JPH0321497Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a fish finder in which the recorded concentration on the recording paper of a pen recorder is displayed in stepwise proportion to the back volume scattering intensity of the fish school. It is.

(Prior Art) Traditionally, fish finders transmit sound waves into the sea, which are reflected by schools of fish, receive the returned sound waves, convert them into electrical signals, and amplify them. A reflected signal voltage (echo voltage) is applied to the pen of the pen recorder to draw an image of a school of fish on recording paper.
The image density of the fish school image on this recording paper is such that if the reflected sound waves from the fish school are strong, they will be drawn darker, and if they are weak, they will be drawn lighter, so by observing the density of the image on the recording paper, it is possible to know the approximate density of the fish school. Therefore, I used this image density as a guideline for operation.

On the other hand, recently, it has been proposed that it is necessary to quantitatively investigate fishery resources in a certain water area using fish finders, and such investigations have begun to be carried out.
One way to measure the size of individual fish and the density of fish schools in these surveys is to use the size and recorded density of fish school images on the recording paper of the pen recorder of the fish finder as clues.

(Problems to be solved by the invention) However, there is a problem in that the conventional fish finder as described above cannot conduct accurate quantitative surveys.

The main cause of this problem is that the recording paper has a non-linear relationship between recording voltage and recording density, so the density of the fish school image drawn on the recording paper is proportional to the voltage applied to the pen (recording voltage). That means no. An example of the recording voltage (applied voltage) vs. recording density characteristics of currently used recording paper is shown in FIG. Figure a shows an example of wet type recording paper, and figure b shows an example of dry type recording paper. In either example, when the applied voltage exceeds a certain level, the change in concentration becomes saturated and becomes dull.

Furthermore, even during the change, the relationship between the applied voltage and the concentration exhibits a curved rather than linear characteristic. Therefore, even if the voltage applied to the pen has a value that is faithfully proportional to the size of an individual fish or the density of a school of fish (a value that is proportional to the back volume scattering intensity), the image density on the recording paper will vary depending on the size of an individual fish or the density of a school of fish. There is a problem that it is not faithfully proportional to the density of .

(Means for Solving the Problems) The present invention takes into consideration the problems of the conventional fish finder as described above, and the image density on the recording paper is proportional to the size of a single fish in the sea or the density of a school of fish, that is, the back volume scattering intensity. It is an object of the present invention to provide a fish finder that displays information in stages according to a predetermined number of stages. That is, in a pen recorder that uses recording paper whose recording density changes with changes in the recording voltage applied to the pen, and in a fish finder that has a receiving amplifier with TVG, the recording voltage vs. recording density characteristic has a non-linear characteristic. Paper: The echo voltage that is the output of the TVG receiving amplifier is input, and the input voltage changes stepwise in a certain interval along a nonlinear characteristic that is opposite to the nonlinear characteristic of the recording voltage vs. recording density characteristic of the recording paper. A recording voltage correction circuit that outputs a voltage as a recording voltage to a pen recording device;

FIG. 1 is a block diagram showing the configuration of the measuring fish finder of the present invention. 1 is a transmitter, 2 is a transducer, 3 is a receiver with TVG, 4 is a recording voltage correction circuit, 5 is a pen, and 6 is recording paper. Here, above
TVG stands for Time Variable Gain, meaning that the time-varying gain, that is, the amplification gain changes over time.A receiving amplifier with TVG means that the amplification gain varies depending on whether it is a school of fish or a single fish. A receiver amplifier that changes over time to compensate for attenuation due to distance.

(Function) The sound wave received by the transducer 2 is converted into an electric signal, amplified by the reception amplifier with TVG 3, and output as an echo voltage. TVG (Time Variable
The gain) circuit controls the gain of the receiving amplifier so that even if the distance from the transducer 2 to the school of fish is different, the echo voltage due to the sound waves reflected from the same size of fish or the same density of fish will be output at the same value. This is the adjustment circuit. In general, the intensity of the sound waves reflected from a single fish received by the transducer is inversely proportional to the fourth power of the distance between the transducer and the single fish, and the intensity of the sound waves reflected from a large school of fish is received by the transducer. It is said that the intensity of the transmitted wave is inversely proportional to the square of the distance between the transducer and the school of fish.
Therefore, when looking at a particular school of fish, the same value of echo voltage can be obtained whether the fish school is far from the transducer 2 or close to it, as long as the state of the fish school (i.e., back volume scattering intensity) does not change. Conversely, when the backscatter intensity changes, in order to obtain an echo voltage proportional to this, it is necessary to change the gain of the receiving amplifier according to the distance. On the other hand, since the time from the emission of the sound wave until the reception of the wave corresponds proportionally to the distance to the school of fish, etc., it is preferable to change the gain of the receiving amplifier according to the time after the emission of the sound wave.

In the weighing fish finder of the present invention, the receiving amplifier 3 with TVG is used because the echo voltages from schools of fish etc. in the same state need to be the same value even if the distances are different. Receiving amplifier 3 with TVG
The echo voltage (hereinafter referred to as _VE ) which is the output of is applied to the recording voltage correction circuit 4.

Input voltage vs. output voltage characteristics of recording voltage correction circuit,
That is, echo voltage V _E versus recording voltage (hereinafter referred to as V _R )
The characteristic is the recording voltage V _R applied to the recorder pen
It has a characteristic of outputting a voltage that changes stepwise in each fixed section of the input voltage along a non-linear characteristic that is the opposite of the non-linear characteristic of the recording density (hereinafter referred to as N) characteristic of the recording paper.

First, the above-mentioned reverse non-linear characteristic means that the recording voltage correction circuit has a characteristic in which V _E / _VR is proportional to N/ _VR of the recording paper. In other words, the input/output voltage characteristics of the recording voltage correction circuit are plotted with the horizontal axis of the recording voltage _VR , which is the output voltage, and the vertical axis of the echo voltage V _E , which is the input voltage, or the characteristic curve is drawn vertically. A characteristic curve that expands or contracts at a constant rate in the axial direction, with the recording voltage V _R on the horizontal axis,
This means that it is equal to the characteristic curve of the recording paper with the recording density N on the vertical axis.

If the characteristic curve of such a recording voltage correction circuit is expressed by taking the echo voltage V _E on the horizontal axis and the recording voltage V _R on the vertical axis, it will become a curve 10 in FIG. 3. Curve 10 in the figure a shows the characteristic when the echo voltage is within a certain range, and the curve b in the figure corresponds to a case where the echo voltage has a wider variation range, that is, when the dynamic range is wider. 2 shows a curve obtained by enlarging the characteristic curve in the horizontal axis direction.

The recording voltage correction circuit used in the present invention has a characteristic of outputting a voltage that changes in steps along the characteristic curve 10 for each fixed section of the input voltage. for example,
If the echo voltage V _E , which is the input voltage, changes stepwise at intervals of 10 V along the curve 10 of FIG.

As an example of a circuit that realizes such voltage input/output characteristics, a circuit as shown in FIG. 4 can be considered, for example, and various other circuit examples can be easily realized. 12 is an input terminal, 21 is an output terminal, 13 to 16 are comparators, and 17 to 20 are switches. Input terminals 1 of the comparators 13 to 16 are commonly connected and input voltages are commonly applied thereto. Reference voltages set at equal intervals such as E to 4E are applied to the input terminals 2 of the comparators 13 to 16.
The output signals of comparators 13 to 16 are applied to switches 17 to 20, respectively, and when the voltage at input terminal 1 of each comparator is lower than the reference voltage at input terminal 2, the movable element of each switch is applied to contact B. On the other hand, when the reference voltage of the input terminal 2 is higher than the reference voltage of the input terminal 2, the contact A is connected.

On the other hand, output voltages V ₁ to V ₄ of predetermined levels are applied to the contacts A of the switches 17 to 20, respectively. Since it is configured like this,
Now, when the voltage V _E applied to the input terminal 12 begins to rise from zero volts, the voltage appearing at the output terminal 21 becomes as follows. That is, when V _E is from 0 to E, all the movers of switches 17 to 20 are connected to contact B, so it is zero, and from E to 2E, the mover of switch 17 is connected to contact A, so V ₁ ,
Between 2E and 3E, the mover of switch 18 is contact A.
Since it is connected to , it becomes V ₂ , and between 3E and 4E, the mover of switch 19 is connected to contact A, so
At 4E or _higher , the movable element of the switch 20 is connected to contact A, so the voltage becomes V ₄ .

Therefore, by setting the above-mentioned V ₁ to _{V 4} to correspond to the voltages at each stage of the voltage characteristics 11 shown in FIG. 3a, the desired characteristics can be easily obtained.

Now, when the output voltage (echo voltage) of the receiving amplifier with TVG is applied to the pen recorder via the recording voltage correction circuit having the characteristics as described above, the relationship between the echo voltage and the image density on the recording paper is shown in Figure 3a. This is a combination of the voltage characteristic 11 shown in FIG. 2 and the recording voltage vs. image density characteristic shown in FIG. 2a.

The result of combining these two characteristics is shown in FIG. 5 when the echo voltage V _E is plotted on the horizontal axis and the image density is plotted on the vertical axis.

Therefore, if an echo voltage proportional to the back volume scattering intensity of a school of fish is input to the recording voltage correction circuit 4, and the output voltage is applied to the pen of the pen recorder as a recording voltage, the density of the image of a school of fish on the recording paper will be the same as the school of fish, etc. It is proportional to the back scattering intensity in stages.
Therefore, by observing the image density on the recording paper, quantitative data can be obtained to know the species and size of a single fish, and if it is a school of fish, it can be used to know the density of the fish species and school. quantitative data can be obtained.

FIG. 6 shows an example of a fish school image 22 recorded on the recording paper of the weighing fish finder of the present invention. 23 shows an example of a density scale for determining observed values corresponding to the density of each stage of a fish school image.

(Effects of the invention) As explained above, the weighing fish finder of the invention uses the echo voltage, which is the output voltage of the receiving amplifier with TVG, to Since the image density on the recording paper is applied to the recorder pen via a recording voltage correction circuit that outputs a voltage that changes stepwise at each fixed interval of the input voltage according to non-linear characteristics, the image density on the recording paper varies depending on the echo voltage. Each category exhibits a proportionally graded concentration.

In a weighing fish finder, by using a receiving amplifier with a TVG, the output echo voltage is proportional to the back volume scattering intensity of a single fish or a school of fish, regardless of the distance from the transducer. Images such as , etc. are projected as concentrations that are stepwise proportional to their backscattered volume intensities. Therefore, by quantitatively understanding the image density on the recording paper, it is possible to accurately determine the species and size of a single fish, and the density of a school of fish. . Therefore, in addition to being able to carry out operations at fishing grounds efficiently, there is also the advantage that quantitative data with higher accuracy than before can be collected in surveys of fishery resources.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the weighing fish finder of the present invention, Figure 2 is a characteristic curve showing an example of the recording voltage vs. density characteristic of recording paper, and Figure a is an example of wet recording paper; Figure b is an example of dry recording paper, Figure 3 is a characteristic curve showing an example of the stepwise output characteristic of the echo voltage versus recording voltage of the recording voltage correction circuit, and figure a is the characteristic curve for the case where the echo voltage range is up to about 50V. Characteristic example, Fig. 4b is a characteristic example when the echo voltage range is up to about 100V.
The figure is a block diagram of a specific configuration example of the recording voltage correction circuit, Figure 5 is a diagram showing the characteristics of the recording paper density with respect to the echo voltage in the weighing fish finder of the present invention, and Figure 6 is a diagram showing the characteristic of the recording paper density with respect to the echo voltage in the weighing fish finder of the present invention. FIG. 3 is a diagram showing an example of a fish school image on a recording paper in a fish finder. 1... Transmitter section, 2... Transducer/receiver, 3... TVG
Receiving amplifier with attached, 4... Recording voltage correction circuit, 5...
Pen, 6...Recording paper, 10...Curve showing a nonlinear characteristic opposite to the nonlinear characteristic of recording voltage vs. recording density of the recording paper, 11...Output voltage follows curve 10 for each fixed section of input voltage. 12...Input terminal, 13-16...Comparator (comparator), 17-20...Switch, 21
... Output terminal, 22 ... Fish school image, 23 ... Density scale.

Claims (1)

[Scope of utility model registration request] A pen recording device that uses recording paper whose recording density changes depending on the recording voltage applied to the pen.
In a fish finder with a receiving amplifier with TVG,
A recording paper whose recording voltage vs. recording density characteristic has a non-linear characteristic; the echo voltage which is the output of the TVG receiving amplifier is input, and the recording paper has a non-linear characteristic which is opposite to the non-linear characteristic of the recording voltage vs. recording density characteristic of the recording paper. 1. A recording voltage correction circuit for outputting a voltage that changes stepwise at each fixed interval of input voltage to a pen recorder as a recording voltage.