JPS62105075A - Fish detecting method - Google Patents

Abstract

PURPOSE:To easily find fishes and to discriminate the quality of water bottom even with the same gain by radiating a main beam which has directivity and an ultrasonic wave which has a side lobe at a wide direction angle at the same time, and displaying reflected waves on the same display device. CONSTITUTION:Eight vibrators 1 are arranged in a square shape as shown in figure to increase the side lobe and the ultrasonic wave with characteristics with a side lobe whose angle theta of incidence on the water bottom is up to about 60 deg., i.e. a wide direction angle is emitted over the entire periphery of a directional main beam. Then, pieces of information obtained from the water bottom reflected waves of the main beam and side lobe are displayed on the same display screen. Consequently, pieces of information on the depth of water and the quality of water are recorded simultaneously and a decision is easily made.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting schools of fish, and more particularly, to a method for detecting schools of fish that allows easy identification of bottom sediment, etc.

[Conventional technology]

2. Description of the Related Art Conventionally, it has been widely used to detect schools of fish or measure water depth by emitting ultrasonic waves underwater and receiving their echoes.

By the way, when performing fish school detection, it is often necessary to obtain information on the bottom sediment at the same time in order to identify target fish and determine the fishing gear to be used.

In such cases, even with conventional detectors, it was possible to distinguish the bottom sediment to some extent by looking at the shading of the bottom record on the display, but this requires considerable skill and can be done by anyone. It wasn't something.

[Problems with conventional technology]

In view of the above, we focused on the difference in ultrasound transmittance depending on the bottom sediment,
Discrimination has been carried out using low-frequency sound waves and by the length of the trailing record display of the water bottom record that appears on the display surface of the return reflected wave, but it is still difficult to make a clear distinction. Moreover, the gain for catching fish schools and the gain for determining sediment are different, making operation cumbersome. [Problems to be solved by the invention] In view of the above problems, this invention The purpose of the gain was to obtain a method for detecting schools of fish that could very easily detect schools of fish and determine the sediment on the bottom of the water.

[Technology to solve problems]

That is, in the fish detection method of the present invention, from an ultrasonic transmitter,
An ultrasonic wave having a characteristic of having a directional main beam and a side lobe with a wide directivity angle around the entire periphery of the main beam with a bottom incidence angle θ of up to approximately 60° is emitted toward the water bottom, and then the main beam is It is characterized by displaying information obtained from underwater emitted waves of beams and side lobes on the same display screen.

C Effect] It is known that when ultrasonic waves are incident obliquely into water, the reflection coefficient from the water bottom in the direction of incidence varies significantly depending on the roughness of the water bottom surface.

For example, if the surface of the water bottom is smooth, such as mud or sand, the reflection coefficient for oblique incidence is small, and conversely, if the surface is rough, such as gravel, it is large.

Therefore, if ultrasonic waves are emitted toward the bottom of the water at oblique incidence,
Differences in intensity occur in the reflected waves, and differences in bottom sediment become noticeable on the display.

On the other hand, in order to measure the water depth (including the depth of the fish bed layer, the same shall apply hereinafter), it is necessary to emit directional ultrasonic waves vertically downward.

Therefore, if the above-mentioned obliquely incident ultrasonic waves and directional ultrasonic waves are emitted at the same time and the reflected waves of both are displayed on the same display, the former will display the bottom sediment, and the latter will display the water depth. It happens.

Note that at this time, the reflected waves of the side lobes always return with a time delay relative to the reflected waves of the main beam, so
There is no confusion between the two on the display.

In the above description, the side lobe S of the ultrasonic wave emitted from the transducer A has a wide directivity angle where the bottom incident angle θ is up to about 60° as shown in FIG.

The reason for this is that if it is 60'' or more, the information from the reflected waves will be dense, but the area of the bottom of the sea to be explored will become too large, resulting in the inconvenience of not being able to accurately explore the bottom of the sea.

Further, the characteristics of the ultrasonic waves in this invention are not necessarily limited to those emitted from a single transducer, and a directional transducer and a transducer having a wide beam width may be combined, and When the above-mentioned vibrators are combined, it is not necessary to make their frequencies the same. This is because it is sufficient to be able to distinguish differences in bottom reflectance due to oblique incidence.

〔Example〕

Next, the present invention will be explained with reference to examples.

Example 1 As shown in Fig. 2, a commonly used vibrator 1...
By arranging 8 L in the shape of a mouth, the side lobes can be set to high < L (-10 to 15 db), and even when L, the side lobes have a wide directivity angle with the bottom incident angle θ up to around 60''. A vibrator A was formed, and the water depth was measured using an ordinary fish finder shown in FIG.

Example 2 As shown in Fig. 4, a transducer 1) emits ultrasonic waves with excellent directivity without side lobes, and a transducer 12 that emits ultrasonic waves with a very wide main beam. The third
The water depth was measured by using it in place of the vibrator A shown in the figure.

Next, when the devices of Examples 1 and 2 were used to detect a seabed with alternating sand and gravel, the records shown in Figure 5 were obtained, and the bottom materials were clearly distinguished and displayed. Ta.

In FIG. 5, the area indicated by range I indicates a sandy bottom with low reflectance, and the area indicated by range ■ indicates a gravel layer with high reflectance.

In addition, FIG. 5 is a record obtained by searching the same seabed using a conventional fish finder as a comparative example.

〔effect〕

As explained above, this invention utilizes the difference in the reflectance of ultrasonic waves obliquely incident on the water bottom to measure the bottom sediment and the water depth directly below with the main beam, and displays them on the same display screen. Therefore, information on both water depth and sediment is recorded at the same time, making it very easy to distinguish between them.Furthermore, because each type of information is obtained from two types of ultrasonic waves that are emitted at the same time, a single transducer is used. If you want to adjust the level difference between the main lobe and side lobe using two oscillators, you can set the output adjustment at the beginning, making it extremely easy to adjust the gain during operation. It can be operated.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the operation of the present invention, FIGS. 2 and 3 are diagrams explaining the configuration of an embodiment, FIG. 4 is an explanatory diagram of the recording state of the embodiment, and FIG. 5 is an explanatory diagram of the recording state of a comparative example. be. Engraving of the drawing (no changes to the content) γ-dan θ+bottom ＼Ejiyu＼ He γ51EJ () Shibetsu! Buta υ tour 2 times (and bitsu bunzake) Teku °ε Shin Fu Seisho (method) % formula % 1. Indication of the incident 1985 Patent Application No. 246019 2. Name of the invention Fish school detection method 3 , Relationship with the case of the person making the amendment Patent Applicant Address 9-52 Ashihara-cho, Nishinomiya City, Hyogo Name Furuno Electric Co., Ltd. Representative Kiyotaka Furuno 4, Agent Address: 662 (1) Detailed description of the invention in the specification Column 7, Contents of amendment +1) In the 8th line of page 6 of the specification, the phrase ``Figure 5 is'' is corrected to ``Figure 6 is''. (2) As shown in the attached sheet, correct the brief explanation column of the drawing. (3) As per the engraving and attached sheet of the drawings originally attached to the application. (No change in content) 4. Brief explanation of the drawings Figure 1 is an explanatory diagram of the operation of this invention, Figures 2 and 3 are illustrations of the configuration of an embodiment, and Figure 4 is an explanation of the configuration of another embodiment. 5 is an explanatory diagram of the recording state of the embodiment, and FIG. 6 is an explanatory diagram of the recording state of the comparative example.

Claims (1)

[Claims] (1) An ultrasonic transmitter sends ultrasonic waves to the water bottom, which have a characteristic of having a directional main beam and side lobes with a wide directivity angle around the entire periphery of the main beam, with the bottom incident angle θ up to about 60°. 1. A method for detecting a school of fish, characterized in that the information obtained from the waves emitted from the bottom by the main beam and side lobes is displayed on the same display screen.