JPH0894754A - Apparatus for receiving net mouth information of trawl - Google Patents

Abstract

PURPOSE: To receive even net-mouth information with an all-around type scanning-sonar wave transceiver. CONSTITUTION: A net-mouth-information receiving part is set at the specified area part facing the stern direction of an all-around type scanning-sonar wave transceiver 1. The received sound wave signal of a piezoelectric transducer constituting the net-mouth-information receiving part is imparted into a phase synthesizing circuit 4 through a preamplifier 3. The phase of the received sound wave signal is manipulated with the phase signal from a phase-signal generating circuit 5 so that the wave receiving surface of the net-mouth-information receiving part forms the specified depression angle with respect to the sea surface. The net-mouth-information signal is extracted with a BPF 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trawl net mouth information receiving device for receiving an ultrasonic signal (net mouth information) from a net mouth information transmitter attached to the net mouth of a trawl fish net, and more particularly to a whole circumference of the trawl net mouth information receiver. The present invention relates to a trawl net mouth information receiving apparatus suitable for a trawler equipped with a scanning scanning sonar.

[0002]

2. Description of the Related Art In trawl fishing, as shown in FIG. 7, a net mouth information transmitter 72 is attached to the net mouth of a trawl fishing net 71 to detect fish shadows in the vicinity of the net mouth and to catch as much as possible. I am operating a towed fish net. As shown in FIG. 8, the net mouth information transmitter 72 is provided with an upward fish school finder 72a and a downward fish school finder 72b, and exceeds information (net mouth information) such as a school of fish entering and leaving the trawl net 71 and net bottom information. The sound waves are sent and transmitted to the fishing boat (trawler) towing the net.

In recent years, the number of trawlers equipped with an all-around scanning sonar has been increasing, but this sonar is not intended to receive the net mouth information transmitted by the net mouth information transmitter 72. Therefore, in the conventional trawler, it is customary to provide a dedicated wave receiver 91 for receiving the net mouth information as shown in FIG. 9, for example.

The signal received by the net mouth information receiver 91 provided in this way is then input to a receiving system different from the receiving system of the all-around scanning sonar provided in the fishing boat,
Therefore, after undergoing amplification and other processing, the net mouth information of the school of fish entering and leaving the net and the bottom of the sea captured by the fish finder of the net mouth information transmitter 72, and the downward direction, is displayed on the Braun tube. ing.

[0005]

However, in the system in which the net mouth information receiver 91 as shown in FIG. 9 is fixed to the bottom of the ship, the noise due to the bubbles flowing directly below the bottom of the ship is received, and the presence of the bubbles causes the ultrasonic waves. There is a problem that the signal-to-noise ratio is low due to the obstacle to the propagation, and the reception becomes impossible. Further, since the wave receiver is fixed and the direction of the received beam is fixed in the stern direction, there is a problem that reception becomes difficult if the fishnet deviates from the stern direction due to the influence of the tidal current.

In order to solve such a problem, conventionally, for example, as shown in FIG. 10, a method of towing an underwater towed body 101 equipped with a net mouth information receiver with a tow line has been adopted. However, in the method of towing the underwater towed body, the net mouth information receiver is shaken together with the underwater towed body, so that the receiving surface lacks stability. It is difficult to adjust the direction to face the transmitter, and there is the problem of disconnecting the towline.

Therefore, paying attention to the fact that the trawler is equipped with an all-around scanning sonar, and if the wave transmitter / receiver of this sonar can also receive the net mouth information, a dedicated net mouth information receiver or underwater towed ship will be provided. It is economical because it can eliminate the body. At that time, it is desired that the reception processing system (network opening information receiving device) for the network opening information taken out in the shared portion of the transmitter / receiver has a simple structure.

The present invention was made by paying attention to the fact that a trawler is equipped with an all-around scanning sonar, and its purpose is to share a wave transmitter / receiver of the all-around scanning sonar and to detect net mouth information sensitively. An object of the present invention is to provide a trawl net mouth information receiving device having a simple structure capable of receiving well.

[0009]

In order to achieve the above object, the trawl net mouth information receiving device of the present invention has the following configuration. That is, in the trawl net mouth information receiving apparatus of the present invention, a predetermined area portion facing the stern direction of the all-round scanning sonar transducer is set as the net mouth information receiving unit; A phase synthesizing circuit for synthesizing the phases of the respective received signals so that the wave receiving surfaces of the plurality of transducers are inclined at a predetermined depression angle from the sea surface; a phase signal generating circuit for giving a required phase signal to the phase synthesizing circuit; And a band-pass filter for extracting the mesh opening information from the output of.

The frequency of the mesh opening information is different from the frequency used in the omnidirectional scanning sonar. In addition, the preamplifier that amplifies the received signals of the plurality of transducers and gives them to the phase synthesizing circuit is either independent or shared with that provided in the receiving unit that receives the received signals of the transducer of the all-round scanning sonar. It becomes

[0011]

Next, the operation of the trawl net mouth information receiving apparatus of the present invention configured as described above will be described. The transducer of the all-round scanning sonar is one in which a large number of transducers are arranged on a cylindrical surface, but in the present invention, a predetermined area portion facing in the stern direction of such a cylindrical transducer is used as a net mouth information. It is set as a wave receiving unit, and the phases of the received signals are combined so that the wave receiving surfaces of the multiple transducers that make up the net mouth information receiving unit are inclined at a predetermined depression angle from the sea surface, and the net mouth information is bandpass filtered. Extract.

Here, the wave transmitter / receiver of the all-round scanning sonar is attached to the tip of the elevating shaft of the elevating device, and is used by projecting downward from the ship bottom so as not to be affected by bubbles immediately below the ship bottom. Since it is customary, according to the invention,
In principle, the net mouth information can be received under good conditions with good sensitivity without being affected by bubbles.

When the fishnet deviates from the stern direction due to the influence of the tidal current, the direction of the wave receiving surface of the net mouth information receiving section is adjusted so that the received beam can be easily directed toward the net mouth information transmitter. Can be turned.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a trawl net mouth information receiving apparatus according to an embodiment of the present invention. In FIG. 1, reference numerals 1 and 2 respectively denote a wave transmitter / receiver and a receiver of an all-round scanning sonar, and a receiver 2 has a preamplifier (not shown) for each transducer of the wave transmitter / receiver 1. The trawl net mouth information receiving apparatus according to the present embodiment includes a preamplifier 3, a phase synthesizing circuit 4, a phase signal generating circuit 5, and a band provided for each transducer of a partial transducer group of the transceiver 1. It is basically composed of a pass filter (BPF) 6.

All-round scanning sonar transducer 1
2 is an array of a large number of transducers 21 arranged on a cylindrical surface as shown in FIG. 2, which is attached to the tip of the elevating shaft 23 of the elevating device and is not affected by bubbles immediately below the bottom of the ship as shown in FIG. It is used by projecting downward from the bottom of the ship. The wave transmitter / receiver 1 merely moves up and down by the lifting device, and is not rotatable. That is, in the transducer 1 attached to the lifting device, the surface in the stern direction, the surface in the bow direction,
Etc. can be specified.

According to the present invention, in such a transducer 1, as shown in FIG. 2, a predetermined area portion facing in the stern direction (m in the circumferential direction and n × n in the vertical direction for convenience). Is set as the trawl net mouth information wave receiver 22.

In a trawler equipped with an all-around scanning sonar, the transmission / reception frequency of the all-around scanning sonar and the frequency of the net mouth information are different from each other so that they do not interfere with each other. The sonar uses a frequency near the resonance point of the oscillator 21. Therefore, the frequency of the net mouth information transmitter 72 is
A frequency outside the resonance point of 1 will be used.

In this embodiment, the transducer 1 is composed of 36 transducers at every 10 ° in the circumferential direction and 288 transducers in 8 stages in the vertical direction, and the spacing between the transducers is in the circumferential direction. To 0.5
It is assumed that λ is 0.5λ in the vertical direction. Specifically, assuming that the transmission frequency is 30 kHz and the underwater sound velocity is 1500 m, the wavelength is λ = 50 mm. Therefore, the intervals between the transducers are 25 mm in the circumferential direction and 25 mm in the vertical direction (0.5λ = 2).
5 mm).

Then, the trawl net mouth information receiving section 22 is
The transducer in the stern direction of the transducer 1 is composed of 16 transducers in four rows (40 °) centering on the stern direction and four stages from the bottom to the top as shown in FIG.

The received signal of each transducer of the trawl net mouth information receiving section 22 thus set is input to the phase synthesizing circuit 4 via the corresponding preamplifier 3, as shown in FIG. The phase synthesizing circuit 4 includes modulators 43 having the same number of oscillators.
And one adder 44. The phase signals (f _{L1 to} f _Lmn ) from the phase signal generation circuit 5 are _supplied to each modulator 43.
Is given.

In this phase synthesizing circuit 4, the trawl net mouth information receiving section 22 is not a plane but a part of a cylindrical surface, but the wave receiving signals of the respective vibrators of the troll net mouth information receiving section 22 are phase signals. By operating with the phase signal from the generating circuit 5, the trawl net mouth information receiving unit 22 is a flat wave receiver,
In addition, the wave-receiving surface is a circuit that obtains directivity so as to point in the direction of the net mouth information transmitter 72.

Since the direction of the net mouth information transmitter 72 is the direction of the depression angle t ° with respect to the sea surface, the trawl net mouth information receiving section 2 is provided.
The wave-receiving surfaces of the 16 transducers that make up element 2 are electronically tilted by t °. As shown in FIG. 4, the signal received by each transducer is shifted by a phase φ _m so that the receiving surface of the transducer in the vertical direction of the receiving portion is inclined by t °, and the signal is inclined by t °. The phases should match.

Now, the transmission frequency of the network information transmitter 72 is set to 4
If the frequency is 0 kHz, the wavelength λ _t is 37.5 mm, and the vertical arrangement interval d of the oscillators is 25 mm.
The phase φ _m required to incline by 5 ° is given by Equation 1.

[0024]

[Equation 1]

Since the array in the circumferential direction has an arc shape as shown in FIG. 5, it is sufficient to shift the phase φ _n so that the phases coincide with each other at the tangent line of the vibrator. If the radius of the transducer 1 is r and the angle of the arrangement position of the oscillator is θ, the phase φ _n is
Becomes

[0026]

[Equation 2]

From the above consideration, the phase of each oscillator is φ _m + φ
_It can be understood that the reception directivity can be synthesized by shifting the _n . The modulator 43 performs the operation of shifting the phase. For example, if the modulated signal (received signal) is A · cos (2πf _I ) and the modulated signal (phase signal) is cos (2πf _L + φ), the output of the modulator is Becomes f _I ± f _L ,
It can be seen that the phase shifts by φ.

[0028]

[Equation 3]

Therefore, if φ = φ _m + φ _n , the phase signal f output from the phase signal generating circuit 5 to one of the modulators 43 is f.
_Lmn is f _Lmn = cos (2πf _L + φ _m + φ _n ),
The output of the modulator is Equation 4.

[0030]

[Equation 4]

When the outputs of the respective modulators 43 are added and synthesized by the adder 44, the wave receiving surface of the trawl net mouth information wave receiving portion 22 is formed with a depression angle t ° in the stern direction. When the signal received by the wave receiving surface is passed through the BPF 6 having the frequency f _I + f _L as the pass band, the net mouth information signal is extracted.

In this way, since the transceiver 1 of the all-round scanning sonar can also receive the trawl net mouth information signal,
The influence of bubbles immediately below the bottom of the ship is also less likely to occur, and the trawl net mouth information signal can be received with good sensitivity and good conditions. In addition, since the wave receiving surface can be directed toward the trawl net mouth by the phase control of the phase combination, the receiving condition is improved as compared with the conventional method.

Here, since the receiving system of the trawl net mouth information has a simple structure and the dedicated wave receiver and the underwater towed body can be eliminated, a great economic effect can be obtained. There is also an advantage that dangerous work can be eliminated, such as the need for difficult ship bottom construction.

Although the dedicated preamplifier 3 is used for the receiving system of the trawl net mouth information in FIG. 1, the preamplifier 61 originally included in the receiving section 2'is shown in FIG. You can share it. Usually, the preamplifier 61 has a wide band, and therefore can be used as it is in many cases. In this way, if shared, the cost can be reduced.

[0035]

As described above, in the trawl net mouth information receiving device, the predetermined area portion facing the stern direction of the all-round scanning sonar transmitter / receiver is set as the net mouth information receiving portion, and the net mouth information receiving portion is set. The phase of each received signal is combined so that the wave receiving surfaces of a plurality of transducers that constitute the information wave receiving unit are inclined at a predetermined depression angle from the sea surface, and the network mouth information is extracted by a band pass filter.

Here, the wave transmitter / receiver of the all-round scanning sonar is attached to the tip of the elevating shaft of the elevating device and is used by projecting downward from the ship bottom so as not to be affected by bubbles immediately below the ship bottom. Since it is customary, according to the invention,
In principle, there is an effect that the network opening information can be received under good conditions with good sensitivity without being affected by bubbles.

Further, when the fishnet deviates from the stern direction due to the influence of the tidal current, the direction of the wave receiving surface of the net mouth information receiving section is adjusted so that the received beam can be easily directed toward the net mouth information transmitter. Since it can be directed, there is an effect that the reception condition can be improved as compared with the conventional method.

Further, since the dedicated wave receiver and the underwater towed body can be eliminated, a great economic effect can be obtained. In addition, there is an effect that dangerous work can be eliminated because difficult ship bottom construction is unnecessary.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a trawl net mouth information receiving device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a relationship between a wave transmitter / receiver of an all-round scanning sonar and a trawl net mouth information wave receiver set therein.

FIG. 3 is an explanatory view of a usage state of a wave transmitter / receiver of an all-around scanning sonar in a trawler.

FIG. 4 is an explanatory diagram of a phase operation on a transducer in a vertical direction.

FIG. 5 is an explanatory diagram of a phase operation on a vibrator in a circumferential direction.

FIG. 6 is a block diagram showing a configuration of a trawl net mouth information receiving device according to another embodiment of the present invention.

FIG. 7 is an explanatory diagram of a conventional method for receiving a network opening information signal, in which a network opening information receiver is attached to the bottom of a ship.

FIG. 8 is an explanatory diagram of a conventional reception method of a net mouth information signal in which a fishing boat tows an underwater towed body equipped with a net mouth information receiver by a tow line.

FIG. 9 is an explanatory diagram of a method of fixing the net mouth information receiver to the bottom of a ship.

FIG. 10 is an explanatory diagram of a system in which a fishing boat tows an underwater towed body equipped with a net mouth information receiver by a tow line.

[Explanation of symbols]

 1 Transmitter / receiver 2, 2'Receiver 3 Preamplifier 4 Phase combiner 5 Phase signal generator 6 Bandpass filter (BPF) 21 Transducer 22 Troll net mouth information receiver 43 Modulator 44 Adder 61 Preamplifier

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G01S 7/52 7/62 15/87 8907-2F 8907-2F G01S 7/52 V 8907-2F 7 / 62 Z

Claims (3)

[Claims] 1. A predetermined area portion of the all-round scanning sonar transducer facing the stern direction is set as a net mouth information receiving section; and a plurality of transducers constituting the net mouth information receiving section are received. A phase combiner circuit that combines the phases of the received signals so that the wavefront is inclined at a predetermined depression angle from the sea surface; a phase signal generator circuit that gives the required phase signal to the phase combiner circuit; And a band pass filter for controlling the network information reception device. 2. The frequency of the mesh opening information is different from the frequency used in the all-round scanning sonar;
The trawl net mouth information receiving device according to claim 1, wherein 3. A preamplifier that amplifies received signals of a plurality of oscillators and supplies the amplified signals to a phase synthesizing circuit, independently of a preamplifier provided in a receiving unit for receiving a received signal of a transceiver of an all-round scanning sonar, or The troll net mouth information receiving device according to claim 1, wherein the trawl net mouth information receiving device is shared.