JPH05288848A - Monitoring apparatus of school of fish coming into and going out from fishing net - Google Patents

Abstract

PURPOSE:To discriminate a school of fish coming into a fishing net from a school of fish going out from the fishing net and to display them by a method wherein a reflected signal from the bottom of the sea or from the fishing net is removed by a Doppler frequency for a received signal by means of a Doppler detection circuit and only a signal representing the school of fish is extracted. CONSTITUTION:At a wave transmitter-receiver 2, a burst signal at a prescribed duty ratio is converted into an ultrasonic pulse; the pulse is radiated into the water. The signal is reflected by a fish of school, by the bottom of the sea and by a fishing net; reflected waves are amplified to a required level by means of an ultrasonic reception circuit 3; they are input to a detection circuit 4 and to a Doppler detection circuit 5. At the circuit 4, the envelope detection of an input signal is performed, and an envelope signal is output to a signal extraction circuit 6. On the other hand, at the circuit 5, the Doppler frequency of the input signal is detected, and information on the movement of a reflecting object is output. At a circuit 6, information on the envelope from the circuit 4 and information on the Doppler frequency from the circuit 5 are processes as positive and negative envelope signals; they are sent to a transmission line 7. A signal separation circuit 8 outputs positive and negative envelope components as separate signals and displays them on separate screens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incoming / outgoing fish school monitoring device for monitoring a group of fish entering / leaving a net such as a fixed net (hereinafter referred to as a fixed net).

[0002]

2. Description of the Related Art A conventional device of this type will be described.
FIG. 4 is a block diagram showing a configuration of a conventional incoming / outgoing fish school monitoring apparatus. In the figure, 1 is an ultrasonic transmission circuit, 2 is a transceiver, 3 is an ultrasonic reception circuit, 4 is a detection circuit, and 10 is a radio. Transmitting circuits, 11 and 12 are antennas, 13 is a wireless receiving circuit, and 14 is a display device. FIG. 5 is a waveform diagram showing the signal waveform of each part of the device shown in FIG.
Is an output waveform from the ultrasonic receiving circuit 3, reference numeral (b) is an output waveform from the detection circuit 4, and reference numeral (c) is a wireless receiving circuit 13.
Is an output waveform from.

As shown in FIGS. 4 and 5, in the conventional fishnet monitoring device for incoming and outgoing nets, the wave transmitter / receiver 2 is directed toward the end of the stationary net where the fish swish in and out so that an unnecessary reflected signal does not enter. It is unavoidable that the reflection signal of itself is input, and not only the fish school signal but also the net signal is included in both the output (a) of the ultrasonic wave receiving circuit 3 and the output (b) of the detection circuit 4, and similarly. The output from the wireless reception circuit 13 also includes a net signal, and the display device 14 displays a mixture of incoming and outgoing nets of fish and images of the seabed and net.

[0004]

As described above, the above-described conventional incoming / outgoing fish school monitoring device displays not only the incoming / outgoing fish school image but also all reflected signals on the display device. It may be wrong to judge whether or not a fish school can be judged, but it is difficult to judge whether it is a fish school entering the set net or a fish school that has left the net, and therefore the fish school in the set net cannot be accurately grasped. There was a problem.

The present invention has been made to solve the above problems, and it is possible to display only the group of fish entering and leaving the set net by distinguishing between the group of incoming fish and the group of outgoing fish. The purpose is to provide a monitoring device.

[0006]

An incoming / outgoing fish school monitoring apparatus according to the present invention comprises a Doppler detection circuit for detecting the Doppler frequency of a received signal, and the received signal input to the receiving circuit is received by the Doppler detection circuit. The reflected signals from the sea floor and nets are removed by the Doppler frequency of, and only the fish school signals are extracted and displayed. Further, it is characterized in that by detecting the Doppler frequency, it is possible to distinguish and display the group of fish entering the fixed net or the group of outgoing nets.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.
In the figure, 1 is an ultrasonic transmission circuit, 2 is a wave transmitter / receiver, 3 is an ultrasonic reception circuit, 4 is a detection circuit, 5 is a Doppler detection circuit, 6 is a signal extraction circuit, 7 is a transmission line, 8 is a signal separation circuit. , 9 are display devices in this embodiment. FIG. 2 is a circuit diagram of FIG. 1, where parts (a), (b), (d), (e),
It is a waveform diagram showing the waveform of (e '), (f), (g),
The same reference numerals as in FIG. 1 are attached.

Next, the operation will be described. A burst signal having a predetermined duty ratio is amplified by the ultrasonic transmission circuit 1, converted into ultrasonic pulses by the wave transmitter / receiver 2, and radiated into water. Then, the ultrasonic pulse signal radiated into the water is reflected by the school of fish, the seabed, and the net, and the reflected wave is transmitted / received by the transducer 2
Is received and converted into an electric signal, amplified by the ultrasonic receiving circuit 3 to a level required for detecting the Doppler frequency, and input to the detection circuit 4 and the Doppler detection circuit 5. This waveform is shown in FIG. The detection circuit 4 performs envelope detection of the input signal and outputs an envelope signal proportional to the reflection intensity of the signal to the signal extraction circuit 6. This waveform is shown in FIG. On the other hand, the Doppler detection circuit 5 detects the Doppler frequency of the input signal and outputs the movement information of the reflector from the input signal.

As is well known, the following equation holds between the moving speed of the reflector and the Doppler frequency. fd = 2f ₀ · V · cos θ / C (1) where (fd) is the Doppler frequency, (f ₀ ) is the carrier frequency of the ultrasonic pulse, and (V) is the moving speed of the reflector.
(C) is the speed of sound in water, and (θ) is the tilt angle of the transducer 2. When the transducer 2 is directed from the fixed net to the end mouth, the fish school signal of the incoming fish school has a positive Doppler frequency, and the fish school signal of the outgoing fish school has a negative Doppler frequency.
Further, the reflected signal from the seabed and the stationary network itself has a Doppler frequency of “0” or a low level during the transmission period of the ultrasonic wave. Therefore, by performing a threshold process in the Doppler detection circuit 5, The reflected signals from the seabed and the net itself are Doppler frequency "0".
Is output as. This process is shown in FIG.

In the signal extraction circuit 6, the received signal below the threshold value is cut by the envelope information of the received signal from the detection circuit 4 and the Doppler frequency information of the received signal from the Doppler detection circuit 5 to correct it. The received signal having a Doppler frequency of 1 is processed as a positive envelope signal, and the received signal having a negative Doppler frequency is inverted and processed as a negative envelope signal and sent to the transmission line 7. This signal waveform is shown in Figure 2.
It shows in (e).

FIG. 3 is a diagram showing an embodiment in which the transmission line 7 shown in FIG. 1 is constituted by a wireless transmission line, and the same reference numerals as those in FIG. 4 indicate the same or corresponding portions. When the wireless transmission path as shown in FIG. 3 is used, the output signal from the signal extraction circuit 6 is V / F converted and amplified by the wireless transmission circuit 10, and the antenna 11
It radiates into the air through. Then, the radiated radio signal is received by the antenna 12 and enters the radio receiving circuit 13,
The signal is F / V converted and input to the signal separation circuit 8. This signal waveform is shown in FIG. The transmission line 7 may be a wired transmission line using a cable.

The signal separation circuit 8 inverts the signals having the positive envelope component among the received signals, and inverts the signals having the negative envelope component, and outputs them as separate signals. These signal waveforms are shown in Fig. 2 (f) and (g).
Shown in. The display device 9 is separated by the signal separation circuit 8.
The two signals are configured to be displayed on different screens, and the display as shown in FIG. 1 is performed. As described above, it is possible to distinguish the group of incoming fish and the group of outgoing fish at a glance,
The comparison becomes easy, and the image of the fixed net is not mixed into the display device 9.

[0013]

As described above, according to the present invention, by displaying the ultrasonic received signal by selecting it by the Doppler frequency and displaying it, unnecessary things other than the group of fish entering and leaving the net such as the reflection of the seabed and the set net itself are displayed. To prevent it from happening,
There is an effect that the group of incoming fish and the group of outgoing fish can be displayed separately and can be distinguished at a glance.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram showing signal waveforms of various parts of the circuit shown in FIG.

FIG. 3 is a block diagram showing a configuration when the transmission line 7 shown in FIG. 1 is configured by a wireless transmission line.

FIG. 4 is a block diagram showing a configuration of a conventional device.

FIG. 5 is a waveform diagram showing a signal waveform of each part of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ultrasonic wave transmission circuit 2 wave transmitter / receiver 3 ultrasonic wave reception circuit 4 detection circuit 5 Doppler detection circuit 6 signal extraction circuit 7 transmission path 8 signal separation circuit 9 display device 10 wireless transmission circuit 11, 12 antenna 13 wireless reception circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04B 7/15

Claims (3)

[Claims] 1. An ultrasonic wave transmitter / receiver is installed in a fish net in water such as a fixed net, and ultrasonic waves are transmitted and received to catch a group of fish entering or leaving the fish net as a reception signal by a receiving circuit,
In an incoming / outgoing fish school monitoring device that transmits and displays via a transmission path, it is equipped with a Doppler detection circuit for detecting the Doppler frequency, and the received signal input to the receiving circuit is An incoming / outgoing fish school monitoring device that selects and extracts only fish school signals and transmits and displays them via a transmission path. 2. An ultrasonic wave transmitter / receiver is installed in an underwater fish net such as a fixed net, and ultrasonic waves are transmitted / received to catch a group of fish entering or leaving the fish net as a reception signal by a receiving circuit.
An incoming / outgoing fish school monitoring device that displays via a transmission line is equipped with a Doppler detection circuit for detecting the Doppler frequency, and the received signal input to the above receiving circuit is selected by the Doppler frequency of the received signal by the above Doppler detecting circuit. Only the fish school signal is extracted, and the fish school signal is further transmitted through the transmission line by distinguishing between the incoming and outgoing nets, and the incoming or outgoing nets are transmitted. An incoming / outgoing fish school monitoring device that distinguishes and displays. 3. The incoming / outgoing fish school monitoring device according to claim 1 or 2, wherein the transmission path is a wireless transmission path.