JPH02711Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a quantitative measurement method for quantitatively measuring the unit volume scattering intensity of a school of fish and the single reflection intensity (target intensity) of a single fish, and for determining the density of a school of fish. Regarding fish finders.

(Prior Art and Problems) In recent years, fish finders have been used to investigate fishery resources, but a relatively simple integration method has been adopted as a method for using conventional fish finders.
This method involves navigating the target water area like a net while operating a fish finder, integrating signals from fish schools detected during navigation, and calculating the total amount of resources in the target water area or their average volumetric scattering. The purpose of this method is to find out the intensity, and it is not possible to measure the reflection intensity of each individual fish (hereinafter referred to as target intensity). Therefore, to determine the density of a school of fish, the average density was estimated by dividing the average volume scattering intensity obtained by the integral method by a target intensity that seemed appropriate. Therefore, errors naturally occur when schools of different species of fish coexist in the survey area. Furthermore, even if only the same species of fish were present in the water, the target strength had to be estimated, and even if measurements were to be taken, they could not be carried out at the same time when surveying the water, resulting in a lack of accuracy.

The purpose of this invention is to consider the above-mentioned conventional problems, and to
The object of the present invention is to provide a measuring fish finder that can actually measure both the unit volume scattering intensity and the target intensity of a school of fish.

(Means for solving the problems) The present invention has the following configuration to achieve the above object. That is, when the input terminals are connected to the same transducer, from the point of transmitting the ultrasonic pulse, the time corresponding to the underwater distance from the transducer is 2 times
A square-law characteristic reception amplifier in which the amplification gain increases in proportion to the power of the power, and a 4-power characteristic reception amplifier in which the amplification gain increases in proportion to the fourth power of the time corresponding to the underwater distance from the transducer. a first storage circuit that stores the output signal of the square power characteristic reception amplifier; and a second storage circuit that stores the output signal of the fourth power characteristic reception amplifier.
a timing control circuit that controls timing of signal readout of the first and second storage circuits, and a timing control circuit that controls readout signals of the first storage circuit and a second
a composition circuit that outputs read signals of the memory circuits of the pen recorder to a common output terminal; a correction circuit that corrects the image recording density on the recording paper of the pen recorder so that it is proportional to the output voltage of the composition circuit; This is a weighing fish finder with

(Function) In general, when a sound wave with an acoustic output Io emitted from a transducer of a fish finder travels a distance R, it undergoes diffusion loss and absorption loss, and its intensity is Io・e ^- 〓 ^R / in the case of spherical diffusion. R ² (where α is the absorption coefficient). If there is a single fish with an equivalent cross-sectional area σ at this distance, its reflection intensity is expressed as Io・e ^- 〓 ^R /R ²・σ. Using this as a virtual sound source, the sound source retraces the same path. reaches the receiver. Therefore, the reflection intensity I _e at the receiver surface is I _e = Io・e ^- 〓 ^R /R ₂・σ・e ^- 〓 ^R /R ₂ = Ioσe ^-2 〓 ^R /R ⁴ ...(1) , after all, in the case of a single fish, it is inversely proportional to the fourth power of the distance.

If the fish is not a single fish but a group, the equivalent cross-sectional area of the fish must be determined by considering the total power of reflection. If the distribution of fish is uniformly random, the reflected power will be the sum of the individual reflected powers on average. Therefore, if the average equivalent cross-sectional area per fish is n and the number of fish is n, then the reflected wave intensity I _e ′ at the receiver surface is I _e ′=Io/R ⁴・e ^-2 〓 ^R・n・ …(2) becomes.

By the way, if the beam width (solid angle) is φ, the pulse length is τ, and the speed of sound is c, the beam irradiation volume v before and after the distance R from the transducer is v=R ²・φ・cτ/2 . Now, if the density of fish in this volume is ρ, the number n of fish in this volume is n=ρ・v=ρ・R ²・φ・cτ/2 (3). Inserting n in equation (3) into equation (2), the reflected wave intensity I _e ′ is: I _e ′=Io/R ⁴・e ^-2 〓 ^R・ρ・R ² φ・cτ/2=Io/ 2
R ²・e ^-2 〓 ^R ρφcτ…(4) In the case of a school of fish, it is inversely proportional to the square of the distance (for more details, see "Marine Acoustics - Basics and Applications", 1982) March 1st, edited and published by Marine Acoustics Research Group, pp. 244-246).

Focusing on this point, the weighing fish finder of the present invention first identifies whether the received video signal is from a school of fish or a single fish, and then calculates the unit volume scattering intensity of the school of fish. The objective is to quantitatively understand the target strength of each individual fish, and then to determine the density of fish schools.

In the weighing fish finder of the present invention, a square power characteristic receiving amplifier and a fourth power characteristic receiving amplifier whose gain is controlled by time variable gain (TVG) transmit signals from a transducer in parallel. It is amplified. At the output of the square-law characteristic reception amplifier, an echo voltage proportional to the unit volume scattering intensity is output from the reflected signal from the school of fish, regardless of the distance. Furthermore, in the output of the fourth power characteristic reception amplifier, an echo voltage proportional to the target intensity is outputted from the reflected signal from a single fish regardless of the distance. These signals based on the echo voltage are stored in the first storage circuit and the second storage circuit, and the readout is performed by the timing signal of the timing control circuit, and the image and the output signal of the square characteristic receiving amplifier are stored.
read out in a preset order such that images by the output signals of the multiplicative receiving amplifier are drawn separately;
It is added to the synthesis circuit to make the output point common. The output of the synthesis circuit is corrected by a correction circuit so that the image density on the recording paper of the pen recorder is proportional to the echo voltage. The output voltage of the correction circuit is applied to the pen of the pen recorder, so that a separate image is drawn on the recording paper with a density proportional to the echo voltage of each receiving amplifier. Therefore, the density of the image of the fish school (hereinafter referred to as the square characteristic image) drawn by the output signal of the square-law characteristic receiving amplifier is proportional to the unit volume scattering intensity of the fish school, while the density of the image drawn by the output signal of the square-law characteristic receiving amplifier is proportional to the unit volume scattering intensity of the fish school. The density of the image of a single fish (hereinafter referred to as the fourth power characteristic image) drawn by the output signal of is proportional to the target intensity. Therefore, by providing in advance a concentration scale calibrated with the unit volume scattering intensity or target intensity, the unit volume scattering intensity of a school of fish or the target intensity of a single fish can be directly and quantitatively determined.

Identifying a school of fish or a single fish on the image on the recording paper
In the case of a single fish, it is weak or does not appear in the square characteristic image, but it shows a clear point-like image in the fourth power characteristic image, so it can be easily identified.

As described above, the unit volume scattering intensity of a school of fish and the target intensity of a single fish near the school can be quantitatively measured simultaneously under the conditions that the underwater conditions and the fish finder used are the same. , the density of the fish school will be obtained by dividing the unit volume scattering intensity by the target intensity.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. The sound wave received by the transducer 1 is converted into an electrical signal, which is applied to a square characteristic receiving amplifier 2 and a fourth power characteristic receiving amplifier 3, where it is amplified. The output signals of the respective amplifiers are converted into digital signals by A/D converters 4 and 5 and applied to the storage circuits 6 and 7 for storage in digital operation. The timing control circuit 8 generates a timing signal for reading at a predetermined timing so that the square characteristic image and the fourth power characteristic image are drawn separately on the recording paper of the pen recorder 13, Control 7. The output of each memory circuit is connected to a D/A converter 9 and a D/A converter 1 for converting it into an analog signal for drawing with a pen recorder.
Added to 0. The signals converted to analog signals are unified in output by a synthesis circuit 11 and sent to a correction circuit 12.
added to. The correction circuit 12 corrects the image density of the recording paper of the pen recorder 13 so that it is proportional to the output voltage level of the synthesis circuit 11, and applies it to the pen recorder.

FIG. 2 shows waveforms of various parts in the configuration of FIG. 1. Figure a is the output electrical signal of the transducer, Figure b is Figure a
The signal is amplified and detected by the square-law characteristic receiving amplifier 2, and the output voltage waveform is the same. Figure c shows the output voltage waveform of the fourth-law characteristic receiving amplifier 3, and the echo signal 19 of a single fish appears more prominently in figure c. ing. Figure d
is the output waveform of the synthesis circuit 11 and shows that the signal in FIG. c is read out after the signal in FIG. b.

FIG. 3 shows an example of an image of a school of fish or a single fish drawn on the recording paper based on the above-mentioned signals. Figure a is a square characteristic image, and 14 shows a school of fish. Figure b is a 4th power characteristic image, 15 is a school of fish, and 16
~18 indicates a single fish.

(Effect of the invention) Since the measuring fish finder of the invention has the configuration and function described above, it can quantitatively grasp the unit volume scattering intensity of a school of fish and the target intensity of a single fish simultaneously under the same conditions. This allows us to accurately determine the density of each school of fish.
Compared to the conventional integration method, which calculates the total amount of fish in a given water area, regardless of whether it is a school of fish or a single fish, and divides it by the estimated uniform target intensity to obtain the average volume scattering intensity. This has the advantage of making it possible to conduct dramatically more accurate surveys of fish resources.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an embodiment of the present invention, Fig. 2 is a diagram showing signal waveforms of each part in the configuration of Fig. 1, and Fig. 3 is a diagram showing the recording paper of the weighing fish finder of the present invention. It is a figure which shows the example of an image. 1... Transducer/receiver, 2... Square characteristic receiving amplifier,
3...4th power characteristic receiving amplifier, 4, 5...A/D converter, 6, 7...memory circuit, 8...timing control circuit, 9, 10...D/A converter, 11...synthesis Circuit, 12... Correction circuit, 13... Pen recorder, 14, 15... Image of fish school, 16, 17, 1
8... Image of a single fish, 19... Echo voltage waveform of a single fish.

Claims (1)

[Scope of utility model registration request] The input ends are connected to the same transducer, and the amplification gain increases in proportion to the square of the time corresponding to the underwater distance from the transducer from the point of transmitting the ultrasonic pulse2. a square-law characteristic receiving amplifier, a fourth-law characteristic receiving amplifier whose amplification gain increases in proportion to the fourth power of the time corresponding to the underwater distance from the transducer, and an output signal of the square-law characteristic receiving amplifier. a first storage circuit that stores the output signal of the fourth power characteristic reception amplifier;
a timing control circuit that controls signal readout timing of the first and second storage circuits;
a composition circuit that outputs the readout signal of the first memory circuit and the readout signal of the second memory circuit to a common output terminal; and a composition circuit that corrects the image recording density on the recording paper of the pen recorder so that it is proportional to the output voltage of the composition circuit. 1. A fish finder for weighing, characterized by having a correction circuit that performs the correction, and a pen recorder.