阅读说明：本技术 一种基于相控参量阵的次声波定向发射系统及方法 (Phased parametric array-based infrasonic wave directional transmitting system and method ) 是由 乔卫东 黄龙 胡颖 于 2021-07-23 设计创作，主要内容包括：本发明公开了一种基于相控参量阵的次声波定向发射系统及方法,系统包括依次连接的矩阵键盘、信号产生模块、信号调制模块、延时模块、数模转换模块、功率放大模块和超声波换能器阵列；信号产生模块用于根据矩阵键盘的控制信号输出待调制的信号以及高频载波；信号调制模块用于根据待调制的信号以及高频载波实现带载波单边带调制,得到多路单边带调制信号；延时模块用于根据所述多路单边带调制信号的偏转角度的大小分别对各路处理信号进行延时,生成多路调制信号；超声波换能器阵列用于根据所有放大后的调制信号发射超声波。本发明将相控阵和参量阵结合成相控参量阵来产生次声波,能够用小体积的设备产生高指向性的次声波,并实现声波的偏转。(The invention discloses a phased parametric array-based infrasonic wave directional transmitting system and a phased parametric array-based infrasonic wave directional transmitting method, wherein the system comprises a matrix keyboard, a signal generating module, a signal modulating module, a time delay module, a digital-to-analog conversion module, a power amplifying module and an ultrasonic transducer array which are sequentially connected; the signal generating module is used for outputting a signal to be modulated and a high-frequency carrier according to a control signal of the matrix keyboard; the signal modulation module is used for realizing single-sideband modulation of the carrier wave according to the signal to be modulated and the high-frequency carrier wave to obtain a plurality of paths of single-sideband modulation signals; the delay module is used for delaying each path of processing signal according to the deflection angle of the multi-path single sideband modulation signal to generate a multi-path modulation signal; the ultrasonic transducer array is used for emitting ultrasonic waves according to all amplified modulation signals. The phased array and the parametric array are combined into the phased parametric array to generate the infrasonic wave, so that the infrasonic wave with high directivity can be generated by using equipment with small volume, and the deflection of the infrasonic wave is realized.)

1. An infrasonic wave directional transmitting system based on a phased parametric array is characterized by comprising a matrix keyboard, a signal generating module, a signal modulating module, a time delay module, a digital-to-analog conversion module, a power amplifying module and an ultrasonic transducer array which are sequentially connected;

the signal generation module is used for outputting a signal to be modulated and a high-frequency carrier according to a control signal of the matrix keyboard;

the signal modulation module is used for realizing single-sideband modulation of the carrier according to the signal to be modulated and the high-frequency carrier to obtain a single-sideband modulation signal;

the delay module is used for delaying each path of processing signal according to the deflection angle of the single-sideband modulation signal to generate a plurality of paths of modulation signals;

the digital-to-analog conversion module and the power amplification module are respectively used for performing digital-to-analog conversion and amplification on each path of modulation signal;

the ultrasonic transducer array is used for emitting ultrasonic waves according to all amplified modulation signals.

2. The phased parametric array-based infrasonic wave directional transmitting system of claim 1, wherein the signals to be modulated output by the signal generating module are sine signals and cosine signals, and the output high-frequency carrier is sine carrier signals and cosine carrier signals of 21kHz to 40 kHz.

3. The phased parametric array-based directional transmitting system for infrasonic waves according to claim 2, wherein the signal modulation module implements single sideband modulation with carrier according to the signal to be modulated and the high frequency carrier, and the process of obtaining the single sideband modulation signal comprises:

according to a carrier-band single-sideband modulation method, a sine signal and a cosine signal to be modulated are multiplied by a cosine carrier signal and a sine carrier signal respectively, and products of the cosine carrier signal and two multipliers are added to obtain an upper sideband signal; finally, respectively obtaining the time delay of each path of signal according to the deflection angle, and then outputting each path of modulation signal according to the time delay.

4. The phased parametric array-based directional transmitting system for infrasonic waves as claimed in claim 1, wherein the ultrasonic transducer arrays are arranged in an octagonal planar array, and each ultrasonic transducer is connected with a modulation signal.

5. The phased parametric array based directional transmitting system of infrasound waves as claimed in claim 4, wherein the ultrasonic transducer array comprises 24 ultrasonic transducers, and the 24 ultrasonic transducers are compounded into an octagonal planar array by a planar array of four rows and three columns and three rows and four columns.

6. The phased parametric array based directional transmitting system for infrasonic waves as claimed in claim 1, further comprising a display module connected to the signal generating module for displaying the frequency of the signal to be modulated output by the signal generating module.

7. An infrasonic wave directional emission method is characterized by comprising the following processes:

generating a control signal;

obtaining a signal to be modulated and a high-frequency carrier according to the control signal;

realizing single-sideband modulation of the carrier according to the signal to be modulated and the high-frequency carrier to obtain a single-sideband modulation signal;

respectively delaying each path of processing signal according to the deflection angle of the single side band modulation signal to generate a plurality of paths of modulation signals;

performing digital-to-analog conversion on each path of modulation signal to obtain a plurality of paths of analog signals;

amplifying the multiple paths of analog signals to obtain multiple paths of amplified signals;

and converting each path of amplified signals in the multiple paths of amplified signals into a path of ultrasonic waves, and transmitting all the ultrasonic waves in an array form and self-demodulating the ultrasonic waves in a propagation medium to obtain infrasonic waves.

8. A method as claimed in claim 7, wherein all of the ultrasonic waves propagating in the array are arranged in an octagonal planar array.

9. A directional transmission method of infrasonic waves according to claim 8, wherein all ultrasonic waves propagate in the form of an octagonal planar array formed by a planar array of four rows and three columns and a planar array of three rows and four columns.

10. The directional transmitting method of infrasound according to claim 7, wherein the signals to be modulated are sine signals and cosine signals, and the output high frequency carrier is sine carrier signals and cosine carrier signals of 21 kHz-40 kHz;

the method comprises the following steps of realizing single-sideband modulation of carrier waves according to signals to be modulated and high-frequency carrier waves, and obtaining single-sideband modulation signals:

according to a carrier-band single-sideband modulation method, a sine signal and a cosine signal to be modulated are multiplied by a cosine carrier signal and a sine carrier signal respectively, and products of the cosine carrier signal and two multipliers are added to obtain an upper sideband signal; finally, respectively obtaining the time delay of each path of signal according to the deflection angle, and then outputting each path of modulation signal according to the time delay.

Technical Field

The invention belongs to the technical field of infrasonic waves, and relates to an infrasonic wave directional transmitting system and method based on a phased parametric array.

Background

An infrasonic wave is a low frequency sound wave with a frequency below 20 Hz. Infrasonic waves are generally generated in the case of earthquakes, tsunamis, volcanic eruptions, rocket launches, and the like. Due to the low-frequency characteristic, the material has wide application prospect in the aspects of biological dispersion, pipeline detection, infrasonic weapons, medical treatment and the like. Meanwhile, the infrasonic wave detection can be used for early warning of some disasters.

The existing infrasonic waves are mainly generated in an air explosion type, a bomb type, a loudspeaker type and a frequency difference beat type. However, these existing methods cannot obtain infrasonic waves with high directivity and realize deflection of the sonic waves.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention aims to provide an infrasonic wave directional transmitting system and method based on a phased parametric array.

The technical scheme adopted by the invention is as follows:

an infrasonic wave directional transmitting system based on a phased parametric array comprises a matrix keyboard, a signal generating module, a signal modulating module, a time delay module, a digital-to-analog conversion module, a power amplifying module and an ultrasonic transducer array which are connected in sequence;

the signal generation module is used for outputting a signal to be modulated and a high-frequency carrier according to a control signal of the matrix keyboard;

the signal modulation module is used for realizing single-sideband modulation of the carrier according to the signal to be modulated and the high-frequency carrier to obtain a single-sideband modulation signal;

the delay module is used for delaying each path of processing signal according to the deflection angle of the single-sideband modulation signal to generate a plurality of paths of modulation signals;

the digital-to-analog conversion module and the power amplification module are respectively used for performing digital-to-analog conversion and amplification on each path of modulation signal;

the ultrasonic transducer array is used for emitting ultrasonic waves according to all amplified modulation signals.

Preferably, the signals to be modulated output by the signal generation module are sine signals and cosine signals, and the output high-frequency carrier is sine carrier signals and cosine carrier signals of 21 kHz-40 kHz.

Preferably, the signal modulation module implements single-sideband modulation of the carrier band according to the signal to be modulated and the high-frequency carrier, and the process of obtaining the single-sideband modulation signal includes:

according to a carrier-band single-sideband modulation method, a sine signal and a cosine signal to be modulated are multiplied by a cosine carrier signal and a sine carrier signal respectively, and products of the cosine carrier signal and two multipliers are added to obtain an upper sideband signal; finally, respectively obtaining the time delay of each path of signal according to the deflection angle, and then outputting each path of modulation signal according to the time delay.

Preferably, the ultrasonic transducer arrays are arranged in an octagonal planar array, and each ultrasonic transducer is connected with one path of modulation signal.

Preferably, the ultrasonic transducer array comprises 24 ultrasonic transducers, and the 24 ultrasonic transducers are compounded into an octagonal planar array by a planar array of four rows, three columns and three rows, four columns.

Preferably, the phased parametric array-based infrasonic wave directional transmitting system further comprises a display module, and the display module is connected with the signal generating module and is used for displaying the frequency of the signal to be modulated output by the signal generating module.

The invention also provides an infrasonic wave directional transmitting method, which comprises the following processes:

generating a control signal;

obtaining a signal to be modulated and a high-frequency carrier according to the control signal;

realizing single-sideband modulation of the carrier according to the signal to be modulated and the high-frequency carrier to obtain a single-sideband modulation signal;

respectively delaying each path of processing signal according to the deflection angle of the single side band modulation signal to generate a plurality of paths of modulation signals;

performing digital-to-analog conversion on each path of modulation signal to obtain a plurality of paths of analog signals;

amplifying the multiple paths of analog signals to obtain multiple paths of amplified signals;

and converting each path of amplified signals in the multiple paths of amplified signals into a path of ultrasonic waves, and transmitting all the ultrasonic waves in an array form and self-demodulating the ultrasonic waves in a propagation medium to obtain infrasonic waves.

Preferably, all the ultrasonic waves are propagated in an array form arranged in an octagonal planar array form.

Preferably, all ultrasonic waves propagate in an octagonal planar array formed by compounding a four-row three-column planar array and a three-row four-column planar array.

Preferably, the signals to be modulated are sine signals and cosine signals, and the output high-frequency carrier is sine carrier signals and cosine carrier signals of 21 kHz-40 kHz;

the method comprises the following steps of realizing single-sideband modulation of carrier waves according to signals to be modulated and high-frequency carrier waves, and obtaining single-sideband modulation signals:

according to a carrier-band single-sideband modulation method, a sine signal and a cosine signal to be modulated are multiplied by a cosine carrier signal and a sine carrier signal respectively, and products of the cosine carrier signal and two multipliers are added to obtain an upper sideband signal; finally, respectively obtaining the time delay of each path of signal according to the deflection angle, and then outputting each path of modulation signal according to the time delay.

The invention has the following beneficial effects:

the phased parametric array based infrasonic wave directional transmitting system demodulates infrasonic waves with high directivity by transmitting ultrasonic waves with controllable directions through the ultrasonic transducer array and the ultrasonic waves in an air medium through a nonlinear self-demodulation effect. The apparatus required for this approach is small and does not require mechanical rotation to achieve electronic deflection of the acoustic beam. The signal modulation module adopts single-sideband modulation with carrier waves, and high-order harmonic waves cannot be automatically demodulated according to Berktai far-field solution. Meanwhile, the transmitting array adopts an ultrasonic transducer array, so that the directivity of the transmitted sound wave can be further improved on the one hand, and the sound pressure level can be improved on the other hand under the condition of more array elements.

Drawings

FIG. 1 is a schematic diagram of an infrasonic wave directional transmitting system based on a phased parametric array according to the present invention;

FIG. 2 is a diagram of a signal generation module according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of single sideband modulation with carrier in an embodiment of the invention;

FIG. 4 is an arrangement of an array of ultrasonic transducers according to an embodiment of the invention;

FIG. 5 is a front panel of the decibel meter according to the present embodiment of the present invention;

fig. 6 is a rear panel of the decibel meter according to the present embodiment of the present invention.

Detailed Description

The invention is further illustrated by the following figures and examples.

The invention provides an infrasonic wave directional transmitting system based on a phased parametric array, which generates infrasonic waves with high directivity and deflection by adopting a phased parametric array method and detects the generated infrasonic waves.

Referring to fig. 1-4, the phased parametric array based infrasonic wave directional transmitting system of the present invention mainly comprises an infrasonic wave transmitting device and an infrasonic wave detecting device. The infrasonic wave transmitting device comprises a control and display module, a signal generating module, a signal modulating module, a time delay module, a digital-to-analog conversion module, a power amplifying module and an ultrasonic transducer array; the infrasonic wave detection device comprises a sonic wave receiver and a decibel meter. The control and display module comprises a matrix keyboard and an OLED display screen; the signal generation module generates sine and cosine signals to be modulated and a carrier signal of 40kHz based on the FPGA by adopting a direct digital frequency synthesis technology and inputs the sine and cosine signals and the carrier signal to the signal modulation module; the signal modulation module generates a modulation signal by adopting a carrier-wave single-sideband modulation method based on the FPGA, inputs the modulation signal into the 24 paths of delay modules for delay respectively, and then inputs the modulation signal into the digital-to-analog conversion module; the digital-to-analog conversion module realizes functions by using a dual-channel 14-bit AD9767 and peripheral circuits thereof; the power amplification module uses an operational amplifier for first-stage amplification, and then uses LM4766 for second-stage amplification. The ultrasonic transducer array is an octagonal planar array and is formed by compounding a planar array with four rows, three columns and three rows, four columns. The decibel meter is compiled by LabVIEW. The front panel of the decibel meter comprises four windows of an original waveform, an original spectrogram, a read or extracted data spectrogram and an extracted data spectrogram. Buttons for measurement, reading, extraction, calculation and the like are arranged below a front panel of the decibel meter, so that the obtained original waveform can be extracted in any length, and the frequency of the original waveform is calculated through a frequency spectrogram and an algorithm.

The infrasonic wave directional transmitting system based on the phased parametric array is based on the phased parametric array principle consisting of the phased array and the broadband parametric array. When certain time delay exists in the driving signals of the ultrasonic transducers, the sound beams generated by the ultrasonic transducer array can be deflected towards different directions. The acoustic parametric array is divided into a dual-frequency parametric array and a broadband parametric array, the dual-frequency parametric array sends two rows of ultrasonic waves with frequency difference below 20Hz through an ultrasonic transducer, and difference frequency waves, namely infrasonic waves, are generated in an air medium through nonlinear action; the broadband parametric array is based on the Berkeley far field solution theory, i.e., the difference frequency sound field of the parametric array is the second derivative of the square of the original frequency envelope. The low-frequency signal is carried on the high-frequency ultrasonic signal, and infrasonic waves are demodulated in the air medium through the nonlinear self-demodulation effect. Since the sound absorption coefficient increases with increasing frequency, high frequency sound waves are rapidly attenuated in air, and finally only infrasonic waves which are not easily attenuated remain.

By utilizing the phased parametric array-based infrasonic wave directional transmitting system, the infrasonic wave directional transmitting method comprises the following steps:

step 1, setting the frequency of a signal to be modulated and the deflection angle of a sound wave through a control and display module, and displaying parameter information on an OLED display screen; the control and display module is controlled by an FPGA (field programmable gate array), and the frequency of a signal to be modulated is stepped by 5Hz to 20Hz at most;

step 2, inputting a control signal output by the control and display module into a signal generation module, outputting a signal to be modulated and a high-frequency carrier by the signal generation module, inputting the signal to be modulated into a signal modulation module to realize single-sideband modulation with the carrier, and delaying each path of signal according to the deflection angle to generate a plurality of paths of modulated signals; the signal generation module and the signal modulation module are both designed logically by using an FPGA. The signal generating module generates sine signals and cosine signals with corresponding frequencies according to the frequency input by the control and display module, simultaneously generates sine and cosine carrier signals with the frequency of 40kHz, and finally inputs the generated signals to the signal modulation module. The signal modulation module comprises two adders and two multipliers, sine signals and cosine signals to be modulated are multiplied by cosine carrier signals and sine carrier signals respectively according to a carrier-wave single-sideband modulation principle, and products of the cosine carrier signals and the two multipliers are added through the two adders to obtain upper sideband signals. Finally, respectively obtaining the time delay of 24 paths of signals according to the deflection angle input by the control and display module, and then outputting the 24 paths of modulation signals to the digital-to-analog conversion module;

step 3, because the modulation signals are digital signals, inputting the modulation signals into a digital-to-analog conversion module to convert digital quantity into analog quantity, amplifying the analog quantity through a power amplification module, respectively driving ultrasonic transducers at corresponding positions of an ultrasonic transducer array to emit ultrasonic waves, and demodulating the required infrasonic waves in the air through nonlinear self-demodulation effect by the ultrasonic waves; the digital-to-analog conversion module converts digital quantity into analog quantity by using the AD9767 as a core and inputs the analog quantity into the power amplification module. The power amplification module firstly performs pre-stage amplification through an operational amplifier, then performs post-stage amplification through LM4766, and finally inputs the power to the ultrasonic transducer array; the ultrasonic transducer array consists of 24 ultrasonic transducers which are arranged in an octagonal plane array, and each ultrasonic transducer is connected with one path of modulation signal.

And 4, receiving the emitted infrasonic waves by using a sonic wave receiver, and then detecting and analyzing the sonic waves by using a decibel meter, wherein the decibel meter is compiled by LabVIEW and is used for displaying the waveform of the received sonic waves, extracting waveform data and carrying out spectrum analysis.

Examples

In the present embodiment, as shown in fig. 1, the phased parametric array based infrasonic wave directional emission system includes a control and display module including a matrix keyboard and an OLED display screen, the matrix keyboard and the OLED display screen are externally connected to an FPGA, a control signal of the matrix keyboard is input to the FPGA, and the FPGA displays corresponding information on the OLED display screen. The signal generating module, the signal modulating module and the time delay module are all designed with logic functions by using FPGA. Because the ultrasonic transducer array has 24 array elements, 24 paths of modulation signals are output from the FPGA, and each path of modulation signal is respectively provided with different delay time according to the deflection angle. And then, performing digital-to-analog conversion and power amplification on each path of signal, finally inputting the signal into an ultrasonic transducer in an ultrasonic transducer array, driving the ultrasonic transducer to emit ultrasonic waves into the air, and demodulating the required infrasonic waves in the air by the ultrasonic waves. The digital-to-analog conversion module realizes a digital-to-analog conversion function by using a dual-channel 14-bit AD9767 to match with a peripheral circuit; the power amplification module uses an operational amplifier for a first stage of amplification followed by a second stage of amplification using LM 4766.

The functional design block diagram of the FPGA logic of the signal generating module is shown in fig. 2. The clock, the reset signal and the frequency word input by the control and display module are input into the module, the input frequency word is mainly used for setting the frequency of the signal to be modulated, the frequency of the carrier wave is equal to the central frequency of the ultrasonic transducer and is 40kHz, and therefore the frequency word is a certain value. The signal generation module adopts direct digital frequency synthesis technology to generate waveform, firstly, a sine signal generation mif file is led into a ROM, then, a table look-up method is used, an accumulator is used for accumulating frequency words and phase words, the accumulated value is used as a query address to generate the waveform to be modulated, the frequency of an output signal can be adjusted by controlling the frequency words, and the phase of the output signal can be adjusted by controlling the phase words. The signal generation module instantiates four DDS modules and generates four paths of signals to be input to the signal modulation module.

The signal modulation module performs its function according to the principle of single sideband modulation with carrier, as shown in fig. 3. One path of the sine signal to be modulated is added with the direct current signal, and the other path of the sine signal is subjected to Hilbert transform, namely the sine signal is a negative cosine signal. Then multiplying the added sum by a high-frequency cosine signal, simultaneously multiplying the signal subjected to Hilbert transform by a high-frequency sine signal, and adding the product of the two signals if a lower sideband is required; if the sidebands need to be taken, subtraction is carried out, the obtained modulation signals are input into a delay module, the delay module calculates the sound path difference of the array elements at different positions according to the deflection angle so as to obtain the delay time of each array element, and finally the delayed modulation signals are input into the corresponding ultrasonic transducer.

In order to improve the directivity and the sound pressure level of the infrasonic wave signal, an ultrasonic transducer array arranged as shown in fig. 4 is adopted, and each array element is a piezoelectric ceramic transducer. The array is formed by compounding a plane array of four rows and three columns and three rows and four columns, and 24 ultrasonic transducers are formed in total, and each transducer is connected with a modulation signal.

Fig. 5 and 6 are front and rear panels of a decibel meter written in LabVIEW. The front panel includes four windows of original waveform, original spectrogram, read or extracted data spectrogram and extracted data spectrogram. Buttons for measurement, reading, extraction, calculation and the like are arranged below the waveform generator, extraction of any length can be carried out on the obtained original waveform, and then the frequency of the original waveform is calculated through a spectrogram and an algorithm. The back panel writes the program in a state machine mode, and calls functions and tools inside the LabVIEW in each state to complete the design and writing of the program. The decibel meter reads, extracts and analyzes the data of the sound wave signals received by the sound wave receiver, and the infrasonic wave is detected.