JPS6259881A - Fish school locater - Google Patents

Abstract

PURPOSE:To display a fish school an plural indication screens by driving plural ultrasonic wave vibrators at slightly different transmission frequencies and transmitting ultrasonic waves. CONSTITUTION:Respective frequency outputs fa-fc from oscillators 401a-401c are transmitted through ultrasonic wave vibrators 2a-2c of a transmitter receiver 41, reflected by the sea bottom, etc., and received by the vibrators 2a-2c. When transmission/reception switches 41a-41c are placed at reception sides, the received signals are passed through resistors 430a-430c and added 431 together. The added received signal is amplified by a preamplifier 432 and then supplied to mixers 433a-433c. The mixers 433a-433c mix the received signals of frequencies fa-fc with outputs of frequencies fca-fcc supplied thereto an only specific frequencies among mixture outputs are passed through filters 434a-434c constituting a frequency demultiplexing means and main amplifiers 435a-435c and amplified by video amplifiers 440a-440c respectively. Their amplification outputs are swept by sweepers 441a-441c and displayed on plural CRTs 442a-442c.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an ultrasonic transducer installed on the bottom of a ship, etc. for transmitting and receiving ultrasonic waves, and an ultrasonic echo received by the ultrasonic transducer. The present invention relates to a fish finder equipped with an indicator that displays the status of fish schools, the seabed, etc. on an instruction screen based on signals received by the fish finder.

(Prior art) In this type of fish finder, by sharpening the directivity angle of the ultrasonic waves transmitted from the ultrasonic transducer, the screen resolution for displaying fish schools and the seabed on the instruction screen can be improved. I can do it. However, while a sharp pointing angle has the advantage of improving resolution, it has the disadvantage of increasing the likelihood of detection failure. Therefore, in order to eliminate this drawback, multiple ultrasonic transducers with sharp directivity angles are arranged on the bottom of the ship, etc., and each ultrasonic wave is displayed on the instruction screen of the indicator provided corresponding to each ultrasonic transducer. Images of schools of fish etc. received by the transducer are displayed.

According to this, since each ultrasonic transducer has a sharp directivity angle, it is possible to obtain an image of a school of fish etc. with excellent resolution. This makes it possible to make effective use of the above-mentioned advantages, and also to eliminate the above-mentioned drawbacks by reducing detection failure due to the plurality of ultrasonic transducers.

By the way, in the directivity of ultrasound transmitted from an ultrasound transducer, there is a main pole (main lobe) and several subsidiary poles (site lobes) that occur on which side of the spread shape. Among the ultrasonic transducers installed on the bottom of the ship, there is an ultrasonic transducer (center ultrasonic transducer) that transmits ultrasonic waves in a direction that includes the seabed directly below, and an ultrasonic transducer arranged next to it. Child(
If adjacent ultrasonic transducers were driven at the same transmission frequency, the following problems occurred. That is, if the ultrasound echoes from the central ultrasound transducer are reflected from below the central ultrasound transducer, for example, if the main lobe has a strong ultrasound intensity, this main lobe may be reflected from the adjacent ultrasonic transducer. The signal is received by the sidelobe of the sound wave transducer. Therefore, on the instruction screen of the indicator of the received signal of the adjacent ultrasonic transducer, not only an image of the seafloor due to the main lobe of the adjacent ultrasonic transducer but also a virtual image of the seafloor (submarine sub) due to the side lobe of the adjacent ultrasonic transducer is displayed. I put it away in No.1.

Such submarine subs are undesirable because they can be mistaken for schools of fish, etc., so conventionally, for example, the transmission frequency of the central ultrasonic transducer and the transmission frequency of adjacent ultrasonic transducers are made to be significantly different, and the central ultrasonic transducer is The main lobe of the sonic transducer is prevented from being received by the side lobes of the adjacent ultrasonic transducer, so that the submarine sub is not displayed on the instruction screen.

However, in ultrasonic transducers having such widely different transmission frequencies, there are large differences in images on the instruction screen based on the reception signals received by each ultrasonic transducer. This difference is, for example, in that a school of fish, etc. is displayed on one instruction screen, but a school of fish, etc. is not displayed in the same way on another instruction screen. In addition to this, since it is not possible to use the same main ultrasonic transducer, there is a problem that the cost of incorporating the ultrasonic transducer into the fish finder is high.

(Objective of the Invention) The object of the present invention is to solve the above-mentioned problems by making it possible to use the same main ultrasonic transducer without significantly changing the transmission frequency. .

(Structure of the Invention) In order to achieve such an object, the present invention includes a plurality of ultrasonic transducers arranged at a predetermined arrangement angle on the bottom of a ship, etc. A transmission system circuit that drives the vibration with the output of a hollow transmission frequency, a reception system circuit that processes the received signal from the ultrasonic transducer, and an indicator that displays the seabed etc. based on the reception system circuit output. The specified receiving system circuit includes frequency separating means for frequency separating the received signals of frequencies corresponding to each of the ultrasonic transducers, and the specified indicating device separates the received signals from each frequency separating means, respectively. It is characterized by being displayed on an instruction screen.

(Description of Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings. FIG. 1 and FIG. 2 are diagrams for explaining the principle of the fish finder according to this embodiment.

FIG. 1 is a diagram showing the relationship between the bottom of a ship, an ultrasonic transducer installed therein, and the main lobe and side lobe of the ultrasonic wave transmitted from the ultrasonic transducer. In Figure 1, ■ indicates the bottom of a ship equipped with an ultrasonic transducer for a fish finder, and 2 a, 2 b, and 2 c indicate the ultrasonic transducers mounted on the bottom l of the ship in an arc.
'iii' and sends ultrasonic waves toward the ocean floor using an ultrasonic transducer. Note that, for convenience of explanation, a case is described in which there are three ultrasonic transducers, but it is sufficient if there are at least two or more ultrasonic transducers. 3 a
, 3 b, and 3 c are ultrasonic transducers 2 a, 3 c, respectively.
The main lobes of 2b and 2c, 4a1 and 4a2 are the sight lobes of the ultrasonic transducer 2a, 4b1 and 4b2 are the sight lobes of the ultrasonic transducer 2b, and 4c1 and 4c2 are the side lobes of the ultrasonic transducer 2c.

5 is the ocean floor. θ is the arrangement angle of each of the ultrasonic transducers 2a, 2b, and 2c installed on the bottom l of the ship.

FIG. 2 is a diagram for explaining the directional characteristics of the ultrasonic transducers 2 a, 2 b, and 2 c, and parts corresponding to those in FIG. 1 are given the same reference numerals. In Fig. 2, fa is the frequency (center frequency) at the point where the transmitting and receiving sensitivity of the ultrasonic transducer 2a is maximum, rb is the center frequency of the ultrasonic transducer 2b, and rc is the center frequency of the ultrasonic transducer 2C. be. Here, each of the ultrasonic transducers 2 a, 2 b, and 2 c is made of a material, such as a barium titanate-based material, such that the difference in frequency sensitivity characteristics decreases near the center during vibration transmission. Each ultrasonic transducer 2a, 2b, 2c has a center frequency faJ
The maximum sensitivity is obtained at b and rc, respectively. ΔF is a frequency range in which the ultrasonic transducers 2 a, 2 b, and 2 c do not experience an extreme decrease in sensitivity when transmitting and receiving waves, that is, can be detuned. 1
The center frequency of each ultrasonic transducer 2a, 2b, 2c is set for each detuned frequency range ΔF from the center frequency of one ultrasonic transducer. Such an ultrasonic transducer 2
a, 2b, and 2c are driven to transmit vibrations at the same time.

FIG. 3 is a circuit block diagram of a fish finder using ultrasonic transducers 2a, 2b, 2c as described in accordance with FIGS. 1 and 2.

40 is a vibration transmission system circuit. This transmission system circuit 40 has a transmission frequency fa to the ultrasonic transducers 2 a, 2 b, and 2 c.
, fb.

Oscillator 401a, 40 lb to provide an output of "C"
.

401c, power amplifiers 402a, 402b, 402
It consists of c.

41a, 4lb, 41c are each ultrasonic transducer 2a
, 2b.

This is a transmitting/receiving switch for switching between transmitting and receiving 2c.

42 is a transducer. This transducer 42 includes ultrasonic transducers 2 a, 2 b, and 2 c shown in numeral 11 on the right.

43 is a receiving circuit. This receiving system circuit 43 includes a resistor 430 that provides a weight for sensitivity correction based on the detuning frequency.
a, 430b, 430c, adder 431, preamplifier 432, output from preamplifier 432 and frequency fc
mixers 433a, 433b, and 433c as frequency separation means for mixing the outputs of a, fcb, and fcc, and filters 434a and 434a, also as frequency separation means.
34b, 434c and main amplifier 4.35a, 435
b, 435c.

44 is an indicator system circuit. The indicator system circuit 44 includes video amplifiers 440a, 4-40b, and 440c, and a sweeper 44.
1a, 441b, 44. lc and CRT442a.

442b and 442c.

45 is each transmission frequency output and CRT442a, 442b,
This is a keying pulse output circuit that outputs key ink pulses for synchronization with 442c.

Note that if the resistors 430a, 430b, and 430c are not provided, they are connected to the main amplifiers 435a, 435b, and 430c.
35c, and use it as a resistor for adjusting the amplification degree.

In the circuit having such a configuration, the transmitter/receiver switchers 41a, 4lb, and 41c of the fish finder are switched to the wave transmitting side.

Each frequency output from the oscillators 401a, 40 lb, and 401c is transmitted to each ultrasonic transducer 2 in the transducer 42.
given to a, 2 b, 2 c. Ultrasonic echoes output from each ultrasonic transducer 2a, 2b, 2c and reflected on the seabed etc. are transmitted to the ultrasonic transducer 2a, 2b.
, received at 2C. Transmission/reception switch 41a, 4 lb,
When 41c is switched to the receiving side, the ultrasonic transducer 2a, 2b, 2c receives the wave and converts it into an electrical signal.
30b and 430C and are added by an adder 431.

The added received signals are amplified by a preamplifier 432 and then output to mixers 433a, 433b, and 433c. The mixers 433a, =i 33b, 433C mix the received signals of frequencies fa, fb, and fc with the outputs of frequencies fca, fcb, and fcc given to each, and of the mixed output, only the output of frequency or "0" is mixed. passes through each filter 434a, 434b, 4.34c and is amplified by main amplifier 435a, 4.35b, 4.35c.As a result, each received signal of the ultrasonic transducer is separated in frequency. .

The outputs of the main amplifiers 435a, 435b, and 435c are
The signals are amplified by video amplifiers 440a, 440b, and 440c, respectively. The amplified output here is a sweeper 441a,
44 lb, swept by 441c and CRT-142
a, 442b, and 44.2c.

4 and 5 show ultrasonic transducers 2a and 2b.
FIG. 2 is a diagram illustrating the display on the instruction screen of each fish finder according to the conventional example and the present embodiment. As shown in FIG. 4, the main lobe from the ultrasonic transducer 2a is called the first main lobe, and the side lobes thereof are called the first main lobe. It is called the second side lobe. Further, the main lobe from the ultrasonic transducer 2b is called the second main lobe, and the side lobe thereof is called the third main lobe. It is called the fourth side lobe.

The seafloor corresponding to the first main lobe is called seafloor B, and the second
The ocean floor corresponding to the main lobe is called ocean floor C. Further, it is assumed that the second side lobe and the third side lobe are directed toward the ocean floor A directly below.

FIG. 5(a) shows the instruction screen of a conventional fish finder. The instruction screen on the left side of the drawing corresponds to the ultrasonic transducer 2a, and the instruction screen on the right side corresponds to the ultrasonic transducer 2b. Compatible. In FIG. 5(a), the diagonal line A' on the left instruction screen indicates the submarine sub-bottom generated by the vibration of the ultrasonic transducer 2h that is received by the second Zydrobe of the ultrasonic transducer 2a, and the dotted line indicates the ultrasonic transducer. The second side lobe of 2a is the submarine sub-bottom caused by the transmission of the received ultrasonic transducer 2a.

On the right side instruction screen, the diagonal line A'' indicates the submarine sub-bottom caused by the vibration of the ultrasonic transducer 2a received by the third side lobe of the ultrasonic transducer 2b, and the dotted line indicates the third side lobe of the ultrasonic transducer 2b. This is a sub-sea submarine created by the transmission of the received ultrasonic transducer 2b.

The cross-hatched area of B on the left side instruction screen is the ultrasonic wave j thousand 2
The image (real image of the ocean floor) produced by the first main lobe of a, and the cross-hatched area C on the right instruction screen are the image (real image of the ocean floor) produced by the second main lobe of the ultrasonic transducer 2b.

FIG. 5(b) is an instruction screen when the directivity angles of the ultrasonic transducers 2a and 2b are sharpened. As the directivity angle becomes sharper, the level difference between the main lobe and the side lobe increases, so the side that was transmitted by the submarine sub, that is, the ultrasonic transducers 2a and 2b themselves, at the dotted line at A° on the instruction screen. There will be no more underwater subs with lobes. In this instruction screen, the side lobe of the ultrasonic transducer 2a receives the submarine sub-bottom, which is transmitted by the ultrasonic transducer 2b. The submarine sub remains.

FIG. 5(c) is an instruction screen according to this embodiment.

In FIG. 5(C), the submarine sub that remained in FIG. 5(b) is no longer displayed. This is because, in this embodiment, the reception system circuit 43 performs frequency separation. That is,
The frequency is "A" on the left instruction screen in Figure 5 (11).
B is the submarine sub with frequency ``a''.Same as the right instruction screen] 2) is the submarine sub with frequency fa, and C is the submarine image with frequency rb. On the other hand, since frequency separation is performed, the obliquely shaded submarine sub-bottom is no longer displayed in FIG. 5(c).

(Effects of the Invention) As explained above, in the present invention, each ultrasonic transducer is driven to transmit at slightly different transmission frequencies. This eliminates the situation where the command is not displayed on the other instruction screen. Also,
The reception system circuit receives a reception signal of a frequency corresponding to each of the ultrasonic transducers. Since a frequency separation means is provided to separate one loss by one, and the received signals from each frequency separation means are displayed on the instruction screen of the indicator, each ultrasonic transducer can be composed of the same main one. This eliminates the high cost of incorporating this ultrasonic transducer.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining the principle of a fish finder according to an embodiment of the present invention, FIG. 3 is a circuit block diagram of the fish finder according to the embodiment, and FIGS. 4 and 5 FIG. 2 is a diagram illustrating the display on the instruction screen in the conventional example and the present embodiment. 40 is a transmission system circuit, 42 is a transducer, 2 a, 2 b
, 2C is an ultrasonic transducer, 43 is a receiving system circuit, 44 is an indicator system circuit, 433a, 433b, 433c are mixers,
4.34a, 434b, and 434c are filters.

Claims (1)

[Claims] (1) A plurality of ultrasonic transducers arranged at a predetermined arrangement angle on the bottom of a ship, etc., and a transmission system circuit that drives each of the ultrasonic transducers to vibrate with outputs of slightly different transmission frequencies. a receiving system circuit that processes the received signal from the ultrasonic transducer; and an indicator that displays the seabed etc. based on the receiving system circuit output, and the receiving system circuit is configured to process the received signal from each of the ultrasonic transducers. 1. A fish finder comprising: frequency separation means for frequency separating received signals of frequencies individually corresponding to the frequency separation means, wherein the indicator displays the received signals from each frequency separation means on an instruction screen.