A method and system for extracting indoor object echo based on acoustic electromagnetic intermodulation

Abstract

The present invention provides a method and system for extracting echoes of indoor objects based on acoustic electromagnetic intermodulation, including transmitting acoustic wave excitation from an electromagnetic wave transceiver, thereby inducing vibration of the object, thereby generating a corresponding acoustic wave signal; selecting an electromagnetic signal capable of modulating the acoustic wave signal according to the required frequency band, transmitting the electromagnetic signal, and using the electromagnetic signal to perform acoustic electromagnetic mutual modulation on the acoustic wave signal to obtain the acoustic electromagnetic echo of the object; the electromagnetic wave transceiver receives the acoustic electromagnetic echo, performs Fourier transform on the acoustic electromagnetic echo to obtain the corresponding spectrum; and filters the spectrum according to the phase shift and amplitude modulation of the acoustic electromagnetic echo, thereby filtering out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, thereby obtaining a characteristic spectrum containing the characteristics of the object. Compared with the traditional method based on electromagnetic wave modulation of weak vibration signals, the amount of information carried by the acoustic wave excitation is increased, and the stability of through-wall detection is improved.

Description

Technical Field

[0001] The present invention relates to the field of target detection technology, and in particular to an indoor object echo extraction method and system based on acoustic and electromagnetic intermodulation. Background Art

[0002] In disaster relief operations, rescue workers often need to go deep into unfamiliar buildings. The lack of information about the interior of the building will pose a greater threat to the smooth progress of the operation and the safety of personnel. Therefore, obtaining internal information before entering an unfamiliar building can provide services for the smooth progress of the operation. How to safely, stably and covertly obtain target information behind the wall and conduct penetration detection inside the building has important practical significance and research value.

[0003] Without destroying the site, detection technologies such as acoustic waves, infrared waves, and electromagnetic waves can achieve penetration detection to varying degrees. Among them, electromagnetic wave detection is the most prominent in terms of penetrating wall types, detection range, and detection accuracy. Therefore, it has become a research hotspot for penetration detection inside buildings in recent years. The technologies for using electromagnetic waves to conduct penetration detection of internal structures of buildings currently mainly include three categories: through-wall radar imaging technology based on reflected wave measurement, radio frequency tomography technology based on transmitted wave measurement, and wall position estimation technology based on multipath signals. These three types of technologies have achieved certain research results with practical significance. However, the research on penetration detection of target information behind the wall has reduced the difficulty of echo extraction, which has led to the defects of large size and exposure of the high-power through-wall radar used, making it difficult to play an auxiliary role in rapid disaster relief operations.

[0004] The present invention proposes an indoor object echo extraction technology based on acoustic electromagnetic intermodulation. Through acoustic wave excitation, the target object is effectively made to produce features that can be modulated by electromagnetic waves. Its main mechanism is to make the object produce self-vibration phenomenon, and then through the acoustic modulation technology of electromagnetic signals, the reflected electromagnetic echo of the indoor object is generated, a reliable echo extraction algorithm based on acoustic electromagnetic intermodulation is designed, and an integrated wall-penetrating detection system is built. The single-frequency continuous wave signal used in the process of extracting the echo signal can modulate the characteristic information of the object excited by the acoustic excitation into the above waveform to achieve the purpose of wall-penetrating detection. Compared with the traditional high-power wall-penetrating radar, this method increases the amount of information carried by the acoustic wave excitation, thereby reducing the electromagnetic wave transmission power and improving the portability of wall-penetrating detection. Summary of the invention

[0005] The present invention proposes a method and system for extracting indoor object echoes based on acoustic and electromagnetic intermodulation to solve the defects of the prior art mentioned above.

[0006] In one aspect, the present invention provides a method for extracting indoor object echo based on acoustic electromagnetic intermodulation, the method comprising the following steps:

[0007] S1: The electromagnetic wave transceiver emits sound wave excitation, thereby causing the object to vibrate, thereby generating a corresponding sound wave signal;

[0008] S2: selecting an electromagnetic signal capable of modulating the acoustic wave signal according to a required frequency band, transmitting the electromagnetic signal, and using the electromagnetic signal to perform acoustic and electromagnetic mutual modulation on the acoustic wave signal to obtain an acoustic and electromagnetic echo of the object;

[0009] S3: The electromagnetic wave transceiver receives the acoustic electromagnetic echo, and performs Fourier transform on the acoustic electromagnetic echo to obtain a corresponding frequency spectrum;

[0010] S4: filtering the spectrum according to the phase shift and amplitude modulation of the acousto-electromagnetic echo, thereby filtering out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, thereby obtaining a characteristic spectrum containing the characteristics of the object.

[0011] The above method identifies typical indoor objects through the modulated electromagnetic signals generated by acoustic and electromagnetic intermodulation according to the characteristics of indoor objects. In the detection scenario, electromagnetic waves can detect human bodies indoors through transmission, but it is difficult to obtain identifiable features for objects that cannot generate self-vibration. By using sound waves to excite static objects, the object features are modulated in the electromagnetic wave waveform to achieve the purpose of through-wall detection. In the process of extracting indoor target echoes, the transceiver equipment built transmits a single-frequency continuous signal and an acoustic wave signal that can excite the object, which can effectively extract the characteristics of indoor objects. Compared with the traditional method based on electromagnetic wave modulation of weak vibration signals, this method increases the amount of information carried by acoustic wave excitation and improves the stability of through-wall detection.

[0012] In a specific embodiment, the S2 further includes:

[0013] A small darkroom is used as a detection device to obtain the acoustic electromagnetic echo, and the inner wall of the small darkroom is made of electromagnetic absorption material to absorb the electromagnetic energy reflection and spillage generated by the electromagnetic signal. This method can eliminate the electromagnetic energy reflection and spillage to the maximum extent.

[0014] In a specific embodiment, the acoustic wave excitation is a single-frequency continuous wave.

[0015] In a specific embodiment, the S4 specifically includes: analyzing, according to the distance between the object and the electromagnetic wave transceiver, the phase shift of the acoustic electromagnetic echo relative to the electromagnetic signal when the distance changes;

[0016] Analyzing the amplitude modulation of the acousto-electromagnetic echo relative to the electromagnetic signal according to the change of the dielectric constant of the material of the object;

[0017] The sideband signal of the acousto-electromagnetic echo is analyzed according to the phase shift and the amplitude modulation, so as to filter the acousto-electromagnetic echo, filter out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, and extract the characteristics of the acousto-electromagnetic echo according to the peaks in the spectrum.

[0018] In a specific embodiment, the acoustic wave excitation is emitted by an ultrasonic transducer.

[0019] According to a second aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a computer processor, the above method is implemented.

[0020] According to a third aspect of the present invention, a system for extracting indoor object echoes based on acoustic electromagnetic intermodulation is proposed, the system comprising:

[0021] Acoustic wave signal excitation module: configured to emit acoustic wave excitation from the electromagnetic wave transceiver, thereby causing the object to vibrate, thereby generating a corresponding acoustic wave signal;

[0022] Acoustic-electromagnetic intermodulation module: configured to select an electromagnetic signal capable of modulating the acoustic wave signal according to a required frequency band, transmit the electromagnetic signal, and obtain the acoustic-electromagnetic echo of the object by performing acoustic-electromagnetic intermodulation on the acoustic wave signal using the electromagnetic signal;

[0023] Acousto-electromagnetic echo receiving module: configured to receive the acousto-electromagnetic echo at the electromagnetic wave transceiver end, and perform Fourier transform on the acousto-electromagnetic echo to obtain a corresponding spectrum;

[0024] Acousto-EM echo feature extraction module: configured to filter the spectrum according to the phase shift and amplitude modulation of the acoustic-EM echo, thereby filtering out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, thereby obtaining a characteristic spectrum containing the characteristics of the object.

[0025] According to the characteristics of indoor objects, the present invention identifies typical indoor objects through modulated electromagnetic signals generated by acoustic and electromagnetic intermodulation. In the detection scenario, electromagnetic waves can detect human bodies indoors through transmission, but it is difficult to obtain identifiable features for objects that cannot generate self-vibration. By using sound waves to excite static objects, the object features are modulated in the electromagnetic wave waveform to achieve the purpose of through-wall detection. In the process of extracting indoor target echoes, the transceiver equipment built transmits a single-frequency continuous signal and an acoustic wave signal that can excite the object, which can effectively extract the characteristics of indoor objects. Compared with the traditional method based on electromagnetic wave modulation of weak vibration signals, this method increases the amount of information carried by acoustic wave excitation and improves the stability of through-wall detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the embodiments and together with the description are used to explain the principles of the present invention. Other embodiments and many expected advantages of the embodiments will be readily appreciated as they become better understood by reference to the following detailed description. Other features, objects and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments made with reference to the following drawings:

[0027] Figure 1 It is a flow chart of a method for extracting indoor object echo based on acoustic and electromagnetic intermodulation according to an embodiment of the present invention;

[0028] Figure 2 It is a design diagram of an electromagnetic wave transmitting software platform of a specific embodiment of the present invention;

[0029] Figure 3 It is a scene diagram of a portable detection device set up in a specific embodiment of the present invention;

[0030] Figure 4 It is a frequency domain analysis diagram of an acousto-electromagnetic echo signal of a specific embodiment of the present invention;

[0031] Figure 5 It is an acoustic electromagnetic echo spectrum diagram extracted from steel of a specific embodiment of the present invention;

[0032] Figure 6 is an acousto-electromagnetic echo spectrum diagram of a polymer extracted according to a specific embodiment of the present invention;

[0033] Figure 7 It is an acoustic electromagnetic echo spectrum diagram of aluminum extraction in a specific embodiment of the present invention;

[0034] Figure 8 It is an acoustic electromagnetic echo spectrum diagram extracted from stainless steel in a specific embodiment of the present invention;

[0035] Fig. 9 It is a time domain diagram of the left band of the sound wave frequency of a specific embodiment of the present invention;

[0036] Fig.10 It is a time domain diagram of the right side band of the sound wave frequency of a specific embodiment of the present invention;

[0037] Fig.11 It is a frequency domain diagram of the left band of the sound wave frequency of a specific embodiment of the present invention;

[0038] Fig.12 It is a frequency domain diagram of the right side band of the sound wave frequency of a specific embodiment of the present invention;

[0039] Fig.13It is a framework diagram of an indoor object echo extraction system based on acoustic and electromagnetic intermodulation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] According to an embodiment of the present invention, a method for extracting indoor object echo based on acoustic electromagnetic intermodulation is provided. Figure 1 FIG. 2 is a flow chart showing a method for extracting indoor object echoes based on acoustic and electromagnetic intermodulation according to an embodiment of the present invention. Figure 1 As shown, the method comprises the following steps:

[0043] S1: The electromagnetic wave transceiver emits sound wave excitation, thereby causing the object to vibrate, thereby generating a corresponding sound wave signal;

[0044] S2: selecting an electromagnetic signal capable of modulating the acoustic wave signal according to a required frequency band, transmitting the electromagnetic signal, and using the electromagnetic signal to perform acoustic and electromagnetic mutual modulation on the acoustic wave signal to obtain an acoustic and electromagnetic echo of the object;

[0045] S3: The electromagnetic wave transceiver receives the acoustic electromagnetic echo, and performs Fourier transform on the acoustic electromagnetic echo to obtain a corresponding frequency spectrum;

[0046] S4: filtering the spectrum according to the phase shift and amplitude modulation of the acousto-electromagnetic echo, thereby filtering out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, thereby obtaining a characteristic spectrum containing the characteristics of the object.

[0047] In a specific embodiment, the S2 further includes:

[0048] A small darkroom is used as a detection device to obtain the acoustic electromagnetic echo. The inner wall of the small darkroom is made of electromagnetic absorption material, which is used to absorb the reflection and spillage of electromagnetic energy generated by the electromagnetic signal.

[0049] In a specific embodiment, the acoustic wave excitation is a single-frequency continuous wave.

[0050] In a specific embodiment, the S4 specifically includes: analyzing, according to the distance between the object and the electromagnetic wave transceiver, the phase shift of the acoustic electromagnetic echo relative to the electromagnetic signal when the distance changes;

[0051] Analyzing the amplitude modulation of the acousto-electromagnetic echo relative to the electromagnetic signal according to the change of the dielectric constant of the material of the object;

[0052] The sideband signal of the acousto-electromagnetic echo is analyzed according to the phase shift and the amplitude modulation, so as to filter the acousto-electromagnetic echo, filter out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, and extract the characteristics of the acousto-electromagnetic echo according to the peaks in the spectrum.

[0053] In a specific embodiment, the acoustic wave excitation is emitted by an ultrasonic transducer.

[0054] The present invention proposes a design of indoor object echo extraction technology based on acoustic and electromagnetic intermodulation. According to the characteristics of indoor objects, indoor objects are stimulated by sound waves, and the object characteristics generated by the excitation are modulated on the transmitted single-frequency continuous wave within a certain detection distance range. In the actual detection process, one-way penetration of sound wave signals and two-way penetration of electromagnetic wave signals are required, but both will be absorbed by the wall and produce a certain attenuation. The portable transceiver device built can meet the effect of sound wave and electromagnetic wave through-wall detection. In order to introduce the content of the present invention in detail, some concepts are explained or stipulated below:

[0055] Definition 1: Doppler shift of reflected electromagnetic waves

[0056] Since the sound wave generates sinusoidal vibration on the surface of the object, it changes the distance between the target and the electromagnetic wave transceiver, generates phase modulation, and thus causes the reflected electromagnetic wave signal to shift, which is mainly reflected as a certain Doppler frequency deviation. The frequency deviation value is related to the frequency and amplitude of the target's vibration under the excitation of the sound wave. The frequency of the reflected electromagnetic wave signal affected by the Doppler effect can be expressed as:

[0057]

[0058] Among them, f r Indicates the frequency of the received signal, f RF is the frequency of the electromagnetic wave signal, ν is the vibration speed of the object surface, c RF is the propagation speed of electromagnetic wave signals.

[0059] Since the vibration speed of the surface of an object is generally much smaller than the propagation speed of electromagnetic waves, the target's vibration speed can be replaced by a distance function that changes with time, expressed as:

[0060] r(t)=R0+d(t)

[0061] Among them, R0 is the distance between the target and the electromagnetic wave transceiver when it is in a static state, and d(t) is the vibration displacement of the target surface.

[0062] At the same time, if the target is excited by sound waves, the surface vibration displacement is in the form of a sine wave, which can be expressed as

[0063] d(t)=d V cos(ω V t)

[0064] Among them, d V is the amplitude of the vibration displacement, ω V is the angular frequency of vibration.

[0065] Ignoring the direct reflection term of electromagnetic waves that is irrelevant to the target, the above formula is expanded to a complex exponential form and the Jacobi Angel expansion is applied, which can be rewritten as

[0066]

[0067] Therefore, the electromagnetic signal reflected by the vibrating target is a wide-spectrum signal containing a transmission signal and a modulated signal located in the upper and lower sidebands. Therefore, in the indoor object echo extraction technology, it is necessary to filter out the transmission signal frequency and the symmetrical sidebands.

[0068] Definition 2: Amplitude fluctuation of reflected electromagnetic waves

[0069] Since different targets are stimulated by sound waves, their resonance velocity v is affected by the shape and material of the target. Therefore, the frequency components in the above power spectrum are usually the result of the combined effect of the material and shape of the target object. Therefore, the micro-Doppler characteristics of acousto-electromagnetic modulation can be used to obtain a preliminary judgment of the object (shape, material). However, due to the aliasing effect of reflection and diffraction (i.e. elastic scattering) of sound waves on the target object, the received echo signal often cannot separate the micro-Doppler components caused by the shape and material of the object. It is necessary to further analyze the amplitude modulation characteristics of the echo for mathematical modeling.

[0070] When sound waves cause the target to vibrate, the electrical properties of the target material will fluctuate, especially the dielectric constant. When sound waves excite the target, the density of the object will change due to the effect of sound pressure, causing the dielectric constant of the material to change periodically, as shown below:

[0071] ε(t)=ε0ε r [1+δ(t)]

[0072] Where δ(t) is the amplitude fluctuation of the dielectric constant, expressed as

[0073]

[0074] where K is the proportionality constant of the Lorentz-Lorentz relation approximation, and p A (t) is the propagating sound pressure at a specific location of the target, ε0 is the free space dielectric constant, ε r is the relative dielectric constant of the target when it is stationary, ρ0 is the target density, c A is the speed of sound wave propagation in the material.

[0075] It can be seen from the above formula that the fluctuation of the dielectric constant is directly affected by the frequency and amplitude of the sound wave. Therefore, the electromagnetic signal reflected by the target under acoustic excitation will be affected by the frequency ω of the sound signal. A and the impact of its harmonics.

[0076] By analyzing the acoustic sidebands of the acoustic electromagnetic echo signal obtained by the above method, it is possible to ensure the effective extraction of indoor object echoes.

[0077] The beneficial effects of the present invention are as follows: the present invention proposes an indoor object echo extraction technology based on acoustic electromagnetic intermodulation, and builds a portable integrated detection system. The sideband signal in the electromagnetic signal reflected by the vibrating target is used for extraction, and a reliable indoor object echo extraction algorithm based on acoustic electromagnetic intermodulation is designed to achieve the purpose of through-wall detection, thereby building an integrated through-wall detection system and improving the portability and reliability of through-wall communication.

[0078] In order to make the purpose, scheme and advantages of the present invention more clearly understood, the present invention is further described below in combination with specific implementations and with reference to the accompanying drawings.

[0079] The purpose of the present invention is to utilize the characteristics of indoor objects and stimulate the indoor objects through sound waves, so that the object characteristics generated by the excitation are modulated on the emitted single-frequency continuous wave within a certain detection distance range. In the actual detection process, unidirectional penetration of sound wave signals and bidirectional penetration of electromagnetic wave signals are required, but both will be absorbed by the wall and produce a certain attenuation. The portable transceiver constructed can meet the effect of sound wave and electromagnetic wave wall-penetrating detection.

[0080] The specific implementation process is as follows:

[0081] Step 1: The ultrasonic transducer emits sound waves to stimulate the object to vibrate

[0082] Step 2: The electromagnetic wave transmitting software platform transmits electromagnetic signals;

[0083] Step 3: The electromagnetic signal is acoustically modulated to generate the object's acoustic electromagnetic echo;

[0084] Step 4: Perform Fourier transform on the acoustic electromagnetic echo;

[0085] Step 5: Filter out the sideband signals outside the target sound wave signal frequency band.

[0086] The echo signal of the indoor object is extracted by the above method, and the indoor object characteristics carried by the signal are analyzed to ensure the reliability of through-wall detection.

[0087] Figure 2 It is a design diagram of an electromagnetic wave transmitting software platform of a specific embodiment of the present invention; Figure 3 It is a scene diagram of setting up a portable detection device according to a specific embodiment of the present invention.

[0088] like Figure 2 , Figure 3 As shown, firstly, an electromagnetic wave transmitting software platform is designed, which can select the frequency band of transmitting electromagnetic signals according to needs and generate electromagnetic signals that can modulate sound waves. Secondly, in order to solve the problems of electromagnetic signal energy spillover and mutual interference, the portable detection equipment is equipped with a small darkroom, the inner wall of which is made of electromagnetic absorption material, which can eliminate the reflection and spillover of electromagnetic energy to the greatest extent.

[0089] Figure 4 This is a frequency domain analysis diagram of an acoustic electromagnetic echo signal of a specific embodiment of the present invention. Since the acoustic wave causes the target surface to vibrate, resulting in the Doppler frequency shift of the reflected electromagnetic wave, the electromagnetic signal reflected by the vibrating target is a wide spectrum signal containing the transmission signal and the modulated signal located in the upper and lower sidebands. It can be found through observation that the sideband signals in the acoustic wave frequency band have similar characteristics. Therefore, it is only necessary to filter out the redundant sideband signals and retain the acoustic wave frequency signal to extract the echo signal containing the characteristic information of the object.

[0090] Figure 5-Figure 8 The following are the extracted echo spectra of different objects. Figure 5 It is an acoustic electromagnetic echo spectrum diagram extracted from steel of a specific embodiment of the present invention; Figure 6 is an acousto-electromagnetic echo spectrum diagram of a polymer extracted according to a specific embodiment of the present invention; Figure 7 It is an acoustic electromagnetic echo spectrum diagram of aluminum extraction in a specific embodiment of the present invention; Figure 8 This is an acoustic electromagnetic echo spectrum diagram extracted from stainless steel in a specific embodiment of the present invention; through observation, it can be found that the left and right sidebands of the acoustic frequency signal carry spike signals with different object characteristics. Since the echo generated by the transmission signal does not carry characteristic information, it is necessary to retain the left and right sidebands and filter out the transmission signal.

[0091] Figure 9-12 The figure shows the time domain and frequency domain analysis of the echo signal after filtering out the transmitted signal. Fig. 9 It is a time domain diagram of the left band of the sound wave frequency of a specific embodiment of the present invention; Fig.10It is a time domain diagram of the right side band of the sound wave frequency of a specific embodiment of the present invention; Fig.11 It is a frequency domain diagram of the left band of the sound wave frequency of a specific embodiment of the present invention; Fig.12 It is a frequency domain diagram of the right side of the sound wave frequency of a specific embodiment of the present invention; the present invention analyzes the acoustic electromagnetic echoes of four different objects ( Figure 5-Figure 8 As shown in the figure, it can be seen that by filtering out the transmitted signal and retaining the left and right sideband signals, the feature information of the object can be extracted.

[0092] The present invention proposes an indoor object echo extraction technology based on acoustic electromagnetics and applies it to an integrated through-wall detection system. By using the acoustic excitation signal modulated by electromagnetic waves, a reliable indoor object echo extraction algorithm based on acoustic electromagnetic intermodulation is designed to achieve the purpose of through-wall detection, thereby building an integrated portable detection system and improving the stability and reliability of through-wall detection.

[0093] The above content is a further detailed description of the present invention by a specific preferred embodiment. The specific embodiments of the present invention cannot be considered to be limited to these descriptions. The present invention is carried out by taking the detection of wooden wall signals as an example. As for the detection research of similar walls such as brick walls and concrete walls, some simple deductions or substitutions are made without departing from the concept of the present invention, which should all fall within the protection scope of the present invention.

[0094] Fig.13 The framework diagram of an indoor object echo extraction system based on acoustic electromagnetic intermodulation according to an embodiment of the present invention is shown. The system includes an acoustic signal excitation module 1301, an acoustic electromagnetic intermodulation module 1302, an acoustic electromagnetic echo receiving module 1303 and an acoustic electromagnetic echo feature extraction module 1304.

[0095] In a specific embodiment, the acoustic wave signal excitation module 1301 is configured to transmit acoustic wave excitation from the electromagnetic wave transceiver, thereby inducing the object to vibrate, thereby generating a corresponding acoustic wave signal;

[0096] The acoustic electromagnetic intermodulation module 1302 is configured to select an electromagnetic signal capable of modulating the acoustic wave signal according to a required frequency band, transmit the electromagnetic signal, and obtain the acoustic electromagnetic echo of the object after performing acoustic electromagnetic intermodulation on the acoustic wave signal using the electromagnetic signal;

[0097] The acousto-electromagnetic echo receiving module 1303 is configured to receive the acousto-electromagnetic echo at the electromagnetic wave transceiver end, and perform Fourier transform on the acousto-electromagnetic echo to obtain a corresponding frequency spectrum;

[0098] The acoustic electromagnetic echo feature extraction module 1304 is configured to filter the spectrum according to the phase shift and amplitude modulation of the acoustic electromagnetic echo, thereby filtering out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, thereby obtaining a characteristic spectrum containing the characteristics of the object.

[0099] Based on the characteristics of indoor objects, this system identifies typical indoor objects through modulated electromagnetic signals generated by acoustic and electromagnetic intermodulation. In the detection scenario, electromagnetic waves can detect human bodies indoors through transmission, but it is difficult to obtain identifiable features for objects that cannot generate self-vibration. By using sound waves to excite static objects, the object features are modulated in the electromagnetic wave waveform to achieve the purpose of through-wall detection. In the process of extracting indoor target echoes, the transceiver equipment built transmits a single-frequency continuous signal and an acoustic wave signal that can excite the object, which can effectively extract the characteristics of indoor objects. Compared with the traditional method based on electromagnetic wave modulation of weak vibration signals, this system increases the amount of information carried by acoustic wave excitation and improves the stability of through-wall detection.

[0100] An embodiment of the present invention further relates to a computer-readable storage medium having a computer program stored thereon, which implements the method described above when the computer program is executed by a computer processor. The computer program includes program code for executing the method shown in the flowchart. It should be noted that the computer-readable medium of the present application may be a computer-readable signal medium or a computer-readable medium or any combination of the above two.

[0101] According to the characteristics of indoor objects, the present invention identifies typical indoor objects through modulated electromagnetic signals generated by acoustic and electromagnetic intermodulation. In the detection scenario, electromagnetic waves can detect human bodies indoors through transmission, but it is difficult to obtain identifiable features for objects that cannot generate self-vibration. By using sound waves to excite static objects, the object features are modulated in the electromagnetic wave waveform to achieve the purpose of through-wall detection. In the process of extracting indoor target echoes, the transceiver equipment built transmits a single-frequency continuous signal and an acoustic wave signal that can excite the object, which can effectively extract the characteristics of indoor objects. Compared with the traditional method based on electromagnetic wave modulation of weak vibration signals, this method increases the amount of information carried by acoustic wave excitation and improves the stability of through-wall detection.

[0102] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above invention concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

Claims

1. A method for extracting indoor object echo based on acoustic electromagnetic intermodulation, characterized in that: The following steps are involved: S1: The electromagnetic wave transceiver emits sound wave excitation, thereby causing the object to vibrate, thereby generating a corresponding sound wave signal; S2: selecting an electromagnetic signal capable of modulating the acoustic wave signal according to a required frequency band, transmitting the electromagnetic signal, and using the electromagnetic signal to perform acoustic and electromagnetic mutual modulation on the acoustic wave signal to obtain an acoustic and electromagnetic echo of the object; S3: The electromagnetic wave transceiver receives the acoustic electromagnetic echo, and performs Fourier transform on the acoustic electromagnetic echo to obtain a corresponding frequency spectrum; S4: filtering the spectrum according to the phase shift and amplitude modulation of the acousto-electromagnetic echo, thereby filtering out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, thereby obtaining a characteristic spectrum containing the characteristics of the object; including analyzing the phase shift of the acousto-electromagnetic echo relative to the electromagnetic signal when the distance changes according to the distance between the object and the electromagnetic wave transceiver, and analyzing the amplitude modulation of the acousto-electromagnetic echo relative to the electromagnetic signal according to the change in the dielectric constant of the material of the object; analyzing the sideband signal of the acousto-electromagnetic echo according to the phase shift and the amplitude modulation, thereby filtering the acousto-electromagnetic echo, filtering out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, and extracting the characteristics of the acousto-electromagnetic echo according to the peaks in the spectrum.

2. The method according to claim 1, characterized in that The S2 further includes: A small darkroom is used as a detection device to obtain the acoustic electromagnetic echo. The inner wall of the small darkroom is made of electromagnetic absorption material, which is used to absorb the reflection and spillage of electromagnetic energy generated by the electromagnetic signal.

3. The method according to claim 1, characterized in that The acoustic wave excitation is a single-frequency continuous wave.

4. The method according to claim 1, characterized in that: The acoustic wave excitation is emitted by an ultrasonic transducer.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a computer processor, the method according to any one of claims 1 to 4 is implemented.

6. An indoor object echo extraction system based on acoustic electromagnetic intermodulation, characterized in that: include: Acoustic wave signal excitation module: configured to emit acoustic wave excitation from the electromagnetic wave transceiver, thereby causing the object to vibrate, thereby generating a corresponding acoustic wave signal; Acoustic-electromagnetic intermodulation module: configured to select an electromagnetic signal capable of modulating the acoustic wave signal according to a required frequency band, transmit the electromagnetic signal, and obtain the acoustic-electromagnetic echo of the object by performing acoustic-electromagnetic intermodulation on the acoustic wave signal using the electromagnetic signal; Acousto-electromagnetic echo receiving module: configured to receive the acousto-electromagnetic echo at the electromagnetic wave transceiver end, and perform Fourier transform on the acousto-electromagnetic echo to obtain a corresponding spectrum; Acousto-EM echo feature extraction module: configured to filter the spectrum according to the phase shift and amplitude modulation of the acousto-EM echo, thereby filtering out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, thereby obtaining a characteristic spectrum containing the characteristics of the object; including analyzing the phase shift of the acousto-EM echo relative to the electromagnetic signal when the distance changes according to the distance between the object and the electromagnetic wave transceiver, and analyzing the amplitude modulation of the acousto-EM echo relative to the electromagnetic signal according to the change in the dielectric constant of the material of the object; analyzing the sideband signal of the acousto-EM echo according to the phase shift and the amplitude modulation, thereby filtering the acousto-EM echo, filtering out the signal in the frequency band where the acoustic wave excitation is located and the symmetrical sideband signal, and extracting the characteristics of the acousto-EM echo according to the peaks in the spectrum.

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