JPS6327650B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wave receiver that receives underwater sound waves and converts them into electrical signals.

This type of receiver includes a type that is sensitive to sound pressure in water and a type that is sensitive to sound pressure gradient in water. An example of the former is a wave receiver using barium titanate porcelain or the like, but this has the disadvantage that directivity cannot be obtained unless the wave receiving area is sufficiently large compared to the wavelength of the sound wave. On the other hand, the latter type always has constant directivity, regardless of the wavelength of the sound wave and the receiving area.
As an example, there is a sound pressure gradient type receiver using a movable wire ring, but the sensitivity is maximum in the moving direction of the wire ring, and the sensitivity in the direction perpendicular to this is zero.

In this way, the sound pressure gradient type receiver has directivity regardless of the frequency even though it is small enough compared to the wavelength of the sound wave, so it is useful when measuring the direction of arrival of sound waves. Although it is a receiver,
On the other hand, it has the following drawbacks.

(1) A sound pressure gradient type receiver will not generate an output voltage unless the receiver itself moves to follow the sound wave (water particle motion) that it is trying to measure, so if it is installed on the seabed as is, Since the receiver does not follow the sound waves, its sensitivity decreases and it cannot be used. Therefore, it is necessary to suspend it underwater so that it can move freely.

(2) When suspended in water or in a freely moving state, a sound pressure gradient receiver may be affected by disturbances other than sound waves due to slight water currents in the water or vibrations caused by suspension. Due to the movement, a noise voltage is generated.
In particular, there is a lot of noise at low frequencies, and measures to suppress noise are required.

The present invention has been made in view of the above points, and includes a sound pressure gradient type receiver body which is hermetically covered with a rectifying cover that is transparent to sound waves, and which further includes a rectifier cover that is transparent to sound waves. The main body is supported within the rectifying cover using an elastic body, and the rectifying cover is filled with water or a liquid approximately equal to the specific acoustic resistance of water.
It is an object of the present invention to provide a sound pressure gradient receiver for installation on the seabed, which does not reduce sensitivity to incoming sound waves and suppresses noise due to disturbances such as water flow.

Next, an embodiment of the wave receiver according to the present invention will be described with reference to the drawings.

Reference numeral 1 in the figure indicates a main body of a sound pressure gradient type receiver, and the receiver main body 1 has a structure shown in FIG. That is, the receiver main body 1 has a movable outer casing 2,
A pair of opposing wall surfaces in the outer casing 2 serve as wave receiving surfaces 2a, 2a, and a movable wire ring 3 is installed between the wave receiving surfaces 2a, 2a. Inside this movable wire ring 3,
A heavy object 4 having a magnetic force is loosely inserted, and the heavy object 4 is suspended from the outer casing 2 by an elastic body 5 such as a spring.

As shown in FIG. 1, the receiver body 1 described above has the following components:
The receiver body 1 is hermetically covered with a rectifier cover 6 that is transparent to sound waves, and is suspended from the rectifier cover 6 by an elastic body 7 such as a spring. The rectifier cover 6 is made of FRP or a thin iron plate formed into a shape with low resistance to water flow, for example, a hollow sphere, and inside this rectifier cover 6 there is a liquid 8.
is fulfilled. This liquid 8 is a liquid such as water that has a specific acoustic resistance equal to the specific acoustic resistance of the environment in which the receiver is installed. Furthermore, installation legs 10 are formed at the lower part of the rectifier cover 6 for installing the rectifier cover 6 on the seabed 9.

Next, the operation of the receiver with the above configuration will be explained.

When the above-mentioned receiver is sunk into the sea, the rectifier cover 6 and the receiver main body 1 covered by the rectifier cover 6 are held by the installation legs 10 so as not to roll over or move on the seabed surface. The receiver main body 1 has directivity in a specific direction at a certain point on the ocean floor 9. Here, when a sound wave arrives, the arriving sound wave passes through the rectifier cover 6, propagates within the liquid 8, and reaches the receiver main body 1. In this way, the movable outer casing 2 of the receiver main body 1 vibrates following the sound waves, and this vibration vibrates the movable wire ring 3, but the heavy object 4 with magnetic force inside the movable wire ring 3 is fixed due to inertia. has been done. Therefore, when the vibration direction of the movable wire ring 3 and the direction of the magnetic lines of force due to the heavy object 4 are perpendicular to each other, an electric signal corresponding to a sound wave is obtained from the movable wire ring 3.

Further, the water flow flows around the outer periphery of the rectifier cover 6 and does not come into direct contact with the receiver main body 1. Since the water flow resistance in the rectifying cover 6 is relatively small, noise generated by the water flow is reduced accordingly.

As explained above, according to the present invention, the main body of the sound pressure gradient type receiver is hermetically covered with a rectifying cover that is transparent to sound waves, and the main body of the receiver is further covered with an elastic body. The structure is such that the rectifier is supported within the rectifying shroud, and the rectifying shroud is filled with water or a liquid approximately equal to the specific acoustic resistance of the water, so there is no risk of sensitivity reduction when installed on the seabed. In addition, the rectifier cover has the effect of suppressing low frequency noise caused by disturbances such as water flow.

Further, according to the present invention, since the rectifying sheath is filled with water or a liquid approximately equal to the specific acoustic resistance of water, the incoming sound waves reach the receiver body without being reflected or scattered. There is an effect.

[Brief explanation of the drawing]

The drawings show an embodiment of the receiver according to the present invention, and FIG. 1 is a partially cutaway perspective view of the same, and FIG. 2 is a cross-sectional explanatory view showing the structure of the receiver main body. 1... Sound pressure gradient type receiver main body, 6... Rectifier cover,
7...Elastic body that supports the receiver body, 8...Liquid.

Claims (1)

[Claims] 1. A sound pressure gradient receiver body, a rectifier cover that hermetically covers the receiver body, an elastic body that supports the receiver body within the rectifier cover, and a rectifier cover that is filled in the rectifier cover. It is equipped with a liquid such as water,
A sound pressure gradient type wave receiver for installation on a seabed, characterized in that the rectifying cover is transparent to sound waves, and the liquid is a liquid that is approximately equal to the specific acoustic resistance of water.