposed manner to add the attenuation to "0 to -6" dB. The other parts are similarly represented.

That is, when the longitudinal direction of the wave receiver is the X direction and the longitudinal direction of the wave transmitter is the Y direction, it can be seen that the intensity decreases as the distance from the center of the cross fan beam increases in the X and Y directions. Therefore, the Y-axis phase difference detector detects the phase difference between the echo signals received by the two receiving fan beams having the directional axes that are separated by a predetermined distance from the wave transmitter, and the directional axis of the wave receiver is similarly detected. The phase difference between the echo signals received by the two receiving fan beams separated by a predetermined distance is detected by the X-axis phase difference detector, and the Y-axis phase difference and the X-axis phase difference are within the predetermined phase difference. If
The phase gate unit is opened to allow the echo signal received by one of the two or three receiving fan beams of the receiver to pass.

In this way, the measurement accuracy is improved by using only the signal from the beam in the stable and highly uniform portion.

Next, as an example of the principle of the phase difference detection by the wave receiver having two wave-receiving fan beams as described above, the configuration of the wave receiver of the embodiment of FIG. 2 and the phase difference detection of FIG. A description will be given based on an explanatory diagram.

2 and 3, 13-1 to 13-7 are ultrasonic transducers (hereinafter simply referred to as transducers), and 15 is the center axis of the X ₁ receiver and the transducers 13-1 to 13-7. -6 is the center axis of the receiving fan beam BX ₁ and 14 is the center axis of the X ₂ receiver. The center of the receiving fan beam BX ₂ formed by the transducers 13-2 to 13-7. The axis 16 is the central axis of the entire X bearing wave device, and is the central axis of the received fan beam BX formed by the vibrators 13-1 to 13-7.

FIG. 3 shows the wave receiver shown in FIG. 2 which receives echo signals from a fish body whose angle with the central axis of the receiving fan beam BX is in the θ direction, X ₁ receiver 21 and X ₂ receiver 22, respectively. It is explanatory drawing at the time of receiving in. It can be considered that the fish body is far away from the axial distance L between the X ₁ receiver and the X ₂ receiver, so the path of the echo signal received by the X ₁ receiver 21 and the X ₂ receiver 22 The paths of the echo signals received at can be regarded as parallel. Therefore, from Fig. 3, the path length difference between the receiving beam BX ₁ and the receiving beam BX ₂
Is obtained by ι ＝ Lsinθ, the phase difference φ is Can be asked.

Therefore, if the phase difference φ within the range of the predetermined angle θ is set in advance, the echo signal within the predetermined angle range can be detected.

Although the X-axis phase difference detection has been described above, the same applies to the Y-axis phase difference detection using the received beam of the wave transmitter.

As described above, the phase difference range in which the X-axis phase difference detection section and the Y-axis phase difference detection section output signals for opening the phase gate section is within the phase difference range in which the direction of the target is the transmitting fan beam and the receiving fan beam. If the angle formed with the central axis of the is set to a value corresponding to a predetermined angle, for example, a nominal directivity width (angle), the echo signal passing through the phase gate section is a signal generated by a beam within the nominal directivity width. Therefore, the error due to the non-uniformity of the beam intensity due to the directional characteristics of the transmitted and received beams is suppressed, and accurate fish length information can be obtained.

As a result, an accurate fish body length can be known by the arithmetic processing of this information.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a fish finder for determining fish length according to the present invention. In FIG. 1, reference numeral 1 designates one transmitting fan beam and a receiving fan beam having a directional axis (L is one transducer interval) spaced by L / 2 on both sides with respect to the directional axis of the transmitting fan beam. It is a wave transmitter / receiver to be formed, and also has a wave receiving function for detecting a phase difference between echo signals. Reference numeral 2 is a receiver which forms three receiving fan beams with the directional axis spacing L / 2 apart from the central receiving beam, and is arranged so that the transmitting fan beam and the fan surface are orthogonal to each other. ing. The structures of the wave transmitter / receiver 1 and the wave receiver 2 are as shown in the block diagram of the embodiment of the wave receiver of FIG.

In FIG. 2, reference numeral 13 denotes an arrayed ultrasonic transducer (hereinafter simply referred to as a transducer), which is composed of seven transducers 13-1 to 13-7. And the oscillator 13-
1 to 13-6 X ₁ receiver consisting of transducer groups and 13-2 to 13-7 X ₂ transducer consisting of transducer groups divided into two parts, which are received separately. It is connected so as to be waved and output an echo signal.

Reference numeral 3 in FIG. 1 denotes a transmitter for generating a transmission signal for giving a transmission signal of ultrasonic frequency to the transducer 1.
The burst signal for transmission is made by obtaining the transmission trigger signal made in. Reference numerals 6 and 7 are a Y ₁ receiving section and a Y ₂ receiving section for receiving the echo signal from the transceiver ₁ . Reference numeral 4 is a receiving unit that receives the echo signals from the entire receiver 2, and 8 and 9 are X ₁ receiving units and X ₂ receiving units that receive the echo signals received by the two receiving fan beams in the receiver _2. Is. 10 is Y ₁
The Y-axis phase difference detection unit receives the echo signal from the reception unit 6 and the echo signal from the Y ₂ reception unit 7, detects the phase difference between them, and outputs an output signal for opening the gate if within a predetermined range.
An X-axis phase difference detector 11 receives an echo signal from the X ₁ receiver 8 and an echo signal from the X ₂ receiver 9 to detect a phase difference between them and outputs an output signal for opening the gate when the echo signal is within a predetermined range. It is a department. 12 is a Y-axis phase difference detection unit 10 and an X-axis phase difference detection unit 11
Detects the phase difference between the respective echo signals, and if both phase differences have a phase difference within a preset range, it receives the output and opens the gate to pass the echo signal which is the output of the receiving section 4 It is a department.

Reference numeral 5 is an echo signal (reflection signal) that has passed through the phase gate unit 12.
It is a display that processes the signal and displays it on a CRT in the form of numbers or images. When detecting the fish length, a fan beam is transmitted from the transducer 1. When there is a fish, an echo signal with an intensity corresponding to the equivalent cross-sectional area of the fish body is transmitted along the same path.
Come back to.

Further, the wave receiver 2 forms a cross fan beam by the wave receiving fan beam of the wave receiver 2 and the wave transmitting fan beam of the wave transmitter / receiver 1, and receives the echo signal returned by the wave receiving fan beam of the wave receiver 2. To wave. The echo signal received by the received beam formed by the entire wave receiver 2 has a phase difference detected by the Y-axis phase difference detection unit 10 and the X-axis phase difference detection unit 11 within a preset range. If so, the phase gate unit 12 is opened and the display 5
Sent to. Therefore, the angle formed by the direction of the target with the central axis of the transmitting fan beam and the central axis of the receiving fan beam of the wave receiver 2 is, for example, the nominal directional characteristics of the beams of the wave receiver 2 and the wave transmitter / receiver 1. If the X-axis phase difference detection unit 11 and the Y-axis phase difference detection unit 10 set a phase difference range for outputting a signal for opening the phase gate unit 12 so as to correspond to the directivity angle, "0--" shown in FIG. Echo signals within the range shown by the thick line of 6 "dB can be selectively extracted. As a result, if the fish length is calculated from this echo signal, it is possible to know the accurate fish length with little error.

(Effects of the Invention) As described above, the fish finder for determining fish length according to the present invention has a function of forming one transmitting fan beam and two receiving fan beams having a predetermined directional axis interval. A cross fan beam is formed by a wave transmitter / receiver and a wave receiver that forms two or three wave receiving fan beams having a predetermined directional axis spacing, and is directed by the Y-axis phase difference detection unit and the X-axis phase difference detection unit. By detecting the phase difference between the echo signals received by the receiver whose axis is separated by a predetermined distance, and extracting only the echo signal within the preset phase difference range, the cross fan beam Since the measurement is performed using a narrower beam range with good uniformity, mixing of changes in echo intensity due to factors of nonuniform characteristics of beam intensity other than changes in echo intensity due to the fish body can be suppressed to a small level, extremely It has an advantage that the fish length can be accurately measured.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a fish finder for determining fish length of the present invention, FIG. 2 is a block diagram of a wave receiver of the embodiment, FIG. 3 is an explanatory view of phase difference detection, and FIG. 4 is FIG. 5 is a diagram showing an example of directional characteristics of a conventional transducer, FIG. 5 is a cross-sectional intensity distribution diagram of a cross fan beam, and FIG. 6 is a block diagram of a fish finder for measuring fish length by a conventional cross fan beam. . 1 ... Transceiver, 2 ... Receiver, 3 ... Transmitter, 4 ...
Receiver, 5 ... Display, 6 ... Y ₁ receiver, 7 ... Y ₂ receiver, 8 ... X ₁ receiver, 9 ... X ₂ receiver, 10 ... Y axis phase difference detector , 11 ... X-axis phase difference detection unit, 12 ... Phase gate unit, 13-1 to 13-7 ... Ultrasonic transducer, 14 ... X ₂ Receiver central axis, 15 ... X ₁ reception unit Center axis of wave vessel, 16 ... X-axis center axis of wave vessel as a whole, 17 ... Side lobe, 18 ... Main lobe side, 19 ... Nominal pointing width (angle), 20 ... Main lobe, 21 ... … X ₁ receiver, 22 …… X ₂ receiver, 23 …… Direction of fish.

Claims (1)

[Scope of utility model registration request] 1. A fish finder for detecting a fish using a cross fan beam, comprising a plurality of transducers arranged linearly in a direction perpendicular to the same direction with the radiation planes directed to the same direction. Forming a transmitted fan beam by exciting with an ultrasonic electric signal, and synthesizing the received signals of the remaining transducers except one or more transducers near one end of the array at the time of reception. Form a first receiving fan beam whose directional axis is separated from the directional axis of the transmitting fan beam, and conversely, the remaining oscillators are removed by the same number as the above-mentioned number of oscillators near the other end of the array. A wave transmitter / receiver that forms a second wave receiving fan beam at a symmetrical position with the wave receiving signal sandwiched between the first wave receiving fan beam and the wave transmitting fan beam; The same direction as the transmitting and receiving surface and the transmission The transducer consists of a plurality of transducers arranged linearly in the direction orthogonal to the transducer array direction, and the main received fan beam is formed by combining the received signals of all transducers and On the other hand, the first received fan beam whose directional axis is separated from the directional axis of the main received fan beam is obtained by synthesizing the received signals of the remaining oscillators except one or a plurality of oscillators near the end. The first received fan beam and the main received fan beam are formed by synthesizing the received signals of the remaining transducers, which are formed by conversely removing the transducers near the other end of the array by the same number as the above-mentioned number. A wave receiver that forms a second wave-receiving fan beam in a symmetrical position with the target signal and the second wave-receiving fan beam received by the first wave-receiving fan beam of the wave transmitter-receiver A Y-axis phase difference detection unit that detects a phase difference from the waved target signal; The first of the receivers
An X-axis phase difference detecting section for detecting a phase difference between the target signal received by the second receiving fan beam and the target signal received by the second receiving fan beam; A phase gate unit that opens a gate and allows an echo signal to pass if the detected phase difference and the phase difference detected by the Y-axis phase difference detection unit are within a predetermined phase difference range; A fish finder for determining fish length.