JPS6012594B2 - Fish finder for seine - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improvement in a fish finder for seine netting.

Fish finders used in seine fishing are equipped with a transmitter attached to the port towed behind the vessel, and send out sound waves or ultrasonic waves (hereinafter referred to as ultrasonic waves) in the direction of the seabed below the net. The distance, in other words, the opening of the net,
This information is used to know the state of fish entering the net, as well as to detect the ocean floor, and also to detect the sea surface by sending out ultrasonic waves to the sea surface above to determine the depth of the silk.This information is transmitted by cable to the ship. It is well known that information is transmitted underwater via ultrasonic waves and automatically recorded and displayed on the recording paper of a recorder. Figures 1 and 2 provide an overview of these methods. 1 in Figure 1 is a transducer attached near the head rope of silk 2, and this transducer is
It consists of a transducer 3 for downward detection, a transducer 4 for upward detection, and a transmission transducer 5. The transducer 3 sends out ultrasonic waves downward to detect ground ropes 6, the seabed 7, etc. , the transducer 4 sends out ultrasonic waves upward to detect the sea surface 8 and the like.

The transducer 5 then transmits the information from below and above to the ship.

The ship's recorder records the information sent from the silk mouth as shown in Figure 2. In other words, the upper part of the recording paper shows the head lobe 9, the school of fish 10, the sea surface 11, etc., and the lower part of the recording paper shows the information sent from the silk mouth. The head rope 9', the net fish 12, the ground rope 13, and the seabed 14 are shown, and the distance from the loose end to the seabed, the opening of the head rope and ground rope, and the depth of the silk from the sea surface can be seen.

In the case of so-called "mid-level towing," in which the silk is towed at any depth between the sea surface and the seabed with the silk sufficiently floating above the seabed, there are no particular problems as conventional equipment can produce satisfactory results.

However, when targeting fish near the ocean floor, it goes without saying that the silk must be brought close to the ocean floor, and the simplest method is to drag the silk along the ocean floor while scraping the ocean floor. This would be easy if it was a monkey bottom-trawl, but in recent fishing situations, agreements have been made between countries,
When seine netting, it is required to float the silk from the ocean bottom, and the net must be oriented in the direction of what is known as ``off-bottom trawl'', and it is necessary to prove that the net is far from the seabed during actual operations. However, if the performance of conventional fish finders is the same, there are disadvantages when it comes to ``sewing the bottom of chicks''.

In other words, in the past, in order to remove the reverberation that occurs after transmitting waves, a TVG was applied and the gain of the receiver was controlled. ``In detecting the ground rope - main maximum and wealth'', since it is inevitable to receive echo signals from the direction of the sub-maximum due to the directional characteristics of the detection transducer. Reverberant signals from both directions of the ditch were returned to the vehicle, and in the recording, the line indicating the ground rope was shown as a trailing thick line.

Therefore, even though the silk is actually far from the ocean floor)
However, the record was recorded as if the net was resting on the seabed, and ``Not only was it impossible to prove that the silk was off the bottom, but the net was unavoidably pulled up from the seabed more than necessary. , it is extremely difficult to catch fish effectively.

From an operational perspective, it is desirable to keep the distance between the seabed and the net as close as possible, and ``We currently hope to be able to identify at least a few dozen species.

The first solution to this problem is to lower the overall sensitivity, but this method has the drawbacks of making it difficult to detect fish entering the net and shortening the detection distance to the seabed and sea surface. It's not the same method.

Second, when controlling the gain of the receiver, the method of increasing the amount of time the TVG is applied is also not the best method, as it makes it difficult to detect fish entering the net.

Third, if we adopt the "white line" method, which is widely used as a means of separating demersal fish from the ocean floor, the reverberation signal from the ground rope is usually not very strong, so it is possible to detect fish that are nearby. The receiver's operating system is controlled by stronger echo signals from the fish, and as a result, it is not possible to expect a separation effect between Grand Lo-3F and the seabed. This system is designed to effectively separate and record the seabed and ground rope, and will be explained below with reference to examples.

FIG. 3 is a block diagram of the embodiment. The first mother-child diagram is an operation explanatory diagram. In Figure 3, 28' is the transducer, 21
is a transmitter, 2=2 is a transmission control section, 23 is a gain control section, 2
4 is a receiver and 25 is an output terminal.

When the transmission control unit 22 generates a control pulse (see Figure 4 A) and drives the transmitter 2, the transducer 20 emits an ultrasonic wave (see Figure 4), and then the echo signal from the object is emitted. When the fish returns to the receiver 24, the receiver receives a signal ○ indicating the guidance associated with the transmission, that is, the time of transmission, a reverberant signal F from the fish, a reverberant signal G from the ground rope, and a reverberant signal G from the seabed. B, etc. (see FIG. 4, c) is applied.

On the other hand, the control pulse is applied to the gain controller 23 at the same time as the transmitter 2 controller.
Two sets of monomulti MHs,
and drives the M Buddha (not shown). Mono multi MH with this)
, Mama also starts operating at the same time as the ultrasonic wave is sent out, and is ON only for time To (section of day 2 in Figure 4), and mono-multi M
H2 is turned off for TG time from the end of To (section L in the tree in FIG. 4). Generally, the extent of the gap between the head rope and ground rope during operation can be estimated from the net design.

Therefore, by sending out ultrasonic waves from a transducer attached to the head rope, it is possible to predict the arrival point of the echo signal coming back from the ground rope. Therefore, taking into account the deformation of the net, etc., set the TD with some margin and set the TD so that it ends earlier than the time when the echo signal is expected to arrive from the ground rope.

Next, the time Tc during which the monomulti MH2 is turned off is set in consideration of the arrival time of the echo signal from the direction of maximum rut.

Since the settings of To and TG can be freely controlled electrically, it is of course possible to record and observe the operating conditions and adjust them to the most desirable conditions.

Now, by determining To and TG as described above, controlling the transmitter 24, and increasing the gain of the receiver during the time corresponding to To and lowering the gain of the receiver during the time corresponding to Tc, the output terminal 25 The output is shown in Figure 5.

In this case, the degree to which the gain should be reduced can be determined and adjusted by looking at the records in the field.

Thus, in terms of recording, the conventional one (see A in Figure 6)
In contrast, the example becomes B in FIG.
The line indicating the ground rope becomes thinner and the separation from the t-sealine becomes clear.

[Brief explanation of the drawing]

Figure 1 shows an overview of a fish finder for seine netting. Figure 2 is a recording example. FIG. 3 is a block diagram of the embodiment. FIG. 4 is an explanatory diagram of the operation. FIG. 5 is an example of receiver gain control according to the embodiment. Figure 6A is the conventional record. FIG. 6B is a record of the example. Moxibustion 1 Fly Winter 2 Diagrams 3 Koji *4 Kaede Tazudakutsu 3 Diagrams

Claims (1)

[Claims] 1 The fish finder for towing nets transmits the information detected downward from the opening of the towed net to the vessel and displays the information on the recorder installed on the vessel, and from the time of transmission, the echo signal of the net ground rope is detected. The receiver's gain is set high until a time slightly earlier than the arrival time, and then the receiver's gain is lowered until the time when the echo signal is expected to arrive from the side of the ground rope. A fish finder for seine fishing characterized by time-controlled gain of the device.