WO2015111937A1

WO2015111937A1 - Method for manufacturing signal conditioning plate for underwater hydrophone using sound-absorbing material

Info

Publication number: WO2015111937A1
Application number: PCT/KR2015/000687
Authority: WO
Inventors: 박철수; 김건도; 설한신; 박영하
Original assignee: 한국해양과학기술원
Priority date: 2014-01-27
Filing date: 2015-01-22
Publication date: 2015-07-30
Also published as: KR101479898B1

Abstract

The present invention provides a method for manufacturing a signal conditioning plate for an underwater hydrophone using a sound-absorbing material, the method comprising the steps of: providing a fixing casing to a lower flat board, and inserting and fixing an underwater hydrophone into/to the fixing casing; forming, in a sound-absorbing board, a hydrophone hole into which the underwater hydrophone can be inserted, and providing the sound-absorbing board on the upper side of the lower flat board; and providing a fixing external board so as to allow an edge of the lower flat board and an edge of the sound-absorbing board to border each other at the same time such that the sound-absorbing board is fixed to the lower flat board, wherein the sound-absorbing board suppresses the generation of a reflected wave by absorbing an incident wave transferred underwater, and also surrounds the perimeter of the underwater hydrophone so as to fix the underwater hydrophone such that the underwater hydrophone does not shake. According to the present invention, it is possible to prevent a size reduction in a signal measured by an underwater hydrophone by suppressing a reflected wave due to a signal conditioning plate when underwater noise is measured, and to firmly fix the underwater hydrophone to the signal conditioning plate such that the fixed state is not released even though the underwater hydrophone is exposed to an underwater environment and an external force is applied to the underwater hydrophone. Thus, problems such as the impossibility of utilizing signals due to a strong signal loss in a specific frequency band when underwater noise is measured, or the deterioration of the reliability of the measurement result, do not occur.

Description

Method of manufacturing hydrophone signal control panel using sound absorbing material

The present invention relates to a signal control plate which can firmly fix the hydrophone while preventing the reduction of the signal size measured by the hydrophone by suppressing the reflected wave by the signal controller as a sound absorbing material.

Underwater noise is measured by using an underwater hydrophone (Underwater Hydrophone) 40, in order to increase the degree of measurement, a plurality of hydrophones 40 are used in an arrangement (Fig. 1). At this time, the plate fixing the hydrophone 40 for the arrangement of the plurality of hydrophones 40 is called a signal conditioning plate (Signal Conditioning Plate) (50). The purpose of the signal control plate 50 is to fix the individual hydrophone 40 in a specific position, and to control the size of the signal.

At this time, the principle of controlling the size of the signal with the signal control plate 50 is as follows. As shown in FIG. 2, in the hydrophone 40 fixed by the signal controller 50, the incident wave Pi transmitted directly to the hydrophone 40 in the water and the reflected wave Pr by the signal controller 50 are included. It is measured at the same time. In this case, the reflection angle r of the reflected wave Pr is equal to the incident angle i of the incident wave Pi when the signal control plate 50 is a flat plate. If the signal measured by the hydrophone 40 is expressed by the equation as follows.

P = Pi + Pr = (1 + Re ^{2ikdcos (r)} ) Pi [Formula 1]

In Equation 1, R is a reflection coefficient, and in general, when the signal control plate 50 is an iron plate, the difference in acoustic impedance with water is close to 1. k is the Wave Number and d is the Standoff Distance, which is the distance between the top end of the hydrophone 40 and the surface of the control panel 50. At this time, there is a phase difference of 2 kdcos (r) between the incident wave and the reflected wave, and the interference between the incident wave and the reflected wave is generated by this phase difference, thereby determining the magnitude of the signal.

When the distance between the top end of the hydrophone 40 and the surface of the signal control plate 50 is 0, that is, when the standoff distance is 0, there is no phase difference between the incident wave and the reflected wave, so that constructive interference between the incident wave and the reflected wave is reduced in all frequency bands. Occurs. Accordingly, as shown in FIG. 3, when the standoff distance is 0, the signal control plate 50 may obtain a signal gain (SR) of about 6 dB. At this time, the signal gain is defined as Equation 2 below.

SR = 20log10 [(Pi + Pr) / Pi] (dB) [Equation 2]

However, as described above, when the standoff distance is 0, it is very difficult to actually implement, and most of the hydrophones 40 that are commercially released are on top of the hydrophone 40 as shown in FIG. The ends should be fixed to protrude above the surface of the signal control plate 50. Therefore, the standoff distance (d) can not be 0, the standoff distance is inevitably changed according to each hydrophone 40.

As such, when the standoff distance is not 0, there is a phase difference between the incident wave and the reflected wave according to the standoff distance, and the frequency varies. 4 is a result of calculating the signal gain according to the angle of incidence in the hydrophone 40 with a standoff distance of 1cm in the existing signal control plate 50 made of a 1cm thick steel plate. In FIG. 4, the frequency region where the signal gain is positive is a region in which constructive interference occurs, and the frequency region where the signal gain is negative is a region where destructive interference occurs. Offset interference is an unavoidable phenomenon caused by the phase difference caused by the standoff distance.

However, if the cancellation interference occurs according to the phase difference caused by the standoff distance, a strong signal loss occurs in a specific frequency band (near 40 kHz, 45 kHz, 75 kHz in FIG. 4), and thus the signal in the frequency band cannot be utilized. In general, there is a problem that the reliability of the measurement results are reduced. The frequency band in which the signal gain becomes -6 dB or less is commonly referred to as an unmeasurable area, and this unmeasurable area varies depending on the standoff distance.

On the other hand, in the case of the hydrophone 40, in addition to the phase difference due to the standoff distance, there is another important factor that lowers the reliability of the measurement results, which is that the hydrophone 40 is still exposed to the underwater environment when measuring noise. to be. There is always a flow of water, such as waves or currents in the water and the hydrophone 40 is subjected to external forces accordingly. In this case, when the external force applied to the hydrophone 40 exceeds a certain size, the hydrophone 40 may be shaken or tilted or may be pulled out of the signal control plate 50 in severe cases. In this case, the magnitude of the signal measured by the hydrophone 40 is not constant and changes randomly or in severe cases, the signal measurement becomes impossible and the reliability of the measurement result is lowered overall. Therefore, it is necessary to solve the above problems.

The present invention has been proposed in order to solve the above problems, by suppressing the reflected wave by the signal control plate as a sound absorbing material to prevent the reduction of the signal size measured by the hydrophone while the sound control panel can be firmly fixed to the hydrophone It aims to provide.

In order to achieve the above object, the present invention comprises the steps of installing a fixed casing on the lower plate and fixing the hydrophone to the fixed casing; Forming a sound absorber hole through which the hydrophone is fitted to the sound absorbing plate and installing the sound absorbing plate on an upper surface of the lower flat plate; And installing a fixed outer plate to be in contact with the edge of the lower plate and the edge of the sound absorbing plate at the same time so that the sound absorbing plate is fixed to the lower plate. In this case, the sound absorbing plate is configured to receive incident waves transmitted in water The present invention provides a method for manufacturing a hydrophone signal control panel using a sound absorbing material, while absorbing and suppressing generation of reflected waves while fixing the hydrophone around the hydrophone.

In the present invention, the lower plate is characterized in that the steel plate.

In the present invention, the lower plate is characterized in that a plurality of the fixed casing is installed so that a plurality of the hydrophones can be arranged.

In the present invention, the fixed casing is characterized in that also serves as an adapter at the same time.

In the present invention, the sound absorbing plate is characterized by having a flat plate shape.

In the present invention, the fixing shell is characterized in that the steel plate.

According to the present invention, by suppressing the reflected wave by the signal control plate during the measurement of underwater noise, it is possible not only to prevent the reduction of the signal size measured by the hydrophone, but also to firmly fix the hydrophone to the signal control panel so that the hydrophone can be used in the underwater environment. Even if exposed to external force, the fixed state is not disassembled. Therefore, when measuring underwater noise, a strong signal loss generated in a specific frequency band does not prevent the use of the signal or the reliability of the measurement result does not occur.

1 illustrates an existing signal control panel for the hydrophone and hydrophone arrangement.

2 is an explanatory diagram illustrating a principle of controlling the magnitude of a signal with a signal control plate.

3 is a signal gain calculation result of the signal control plate when the standoff distance is zero.

4 is a signal gain calculation result of the signal control plate when the standoff distance is 1cm.

5 is a configuration and operation principle of the signal control plate according to the present invention.

6 is a shape of the sound absorbing plate according to the present invention.

7 is a performance measurement result of the sound absorbing plate according to the present invention.

8 is a signal gain comparison of the signal control plate according to the present invention and a signal control plate consisting of the conventional iron plate only.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the present invention. First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible, even if shown on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

Figure 5 shows the configuration and operation principle of the signal control plate according to the present invention.

An object of the present invention is to provide a signal control plate that can firmly fix the hydrophone 40 while preventing the reduction of the signal size measured by the hydrophone 40 by suppressing the reflected wave by the signal control plate as a sound absorbing material. Bar, the signal control plate according to the present invention is made through the following process.

First, the fixed casing 11 is installed on the lower flat plate 10, and the hydrophone 40 is fixed to the fixed casing 11. Next, the sound absorbing plate 20 is formed in the sound absorbing plate 40, the sound receiver hole 21 can be fitted to the sound absorbing plate 20 is installed on the upper surface of the lower flat plate 10. Next, the fixing plate 30 is installed to be in contact with the edge of the lower plate 10 and the edge of the sound absorbing plate 20 at the same time so that the sound absorbing plate 20 is fixed to the lower plate 10.

Therefore, the signal control plate according to the present invention comprises a lower plate 10, a sound absorbing plate 20 and a fixed outer plate (30). Hereinafter, the configuration and operation principle of the signal control plate according to the present invention will be described in detail.

The lower plate 10 forms a lower structure of the signal control plate according to the present invention as shown in FIG. 5, and includes a fixed casing 11 to which the hydrophone 40 can be fitted. Therefore, when the hydrophone 40 is inserted into the fixed casing 11 when the underwater noise is measured, the hydrophone 40 is fixed to the lower plate 10.

In this case, since it is common to use a plurality of hydrophones 40 arranged in an array in order to increase the degree of measurement, the lower flat plate 10 also preferably includes a plurality of fixed casings 11. At this time, since the fixed casing 11 also serves as an adapter at the same time, when the signal line 12 is connected to the fixed casing 11, the hydrophone 40 can receive the signal measured by the hydrophone 40.

On the other hand, the lower flat plate 10 is preferably made of a rigid steel plate for the rigid fixing of the hydrophone 40, in this case, the lower flat plate 10 is firmly attached to the position where each hydrophone 40 is designed correctly It will serve as a foundation structural material.

Sound absorbing plate 20 is installed on the upper surface of the lower plate 10 as shown in Figure 5 forms an integral with the lower plate 10. The sound absorbing plate 20 is made of a sound absorbing material so as to absorb the incident wave transmitted in the water to suppress the generation of the reflected wave.

Therefore, in the case of the present invention, the hydrophone 40 is measured only the incident wave transmitted directly from the water to the hydrophone 40 as shown in FIG. 5 and the reflected wave is not measured or even if measured even if the measurement is very weak. In this case, the sound absorbing plate 20 is preferably formed in a flat plate shape as shown in FIG. 6 so that the reflection is not reflected in case the reflected wave is weakly measured.

Therefore, in the case of the present invention (even if the standoff distance is not 0), there is no phase difference between the incident wave and the reflected wave according to the standoff distance, and as a result, there is no offset interference enough to seriously affect the measurement result. do. That is, according to the present invention it is possible to prevent the occurrence of a strong signal loss in a specific frequency band by the action of the sound absorbing plate 20.

In this regard, Figure 7 shows the results of the performance measurement of the sound absorbing plate 20 according to the present invention, Figure 8 shows the signal gain comparison results of the signal control plate made of the conventional steel plate and the signal control plate according to the present invention.

In FIG. 7, it can be seen that the sound absorbing plate 20 according to the present invention has an average sound absorbing performance (SPL) of 5 dB or more in all frequency bands. And in the case of the signal control plate made of only the conventional iron plate in Figure 8 is not possible to use in the frequency band due to the strong signal loss generated around 40kHz, the signal control plate according to the present invention the frequency compared to the conventional signal control plate It can be seen that the signal loss in the band is significantly weakened.

As such, the sound absorbing plate 20 serves to prevent the generation of reflected waves to prevent signal loss in a specific frequency band, but also surrounds the hydrophone 40 so that the hydrophone 40 is not shaken. It also serves to fix.

That is, as shown in FIG. 5, when the sound absorbing plate 20 surrounds the hydrophone 40 in a state where the sound absorbing plate 20 is installed on the upper surface of the lower flat plate 10, the hydrophone 40 is prevented from being exposed to the underwater environment. Therefore, the external force according to the flow of water, such as waves or currents can be prevented from being applied to the hydrophone 40 as it is. Therefore, in this case, the hydrophone 40 is not shaken or tilted due to the external force or, in severe cases, does not occur in the lower plate 10. As such, if the hydrophone 40 is kept in a stable state despite the external force, the size of the signal measured by the hydrophone 40 can be kept constant, and the size of the signal changes randomly or the hydrophone 40 Does not cause the problem of not measuring the signal.

On the other hand, the sound absorbing plate 20 has a sound receiver hole 21 into which the hydrophone 40 can be fitted (FIG. 6). In this case, the sound absorber hole 21 penetrates up and down the sound absorbing plate 20, for example. It may be formed in the form (Fig. 5). At this time, if the hearing aid hole 21 is formed in the sound absorbing plate 20 in advance so as to correspond to the size of the hydrophone 40 and each of the hydrophones 40 is exactly designed, the installation work of the sound absorbing plate 20 is performed. This can be done much faster and easier (FIG. 6).

When the sound absorbing plate 20 is installed on the lower plate 10, it is also possible to fix the sound absorbing plate 20 to the lower plate 10 using an adhesive, but as shown in FIG. 5, the sound absorbing plate 30 is fixed using the fixing plate 30. Fixing the 20 may increase the overall rigidity of the signal adjusting plate according to the present invention so that the fixing of the hydrophone 40 and the sound absorbing plate 20 may be more firm. The fixed outer plate 30 is installed at the edge of the lower plate 10 and at the same time is installed to be in contact with the edge of the sound absorbing plate 20, the sound absorbing plate 20 by the action of the fixing plate 30 is the lower plate 10 and It is firmly fixed to the lower plate 10 in a completely integral state. In this case, the fixing outer plate 30 is preferably made of an iron plate having rigidity for firm fixing of the sound absorbing plate 20.

As described above, according to the present invention, it is possible to prevent the reduction of the signal size measured by the hydroacoustic listener 40 by suppressing the reflected wave by the signal regulating plate during underwater noise measurement. It is firmly fixed so that the hydrophone 40 is exposed to the underwater environment, even if it receives an external force, the fixed state is not dismantled. Therefore, when measuring underwater noise, a strong signal loss generated in a specific frequency band does not prevent the use of the signal or the reliability of the measurement result does not occur.

The above description is merely illustrative of the technical idea of the present invention, and various modifications, changes, and substitutions may be made by those skilled in the art without departing from the essential characteristics of the present invention. will be. Therefore, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

According to the present invention can increase the reliability of the underwater noise measurement results, the present invention is a technology that can be widely used in the shipbuilding and marine industry to realize its practical and economic value.

Claims

Installing a fixed casing (11) on the lower plate (10) and fixing the hydrophone (40) to the fixed casing (11);

Forming a sound receiver hole (21) into which the hydrophone (40) can be fitted in the sound absorbing plate (20) and installing the sound absorbing plate (20) on the upper surface of the lower flat plate (10);

Installing a fixing outer plate 30 to be in contact with an edge of the lower plate 10 and an edge of the sound absorbing plate 20 at the same time so that the sound absorbing plate 20 is fixed to the lower plate 10;

Including, in this case,

The sound absorbing plate 20 absorbs the incident wave transmitted in the water to suppress the generation of the reflected wave, while fixing the hydrophone 40 around the hydrophone 40 so as not to shake.

The fixed casing (11) is also characterized in that the role of the adapter at the same time, hydrophone signal control panel manufacturing method using a sound absorbing material.
The method according to claim 1,

The lower plate 10 is characterized in that the steel plate, sound absorber using the sound absorbing material manufacturing method of the sound control board.
The method according to claim 1,

The lower plate (10) is characterized in that a plurality of the fixed casing (11) is installed so that the plurality of hydrophones (40) can be arranged, hydrophone signal control panel manufacturing method using a sound absorbing material.
The method according to claim 1,

The sound absorbing plate (20) is characterized in that it is made of a flat plate, sound absorbing signal control panel manufacturing method using a sound absorbing material.
The method according to claim 1,

The fixed outer plate 30 is characterized in that the steel plate, sound absorber using the sound absorbing material manufacturing method of the sound control board.