Holographic imaging radar imaging method and inversion holographic imaging system

Abstract

The invention provides a holographic imaging radar imaging method and an inversion holographic imaging system, and relates to the technical field of radars. The method comprises the steps that a time sequence control module generates a first clock signal and a second clock signal, a pulse source module generates pulse signals with different frequencies according to the first clock signal and the second clock signal, and a first receiving and transmitting antenna and a second receiving and transmitting antenna convert the pulse signals into electromagnetic waves with different frequencies; electromagnetic waves are emitted to an underground target object; and the upper computer acquires reflection echoes of the underground target object under the electromagnetic waves with different frequencies, determines the phase difference between the reflection echoes under the electromagnetic waves with different frequencies, and performs inversion imaging processing based on the phase difference to generate a three-dimensional image of the underground target object. According to the invention, the time sequence control module controls the two groups of antennas to work in a time-sharing manner, and the echo signals of the underground target object are precisely processed through an interference inversion algorithm, so that the three-dimensional holographic image of the underground target object with higher precision and high resolution is generated.

Description

Technical Field

[0001] The present application relates to the field of radar technology, and in particular to a holographic imaging radar imaging method and an inversion holographic imaging system. Background Art

[0002] Ground Penetrating Radar (GPR) has been widely used as a non-destructive underground detection tool in many fields such as engineering geological exploration, archaeology, environmental monitoring and disaster prevention. Traditional ground penetrating radar systems mainly rely on single-frequency electromagnetic wave signals to detect and image underground structures or objects. However, when faced with complex and changeable geological conditions, single-frequency signals often cannot meet the requirements of detection depth and resolution, resulting in poor imaging quality and limiting its scope of application.

[0003] At present, in order to improve the limitations of single frequency signals, multi-band ground penetrating radar systems are usually used to transmit signals of different frequency bands to meet different detection needs. However, most of the current multi-band ground penetrating radar systems are simply combined use of signals of each frequency band. Although the detection effect has been improved to a certain extent, it has failed to effectively combine the advantages of signals of different frequency bands to give full play to the synergistic effect between signals of different frequency bands, resulting in limited detection accuracy, insufficient detection accuracy, and insufficient image resolution. Summary of the invention

[0004] The purpose of the present application is to provide a holographic imaging radar imaging method and an inversion holographic imaging system to address the deficiencies in the above-mentioned prior art, so as to solve the problem that the prior art fails to effectively combine the advantages of signals in different frequency bands to give full play to the synergistic effect between signals in different frequency bands, thereby resulting in limited detection accuracy, insufficient detection accuracy, insufficient image resolution and other limitations.

[0005] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] In a first aspect, an embodiment of the present application provides a holographic imaging radar imaging method, which is applied to an inversion holographic imaging system, wherein the inversion holographic imaging system includes: a timing control module, a pulse source module, a first transceiver antenna, a second transceiver antenna, and a host computer, wherein the first transceiver antenna and the second transceiver antenna have different frequencies, and there is a preset angle between the first transceiver antenna and the second transceiver antenna; the method includes:

[0007] The timing control module generates a first clock signal and a second clock signal, and sends the first clock signal and the second clock signal to the pulse source module, so that the pulse source module generates pulse signals of different frequencies according to the first clock signal and the second clock signal, and sends the pulse signals of different frequencies to the first transceiver antenna and the second transceiver antenna, so that the first transceiver antenna and the second transceiver antenna convert the pulse signals into electromagnetic waves of different frequencies, and transmit the electromagnetic waves of different frequencies to the underground target object;

[0008] The host computer collects reflected echoes of the underground target object under the electromagnetic waves of different frequencies, determines the phase difference between the reflected echoes under the electromagnetic waves of different frequencies, and performs inversion imaging processing based on the phase difference to generate a three-dimensional image of the underground target object.

[0009] As a possible implementation manner, the preset angle is determined according to the following steps:

[0010] The preset angle is determined according to the frequency of the electromagnetic wave, the distance between the first transceiver antenna and the second transceiver antenna, the effective dielectric constant and the speed of light.

[0011] As a possible implementation manner, determining the preset angle according to the frequency of the electromagnetic wave, the distance between the first transceiver antenna and the second transceiver antenna, the effective dielectric constant, and the speed of light includes:

[0012] Acquiring detection information of the underground target object, the detection information including the burial depth of the underground target object, the dielectric constant of the underground target object, the dielectric constant of the stratum and the total detection depth;

[0013] Determining the effective dielectric constant according to the detection information;

[0014] The wavelength of the electromagnetic wave is determined according to the effective dielectric constant, the frequency of the electromagnetic wave and the speed of light, and the preset angle is determined according to the wavelength of the electromagnetic wave and the distance between the first transceiver antenna and the second transceiver antenna.

[0015] As a possible implementation, the effective dielectric constant is given by the formula Calculated, where ε effective represents the effective dielectric constant, ε r Represents the dielectric constant of the underground target, ε s represents the dielectric constant of the stratum, h represents the burial depth of the underground target, and L represents the total detection depth;

[0016] The preset angle is given by the formula Calculated, where θopt Indicates the preset angle, ε effective represents the effective dielectric constant, d represents the distance between the first transceiver antenna and the second transceiver antenna, f represents the frequency of the electromagnetic wave, c represents the speed of light, and arcsin represents the inverse sine function.

[0017] As a possible implementation manner, determining the phase difference between the reflected echoes under the electromagnetic waves of different frequencies includes:

[0018] Acquire position information of the first transceiver antenna, the second transceiver antenna, and a radar wave source;

[0019] Determine the phase of the first electromagnetic wave at the target position according to the wavelength of the first electromagnetic wave emitted by the first transceiver antenna, the position information of the first transceiver antenna, the position information of the radar wave source, and the buried depth of the underground target object;

[0020] Determine the phase of the second electromagnetic wave at the target position according to the wavelength of the second electromagnetic wave emitted by the second transceiver antenna, the position information of the second transceiver antenna, the position information of the radar wave source, and the burial depth of the underground target object;

[0021] The phase difference is determined according to the phase of the first electromagnetic wave at the target position and the phase of the second electromagnetic wave at the target position.

[0022] As a possible implementation manner, performing inversion imaging processing based on the phase difference to generate a three-dimensional image of the underground target object includes:

[0023] generating an interference pattern according to the phase difference, wherein the interference pattern is used to indicate the interaction of electromagnetic waves of different frequencies in space;

[0024] The interference pattern is converted into an electromagnetic property distribution map, and based on the electromagnetic property distribution of the underground target object in the electromagnetic property distribution map, a three-dimensional image of the underground target object is generated.

[0025] As a possible implementation manner, generating a three-dimensional image of the underground target object based on the electromagnetic property distribution of the underground target object in the electromagnetic property distribution map includes:

[0026] For each pixel point on the underground target object in the electromagnetic characteristic distribution map, determine the electromagnetic wave response corresponding to each pixel point, and determine the electromagnetic wave response of the underground target object based on the electromagnetic wave response corresponding to each pixel point;

[0027] Inversion imaging processing is performed based on the electromagnetic wave response of the underground target object to generate a three-dimensional image of the underground target object.

[0028] As a possible implementation manner, the determining the electromagnetic wave response corresponding to each pixel point includes:

[0029] The electromagnetic wave response corresponding to each pixel point is determined based on the position information of each pixel point, the phase of the first electromagnetic wave emitted by the first transceiver antenna at the target position, the phase of the second electromagnetic wave emitted by the second transceiver antenna at the target position, the wavelength of the first electromagnetic wave, and the wavelength of the second electromagnetic wave.

[0030] As a possible implementation, the electromagnetic wave response is expressed by the formula Calculated, where represents the electromagnetic wave response, N represents the number of pixels, λ1 represents the wavelength of the first electromagnetic wave, λ2 represents the wavelength of the second electromagnetic wave, represents the phase of the first electromagnetic wave emitted by the first transceiver antenna at the target position, represents the phase of the second electromagnetic wave emitted by the second transceiver antenna at the target position, Indicates the position information of the lth pixel.

[0031] In a second aspect, an embodiment of the present application provides an inversion holographic imaging system, comprising: a timing control module, a pulse source module, a first transceiver antenna, a second transceiver antenna, and a host computer, wherein the first transceiver antenna and the second transceiver antenna have different frequencies, and there is a preset angle between the first transceiver antenna and the second transceiver antenna;

[0032] The inversion holographic imaging system is used to execute the steps of the holographic imaging radar imaging method described in any one of the first aspects above to achieve underground target imaging.

[0033] In a third aspect, an embodiment of the present application provides an electronic device, which is a host computer. The electronic device includes: a processor, a storage medium and a bus. The storage medium stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the storage medium through the bus, and the processor executes the machine-readable instructions to execute the steps performed by the host computer in the holographic imaging radar imaging method as described in any one of the first aspects above.

[0034] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps in the holographic imaging radar imaging method as described in any one of the first aspects above are executed.

[0035] According to the holographic imaging radar imaging method and inversion holographic imaging system of the embodiment of the present application, the inversion holographic imaging system includes: a timing control module, a pulse source module, a first transceiver antenna, a second transceiver antenna and a host computer, wherein the frequencies of the first transceiver antenna and the second transceiver antenna are different, and there is a preset angle between the first transceiver antenna and the second transceiver antenna. The timing control module generates the clock signals required for the operation of the two pulse source modules, namely the first clock signal and the second clock signal, and sends the first clock signal and the second clock signal to the pulse source module, so that the pulse source module generates pulse signals of different frequencies according to the first clock signal and the second clock signal, and sends the pulse signals of different frequencies to the first transceiver antenna and the second transceiver antenna, so that the first transceiver antenna and the second transceiver antenna convert the pulse signals into electromagnetic waves of different frequencies, and transmit electromagnetic waves of different frequencies to the underground target. The host computer collects the reflected echoes of the underground target under electromagnetic waves of different frequencies, determines the phase difference between the reflected echoes under electromagnetic waves of different frequencies, and performs inversion imaging processing based on the phase difference to generate a three-dimensional image of the underground target. According to the embodiment of the present application, the inversion holographic imaging system uses two groups of antennas with different frequencies, and there is a preset angle between the two groups of antennas, and the timing control module is used to accurately control the two groups of antennas to emit electromagnetic waves at different times. Since electromagnetic waves of different frequencies have different characteristics when penetrating underground media, the combination of two groups of electromagnetic waves of different frequencies can obtain more abundant underground target information, thereby improving the accuracy of detection and the resolution of the image. The setting of the preset angle between the two groups of electromagnetic waves helps to capture multi-angle reflection information from underground targets, increases the diversity and integrity of data, and multi-angle data acquisition helps to more accurately reconstruct the three-dimensional structure of underground targets. In addition, the two groups of antennas with different frequencies are controlled to emit electromagnetic waves at different times. This time-sharing mechanism avoids signal interference between the two groups of antennas, ensures the accuracy and reliability of data, and also enables the system to efficiently collect and process signals from different frequencies. On this basis, after the host computer collects the reflected echoes of the underground target under electromagnetic waves of different frequencies, by determining the phase difference between the reflected echoes, and based on the interference inversion algorithm, the phase relationship between the signals of different frequencies is used to extract more refined underground structure information, thereby generating a high-resolution three-dimensional holographic image of the underground target. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A schematic diagram of the architecture of an inversion holographic imaging system provided in an embodiment of the present application is shown;

[0038] Figure 2 A schematic diagram of a process of a holographic imaging radar imaging method provided in an embodiment of the present application is shown;

[0039] Figure 3 A schematic diagram of a process for determining a preset angle provided in an embodiment of the present application is shown;

[0040] Figure 4 A schematic diagram of a process flow of a phase difference determination method provided in an embodiment of the present application is shown;

[0041] Figure 5 A schematic diagram of a process of generating a three-dimensional image provided by an embodiment of the present application is shown;

[0042] Figure 6 A schematic structural diagram of an electronic device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0043] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart under the guidance of the content of the present application, or remove one or more operations from the flowchart.

[0044] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0045] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0046] At present, the existing ground-penetrating radar imaging methods and systems have the following limitations: (1) Traditional ground-penetrating radar usually uses a single frequency or a limited frequency band for detection, which limits the detection accuracy and resolution of underground targets; (2) It is difficult to effectively process the phase difference between multi-band signals, resulting in insufficient image resolution; (3) The antenna layout method leads to limited signal coverage or blind spots, affecting the detection effect; (4) The system cannot accurately coordinate the transmission and reception process of multi-band signals; (5) The synergistic effect between signals in different frequency bands is not fully utilized.

[0047] In view of the above problems, the embodiment of the present application provides a holographic imaging radar imaging method and an inversion holographic imaging system. The inversion holographic imaging system uses two groups of antennas with different frequencies. The lower frequency signal has better penetration ability, while the higher frequency signal provides higher resolution, so as to combine the advantages of signals in different frequency bands. And the timing control module is used to realize high-precision timing control, and the two groups of antennas are controlled to transmit clock signals of different frequencies to the pulse source module at different times, so as to ensure that electromagnetic waves of different frequencies can be accurately transmitted and received at a predetermined time point, that is, in the same detection cycle, the inversion holographic imaging system can obtain echo data from two different frequency bands, so as to make full use of the unique advantages of each frequency band. In addition, there is a preset angle between the two groups of antennas with different frequencies, which can ensure that the distribution of the two groups of antennas in space is more reasonable, so as to not only expand the detection range, but also reduce signal interference and improve detection accuracy. On this basis, the interference inversion algorithm is introduced, and the phase difference of the reflected echo of electromagnetic waves of different frequencies is accurately measured and processed, so as to capture subtle geological structure changes and generate high-resolution three-dimensional holographic images.

[0048] Figure 1 FIG. 1 is a schematic diagram showing the architecture of an inversion holographic imaging system provided in an embodiment of the present application. Figure 1 As shown, the inversion holographic imaging system includes a timing control module, a pulse source module, a first transceiver antenna, a second transceiver antenna and a host computer, wherein the frequencies of the first transceiver antenna and the second transceiver antenna are different, and there is a preset angle between the first transceiver antenna and the second transceiver antenna.

[0049] Optionally, the timing control module can be a programmable logic device (Field-Programmable Gate Array, FPGA). Using the programmable logic device FPGA as the timing control module can provide highly precise time control to ensure the generation of the first clock signal and the second clock signal required for the operation of the two pulse source modules, and the pulse source module generates pulse signals of different frequencies according to the first clock signal and the second clock signal, and transmits the pulse signals of different frequencies to the first transceiver antenna and the second transceiver antenna, so that the first transceiver antenna and the second transceiver antenna convert the pulse signals into electromagnetic waves of different frequencies and emit them. Among them, the first transceiver antenna and the second transceiver antenna are respectively a group of low-frequency transceiver antennas and a group of high-frequency transceiver antennas. For example, the frequency of the first transceiver antenna is 200 MHz, and the frequency of the second transceiver antenna is 270 MHz. The timing control module can generate a first clock signal and a second clock signal in sequence according to a preset timetable or sequence. After the pulse source module generates two pulse signals of different frequencies of 200 MHz and 270 MHz according to the first clock signal and the second clock signal, the pulse source module transmits the two pulse signals of 200 MHz and 270 MHz to the first transceiver antenna and the second transceiver antenna, so that the first transceiver antenna and the second transceiver antenna convert the two pulse signals of 200 MHz and 270 MHz into electromagnetic waves of corresponding frequencies and transmit them.

[0050] It should be noted that the frequencies of the first transceiver antenna and the second transceiver antenna are not limited to the 200MHz and 270MHz exemplified above, but the selection of the frequencies of the transceiver antennas should take into account the penetration of electromagnetic waves in the strata and the accuracy of detection. Generally speaking, the higher the frequency of the electromagnetic wave, the weaker the penetration and the higher the detection accuracy, and the lower the frequency of the electromagnetic wave, the stronger the penetration and the lower the detection accuracy. Therefore, low-frequency electromagnetic waves are responsible for detecting underground targets as far as possible, while high-frequency electromagnetic waves are responsible for providing as much detailed feedback as possible. Therefore, in the present application, the first transceiver antenna and the second transceiver antenna not only work in time-sharing, but one of them should be a high-frequency antenna and the other should be a low-frequency antenna. By alternately transmitting two electromagnetic waves of different frequencies, two sets of different reflection data can be obtained in the same detection cycle, thereby better capturing the details of the underground structure, obtaining more geological information, and improving detection accuracy.

[0051] Optionally, the pulse source module can generate a pulse signal of a corresponding frequency based on the received clock signals of different frequencies, and transmit the pulse signal to the first transceiver antenna and the second transceiver antenna. Specifically, after receiving the clock signal from the timing control module, the pulse source module generates a pulse signal corresponding to the input clock frequency through internal circuit adjustment, and transmits the pulse signal to the first transceiver antenna and the second transceiver antenna, and the first transceiver antenna and the second transceiver antenna convert the pulse signal into an electromagnetic wave and transmit it to detect underground targets.

[0052] Optionally, the host computer can collect electromagnetic wave signals of different frequencies reflected by underground targets, that is, reflected echoes, based on the internal acquisition module, and extract more information about the location and characteristics of the underground targets by analyzing the phase difference between the reflected echoes of electromagnetic waves of different frequencies. Based on the phase difference and other related information, an interference inversion algorithm is used to construct a three-dimensional image of the underground target.

[0053] Based on this, the inversion holographic imaging system provided in the embodiment of the present application uses a timing control module to coordinate the working timing of different devices, detects underground targets by emitting electromagnetic waves of different frequencies, and uses a host computer to collect and analyze reflected echoes to generate a three-dimensional image.

[0054] The following is combined with the above Figure 1 The contents described in the inversion holographic imaging system shown are used to explain in detail the holographic imaging radar imaging method provided in the embodiment of the present application.

[0055] Figure 2 The flowchart of a holographic imaging radar imaging method provided by an embodiment of the present application is shown. Figure 2 As shown, the method is applied to the above-mentioned inversion holographic imaging system, and the method specifically comprises the following steps:

[0056] S201, the timing control module generates a first clock signal and a second clock signal, and sends the first clock signal and the second clock signal to the pulse source module, so that the pulse source module generates pulse signals of different frequencies according to the first clock signal and the second clock signal, and sends the pulse signals of different frequencies to the first transceiver antenna and the second transceiver antenna, so that the first transceiver antenna and the second transceiver antenna convert the pulse signals into electromagnetic waves of different frequencies and emit electromagnetic waves of different frequencies to the underground target object.

[0057] Optionally, taking the frequency of the first transceiver antenna as 200MHz and the frequency of the second transceiver antenna as 270MHz as an example, the timing control module can provide highly accurate time control to ensure that each antenna works at the correct time point. Specifically, the timing control module can generate the first clock signal and the second clock signal required for the pulse source module to work according to a preset schedule or sequence, so that after the pulse source module receives the clock signal from the timing control module, it adjusts the internal circuit to generate a pulse signal corresponding to the input clock frequency, such as a pulse signal of 200MHz and 270MHz, and transmits the 200MHz pulse signal to the first transceiver antenna, and transmits the 270MHz pulse signal to the second transceiver antenna. The first transceiver antenna and the second transceiver antenna convert the 200MHz pulse signal and the 270MHz pulse signal into electromagnetic waves and transmit them to detect underground targets.

[0058] Optionally, based on the control of the timing control module, ensure that the first transceiver antenna and the second transceiver antenna work in time-sharing mode, so as to obtain two sets of different reflection data within the same detection cycle by alternately transmitting two electromagnetic waves of different frequencies, so as to better capture the details of the underground structure, that is, to obtain more geological information by using electromagnetic waves of different frequencies, which helps to improve the detection accuracy.

[0059] S202, the host computer collects reflected echoes of underground targets under electromagnetic waves of different frequencies, determines the phase difference between the reflected echoes under electromagnetic waves of different frequencies, and performs inversion imaging processing based on the phase difference to generate a three-dimensional image of the underground target.

[0060] Optionally, the host computer collects electromagnetic wave signals of different frequencies reflected by underground targets, i.e., reflected echoes. During data collection, the host computer needs to keep in sync with the transmission process in order to accurately record the reflected echoes corresponding to each frequency of electromagnetic waves, and since there are two antennas with different frequencies, the host computer must be able to distinguish and process the echo signals received from the two antennas separately.

[0061] Optionally, the host computer performs phase measurement on each pair of frequencies, such as the reflected echo of 200MHz and 270MHz, and calculates the phase difference between the two. The phase difference can reflect the geometric shape, material characteristics and other information of the underground target, that is, the host computer extracts more information about the location and characteristics of the underground target by analyzing the phase difference between the reflected echoes of electromagnetic waves of different frequencies. On this basis, a three-dimensional image of the underground target is constructed based on the phase difference and other related information. Specifically, an interference inversion algorithm is used to generate a high-resolution three-dimensional holographic image by combining the reflection data of electromagnetic waves of different frequencies, that is, the original reflected echo data is converted into an intuitive three-dimensional image to show the specific morphology and distribution of the underground target.

[0062] Based on this, according to the holographic imaging radar imaging method provided by the present application, the inversion holographic imaging system uses two groups of antennas with different frequencies, and there is a preset angle between the two groups of antennas, and the timing control module is used to accurately control the two groups of antennas to emit electromagnetic waves at different times. Since electromagnetic waves of different frequencies have different characteristics when penetrating underground media, the combination of two groups of electromagnetic waves with different frequencies can obtain richer underground target information, thereby improving the accuracy of detection and the resolution of the image. The setting of the preset angle between the two groups of electromagnetic waves helps to capture multi-angle reflection information from underground targets, increases the diversity and integrity of the data, and multi-angle data acquisition helps to more accurately reconstruct the three-dimensional structure of underground targets. In addition, the two groups of antennas with different frequencies are controlled to emit electromagnetic waves at different times. This time-sharing working mechanism avoids signal interference between the two groups of antennas, ensures the accuracy and reliability of the data, and also enables the system to efficiently collect and process signals from different frequencies. On this basis, after the host computer collects the reflected echoes of underground targets under electromagnetic waves of different frequencies, it determines the phase difference between the reflected echoes and uses the phase relationship between signals of different frequencies based on the interference inversion algorithm to extract more detailed underground structure information, thereby generating a high-resolution three-dimensional holographic image of the underground target.

[0063] As a possible implementation manner, the preset angle is determined according to the following steps: the preset angle is determined according to the frequency of the electromagnetic wave, the distance between the first transceiver antenna and the second transceiver antenna, the effective dielectric constant and the speed of light.

[0064] Optionally, the present application utilizes two sets of antennas with different frequencies and appropriate angles to transmit signals of two frequency bands to underground targets at different times, and then receives the echo signals reflected by the underground targets through the first transceiver antenna and the second transceiver antenna, and performs interference inversion processing on the echo signals, and finally obtains an accurate three-dimensional image of the underground targets. In this process, the key lies in the antenna angle setting and information processing imaging, and the angle between the antennas is related to the best interference effect. In the dual-antenna interference imaging system, the determination of the optimal angle for the antenna angle setting is closely related to the following factors: the relationship between the antenna spacing and the wavelength, the phase difference of the interference signal, and the depth and size of the detection target. Among them, the antenna spacing and the wavelength of the electromagnetic wave signal have a direct impact on the interference effect. The antenna spacing needs to be in a certain proportion to the wavelength of the electromagnetic wave signal to avoid interference between signals or failure to obtain sufficient interference effect. In general, the antenna spacing should be set to a small multiple of the wavelength.

[0065] Optionally, when the interference effect is the strongest, that is, when the best antenna placement angle makes the interference effect of the transmitted electromagnetic wave the strongest, the relative relationship between the angle between the antennas and the propagation direction and the receiving direction of the electromagnetic wave signal is crucial. The optimal angle between the antennas is usually also within a certain interference range, so that the received interference signal has sufficient phase difference, thereby ensuring the accuracy of imaging. In the embodiment of the present application, the preset angle between the first transceiver antenna and the second transceiver antenna is determined according to the frequency of the electromagnetic wave, the spacing between the first transceiver antenna and the second transceiver antenna, the effective dielectric constant and the speed of light, wherein the electromagnetic wave frequency refers to the frequency of the emitted electromagnetic wave, such as 200MHz and 270MHz, the antenna spacing refers to the physical distance between the first transceiver antenna and the second transceiver antenna, the effective dielectric constant is the dielectric constant under the joint influence of the underground target and the stratum, and the effective dielectric constant can affect the propagation speed of the electromagnetic wave in the medium, and the speed of light refers to the speed of light in a vacuum, which is about 3×10 8 m / s.

[0066] Figure 3 A schematic diagram of a process flow of a method for determining a preset angle provided in an embodiment of the present application is shown. Figure 3 As shown, the preset angle is determined according to the following steps:

[0067] S301. Acquire detection information of underground targets, where the detection information includes the burial depth of the underground targets, the dielectric constant of the underground targets, the dielectric constant of the strata, and the total detection depth.

[0068] Exemplarily, the burial depth of an underground target object refers to the depth of the underground target object below the ground surface, the dielectric constant of the underground target object refers to the dielectric constant of the material of the target underground object, which affects the propagation speed of electromagnetic waves inside the target underground object, the dielectric constant of the formation refers to the dielectric constant of the formation material where the underground target is located, which also affects the propagation characteristics of electromagnetic waves, and the total detection depth refers to the maximum depth that the ground penetrating radar plans to detect.

[0069] S302: Determine the effective dielectric constant according to the detection information.

[0070] Exemplarily, the effective dielectric constant is calculated by the following formula (1):

[0071]

[0072] Among them, ε effective represents the effective dielectric constant, ε r Represents the dielectric constant of the underground target, ε s represents the dielectric constant of the stratum, h represents the burial depth of the underground target, and L represents the total detection depth.

[0073] Specifically, assuming that the buried depth h of the underground target is 2 meters, the dielectric constant ε of the underground target is r is 9, the dielectric constant ε of the formation s is 4, and the total detection depth L is 5 meters. Based on the above formula (1), the effective dielectric constant can be calculated to be 6 by weighted average.

[0074] S303: Determine the wavelength of the electromagnetic wave according to the effective dielectric constant, the frequency of the electromagnetic wave and the speed of light, and determine the preset angle according to the wavelength of the electromagnetic wave and the distance between the first transceiver antenna and the second transceiver antenna.

[0075] For example, since the propagation speed of radar waves in different media is different, the length of the electromagnetic wave can be calculated by the following formula (2):

[0076]

[0077] Among them, λ represents the wavelength of the electromagnetic wave, ε effectiye represents the effective dielectric constant, c represents the speed of light, and f represents the frequency of the electromagnetic wave.

[0078] Specifically, assuming that the frequency f of the electromagnetic wave is 200 MHz and the speed of light c is 3×10 8 m / s, effective dielectric constant ε effective is 6. Based on the above formula (2), it can be calculated that the wavelength of the electromagnetic wave with a frequency of 200 MHz is 0.612 meters.

[0079] Exemplarily, the preset angle is calculated by the following formula (3):

[0080]

[0081] Among them, θ opt Indicates the preset angle, ε effective represents the effective dielectric constant, d represents the distance between the first transceiver antenna and the second transceiver antenna, f represents the frequency of the electromagnetic wave, c represents the speed of light, and arcsin represents the inverse sine function.

[0082] Specifically, assuming that the distance d between the first transceiver antenna and the second transceiver antenna is 1 meter, the effective dielectric constant ε calculated above is continued to be used. effective is 6, the frequency of electromagnetic waves f is 200MHz, and the speed of light c is 3×10 8 m / s, based on the above formula (3), the preset angle can be calculated to be 37.7 degrees.

[0083] It should be noted that the above calculation is only an example. In another example, if the wavelength of the first electromagnetic wave of 200MHz is 1.5 meters, the wavelength of the second electromagnetic wave of 200MHz is 1.11 meters, and the interval between the first transceiver antenna and the second transceiver antenna is 1.5 meters, it can be concluded according to the above calculation method that in order to detect underground targets within a depth of 10 meters, the optimal angle between the first transceiver antenna and the second transceiver antenna is 20°. Therefore, when the angle between the antennas is greater than 20° or even much greater than 20°, the phase difference will be too large, making it difficult to effectively match the interference signal, thereby affecting the accuracy of the inversion algorithm. At the same time, the complexity of signal interference increases, which may cause signal distortion. When the angle between the antennas is less than 20° or even close to 0°, the first transceiver antenna and the second transceiver antenna will receive almost the same signal, resulting in insufficient interference information and low imaging accuracy.

[0084] In addition, the optimal angle between the two antennas is the sine of the ratio of the antenna spacing to the signal wavelength, as shown in the following formula (4). This optimal angle can ensure that the phase difference between the antennas is optimal, so that the echo signal can produce the clearest interference fringes, thereby achieving the best imaging effect.

[0085]

[0086] Among them, θ opt represents a preset angle, λ represents the wavelength of the electromagnetic wave, d represents the distance between the first transceiver antenna and the second transceiver antenna, and arcsin represents an inverse sine function.

[0087] On the basis of the above formula (4), combined with the calculation expression of the wavelength expressed by the above formula (2) and the calculation expression of the effective dielectric constant expressed by the above formula (3), the expression of the above formula (1) can be derived.

[0088] Based on this, the present application not only takes into account the actual characteristics of the underground medium, but also optimizes the performance of the system through precise angle settings, ensuring that the two beams of electromagnetic waves produce an effective interference effect at the underground target, enabling the ground penetrating radar to generate higher resolution three-dimensional images, thereby improving imaging quality and detection accuracy.

[0089] Figure 4 FIG. 1 is a flow chart of a phase difference determination method provided in an embodiment of the present application. Figure 4 As shown, the above step S202 determines the phase difference between the reflected echoes under electromagnetic waves of different frequencies, and specifically includes the following steps:

[0090] S401, obtaining position information of a first transceiver antenna, a second transceiver antenna, and a radar wave source.

[0091] Alternatively, in holographic microwave imaging ground penetrating radar, the core mechanism of the dual-frequency interferometric inversion imaging model is to cleverly use two radar waves of different frequencies, such as 200MHz and 270MHz, to perform interferometric measurements on underground targets from a variety of angles. The core of this process relies on the interference effect, that is, when the radar wave signals of these two frequencies interact with each other, phase difference information is generated, and the generated phase difference information is used to reconstruct the spatial distribution of underground targets. Specifically, the two radar waves of different frequencies are first used to obtain the reflected signals of underground targets, and then the structural information of underground targets is extracted by precisely calculating the phase difference between the two sets of radar waves. This phase difference is the key basis in the image reconstruction process, which can accurately reflect the phase relationship between the reflected echoes of the two sets of frequency radar waves, thereby realizing three-dimensional imaging of underground targets.

[0092] For example, the position of the radar wave source is also the position of the pulse source module, and the position of the radar wave source is recorded as and the position of the antenna is recorded as Specifically, the position of the first transceiver antenna is denoted as The position of the first transceiver antenna is denoted as It should be noted that the propagation path of the radar wave interacts with the underground target through the reflection process, and the path difference and the phase difference of the signal are the key to imaging.

[0093] S402: Determine the phase of the first electromagnetic wave at the target position according to the wavelength of the first electromagnetic wave emitted by the first transceiver antenna, the position information of the first transceiver antenna, the position information of the radar wave source, and the burial depth of the underground target object.

[0094] Exemplarily, the phase expression is shown in the following formula (5):

[0095]

[0096] in, represents the phase difference of the electromagnetic wave at the target position, ω represents the target position, λ(ω) represents the wavelength of the electromagnetic wave emitted to the target position ω, and h represents the depth of the underground target object. Indicates the location information of the radar wave source. Indicates the location information of the antenna.

[0097] Specifically, combined with the above formula (5), the position information of the first transceiver antenna is Substituting into the above formula (5), the phase of the first electromagnetic wave emitted by the first transceiver antenna at the target position ω can be calculated:

[0098] S403: Determine the phase of the second electromagnetic wave at the target position according to the wavelength of the second electromagnetic wave emitted by the second transceiver antenna, the position information of the second transceiver antenna, the position information of the radar wave source, and the burial depth of the underground target object.

[0099] Exemplarily, in combination with the above formula (5), the position information of the second transceiver antenna is Substituting into the above formula (5), the phase of the second electromagnetic wave emitted by the second transceiver antenna at the target position ω can be calculated:

[0100] S404: Determine a phase difference according to the phase of the first electromagnetic wave at the target position and the phase of the second electromagnetic wave at the target position.

[0101] For example, assuming that two sets of radar wave sources with frequencies f1=200 MHz and f2=270 MHz are used respectively, the propagation phase difference is specifically shown in the following formula (6):

[0102]

[0103] in, represents the phase difference, represents the phase of the first electromagnetic wave at the target position, and represents the phase of the second electromagnetic wave at the target position.

[0104] Based on this, the phase difference can characterize the location, size, and material properties of underground targets, mainly because electromagnetic waves are affected by underground media during propagation, and electromagnetic waves of different frequencies interact with underground targets in different ways. This application ensures the accurate measurement of the phase difference between the reflected echoes of electromagnetic waves of different frequencies, so that the phase difference of the dual-frequency signal can characterize the reflected signal of the underground target. By using the multi-frequency interferometric inversion algorithm, the three-dimensional structure of the underground target can be inverted from the phase difference of the two-frequency radar waves.

[0105] Figure 5 A schematic diagram of a process flow of a three-dimensional image generation method provided in an embodiment of the present application is shown. Figure 5 As shown, the above step S202 performs inversion imaging processing based on the phase difference to generate a three-dimensional image of the underground target object, which specifically includes the following steps:

[0106] S501. Generate an interference pattern according to the phase difference, where the interference pattern is used to indicate the interaction of electromagnetic waves of different frequencies in space.

[0107] For example, all measured phase differences A matrix is ​​formed in which each element represents the phase difference at a spatial location, such as a point on a two-dimensional grid. The phase difference matrix is ​​then used to generate an interference pattern, which can be an intuitive visualization showing the interference effect of electromagnetic waves of different frequencies at various locations.

[0108] S502: Convert the interference pattern into an electromagnetic property distribution map, and generate a three-dimensional image of the underground target object based on the electromagnetic property distribution of the underground target object in the electromagnetic property distribution map.

[0109] Optionally, the interference pattern is converted into an electromagnetic property distribution map, that is, the electromagnetic property distribution information of the underground target object is extracted from the interference pattern, and a corresponding electromagnetic property distribution map is generated. Exemplarily, based on the phase difference information in the interference pattern, combined with known geological parameters such as dielectric constant, conductivity, etc., the electromagnetic properties at each measurement point, such as reflection coefficient, transmission coefficient, etc., are calculated, and the calculated electromagnetic property values ​​are mapped to the corresponding two-dimensional or three-dimensional spatial positions to generate an electromagnetic property distribution map.

[0110] Optionally, for each pixel point on the underground target object in the electromagnetic property distribution map, the electromagnetic wave response corresponding to each pixel point is determined, and based on the electromagnetic wave response corresponding to each pixel point, the electromagnetic wave response of the underground target object is determined; inversion imaging processing is performed based on the electromagnetic wave response of the underground target to generate a three-dimensional image of the underground target object.

[0111] Exemplarily, for each pixel, the response of the pixel to the incident electromagnetic wave is calculated based on the electromagnetic characteristics of the pixel, such as the reflection coefficient, such as the reflection intensity, phase change, etc. Then the electromagnetic wave responses of all the pixels are combined to form the electromagnetic wave response function of the entire underground target.

[0112] Optionally, determining the electromagnetic wave response corresponding to each pixel point includes: determining the electromagnetic wave response corresponding to each pixel point according to the position information of each pixel point, the phase of the first electromagnetic wave emitted by the first transceiver antenna at the target position, the phase of the second electromagnetic wave emitted by the second transceiver antenna at the target position, the wavelength of the first electromagnetic wave, and the wavelength of the second electromagnetic wave. On this basis, the electromagnetic wave response of the underground target object, that is, the electromagnetic wave response function is shown in the following formula (7):

[0113]

[0114] in, represents the electromagnetic wave response, N represents the number of pixels, λ1 represents the wavelength of the first electromagnetic wave, λ2 represents the wavelength of the second electromagnetic wave, represents the phase of the first electromagnetic wave emitted by the first transceiver antenna at the target position, represents the phase of the second electromagnetic wave emitted by the second transceiver antenna at the target position, Indicates the position information of the lth pixel.

[0115] Exemplarily, commonly used image reconstruction methods include interferometric inversion algorithms and least squares methods, the goal of which is to reconstruct the shape of underground targets by minimizing the difference between the phase difference actually measured and the phase difference theoretically calculated. On this basis, by selecting a suitable inversion algorithm, such as least squares method, Bayesian inversion, sparse reconstruction, etc., the true shape and distribution of underground targets can be restored from the electromagnetic wave response, and the three-dimensional model of the underground target can be constructed through the data processed by the inversion algorithm, and a visual three-dimensional image can be generated.

[0116] Exemplarily, for each pixel point, based on its position relative to the two transmitting and receiving antennas, the difference in path lengths of the first electromagnetic wave and the second electromagnetic wave propagating from their respective antennas to the pixel point is calculated, and the phase difference between the two electromagnetic waves when they arrive at the pixel point is calculated using the path length difference and wavelength information, and then the composite field intensity of the two electromagnetic waves at each pixel point is calculated, and a characteristic vector representing the response of each pixel point to the incident electromagnetic wave is generated, and the characteristic vector may include but is not limited to: reflection coefficient, transmission coefficient, scattering cross section, etc., and the characteristic vector will be used to describe the electromagnetic characteristics of the underground target at the pixel point, and serve as the basic data for subsequent inversion imaging.

[0117] Based on this, the electromagnetic wave response of each pixel on the underground target is accurately determined, providing a solid foundation for further image reconstruction and three-dimensional modeling. Especially under complex geological conditions or when the target has subtle differences, this application can more accurately capture the detailed features of the underground target, provide more reliable underground information, and ensure the detection accuracy while improving the resolution of the three-dimensional holographic imaging of the underground target.

[0118] The present application embodiment also provides an electronic device 600, such as Figure 6 As shown, it is a schematic diagram of the structure of an electronic device 600 provided in an embodiment of the present application. The electronic device may be a host computer, and the electronic device includes: a processor 601, a memory 602, and optionally, a bus 603. The memory 602 stores machine-readable instructions executable by the processor 601. When the electronic device 600 is running, the processor 601 communicates with the memory 602 through the bus 603. When the machine-readable instructions are executed by the processor 601, the method steps executed by the host computer in any of the above holographic imaging radar imaging methods are executed.

[0119] An embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method steps in any of the above holographic imaging radar imaging methods are executed.

[0120] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the method embodiment, and will not be repeated in this application. In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0121] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or part of the technical solution that contributes to the prior art or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, RandomAccess Memory), disk or optical disk and other media that can store program code.

[0122] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A holographic imaging radar imaging method, characterized in that: Applied to an inversion holographic imaging system, the inversion holographic imaging system comprises: a timing control module, a pulse source module, a first transceiver antenna, a second transceiver antenna and a host computer, wherein the first transceiver antenna and the second transceiver antenna have different frequencies, and there is a preset angle between the first transceiver antenna and the second transceiver antenna; the method comprises: The timing control module generates a first clock signal and a second clock signal, and sends the first clock signal and the second clock signal to the pulse source module, so that the pulse source module generates pulse signals of different frequencies according to the first clock signal and the second clock signal, and sends the pulse signals of different frequencies to the first transceiver antenna and the second transceiver antenna, so that the first transceiver antenna and the second transceiver antenna convert the pulse signals into electromagnetic waves of different frequencies, and transmit the electromagnetic waves of different frequencies to the underground target object; The host computer collects reflected echoes of the underground target object under the electromagnetic waves of different frequencies, determines the phase difference between the reflected echoes under the electromagnetic waves of different frequencies, and performs inversion imaging processing based on the phase difference to generate a three-dimensional image of the underground target object.

2. The method according to claim 1, characterized in that The preset angle is determined according to the following steps: The preset angle is determined according to the frequency of the electromagnetic wave, the distance between the first transceiver antenna and the second transceiver antenna, the effective dielectric constant and the speed of light.

3. The method according to claim 2, characterized in that Determining the preset angle according to the frequency of the electromagnetic wave, the distance between the first transceiver antenna and the second transceiver antenna, the effective dielectric constant and the speed of light includes: Acquiring detection information of the underground target object, the detection information including the burial depth of the underground target object, the dielectric constant of the underground target object, the dielectric constant of the stratum and the total detection depth; Determining the effective dielectric constant according to the detection information; The wavelength of the electromagnetic wave is determined according to the effective dielectric constant, the frequency of the electromagnetic wave and the speed of light, and the preset angle is determined according to the wavelength of the electromagnetic wave and the distance between the first transceiver antenna and the second transceiver antenna.

4. The method according to claim 3, characterized in that The effective dielectric constant is given by the formula Calculated, where ε effective represents the effective dielectric constant, ε r Represents the dielectric constant of the underground target, ε s represents the dielectric constant of the stratum, h represents the burial depth of the underground target, and L represents the total detection depth; The preset angle is given by the formula Calculated, where θ opt Indicates the preset angle, ε effective represents the effective dielectric constant, d represents the distance between the first transceiver antenna and the second transceiver antenna, f represents the frequency of the electromagnetic wave, c represents the speed of light, and arcsin represents the inverse sine function.

5. The method according to claim 1, characterized in that The determining of the phase difference between the reflected echoes under the electromagnetic waves of different frequencies comprises: Acquire position information of the first transceiver antenna, the second transceiver antenna, and a radar wave source; Determine the phase of the first electromagnetic wave at the target position according to the wavelength of the first electromagnetic wave emitted by the first transceiver antenna, the position information of the first transceiver antenna, the position information of the radar wave source, and the buried depth of the underground target object; Determine the phase of the second electromagnetic wave at the target position according to the wavelength of the second electromagnetic wave emitted by the second transceiver antenna, the position information of the second transceiver antenna, the position information of the radar wave source, and the burial depth of the underground target object; The phase difference is determined according to the phase of the first electromagnetic wave at the target position and the phase of the second electromagnetic wave at the target position.

6. The method according to claim 1, characterized in that The performing inversion imaging processing based on the phase difference to generate a three-dimensional image of the underground target object includes: generating an interference pattern according to the phase difference, wherein the interference pattern is used to indicate the interaction of electromagnetic waves of different frequencies in space; The interference pattern is converted into an electromagnetic property distribution map, and based on the electromagnetic property distribution of the underground target object in the electromagnetic property distribution map, a three-dimensional image of the underground target object is generated.

7. The method according to claim 6, characterized in that The generating a three-dimensional image of the underground target object based on the electromagnetic property distribution of the underground target object in the electromagnetic property distribution map comprises: For each pixel point on the underground target object in the electromagnetic characteristic distribution map, determine the electromagnetic wave response corresponding to each pixel point, and determine the electromagnetic wave response of the underground target object based on the electromagnetic wave response corresponding to each pixel point; Inversion imaging processing is performed based on the electromagnetic wave response of the underground target object to generate a three-dimensional image of the underground target object.

8. The method according to claim 7, characterized in that The determining of the electromagnetic wave response corresponding to each pixel point includes: The electromagnetic wave response corresponding to each pixel point is determined based on the position information of each pixel point, the phase of the first electromagnetic wave emitted by the first transceiver antenna at the target position, the phase of the second electromagnetic wave emitted by the second transceiver antenna at the target position, the wavelength of the first electromagnetic wave, and the wavelength of the second electromagnetic wave.

9. The method according to claim 8, characterized in that The electromagnetic wave response is given by the formula Calculated, among which, represents the electromagnetic wave response, N represents the number of pixels, λ1 represents the wavelength of the first electromagnetic wave, λ2 represents the wavelength of the second electromagnetic wave, represents the phase of the first electromagnetic wave emitted by the first transceiver antenna at the target position, represents the phase of the second electromagnetic wave emitted by the second transceiver antenna at the target position, Indicates the position information of the lth pixel.

10. An inversion holographic imaging system, characterized in that: include: A timing control module, a pulse source module, a first transceiver antenna, a second transceiver antenna and a host computer, wherein the first transceiver antenna and the second transceiver antenna have different frequencies, and there is a preset angle between the first transceiver antenna and the second transceiver antenna; The inversion holographic imaging system is used to execute the steps of the holographic imaging radar imaging method described in any one of claims 1 to 9 to achieve imaging of underground targets.

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