JP2002131430A - Fish detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fish detector that can get a position relation of a shoal of fish to a boat relatively in detail. SOLUTION: The fish detector comprises a light emission part 1 that irradiates a burst signal by laser light in the sea, a changing means for changing the direction of radiation 2 that changes the direction of radiation of the burst signal to a fixed orbit, a light receiving part 3 that receives the reflection signal of the burst signal, and a signal processing part 4 that processes the reflection signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fish finder.

[0002]

2. Description of the Related Art Conventionally, a fish finder has employed a method of transmitting a pulsed ultrasonic wave into water and receiving and analyzing a reflected signal to determine the presence or absence of a target fish shoal.

[0003]

However, in the above-mentioned conventional fish finder, the available information is limited due to the slow response due to the characteristics of the ultrasonic waves, and even if a fish school is found due to the low directivity. It is not possible to specify whether the school of fish is directly below the ship or on the starboard or port side, and the school of fish can be recognized only as a planar two-dimensional image, so that the school of fish can be quickly and accurately detected. Could not do.

The present invention has been made in view of the above circumstances, and has as its object to provide a fish finder capable of obtaining a relative position of a fish shoal relative to a ship in a relatively detailed manner.

[0005]

According to the present invention, there is provided a fish finder for irradiating a burst signal by laser light into the sea, and irradiating the burst signal with a fixed orbit. And a light receiving unit for receiving a reflection signal of the burst signal, and a signal processing unit for processing the reflection signal. With this configuration, the processing result of the reflection signal is displayed as a chart using at least two axes of the traveling direction axis of the ship, the lateral direction axis of the ship, and the depth axis, and particularly includes the lateral direction axis of the ship. It is also possible to provide a configuration including display means for displaying a chart using at least two axes.

The burst signal has a wavelength of about 35.
It is desirable to use a light beam in the blue to near-ultraviolet region of visible light of 0 nm to 550 nm, which is generated intermittently as a burst (pulse) waveform for several to several tens of percent of the burst transmission period. To change the irradiation direction in a fixed orbit includes, for example, a case where the irradiation direction is linearly reciprocated or rotated in the side direction of the ship. Specific display modes by the display means include a two-dimensional image such as a cross-sectional image viewed from the direction of travel of the ship, a cross-sectional image viewed from the side of the ship, or a cross-sectional image viewed from above and below the ship; An image in which the region is viewed obliquely is exemplified.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fish finder according to the present invention will be described below in detail with reference to the drawings. In the embodiment exemplified here, as shown in the block diagram of FIG.
An irradiation direction changing means 2 for changing the irradiation direction of the burst signal in a fixed orbit, a light receiving unit 3 for receiving a reflection signal of the burst signal, a signal processing unit 4 for processing the reflection signal, A display data forming means 5 and a display means 6 for displaying the results of the processing in a chart using at least two axes of the ship's traveling direction axis, the ship's lateral axis, and the water depth axis; And a hull inclination detecting means 7 for detecting inclination in the left-right direction with respect to the traveling direction;
The hull position detecting means 8 is provided.

The light emitting section 1 is mounted downward on the bottom of a ship as shown in FIG. 1, and comprises a laser diode 9 as a light emitting element and a laser diode 9 as shown in FIG.
And a signal generator 10 for giving a waveform and irradiation timing. The signal generator 10 includes, for example, an oscillating unit 11 that generates a sine wave of a predetermined frequency and the like, and a timer 12 that forms an irradiation timing.
50 nm to 550 nm, velocity ν: 223,900,00
0 m / s burst waveform, burst width t: 0.1 μs
To several μs, burst transmission cycle T2: can be transmitted in a period of several μs to several tens μs.

The irradiation direction changing means 2 changes the irradiation direction of the laser diode 9 right and left with respect to the traveling direction of the ship. As a scanning mode, a range of about 15 degrees in the left and right directions about the axis fixed near the center line extending in the traveling direction of the ship (a distance of about several tens m
A structure having a scanning base capable of oscillating the width, or a structure for rotating the scanning base in one direction at a high speed to enable faster scanning, or a prism 19 disposed in front of a light source such as a laser diode. And the prism 19
Is rotated so that the burst signal is refracted and the irradiation direction is changed. In any case, it is necessary to provide a scanning amount detection sensor 13 for detecting the scanning amount (position change amount of the scanning point) of the light emitting unit 1. For example, the light emitting unit 1 and the prism 19 are rotated (oscillated). In this case, a rotary encoder or the like may be used.

The light receiving section 3 is mounted downward on the ship bottom together with the light emitting section 1 as shown in FIG. 1, and for example, as shown in FIG. 3, using a photomultiplier tube 17 having light receiving selectivity in terms of wavelength. The reflected signal of the burst signal is received, and the received level (potential) is level-converted appropriately by the amplifier 18 to form an evaluation value for judging the presence or absence of a school of fish. As described above, the burst signal is radiated over a fixed width in the horizontal direction of the hull, so that the signal can be received at a relatively large diameter and wide angle so that the entire range can be received without tracking according to the irradiation direction. It is desirable to use a hemispherical type photomultiplier tube capable of catching light from the viewpoint of improving the detection probability or reducing the manufacturing cost.

The signal processing section 4 is constructed as a computer system including a CPU, a memory, and the like. As shown in FIG. 3, an A / D converter 14 for digitizing the evaluation value, a digitized evaluation value A storage means 15 for storing the evaluation value; a calculation means 16 for analyzing the evaluation value;
Display data forming means 5 for converting the analysis result into image data
Is provided.

The display means 6 receives the image data formed by the signal processing section 4 and displays the image data on a display of a liquid crystal display or a CRT. If necessary, an alarm generating means (not shown) is provided. There is also.

The hull inclination detecting means 7 includes various acceleration sensors and the like, and the hull position detecting means 8 includes a so-called GPS.
(Global Positioning System).

The burst signal by the laser beam has an advantage that the directivity is sharp, the irradiation destination is determined at a pinpoint, and the response, that is, a large amount of underwater information can be obtained in a short time due to its high speed. In addition, 350 nm to 550 irradiated by the light emitting unit 1
Those having a wavelength of nm have the least attenuation due to passing through seawater, and can reach a distance of several hundred meters in principle.

The burst signal emitted from the light emitting unit 1 into the sea is reflected by an obstacle in the sea, and the reflected signal is detected by the light receiving unit 3 at each burst transmission cycle T2, and is used as the evaluation value. The data is digitized by the A / D converter 14 of the signal processing unit 4 and stored in the storage unit 15.
At this time, in synchronization with the burst transmission cycle T2, the hull inclination data, the hull position data and the scanning amount data detected from the hull inclination detecting means 7, the hull position detecting means 8 and the scanning amount detecting sensor 13 are converted into the reflection signal. Is stored together with the evaluation value of.

In such underwater detection, by designing the time required per unit scan to be within 0.5 ms, it is possible to scan the distance that the ship advances in one second more than 2,000 times. While adjusting the cycle,
By examining the level displacement ΔV / Δs (ΔV: amount of level change of the reflected signal received, Δs: amount of position change of the ship in the direction of travel) in the traveling direction, it is possible to estimate the presence and type of fish school Becomes

Further, by satisfying the specification enabling transmission in the burst transmission period T2, irradiation of a burst signal and reception of a reflected signal of the irradiated burst signal at a practical water depth can be ensured during one period. And several tens to several hundreds of locations can be detected during a unit scan. In this case, by scanning the ship sideways, the level displacement ΔV / Δθ (ΔV: the amount of change in the level of the received reflected signal, Δθ: the amount of change in the scanning direction) in the sideways direction of the ship is examined, so that the fish school The presence / absence and its type can be estimated with relatively high accuracy.

When detecting the reflection signal, the coordinates of the horizontal direction with respect to the hull are obtained from the output of the scanning amount detection sensor 13 for detecting the scanning direction, and stored in the storage means 15 of the signal processing unit 4 together with the evaluation values. By doing so, the planar distribution of the school of fish with respect to the hull can be ascertained from the level distribution of the reflected signal with respect to the coordinates, and the water depth at which the fish school exists can be ascertained from the level intensity of the reflected signal. When using a burst signal by laser light to determine the water depth at which a school of fish exists, the sound velocity can be compared with a sound velocity of about 10 mm or less per meter (2 m to 5 m when the water temperature changes by 1 ° C). It will be a small value that does not have to be.

The signal processing section 4 can estimate the presence or absence and the type of fish school based on the level displacement in the traveling direction and the side direction of the ship. As an estimation method, the scanning cycle is adjusted as described above. At the same time, the burst transmission period T2 is increased or decreased stepwise in units of half (or a positive multiple thereof) the scanning period, and the burst transmission period T2 that has the most remarkable level displacement is found. It is estimated from the correspondence between the cycle T2 and the types of fish constituting the fish school. It is also conceivable that this estimation result is further linked to the water depth at which the school of fish exists to make it more reliable.

The display data for displaying an image on the display means 6 includes the evaluation value which is the level data of the reflection signal, the coordinates of the axis in the traveling direction of the ship derived from the output of the hull position detection means 8, and the output of the scanning amount detection sensor 13. Which has two-dimensional coordinates consisting of lateral axis coordinates derived from the above, and further comprises water depth axis coordinates derived from the evaluation value, and further includes a tilt component derived from the output of the hull tilt detection means 7. The coordinates are corrected in consideration of the above, and the base data obtained by converting the evaluation value distribution in the three-dimensional coordinate system into data is edited into a form that can be visualized. For example, the evaluation value distribution thus derived is
A symbol corresponding to the evaluation value is recorded in a memory space paged for each frame by imitating a three-dimensional coordinate system, and in response to a request by an input operation to the signal processing unit 4, the space is set to one of three axes. The evaluation value distribution (two-dimensional image (see FIGS. 4 to 6)) on the cross section cut along or obliquely or the evaluation value distribution (three-dimensional image)
The image is edited as flat image data designed to make the frame easy to see and output to the display means 6.

The burst transmission period T2 and the scanning period are selected from practical burst transmission periods in consideration of the realization of a real-time screen display and the signal processing time in the current technical level. However, it is also possible to make the burst transmission period T2 shorter with the advance of technology.

[0022]

As described above, when the fish finder according to the present invention is used, a large amount of underwater information can be obtained in a short time due to the sharpness of the directivity and the speed of response, which are the characteristics of the laser beam. It is possible to relatively quickly and accurately determine the detailed positional relationship and size of the school of fish, which has been difficult to determine with a detector, and the type of fish that make up the school of fish. In addition, it is possible to obtain a planar image composed of a two-dimensional coordinate system or a three-dimensional image composed of a three-dimensional coordinate system as an easily recognizable image from the data, and whether the fish school exists directly below the ship. Or, it can be easily recognized whether it exists on the starboard side or the port side, or in what depth area it exists, even if the person is unfamiliar.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a fish finder according to the present invention.

FIG. 2 is a block diagram illustrating an example of a light emitting unit and an irradiation direction changing unit of the fish finder according to the present invention.

FIG. 3 is a block diagram illustrating an example of a light receiving unit and a signal processing unit of the fish finder according to the present invention.

FIG. 4 is a block diagram showing an example of a screen display of a fish finder according to the present invention.

FIG. 5 is a block diagram showing an example of a screen display of a fish finder according to the present invention.

FIG. 6 is a block diagram showing an example of a screen display of a fish finder according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light emitting unit 2 irradiation direction changing unit 3 light receiving unit 4 signal processing unit 5 display data forming unit

Claims (2)

[Claims] A light emitting unit for irradiating a burst signal by a laser beam into the sea; an irradiation direction changing means for changing an irradiation direction of the burst signal in a constant orbit; and a reflection signal of the burst signal. A light receiving unit (3) for receiving;
A fish finder comprising: a signal processing unit (4) for processing the reflected signal. 2. The signal processing unit (4) displays a result of processing the reflected signal in a chart using at least two axes of a ship traveling direction axis, a ship lateral direction axis, and a water depth axis. The fish finder according to claim 1, further comprising a display data forming means (5) adopting the following formula.