JPS60114782A - Detection of reaching bottom of fishing net - Google Patents

Abstract

PURPOSE:To enhance fishery efficiency by certainly detecting the reaching of fishing net to the sea bottom and performing trawling without anxiety in a state extremely close to the sea bottom but spaced apart therefrom, by providing a means for detecting noise generated when the fishing net arrives on the sea bottom. CONSTITUTION:A school-of-fish signal receiving time Tr is usually set to a fish finder and the remaining time TH is set to an idle time. Herein, the amplification gain of a receiving part 5 may be enhanced to a degree capable of detecting sliding noise, generated when a fishing net arrives on the sea bottom, only for a time shown by (a) by utilizing said idle time. That is, the wave form (a) is formed on the basis of the signal from a timing part 1 by a received gain controlling signal generator 6 using a monostable multi-vibrator and applied to the gain control circuit of the receiving part 5 to make it possible to achieve the purpose. If the fishing net touches the sea bottom, a noise signal appears to a time part where gain is made high and, if does not touch, said noise does not appear. As a result, whether the fishing net comes in contact with the sea botbom can be certainly detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for detecting the bottom of a fishing net as part of the fishing WJ monitoring in seine fishing.

(Technical background) In trawling fisheries, so-called "bottom trawling," most fishing has traditionally been bottom trawling, but recently, mid-level trawling and off-bottom trawling have also become common. The first reason is that the ground lobes scrape the ocean floor when they land on the bottom, which can lead to the devastation of fishing grounds. The second reason is that the density of fish schools has been on the decline in recent years, and depending on the season, mid-level trawls and off-bottom trawls with large mesh areas may be more efficient.

The structure of such nets for mid-level towing and off-bottom towing is not based on the assumption that they will land on the bottom and be dragged along the seabed, so they have a simpler and lighter structure than those in the Kamogawa River that land on the bottom. If you land on the bottom and trawl for a long time, the net will break.

However, when towing the net off the bottom, it is said that it is more effective to tow the net as far as it can go.

Therefore, it is necessary to operate while always being sensitive to whether or not the fishing net has landed on the bottom.

(Prior Art and Problems) Even with conventional fishing net monitoring devices, it is not impossible to monitor whether the fishing net has landed on the bottom or not. If there is a sufficient distance between the ground rope of the fishing net and the seabed, the sound reflected from the ground rope and the sound reflected from the seabed will be received and received separately, and a white gap will appear between the two signals on the recorder. It is clear that the market has bottomed out. However, as the fishing net approaches the ocean floor and the distance between the ground rope and the ocean floor becomes narrower than a certain distance, even if the ground rope has not touched the bottom of the ocean, the signal from the reflected sound from the ground rope and the ocean floor will appear on the recorder. The signals from the reflected sound from the ground lobe are superimposed and merged into one, making it impossible to tell whether the ground lobe has not yet touched the bottom or whether it has already touched the bottom. This is a constraint that is unavoidable due to the structure of the ground lobe, pulse width, directivity width, band width of the vibrator and circuit, etc.

For the above reasons, in a general fishing net monitoring device, if the ground lobe is one to several rms away from the seabed, it will not appear to be off the bottom on the recorder.

For this reason, in the past, it was assumed that when the reflected signal from the ground lobe on the recorder and the reflected signal from the seabed overlapped, it was considered to have touched the bottom, but in reality, it had not touched the bottom and the signal was connected to the ground rope. In some cases, the distance from the ocean floor is several meters. As mentioned earlier, in order to improve fishing efficiency when using off-bottom towing, it is necessary to tow nets at the very edge of the seabed, less than 1 m below the seabed. Since it is not possible to monitor whether or not the ground lobe has landed on the bottom at the location, the bottom of the upper part of the recorder cannot be seen and fishing must be carried out at a distance of 1 to several meters, which has the drawback of not necessarily achieving high fishing efficiency.

The way to detect whether or not the ground rope has touched the bottom is by detecting the weak bottoming that is emitted when the ground rope hits the bottom! It is possible to detect the IE sound by increasing the gain of the receiver for downward detection and detecting the bottom landing, but if the gain of the receiver is increased enough to detect the YIE sound of landing on the bottom, the reflected signal from the school of fish is detected. They face the problem of not being able to detect schools of fish because they are masked by noise.

(Purpose of the Invention) The present invention addresses the above-mentioned drawbacks of conventional fishing net monitoring devices, and achieves this without causing any hindrance to the detection of schools of fish. The purpose of this invention is to provide a method for reliably detecting the presence or absence of actual bottoming.

(Structure of the Invention) In order to achieve the above object, the present invention has the following structure. In other words, in a fishing net monitoring device for seine fishing,
The amplification gain of a receiving section for downward detection in a transmitter attached near a head lobe 11 of a fishing net is increased during idle time outside the effective time for receiving fish school signals, and the noise of the fishing net landing on the bottom is detected. This is a method for detecting fishing net landing on the bottom, which is characterized by detecting landing of a fishing net on the bottom.

(Example of the invention) Hereinafter, a detailed explanation of the present invention will be given based on the drawings.

FIG. 1 is a block diagram showing the configuration of a detection section transmission/reception system in a transmitter of a fishing net monitoring device to which the present invention is applied.

1 is a timing section, 2 is a transmitting section, 3 is a transmitting/receiving switch 4 is a transducer, 5 is a receiving section, 6 is a receiving gain control signal generator,
7 is the seabed, and 8 is a school of fish.

FIG. 2 is a timing chart of operations in the configuration shown in FIG. 19. The transmitting section 2 is connected from the timing section 1 to Fig. 2 (a).
), a pulse-like transmission signal as shown in FIG. It is converted into sound waves and sent into the water. At the same time as the wave is transmitted, the transmission is started, and the reflected sound received by the transducer 4 is converted into an electrical signal and applied to the receiver 5 via the transceiver switch 3. The output signal of this receiver 5 is the signal shown in FIG. 2(C), where a strong signal 9 first appears at the position of the transmitted pulse, and then a reflected signal 10 from a school of fish and a reflected signal 11 from the seabed appear.

A fish finder is usually set with a valid fish signal reception time Tr, and the remaining time 1゛H is set as an idle time.

And the 19 margin of receiving IC section 5? The gradient is set to such an extent that reflected signals from schools of fish, ground ropes, or the seabed can be clearly recorded, and with this level of gain, it is not possible to detect the noise of the fishing net hitting the bottom.

On the other hand, if the gain is set high enough to detect the noise, the signals reflected from the fish school etc. will be masked by the noise, making it impossible to identify the fish school signal.

Therefore, in the present invention, by using the idle time TH, it is possible to detect the bottom rubbing noise due to the amplification gain of the receiving section 5, for example, during the time represented by the rectangular wave in FIG. 2(d). It is intended to increase the level of performance. The signal waveform shown in FIG. 2(d) is generated by the reception gain control signal generator 6 using a monostable multivibrator or the like based on the signal from the timing section 1, and is added to the gain control circuit of the reception section to generate the above-mentioned signal waveform. You can reach your goal. By doing this, if the fishing net has landed on the bottom, a noise signal will appear in the time portion where the gain is set high, and if it has not landed on the bottom, it will not appear, making it possible to ensure whether or not the fishing net has actually landed on the bottom. It can be detected.

The reflected signals from the fish school, the ground rope, the seabed, and the bottom-striking noise signals obtained as described above are transmitted to the receiving and recording device on the trawl vessel via a cable or an FM transmission system using ultrasonic waves. The receiving and recording device can extract the bottom-striking noise signal of the fishing net from the transmitted signal, and can sound an alarm or write a bottom-striking mark on the recording paper.

FIG. 3 is a block diagram showing the configuration of the receiving section of the reception recording device when FM transmission is performed in an embodiment to which the present invention is applied. 12 is a receiver, 13 is a reception amplifier, 14 is an FM demodulator, 15 is a synchronization detector, 16 is a monostable multivibrator for delay, 17 is a monostable multivibrator for gate, 18 is an AND circuit, and 19 is a recording signal. output terminal,
20 is a bottoming signal output terminal.

The transmission FM ultrasonic wave emitted from the transmitter is received by the receiver 12, where it becomes an electrical signal, amplified by the reception amplifier 13, and then demodulated by the FM demodulator 14, resulting in a signal as shown in FIG. 4(a). Get a signal. 21 indicates 1m of landing on the bottom and a 4-stroke sound (E sound; such a signal does not appear when the boat is not on the bottom.Other signals are the same as the signal waveforms in Fig. 2(c). A synchronization detector 15, a monostable multivibrator 16 for delay, a monostable multivibrator 17 for gate, and an AND circuit 18 are provided in order to extract only the signal at the temporal position where the bottom sliding noise signal appears.Synchronization detection The device 15 receives the signal shown in FIG. 4(a) and synchronizes with the signal 9 in FIG.
) is generated and supplied to the delay monostable multivibrator 16. The multivibrator 16 is activated by the rising edge of this synchronization signal, and the multivibrator 16 has a width up to the temporal position where the bottom-striking noise signal 21 appears (C
) is generated and applied to the gate monostable multivibrator 17. The multivibrator 17 is activated by the falling edge of the waveform shown in FIG.
), a gate signal having a time width suitable for extracting the bottoming 111 friction noise signal 21 is generated. here,
By adding the output signal of the demodulator shown in FIG. 4(a) and the gate signal to the AND circuit 18, it is possible to extract only the presence or absence of the bottom-rubbing noise signal as shown in FIG. 4(e). .

(Effects of the Invention) As explained above, in the conventional fishing net monitoring device, due to limitations due to the distance resolution of the fish finder, when the fishing net approaches a position of 1 to several Ill from the seabed, the recorder shows that it has landed on the bottom. In order to avoid the risk of breaking the net, the net is trawled one to several meters from the seabed, where it would normally be better to trawl the seabed. Although there was a drawback that fishing nets were not operating in good conditions, by applying the present invention, it is possible to reliably detect the presence or absence of actual landing on the bottom by a method of detecting the noise generated by fishing nets landing on the bottom. Since it is possible to
N'+In There is an advantage that fishing off the bottom can be carried out safely at the edge of the bottom, and high fishing efficiency can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a detection unit transmitting/receiving system in a transmitter of a fishing net monitoring device to which the present invention is applied;
The diagram is a timing chart of the operation in the configuration shown in Figure 1.
FIG. 3 is a block diagram showing the configuration of an embodiment of the receiving section of the reception/recording apparatus to which the present invention is applied, and FIG. 4 is a diagram showing waveforms of each part in the configuration of FIG. 3. 1-timing section, 2-transmission section, 3-transmission/reception switch 4-transducer, 5-reception section, 6-reception gain control signal generator, 7-bottom sea floor, 8-fish school, 9-during transmission pulse Strong signal, 10-Reflected signal from fish school, 11-Reflected signal from the seabed, 12-Receiver, +3-1 receiving amplifier, 14-FM
demodulator, 15- synchronization detector, 16- monostable multivibrator for delay, 17- monostable multivibrator for gate 1B-AND circuit, 19- recording signal output terminal,
20-Bottom landing signal output terminal, agent Yoshihiro Yawata, patent attorney Figure 1, Part 2 (d) Figure 3 Figure 4 (♂) 1 (e)

Claims (1)

[Claims] In a fishing net monitoring device for seine fishing, the amplification gain of the receiver for downward detection in the transmitter attached near the spatula lobes of the fishing net is increased during the idle time outside the effective time for receiving fish school signals, and the A method for detecting fishing net landing on the bottom, characterized by detecting landing of a fishing net on the bottom by detecting bottom sliding noise.