JPH0285787A - Fish finder - Google Patents

Abstract

PURPOSE:To directly estimate the body length of fishes forming a group from the video of the fish group by using a transmitter-receiver which forms cross fan beams in the transmitting and received acoustic waves. CONSTITUTION:A transmission circuit 2 produces pulse signals and sends the pulse signals to a transmitter 3 upon receiving a transmission trigger signal from a display 1. The transmitter sends electric signals into water after converting the signals into ultrasonic wave signals. A receiver 4 converts echo pulses into electric signals upon receiving the echo pulses. While the directivity of the receiver 4 is also controlled by a fan beam, the transmitter 3 and receiver 4 are fitted to the bottom or side of a fishing boat in a T-shape or after the transmitter 3 and receiver 4 are assembled to a T-shape by shifting the receiver 4 from the transmitter 3 by 90 deg. so that the fan beams can become wider in the length direction and very narrow in the width direction of the boat. A reception circuit 5 is provided with a time variable gain (TVG) circuit which cancels the diffusion and absorption of acoustic waves and sends an echo level to a display 1 after the circuit 5 faithfully amplifies the magnitude of the echo level. The display 1 causes a trigger signal for transmission to be generated and, at the same time, display received signals with a density or color corresponding to the level of the received signals.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a fish finder that emits ultrasonic pulses into the water from a transducer attached to the bottom or side of a ship, and detects schools of fish etc. by the echoes of the ultrasonic pulses. It is. The purpose of the present invention is not only to detect schools of fish, but also to separate and detect the individual fish that make up the school, and to make it possible to estimate the length of the fish from the echo density and its level. be.

(Prior art) When a school of fish is found using a fish finder, it is important for fishermen to determine whether it is a target fish species or not, and to prevent wasteful operations and to adjust the mesh size of the net to be cast. This is important for selecting operational procedures such as selection, and is also important from the perspective of resource conservation. A powerful clue for determining fish species is knowing the body lengths of the individual fish that make up the fish school.

On the other hand, with conventional fish finders, even at high frequencies such as 200KH2, which is said to have the sharpest directivity, the pointing width is about 5 degrees, and the detection range at a depth of 100 meters is about 60 meters. tan2.5°
Devices have been created that faithfully display the echo intensity by correcting (a1n: time variable gain), but these devices are mainly used for resource surveys, and theoretically, they widen the directivity of the beam.
It actively utilizes the superimposed echoes from schools of fish, processes them, and displays them.

(Problem to be solved by the invention) However, when a school of fish is detected using directivity like a conventional fish finder, as shown in Figure 4, the echoes of each individual fish within the range are received in a state where they are overlapped. These echoes are processed and displayed as one echo, and if there are many fish in the same area, they are displayed at a strong level, and when there are few, they are displayed at a weak level. If the purpose is simply to detect a school of fish, there is no problem, but since only the combined echo level information can be obtained, it is impossible to estimate the body length of the fish that make up the school of fish.

It is also possible to estimate the body length of swimming fish as part of the function of weighing fish finders and scientific fish finders.
The directivity is wide based on the Seki 1 system, which prioritizes the measurement accuracy of the entire fish school, so the target fish for which fish length can be estimated are limited to fish that are far away from the school or fish that swim at intervals of several meters or more. It is not possible to directly estimate the length of fish that form a school from the display. As described above, there is no conventional fish finder that can directly determine or estimate the body length of fish forming a school.

The purpose of the present invention is to take into consideration the importance of knowing the body length of the fish constituting the fish school and the problems of the prior art.
The present invention aims to provide a fish finder that can directly estimate the body length of fish forming a school from images of the school of fish.

(Means for solving the problem) The present invention has the following configuration to achieve the above object. That is, the fish finder of the present invention includes a transmitter having a fan-shaped transmitting beam pattern and a fan-shaped receiving beam pattern, which are arranged or can be arranged so that the fan surfaces of each beam pattern are perpendicular to each other. a receiver having;
A transmitting circuit that supplies a transmitted signal to the transmitter; A receiving circuit with TVG that amplifies and processes the received signal from the receiver; A display that displays the signal from the receiving circuit; Features.

(Embodiments) Hereinafter, embodiments of the fish finder of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the present invention.

Reference numeral 1 denotes a display which has the same function as the display of a normal fish finder, generates a trigger signal for transmission, and displays in shading or color depending on the level of the received signal.

2 is a transmission circuit which receives a transmission trigger from the display 1, generates a pulse signal, and sends it to the transmitter 3; The transmitter 3 converts the electrical signal into an ultrasonic signal and sends it into the water. For example, its directivity is very narrow in the front and rear directions of the ship, but wide in the left and right directions.
It has a so-called fan beam (a beam with a fan-shaped beam pattern).

4 is a wave receiver that receives echo pulses and converts them into electrical signals.The directivity of this device is also a fan beam, but it is shifted by 90 degrees from transmitter 3, wide in the front and rear directions of the ship, and wide in the left and right directions. Transmitter 3 and receiver 4 are placed on the bottom or side of the ship in a very narrow space.
For example, they are attached in a T-shape, or those assembled in a T-shape in advance are attached. 5 is a receiving circuit which has a TVG circuit that cancels the diffusion and absorption of sound waves, and faithfully amplifies the magnitude of the echo level and displays the display 1.
send to

The operation of the above fish finder will be explained below.

A school of fish is said to be made up of fish of the same species and age based on their swimming speed and gentle tethering behavior. Also, the spacing between individuals is almost proportional to the size of the fish, for example, an anchovy with a body length of less than 10 cm and an anchovy with a body length of less than 10 cm.
There is a difference in the swimming interval for mackerel with 0CI11. Now, I
Assuming that they swim at intervals of B L (Body Length), the intervals are 10 cm and 50 cm.
This is a 5 times difference.

It is said that the echo level is roughly proportional to the square of the body length, so in the above example, the difference is about 25 times louder. In addition, 1
The layer number density of 2-13 cm sardine fish school is 0.18 fish/
Focusing on the above 9 facts, which are reported to be relatively sparse at about 0.5 m', if a very sharp beam with a directional width of about 0.5° is used for detection, the beam at a depth of 100 m is If the spread is 0.873 x 0.873 m'' and the transmission pulse width is set to 0.4 m5 (equivalent to 0.3 m), the detected ice block will be 0.18 m', so it will be possible to detect fish forming a school. It is possible to detect almost one fish at a time.

The fish finder of the present invention has a fan-shaped beam (fan beam),
That is, the beam width in one direction (e.g., longitudinal direction) within a plane perpendicular to the main axis of the beam is very narrow (e.g., 0.5°);
It has a transmitter that has a beam with a very wide beam width (for example, several tens of degrees) in a direction perpendicular to this direction (for example, the lateral direction), and a receiver that also has a fan beam. A fan beam is used by arranging its fan plane at right angles (this is called a cross fan beam). Therefore, when a wave is transmitted from a transmitter and an echo is received by a receiver, the beam cross section is exactly This is the same as receiving waves with a beam whose length and width are the narrower angular width of both the transmitting and receiving beams. In other words, the narrower beam width of the fan beam is 0.5
If the angle is 0.5°, it will be the same as receiving the wave with a 0.5° beam.

This situation is shown in Figure 2. If you simply want to form a narrow beam, you only need to increase the area of the transducer, but if you use a pencil beam with a directional width of 0.5° to detect fish schools, it will be difficult to detect a rolling beam. The center axis of the transmitter and the center axis of the receiver may deviate significantly due to pitching or pitching, and the difference in echo level becomes very large even for the same fish, making it difficult to determine what size the fish is. become unable.

In order to solve these problems, it is necessary to detect rolling and pitching and stabilize the pointing axis, but such a stabilizing device would be expensive. In the case of a cross fan beam, if you design the angle of the wide beam to correspond to the rolling and pitching angles, you will always be able to receive the echo of any fish no matter how agitated it is. It is possible to receive at a nearly constant echo level, and it is possible to stabilize the echo level against rolling and pitching of the equipped ship.

In this way, by using a cross-fan beam, it is equivalent to transmitting and receiving waves with a narrow beam, and by selecting the beam width, it is possible to detect each fish forming a school of crabfish. Become. When a school of fish is detected using a Ross fan beam in this way, in the case of small fish, the swimming interval is small and the number of layers is high, so the echo density (frequency) is high and the echo level is low.

Conversely, if the fish is large, the echo density will be low and the echo level will be high. Furthermore, since the receiving circuit is equipped with a TVG circuit, regardless of the depth of the school of fish, the magnitude of the echo level from the fish body is faithfully amplified and sent to display 1, so the magnitude of the signal level to the display is It refers to the size of the fish.

What we know from not only the echo density but also the echo level is that the swimming interval is not constant depending on the length of the fish;
This is necessary to more reliably estimate the length of the fish, as it changes depending on the natural environment and other conditions such as water temperature, current, and underwater illumination.

Figure 3 is a fish school image displayed on the display by the fish finder of the present invention. Figure 0 (a) is a record of a school of small fish, and the dots recorded are finely grained and have pale or low-level colors. It becomes a record.

Figure (b) shows a record of a school of large fish, with fine texture and dark or high-level colors recorded in spots. In addition, when fish of various sizes are mixed together, such as when fish are being fished, the display will look like a superimposition of Figures 3(a) and 3(b).

The length of the fish can be estimated based on the spacing between these dots and their shading or color, and the species of the fish can therefore be determined.

(Effects of the Invention) As explained above, the fish finder of the present invention uses a transducer that forms a cross fan beam for transmitting and receiving sound waves, and has a receiving circuit with a TVG circuit, so that it is possible to record video. The spacing of dots representing individual fish and their shading (or color)
From this, it is possible to estimate the fish length. Therefore, it is possible for fishermen to judge whether or not the fish are targeted for fishing before starting operations, which has a large economic effect and is also effective in terms of resource conservation. In addition, in a specific example, in purse seine fishing, when a fish is cast in a net expecting to be a large fish, the width of the fish almost matches the mesh, so accidents such as getting caught in the mesh can be avoided.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is an explanatory diagram of a cross fan beam, Figure (a) is a diagram showing a transducer and orthogonal fan beam, and Figure (b) is a view seen from the main axis direction. Beam cross-sectional view, Figure (C) is a diagram showing an example of display on the display, 3rd
The figure shows an example of fish record display of the fish finder of the present invention.
Figure (a) is for a school of small fish, Figure (b) is for a school of large fish, Figure 4 is an explanatory diagram of the beam of a conventional fish finder, and Figure (a) is for a transducer. Figure (b) is a diagram showing a beam cross section, and Figure (c) is a diagram showing an example of display on a display. 1...Display, 2...Transmission circuit, 3.
...Transmitter, 4...Receiver, 5...
・TVG circuit 1-inch receiving circuit, 6...Transmission beam, 6'... Cross section of transmission beam, 7...
・Receiving beam, 7'...Cross section of the receiving beam,
8...Fish, 8'...Image of a fish, 9
...Undersea image, 10...Oscillation line (equivalent to the sea surface), 11...Transducer/receiver, 12...
...Transmission and reception beam. Agent Patent Attorney Yoshihiro Hachiman Figure 7? (a) (b) Figure 3

Claims (1)

[Claims] a transmitter having a fan-shaped transmitting beam pattern and a receiver having a fan-shaped receiving beam pattern, the transmitter having a fan-shaped transmitting beam pattern, and a receiver having a fan-shaped receiving beam pattern, the transmitter being arranged or capable of being arranged such that the fan surfaces of each beam pattern are at right angles to each other; a transmitting circuit that supplies a transmitting signal to; a T that amplifies and processes the received signal from the receiver;
A fish finder comprising: a receiving circuit with a VG; and a display for displaying a signal from the receiving circuit.