Resonance frequency linear modulation method and device based on double-bubble cross-medium sound propagation system

Abstract

A method for linear modulation of the resonant frequency based on a double-bubble cross-medium sound propagation system includes: establishing a double-bubble cross-medium sound propagation system; fixing the horizontal spacing of the double bubbles and the depth of the bubbles closer to the water surface; modulating the depth of the deeper bubbles, accurately changing the vertical spacing of the double bubbles, and linearly modulating the resonant frequency of the double bubbles. The invention can realize linear modulation of the resonant frequency of the double-bubble cross-medium sound propagation system, and can accurately control the resonant frequency of the double-bubble cross-medium sound propagation system; using underwater double bubbles with adjustable vertical spacing as acoustic impedance matchers provides a potential method for designing cross-sea and air broadband acoustic communication technology.

Description

Technical Field

[0001] The present invention belongs to the field of communications, and in particular relates to a resonant frequency linear modulation method and device based on a double-bubble cross-medium sound propagation system, which can be applied to cross-sea and cross-air broadband sound communications. Background Art

[0002] At present, in the field of cross-media communication, the research on technical methods for obtaining underwater information in time directly in the air has received more and more attention. The implementation of this technology can be used in the efficient exploration of marine life and underwater environment, the precise positioning of underwater equipment, and the effective detection of underwater facility failures. According to previous studies, there are many technical methods to achieve cross-sea and air information interaction. One of the methods is to achieve cross-media communication by combining the transmission of underwater sound waves and electromagnetic waves in the air. The specific steps are divided into two steps. First, the sound waves emitted underwater excite the water surface to vibrate, and then the radar in the air detects the displacement of the water surface vibration and decodes it. Finally, the underwater information carried by the underwater sound waves is obtained to achieve cross-sea and air information interaction. However, this method has certain limitations. Since the radar sensor cannot accurately detect the excited displacement on a random surface, this method cannot be applied in harsh sea conditions. In addition, the transmitting sound transducer and the receiving radar sensor must work perpendicular to the water surface, which is not always possible in engineering.

[0003] Another technical method that may realize cross-sea and air information interaction is the application of impedance matching devices. As we all know, there is a 3,600-fold difference in impedance between water and air, which makes it almost difficult to achieve cross-medium propagation of sound waves. The transmission coefficient of sound waves in the natural state is less than 1%. However, the rational use of impedance matching devices can alleviate the acoustic impedance gap between water and air and increase the possibility of cross-medium propagation of sound waves and information interaction. At present, bubbles have been widely studied as a popular and effective acoustic impedance matching device. When the bubble is located at a certain depth underwater, its cross-water and air transmission coefficient for sound waves of a certain frequency band is greatly improved. Under the ideal resonance state, the corresponding excitation sound wave can be perfectly transmitted across the medium (the transmission coefficient reaches 100%). Under the action of bubbles, effective cross-medium transmission of acoustic energy can be achieved. However, the effect of a single bubble on the transmission coefficient of sound waves is only good when it is close to the bubble resonance frequency, and the frequency band that can act is narrow, which is not conducive to broadband cross-medium communication. In order to overcome this shortcoming, the present invention realizes linear precise modulation of the resonance frequency of the corresponding double-bubble cross-medium sound propagation system by adjusting the vertical spacing of the double-bubble combination, thereby broadening the effective frequency range of the bubbles as acoustic impedance matchers and providing a new way to achieve broadband cross-medium communication. Summary of the invention

[0004] In view of the shortcomings of existing cross-sea and air information interaction technologies and the characteristics of bubbles as impedance matchers, the present invention proposes a resonant frequency linear modulation method based on a double-bubble cross-medium sound propagation system, which can achieve linear and precise modulation of the resonant frequency of the system, providing a potential method for designing cross-sea and air broadband acoustic communication technology.

[0005] The technical solution of the present invention is as follows:

[0006] A resonant frequency linear modulation method based on a double-bubble cross-medium sound propagation system, comprising:

[0007] Establish a double-bubble cross-medium sound propagation system;

[0008] Fixed the horizontal spacing of double bubbles and the depth of the bubbles closer to the surface;

[0009] Modulating the depth of the deeper bubble precisely changes the vertical spacing of the double bubble, linearly modulating the resonant frequency of the double bubble.

[0010] The working principle of the present invention is that the resonant frequency of the bubble changes with the change of its size and depth. For the established double-bubble cross-medium sound propagation system, the sizes of the two bubbles in the system are consistent and almost unchanged. When the shallower bubble is fixed and the depth of the deeper bubble is changed, the resonant frequency of the system decreases linearly with the increase of the vertical distance between the two bubbles. According to the negatively correlated linear relationship, the resonant frequency of the system can be linearly and precisely modulated.

[0011] A resonant frequency linear modulation method based on a double-bubble cross-medium sound propagation system specifically comprises the following steps:

[0012] S1. Establish a double-bubble cross-medium sound propagation system with periodicity and reciprocity;

[0013] S2. The double bubbles as impedance matchers are at a certain depth underwater, and the shallower bubble is fixed to keep the horizontal distance between the two bubbles unchanged;

[0014] S3. Adjust the depth of the deeper bubble, stably and accurately change the vertical spacing between the two bubbles, and obtain a linear relationship between the vertical spacing between the two bubbles and the resonant frequency of the corresponding double bubble cross-medium sound propagation system;

[0015] S4. According to the linear relationship between the resonant frequency and the vertical spacing, the resonant frequency of the double-bubble cross-medium sound propagation system is linearly modulated.

[0016] Preferably, the double-bubble cross-medium sound propagation system is periodic, and a plurality of identical double-bubble combinations can be arranged at equal horizontal intervals at a certain depth in a water tank or related waters to form the double-bubble cross-medium sound propagation system.

[0017] Preferably, the reciprocity in step S1 means that the propagation of sound waves from air to water in the system is equivalent to the propagation of sound waves from water to air, and the sound waves are emitted by a transmitting transducer (underwater) or a loudspeaker (in air) and received by a hydrophone (underwater) or a microphone (in air), both of which are perpendicular to the water surface and arranged above and below the water surface.

[0018] Preferably, the linear relationship in step S3 is a linear relationship between the vertical spacing of the corresponding double bubble combination and its resonant frequency. By emitting sound waves of a certain frequency band from the air or water and then receiving the sound waves on the other side, the transmission coefficient curves of incident sound waves of different frequencies in the double bubble cross-medium sound propagation system with different vertical spacings can be measured. By analyzing the frequency of the incident sound wave corresponding to the peak of the curve and the corresponding vertical spacing, a negatively correlated linear relationship can be obtained in which the resonant frequency of the system decreases linearly with the increase of the vertical spacing between the two bubbles.

[0019] Preferably, the bubbles in step S2 are fixed by a bubble fixing system (a method of fixing bubbles using a sound field), or a bubble-like structure made of a polyhedral frame is used to replace the bubbles.

[0020] The present invention also provides a double-bubble cross-medium sound propagation system for implementing the above method, which is characterized in that it includes multiple double-bubble combinations, each double-bubble combination is placed in the water area with equal horizontal spacing, and contains deeper bubbles with adjustable depth and shallower bubbles with fixed depth, as well as equipment for transmitting and receiving sound waves.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The established double-bubble cross-medium acoustic propagation system is periodic and can be deployed over a large area to achieve cross-medium communication over a large water area. At the same time, due to reciprocity, information interaction from water to air and from air to water can be achieved in this system. The cross-medium information interaction is bidirectional, which makes cross-sea and air information interaction more convenient and efficient.

[0023] (2) To overcome the frequency band limitation of single bubble on the improvement of acoustic wave transmission coefficient, a modulation technology is proposed, which can realize the linear and precise modulation of the resonance frequency of the double bubble cross-medium acoustic propagation system, that is, its action frequency band range. By adjusting the vertical spacing of the double bubble combination to realize the linear and precise modulation of the resonance frequency of the corresponding double bubble cross-medium acoustic propagation system, the transmission coefficient curve corresponding to the double bubble system can be accurately shifted to realize the cross-medium communication of the required frequency band signal, which broadens the action frequency range of the bubble as an acoustic impedance matcher and provides a new way to realize broadband cross-medium communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1It is a flow chart of the resonant frequency linear modulation method based on the double-bubble cross-medium sound propagation system of the present invention;

[0025] Figure 2 It is an example of a periodic double-bubble trans-medium sound propagation system;

[0026] Figure 3 It is a schematic diagram of reciprocity proof;

[0027] Figure 4 It is the transmission coefficient curve corresponding to the double bubble combination with different vertical spacing;

[0028] Figure 5 It is a linear relationship diagram between the vertical spacing of double bubbles and the resonance frequency of the corresponding double bubble cross-medium sound propagation system. DETAILED DESCRIPTION

[0029] The invention scheme of the present invention will be described completely and clearly below in conjunction with the embodiments and drawings, but this should not limit the protection scope of the present invention.

[0030] like Figure 1 As shown, a resonant frequency linear modulation method based on a double-bubble cross-medium sound propagation system includes the following contents:

[0031] A double-bubble cross-medium sound propagation system is established. The double-bubble cross-medium sound propagation system used in the present invention is as follows: Figure 2 In a water tank or related water area, multiple identical double bubble combinations are placed at equal horizontal intervals at a certain depth from the water surface to form a periodic double bubble cross-medium sound propagation system as shown in the figure. The reciprocity of the system is then tested to determine whether sound waves can be bidirectionally transmitted across the medium in the system.

[0032] Reciprocity verification of the system. In the system, speakers and hydrophones or microphones and transmitting transducers arranged vertically above and below the water surface are used to perform two-way cross-medium sound wave propagation and reception, and the transmission coefficients of incident sound waves of different frequencies are obtained, and a transmission coefficient curve is drawn, such as Figure 3 As shown, the consistency of the transmission coefficient curves from air to water and from water to air is observed.

[0033] Fixed horizontal spacing of shallow bubbles and double bubble combinations. The basic layout of double bubbles is as follows Figure 2 As shown, the depth of the shallower bubble and the horizontal distance between the two bubbles need to be kept constant, and it is assumed that the tiny vibration of the bubble caused by the sound wave will not have much effect on the radius of the bubble.

[0034] The linear relationship between the vertical spacing of the double bubbles and the resonant frequency of the corresponding double bubble cross-medium sound propagation system is obtained. After the appropriate system is established, the depth of the deeper bubble is adjusted to change the vertical spacing of the double bubble combination in the system. By emitting sound waves of a certain frequency band from the air or water and then receiving the sound waves at the other side, the transmission coefficient curve of the incident sound wave in the double bubble cross-medium sound propagation system with different vertical spacings is obtained, such as Figure 4 Then, the frequency of the incident sound wave and the corresponding vertical spacing corresponding to the peak value of each curve are analyzed, and a negative correlation linear relationship is obtained, in which the resonant frequency of the system decreases linearly with the increase of the vertical spacing between the two bubbles, as shown in Figure 5 shown.

[0035] The linear relationship is used to linearly modulate the resonant frequency of the double-bubble cross-medium sound propagation system. Figure 5 The negative correlation linear relationship diagram of the resonance frequency and the corresponding double bubble vertical spacing is linearly regressed to obtain the corresponding linear relationship. Then, according to the analytical expression, the resonance frequency of the corresponding double bubble cross-medium sound propagation system is linearly precisely modulated by changing the double bubble vertical spacing.

[0036] The bubble fixation adopts a bubble fixation system (a method of fixing bubbles using a sound field), or adopts a bubble-like structure made of a polyhedral frame to replace the bubbles.

[0037] The linear relationship between the vertical spacing of the double bubbles and the resonant frequency of the corresponding double bubble cross-medium sound propagation system is the result of the influence of the double bubble resonant frequency on the depth. Generally speaking, as the depth of the bubble increases, the resonant frequency of the bubble will decrease, and the effective mass of the bubble itself will increase. At this time, there is no linear relationship for a single bubble, but when two bubbles are combined, they will interfere with each other through the scattering and radiation of sound waves, thereby affecting each other's resonance, resulting in a negatively correlated linear relationship between the resonant frequency of the double bubble combination and the vertical spacing of the two bubbles. By obtaining this linear relationship, linear and precise modulation of the resonant frequency of the corresponding double bubble cross-medium sound propagation system can be achieved.

[0038] The transmission coefficient curve of the double bubble system with different vertical spacing has two peaks, and the effect of improving the transmission coefficient of incident sound waves of different frequencies is similar to that of the single bubble within a certain frequency band, such as Figure 4 As shown, the relationship between the incident sound wave frequency corresponding to the peak value of the left main peak of the transmission coefficient curve and the vertical spacing of the double bubble combination corresponding to the transmission coefficient curve at this time is plotted and analyzed, and a negatively correlated linear relationship between the vertical spacing of the double bubbles and the resonant frequency of the corresponding double bubble cross-medium sound propagation system can be obtained.

[0039] The resonant frequency linear modulation method used in the present invention uses the negative correlation linear relationship between the vertical spacing of the double bubbles and the resonant frequency of the system as the basis for modulation. By adjusting the depth of the deeper bubble, the vertical spacing of the double bubbles can be changed, thereby linearly modulating the resonant frequency of the corresponding double bubble cross-medium sound propagation system. This method can accurately shift the transmission coefficient curve corresponding to the double bubble system, realize cross-medium communication of signals in the required frequency band, broaden the frequency range of the bubble as an acoustic impedance matcher, and provide a feasible path for realizing broadband cross-sea and air communication.

[0040] Example

[0041] The following is an embodiment of linearly modulating the resonant frequency of a double-bubble trans-medium acoustic propagation system.

[0042] According to the method described above, multiple identical double bubble combinations (bubble radius is 5mm) are placed at an equal horizontal spacing (spacing is 40mm) at a depth of 7mm underwater to form a periodic double bubble cross-medium sound propagation system. In this system, a unit contains a double bubble combination, and the unit water width is 40mm. The depth of the shallower bubble in the double bubble combination is 7mm, the horizontal spacing between the two bubbles is 2mm, and the depth of the deeper bubble can be changed arbitrarily.

[0043] An ideal plane wave with an amplitude of 1 Pa is used as the incident sound wave, and the frequency band is selected to be 100-700 Hz. In this system, sound waves of different frequencies in the selected frequency band are vertically incident from the air or water and propagate across the medium.

[0044] The vertical spacing between the double bubbles in this periodic double-bubble cross-medium sound propagation system is set to 2 mm. Sound waves are incident vertically from the air and water and received on the other side. The transmission coefficients of incident sound waves of different frequencies in the selected frequency band are measured, and the transmission coefficient curves are plotted to observe the consistency of the transmission coefficient curves from air to water and from water to air.

[0045] After establishing a suitable system, keep the depth of the shallower bubble and the horizontal spacing of the double bubbles unchanged, adjust the depth of the deeper bubble, change the vertical spacing of the double bubble combination in the system, and when the vertical spacing h1 is 2:2:20mm, vertically incident sound waves from the air and received in the water on the other side, and obtain the incident sound wave transmission coefficient curve in the double bubble cross-medium sound propagation system with different vertical spacings, as shown in Figure 4 Then, the frequency of the incident sound wave and the corresponding vertical spacing corresponding to the peak value of the left main peak of each curve are analyzed, and a negative correlation linear relationship is obtained that the resonant frequency of the system decreases linearly with the increase of the vertical spacing between the two bubbles, as shown in Figure 5 shown.

[0046] For example Figure 5The negative correlation linear relationship diagram of the resonant frequency and the corresponding double bubble vertical spacing is linearly regressed to obtain the linear relationship y=-2.7636x+262.2, and the regression variance is 0.9972, where y is the resonant frequency of the double bubble trans-medium sound propagation system, and x is the vertical spacing of the corresponding double bubble combination. According to the analytical formula, the resonant frequency of the corresponding double bubble trans-medium sound propagation system is linearly precisely modulated by changing the double bubble vertical spacing.

[0047] For example, if the resonant frequency of the established periodic double-bubble trans-medium sound propagation system is to be linearly modulated to 180 Hz, the vertical spacing of the double-bubble combination corresponding to the system needs to be adjusted to 29.7438 mm. Therefore, according to the analytical formula, we can linearly modulate the resonant frequency of the system in a larger range. In this embodiment, the linear and precise modulation of the resonant frequency of the double-bubble trans-medium sound propagation system is successfully achieved.

Claims

1. A resonant frequency linear modulation method based on a double-bubble cross-medium sound propagation system, characterized in that: include: S1. Establishing a double-bubble cross-medium sound propagation system, the system comprises a plurality of double-bubble combinations, each of which is placed in a water tank or related water area with equal horizontal spacing to form a periodic system structure; S2. Check the reciprocity of the double-bubble cross-medium sound propagation system, and use speakers, hydrophones or microphones and transmitting transducers arranged above and below the water surface to perform two-way cross-medium sound wave propagation and reception to verify whether the sound wave can be bidirectionally propagated across the medium in the double-bubble cross-medium sound propagation system; S3. The double bubbles as impedance matchers are placed at a certain depth underwater, the depth of the shallower bubbles and the horizontal spacing of the double bubble combination are fixed, the depth of the deeper bubbles is adjusted, the vertical spacing of the double bubble combination is changed, and the transmission coefficient curve of the incident sound wave under different vertical spacings is obtained by transmitting and receiving sound waves at different positions; S4. Analyze the relationship between the incident sound wave frequency corresponding to the peak value of each transmission coefficient curve and the corresponding vertical spacing, and determine the negative correlation linear relationship that the resonant frequency of the double-bubble cross-medium sound propagation system decreases linearly with the increase of the double-bubble vertical spacing; S5. Perform linear regression using the negative correlation linear relationship to obtain a linear relationship, and based on this, linear modulation of the resonant frequency of the double-bubble cross-medium sound propagation system is achieved by adjusting the vertical spacing between the double bubbles.

2. The resonant frequency linear modulation method based on the double-bubble cross-medium sound propagation system according to claim 1 is characterized in that: The double-bubble cross-medium sound propagation system is periodic, and a plurality of identical double-bubble combinations can be arranged at equal horizontal intervals at a certain depth in a water tank or related waters to form the double-bubble cross-medium sound propagation system.

3. The resonance frequency linear modulation method based on the double-bubble cross-medium sound propagation system according to claim 1 is characterized in that: The reciprocity in step S2 means that the propagation of sound waves from air to water in the system is equivalent to the propagation of sound waves from water to air. The sound waves are emitted by a transmitting transducer or a loudspeaker and received by a hydrophone or a microphone, both of which are perpendicular to the water surface and arranged above and below the water surface.

4. The resonant frequency linear modulation method based on the double-bubble cross-medium sound propagation system according to claim 1 is characterized in that: The linear relationship in step S4 is a linear relationship between the vertical spacing of the double bubble combination and its resonant frequency. By emitting sound waves of a certain frequency band from the air or water and then receiving the sound waves on the other side, the transmission coefficient curves of incident sound waves of different frequencies in the double bubble cross-medium sound propagation system with different vertical spacings can be measured. By analyzing the frequency of the incident sound wave corresponding to the peak of the curve and the corresponding vertical spacing, a negatively correlated linear relationship can be obtained in which the resonant frequency of the system decreases linearly with the increase of the vertical spacing between the two bubbles.

5. The resonant frequency linear modulation method based on the double-bubble cross-medium sound propagation system according to claim 1 is characterized in that: In step S3, the bubbles are fixed by a bubble fixing system, or a bubble-like structure made of a polyhedral frame is used to replace the bubbles.

6. The resonance frequency linear modulation method based on the double-bubble cross-medium sound propagation system according to claim 1 is characterized in that: The incident sound wave is a plane wave with a frequency band selected between 100 and 700 Hz, and is vertically incident through air or water and propagates across the medium.

7. A double bubble cross-medium sound propagation system for implementing the method described in any one of claims 1 to 6, characterized in that , including a plurality of double bubble combinations, each of which is placed in the water area with equal horizontal spacing and contains deeper bubbles with adjustable depth and shallower bubbles with fixed depth, as well as equipment for transmitting and receiving sound waves.

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