JPH0413668B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention shields the direct propagation of propulsion mechanism noise to an ultrasonic transceiver device that detects the current velocity of a tidal current, the presence or absence of a school of fish, etc. The present invention relates to a device that improves the S/N ratio of ultrasonic signals from a wave transmitting/receiving device.

[Conventional technology]

In recent fishing vessels, etc., an ultrasonic transducer is attached to the outer surface of the bottom of the ship, and the transducer is covered with a dome.The ultrasonic transducer is used to detect current speed and schools of fish, allowing for efficient fishing. I try to do it. In the case of ultrasonic wave transmitting and receiving equipment that detects the current velocity of tidal currents, the frequency of reflected waves from the ocean floor and the frequency of reflected waves in the water from plankton, etc. are compared with the transmitting frequency to identify the oscillation source. The speed of the own ship and the relative speed of the tidal current at a predetermined water depth relative to the own ship are obtained. Then, the absolute speed of the tidal current is obtained from the difference in these speeds. If reflected waves from the ocean floor cannot be obtained,
The current velocity of the tidal current is obtained by comparing the boat speed from the engine of the fishing boat and the absolute speed difference of the tidal current at a predetermined water depth. The current velocity obtained in this way can be used to detect tides where fish tend to gather,
This is used as data such as when to throw in the net and the speed of the boat when towing the net.

[Problem that the invention seeks to solve]

Therefore, such an ultrasonic wave transmitting/receiving device is merely attached so as to protrude from the outer surface of the bottom of the ship. Therefore, wave noise from the propulsion mechanism (screw), rotation noise of the propulsion mechanism itself, vibration noise of other engines, etc. are propagated from the propulsion mechanism into the water, and these underwater noises are received by the ultrasonic transceiver device. Something happened. In particular, when measuring tidal currents, the ultrasonic wave transmitter/receiver must receive reflected waves returning from underwater bubbles, microorganisms, etc. However, since these reflected waves are very weak signals, it is difficult to avoid the above-mentioned underwater noise. It was very susceptible to influence. Underwater noise caused by such a propulsion mechanism deteriorates the S/N ratio of the transmitted and received signals of the ultrasonic wave transmitting/receiving device, and reduces its analytical ability. Conventionally, in order to reduce the influence of underwater noise caused by the propulsion mechanism, the ultrasonic transceiver is installed as far away from the propulsion mechanism as possible on the bow side.
Attempts have been made to select an installation location that is less affected by the underwater noise. However, recent fishing vessels are becoming faster and faster.
There is a drawback that when the ship is sailing, the bow side is exposed from the water surface, making it impossible for the ultrasonic wave transmitting/receiving device to transmit and receive ultrasonic waves. Even in this case, the influence from the propulsion mechanism is only slightly reduced,
The S/N ratio was not significantly improved, and improvement was desired.

[Means for solving problems]

The present invention improves and eliminates the above-mentioned conventional problems, and prevents underwater noise caused by the propulsion mechanism from being directly received by the ultrasonic transmitter/receiver. It is an object of the present invention to provide a propulsion mechanism noise shielding device in an ultrasonic wave transmitting/receiving device, which dramatically improves the S/N ratio of signals transmitted and received by the ultrasonic wave device.

The means adopted by the present invention in order to solve the above-mentioned problems is, in a ship in which an ultrasonic wave transmitting/receiving device for transmitting and receiving ultrasonic signals underwater is installed so as to protrude from the outer surface of the ship's bottom. A shielding wall for underwater noise, which is continuous with the ultrasonic wave transmitting and receiving device, is provided at a position of the keel near the propulsion mechanism that is continuous with the device, and the side surface of the shielding wall has an approximately inverted triangular shape, and the triangular shape of the shielding wall The protrusion dimension and width dimension of the apex from the ship's bottom are set to such dimensions that the propulsion mechanism cannot be seen from the ultrasonic transceiver.It is a shielding device for propulsion mechanism noise in an ultrasonic transceiver. .

[Effect]

As is clear from the embodiments shown in FIGS. 1 to 4,
A shielding wall 3 installed on the outer bottom surface 4 between the propulsion mechanism 5 and the ultrasonic transceiver 2 allows
Direct propagation of the underwater noise caused by this to the ultrasonic wave transmitting/receiving device 2 is blocked. Therefore, the signal received by the ultrasonic transceiver 2 has an increased proportion of reflected wave signal components from the target object, resulting in an excellent S/N ratio.
The ratio is obtained. In other words, the analytical ability of the ultrasonic transceiver 2 can be dramatically improved, and even more efficient operation is possible.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below based on embodiments shown in the drawings.

1 to 4 relate to one embodiment of the present invention, in which FIG. 1 is a side view showing the entire fishing boat 1, FIG. 2 is a schematic bottom view of the same, and FIG. 3 is an ultrasonic transmission/reception. FIG. 4 is a longitudinal cross-sectional front view of the wave device 2, and a partially enlarged side view of the bottom 4 showing the ultrasonic wave transmitting and receiving device 2 and the shielding wall 3. As shown in the figure, in this embodiment, a shield made of metal, synthetic resin, wood, etc. is provided at the keel 6 on the outer bottom surface 4 between the propulsion mechanism 5 and the ultrasonic wave transmitting/receiving device 2. Installing wall 3.
The shielding wall 3 has a substantially triangular shape when viewed from the side, is arranged so that the apex of the triangle is farthest from the outer surface 4 of the bottom of the ship, and is provided continuously to the ultrasonic wave transmitting/receiving device 2 . The shielding wall 3 has a width that prevents the propulsion mechanism 5 from being directly visible from the transducer 7 of the ultrasonic transceiver 2 (see FIG. 2), and a dimension that projects into the water.

With this configuration, underwater noise caused by the propulsion mechanism 5, that is, wave noise caused by the propulsion mechanism 5, rotation noise of the propulsion mechanism 5 itself, vibration noise of other engines, etc., propagates underwater and is blocked by the shielding wall 3. , are not directly propagated to the ultrasonic wave transmitting/receiving device 2. Therefore, the signal received by the ultrasonic transceiver 2 is
The ratio of reflected wave signals from the target object increases, and it is possible to dramatically improve the S/N ratio.

Figures a and b in FIG. 5 show the propulsion mechanism 5 in the case of a conventional example in which the shielding wall 3 is not provided and in the case of the embodiment according to the present invention in which the shielding wall 3 is actually attached to the keel 6 of the fishing boat 1. This figure shows the results of measuring the underwater noise caused by the noise at the test point of the amplifier output terminal. In this case, the specifications of fishing boat 1 are: propeller diameter 1.5 m, propeller pitch 20 degrees, and propeller rotation speed.
Total length 30m, displacement with 750rpm propulsion mechanism 5
It is a 90t fishing boat that specializes in exploration. In addition, the specifications of the ultrasonic wave transmitter/receiver 2 are that the size of the dome 9 is 970 mm in length x 320 mm in width x 350 mm in height, and the installation location is on the keel 6 at a position 22 m toward the bow side from the propulsion mechanism 5. It is. Further, in this case, the length L of the shielding wall 3 is 300 mm, the width is 320 mm, and the height H protruding from the lower surface of the dome 9 is 50 mm. According to the measurement results, the waves of underwater noise in the case of the conventional example without the shielding wall 3 are ±3V on average, and the maximum is ±5.5V, but the waves of underwater noise in the case of the embodiment according to the present invention are is ±1V on average and ±3V at maximum. Moreover, in the case of the conventional example, the wave cutting noise caused by the propulsion mechanism 5 is included in the maximum part A of the underwater noise waves. Note that this wave noise appears as a white bright spot on a cathode ray tube. It is clear from the measurement results that the shielding wall 3
In the case of the embodiment according to the present invention in which the ultrasonic transmitter/receiver 2 is provided, the underwater noise caused by the propulsion mechanism 5 received by the ultrasonic wave transmitter/receiver 2 is significantly reduced, and the S/N ratio is dramatically improved. That is to say.

By the way, the present invention is not limited to the embodiments described above, and can be modified as appropriate. For example, the installation location, shape, size, etc. of the shielding wall 3 are as follows:
Located between the propulsion mechanism 5 and the ultrasonic transceiver 2, underwater noise caused by the propulsion mechanism 5 is blocked by the shielding wall 3 and is not directly propagated to the transducer 7 of the ultrasonic transceiver 2. It may be located at a position other than the keel 6, and may have other shapes and sizes, such as a flat plate shape or a cylindrical shape. In addition, the above embodiment is
Although the case where the present invention is used in an ultrasonic transceiver device for measuring tidal currents has been described, it goes without saying that the present invention can be used not only for tidal current measurement but also for fish finders that receive reflected waves from schools of fish.

〔Effect of the invention〕

As explained above, in the present invention, underwater noise caused by the propulsion mechanism is blocked by the shielding wall midway along the outer surface of the bottom of the ship, and is not directly propagated to the transducer of the ultrasonic transducer. Therefore, the signal received by the transducer of the ultrasonic transducer is
The ratio of the signal reflected from the target increases, and it is possible to dramatically improve the S/N ratio of the ultrasonic wave transmitting/receiving device. Therefore, very efficient fishing operations are possible. Furthermore, it is possible to provide a shielding wall without removing the existing ultrasonic transceiver device, which provides excellent versatility. Furthermore, the sound insulation effect can be freely adjusted by simply changing the thickness, height, etc. of the shielding wall according to the propulsion mechanism, the size of the ship, the shape of the bottom of the ship, etc., and the setting is easy.

Furthermore, the side surface shape of the shielding wall is generally inverted triangular and streamlined to prevent air bubbles from forming on the rear side of the shielding wall. In conventional systems that simply have a plate-shaped shielding wall, air bubbles are generated at the rear of the shielding wall, and these air bubbles reduce the signal level value of the echo sound received by the ultrasonic transceiver device installed next to it. However, since the shielding wall of the present invention suppresses the generation of bubbles on the rear side thereof as described above, such a problem does not occur.

[Brief explanation of drawings]

1 to 4 relate to one embodiment of the present invention, in which FIG. 1 is a side view showing the entire structure when the shielding wall is attached to a fishing boat, FIG. 2 is a schematic bottom view of the fishing boat, Fig. 3 is a longitudinal cross-sectional front view of the bottom of the ship showing the ultrasonic transceiver, Fig. 4 is a partially enlarged side view of the bottom of the ship showing the installation area of the shielding wall, and Fig. 5 is a view of the embodiment of the present invention. 7 is a drawing showing measurement results of underwater noise caused by a propulsion mechanism in the case of a conventional example. 2...Ultrasonic wave transceiver device, 3...Shielding wall, 4...
... Outer surface of the bottom of the ship, 5... Propulsion mechanism.

Claims (1)

[Claims] 1. In a ship in which an ultrasonic transceiver device for transmitting and receiving ultrasonic signals underwater is installed protruding from the outer surface of the ship's bottom, the ultrasonic transceiver device is installed at a position in the keel adjacent to the propulsion mechanism that is continuous with the ultrasonic transceiver device. A continuous underwater noise shielding wall is provided, and the side surface of the shielding wall has an approximately inverted triangular shape, and the protrusion dimension of the triangular apex of the shielding wall from the bottom of the ship and the width dimension are as follows: 1. A propulsion mechanism noise shielding device in an ultrasonic wave transmitting/receiving device, characterized in that the propulsion mechanism is set to such a size that the propulsion mechanism cannot be seen from the ultrasonic transceiver.