Data fusion method, device and storage medium for stepped frequency radar signal

Abstract

The present invention discloses a data fusion method, device and storage medium for stepped frequency radar signals, wherein the method comprises: obtaining sinusoidal continuous wave transmission signals of different frequencies; obtaining reflected signals corresponding to the transmission signals; performing orthogonal decomposition on each frequency reflected signal to obtain the corresponding in-phase component I n and the quadrature component Q n ; For each frequency f n Corresponding I n and Q n The cut-off frequency is f n The low-pass filter is used to process, and the corresponding I n and Q n The difference frequency component I' in the result n and Q' n ; The reflected signal of each frequency is passed through I′ in the frequency domain n +jQ′ n The conjugate symmetric sequence of reflected signals of all frequencies in the frequency domain is expressed in the form of inverse Fourier transform to the time domain for signal fusion. This scheme makes the frequency components of the fused signal flexible and controllable, and the synthesized radar image has a higher signal-to-noise ratio than the conventional pulse signal; because the transmitted signal is a continuous wave signal, the transmission power of the signal in use is increased, and the detection depth is also greater.

Description

Technical Field

[0001] The present invention relates to the field of exploration geophysical data processing, and in particular to a multi-frequency data fusion method, device and storage medium for stepped frequency radar signals. Background Art

[0002] As a highly efficient non-destructive testing technology, ground penetrating radar is widely used in engineering surveys, concrete component defects, road surface inspections, roadbed disease detection, etc., and has achieved good detection results. Generally speaking, if high-resolution detection results are required, a radar system with a higher center frequency is required, but the detection depth is shallow. If a larger exploration depth is required, a radar system with a lower center frequency is selected, but the resolution is lower.

[0003] However, the two performance indicators of ground penetrating radar, detection resolution and exploration depth, cannot be taken into account at the same time as the needs of practical applications. The traditional pulse radar has an extremely short pulse transmission time, a small average power of the transmitted signal, and a low signal-to-noise ratio of the echo, which affects the exploration depth and resolution of the ground penetrating radar. As a type of frequency domain ground penetrating radar, stepped frequency ground penetrating radar has gradually become a research hotspot in this field in recent years. Its advantages in detection depth and resolution compared to impact pulse ground penetrating radar are also reflected in research and applications. However, there is currently no mature method for data fusion of stepped frequency radar signals containing multiple frequencies, which makes it difficult to interpret radar signals received by stepped frequency radars at multiple frequencies. Summary of the invention

[0004] The present invention provides a data fusion method, device and storage medium for stepped frequency radar signals, so as to solve the current problem of difficulty in interpreting radar signals of multiple frequencies received by stepped frequency radar.

[0005] In a first aspect, a data fusion method for stepped frequency radar signals is provided, comprising:

[0006] Obtain sinusoidal continuous wave transmission signals of different frequencies and express them as Tx(f1), Tx(f2)...Tx(f n ), where f n Indicates the nth frequency of the step frequency;

[0007] Obtain the reflected signals corresponding to the sinusoidal continuous wave transmission signals of different frequencies and express them as Rx(f1), Rx(f2)…Rx(f n );

[0008] Perform orthogonal decomposition on the reflected signal of each frequency to obtain the corresponding in-phase component I n and the quadrature component Q n ;

[0009] For each frequency f n The corresponding in-phase component and quadrature component adopt cutoff frequency f n The low-pass filter is used to process the difference frequency component I' in the in-phase component and the orthogonal component results. n and Q' n ;

[0010] The reflected signal of each frequency is passed through I′ in the frequency domain n +jQ′ n :

[0011] The conjugate symmetric sequence composed of the reflected signals of all frequencies in the frequency domain is transformed into the time domain through inverse Fourier transformation for signal fusion.

[0012] Furthermore, the transmission signal is obtained by the following method:

[0013] Select the bandwidth range of the stepped frequency continuous wave signal;

[0014] Sine continuous wave signals with different frequencies are generated as transmission signals based on the bandwidth range.

[0015] Further, the orthogonal decomposition of the reflected signal of each frequency to obtain the corresponding in-phase component and orthogonal component specifically includes:

[0016] The reflected signal Rx(f n ) and the transmitting signal Tx(f n ) are multiplied to obtain the in-phase component;

[0017] The reflected signal Rx(f n ) is multiplied with a cosine signal of the same frequency to obtain a quadrature component; wherein the cosine signal is the same as the transmission signal Tx(f n ) Same frequency but different phase signal.

[0018] Further, the transmission signal is expressed as:

[0019]

[0020] Among them, t is the duration, k is a constant less than 1; through kf n t to control the amplitude of the early transmission signal. n When t<1, the amplitude of the transmitted signal increases with the time length t. The smaller k is, the slower the amplitude increases. n When t>1, the amplitude of the transmitted signal is 1.

[0021] Furthermore, the reflection signal is obtained by forward modeling based on the constructed two-dimensional geological model and a forward modeling program based on a finite difference method. The reflection signal is expressed as follows:

[0022]

[0023] Among them, A n is the echo amplitude; f n =f0+(n-1)Δf, f0 is the step start frequency, n represents the nth frequency point of the step frequency, Δf is the frequency step length; is the phase change of the reflected signal relative to the transmitted signal, v is the propagation speed of the transmitted signal or the reflected signal in the medium to be tested, and d is the position of the detection point and the target to be detected.

[0024] Furthermore, the in-phase component I n and the quadrature component Q n They are obtained by the following formulas:

[0025]

[0026]

[0027] For each frequency f n The corresponding in-phase component I n and the quadrature component Q n The cut-off frequency is f n The low-pass filter is used to process the difference frequency component I' in the in-phase component and the orthogonal component results. n and Q' n , expressed as:

[0028]

[0029]

[0030] Then, the reflected signal of each frequency is expressed in the frequency domain as:

[0031] Rx(n)=I′ n +jQ′ n .

[0032] In a second aspect, a data fusion device for stepped frequency radar signals is provided, comprising:

[0033] The transmission signal acquisition module is used to obtain sinusoidal continuous wave transmission signals of different frequencies and express them as Tx(f1), Tx(f2)...Tx(f n ), where f n Indicates the nth frequency of the step frequency;

[0034] A reflection signal acquisition module is used to acquire reflection signals corresponding to sinusoidal continuous wave transmission signals of different frequencies, and express them as Rx(f1), Rx(f2)...Rx(fn);

[0035] The orthogonal decomposition module is used to perform orthogonal decomposition on the reflected signal of each frequency to obtain the corresponding in-phase component I n and the quadrature component Q n ;

[0036] Filter module, used for each frequency f n The corresponding in-phase component and quadrature component adopt cutoff frequency f n The low-pass filter is used to process the difference frequency component I' in the in-phase component and the orthogonal component results. n and Q' n ;

[0037] Multi-frequency data fusion module is used to combine the reflected signals of each frequency in the frequency domain through I′ n +jQ′ n The conjugate symmetric sequence composed of the reflected signals of all frequencies in the frequency domain is transformed into the time domain through inverse Fourier transformation for signal fusion.

[0038] In a second aspect, a computer-readable storage medium is provided, which stores a computer program, wherein the computer program is suitable for being loaded by a processor and executing the data fusion method for stepped frequency radar signals as described above.

[0039] Beneficial Effects

[0040] The present invention proposes a data fusion method, device and storage medium for stepped frequency radar signals, which obtains the corresponding in-phase component I by orthogonally decomposing the reflected signal of each frequency. n and the quadrature component Q n , and use the cutoff frequency f n The low-pass filter is used to process the difference frequency component I' in the in-phase component and the orthogonal component results. n and Q' n ; Then the reflected signal of each frequency is passed through I′ in the frequency domain n +jQ′ n; finally, the conjugate symmetric sequence composed of the reflected signals of all frequencies in the frequency domain is transformed into the time domain through inverse Fourier transformation for signal fusion to obtain a time domain radar image. This scheme makes the frequency components of the fused signal flexible and controllable, with good anti-noise performance. The synthesized radar image has a higher signal-to-noise ratio than conventional pulse signals under noise conditions. And because a continuous wave signal is transmitted, the transmission power of the signal increases in actual use, and the detection depth will also be greater. This scheme takes into account both the detectable resolution and the exploration depth. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 is a flow chart of a data fusion method for stepped frequency radar signals provided by an embodiment of the present invention;

[0043] Figure 2 It is a two-dimensional geological model map for forward simulation provided by an embodiment of the present invention;

[0044] Figure 3 is a 100 MHz transmission signal waveform provided by an embodiment of the present invention;

[0045] Figure 4 The first reflected signal waveform of 100 MHz provided by the embodiment of the present invention;

[0046] Figure 5 It is a time domain signal formed by merging 201 frequencies at the first position provided by an embodiment of the present invention;

[0047] Figure 6 It is a Bscan image generated by step frequency fusion data under noise-free conditions provided by an embodiment of the present invention;

[0048] Figure 7 is a Bscan image generated by step frequency fusion data under noise conditions provided by an embodiment of the present invention;

[0049] Figure 8 is a Bscan image obtained by forward modeling of a Ricker wavelet signal under noise-free conditions provided by an embodiment of the present invention;

[0050] Fig. 9 It is a Bscan image obtained by forward modeling of a Ricker wavelet signal under noise conditions provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0052] Example 1

[0053] like Figure 1 As shown, this embodiment provides a data fusion method for stepped frequency radar signals, including:

[0054] (1) Obtain sinusoidal continuous wave transmission signals of different frequencies and represent them as Tx(f1), Tx(f2)…Tx(f n ), where f n Indicates the nth frequency of the step frequency;

[0055] (2) Obtain the reflected signals corresponding to the sinusoidal continuous wave transmission signals of different frequencies and express them as Rx(f1), Rx(f2)…Rx(f n );

[0056] (3) Perform orthogonal decomposition on the reflected signal of each frequency to obtain the corresponding in-phase component I n and the quadrature component Q n ;

[0057] (4) For each frequency f n The corresponding in-phase component and quadrature component adopt cutoff frequency f n The low-pass filter is used to process the difference frequency component I' in the in-phase component and the orthogonal component results. n and Q' n ;

[0058] (5) The reflected signal of each frequency is transmitted in the frequency domain through I′ n +jQ′ n :

[0059] (6) The conjugate symmetric sequence composed of the reflected signals of all frequencies in the frequency domain is transformed into the time domain through inverse Fourier transformation for signal fusion.

[0060] Specifically, the transmission signal is obtained by the following method:

[0061] Select the bandwidth range of the stepped frequency continuous wave signal;

[0062] Sine continuous wave signals with different frequencies are generated as transmission signals based on the bandwidth range.

[0063] The orthogonal decomposition of the reflected signal of each frequency to obtain the corresponding in-phase component and orthogonal component specifically includes:

[0064] The reflected signal Rx(f n ) and the transmitting signal Tx(f n ) are multiplied to obtain the in-phase component;

[0065] The reflected signal Rx(f n ) is multiplied with a cosine signal of the same frequency to obtain a quadrature component; wherein the cosine signal is the same as the transmission signal Tx(f n ) Same frequency but different phase signal.

[0066] In order to further understand the technical solution of the present invention, a forward simulation example of a stepped frequency ground penetrating radar is used for illustration below.

[0067] First, a two-dimensional geological model for forward modeling is constructed, such as Figure 2 As shown, the model set is a layered model. The upper layer is medium 1, with a layer thickness of 2m, a relative dielectric constant of 7, and a conductivity of 0.005S / m; the lower layer is medium 2, with a layer thickness of 2m, a relative dielectric constant of 12, and a conductivity of 0.002S / m; a circular cavity with a radius of 0.3m is set in the middle of the model, and the relative dielectric constant of the cavity is 1 and the conductivity is 0.

[0068] The model was meshed using the forward modeling procedure of the ground penetrating radar based on the finite difference algorithm. The selected step frequency range was 100MHz to 300MHz, with a step length of 1MHz. There were 201 frequency points in total. The model size was 10m×4.2m. The transmitting point was located at x=0.1m, y=4m, and the receiving point was located at x=0.2m, y=4m. The moving step length of the transmitting point and the receiving point was 0.05m. A total of 194 data were collected, with 8192 sampling points for each data (time window 96ns).

[0069] The transmitted signal is in the form of a continuous sine wave. Taking 100MHz as an example, its waveform is shown in Figure 3 In order to avoid introducing high-frequency noise into the forward modeling results, it is necessary to control the amplitude of the transmitted signal to increase slowly from zero to 1. The transmitted signal is expressed as:

[0070]

[0071] Where t is the duration, k is a constant less than 1 (0.25 in this example), and f n is the nth frequency of the step frequency, use kfn t to control the amplitude of the early transmission signal. n When t<1, the amplitude of the transmitted signal increases slowly with the time length t. The smaller k is, the slower the amplitude increases. n When t>1, the amplitude of the transmitted signal is 1.

[0072] Let v represent the speed of signal propagation in a uniform medium. The reflected signal from a target at a distance d can be expressed as:

[0073]

[0074] Among them, A n is the echo amplitude, f0 is the step start frequency, n represents the nth frequency point of the step frequency, Δf is the frequency step length, It is the two-way travel time of the signal.

[0075] The above reflection signal can be simplified as:

[0076]

[0077] Among them, f n =f0+(n-1)Δf, which is the nth frequency of the step frequency; is the phase change of the reflected signal relative to the transmitted signal.

[0078] The reflected signal waveform corresponding to the 100MHz transmitted signal at the first position is shown in Figure 4 .

[0079] After obtaining the reflected signal of each frequency, it is necessary to perform orthogonal decomposition, where the in-phase component I n and the quadrature component Q n They are obtained by the following formulas:

[0080]

[0081]

[0082] That is, the reflected signal of each frequency is multiplied by the transmitted signal of the same frequency to obtain the in-phase component, and the reflected signal of each frequency is multiplied by the cosine signal of the same frequency (the cosine signal is the same frequency as the transmitted signal but with a phase difference of The cosine signal of the frequency is multiplied to obtain the orthogonal component. Then, for each frequency, the in-phase component I n and the quadrature component Q n With cutoff frequency f n The difference frequency component I' is obtained by low-pass filter. n and Q' n :

[0083]

[0084]

[0085] Then, the reflected signal of each frequency is expressed in the frequency domain as:

[0086] Rx(n)=I′ n +jQ′ n

[0087] Where j is the symbol of the complex imaginary part.

[0088] For the sequence Rx(n) generated by 201 frequency points, a conjugate symmetric sequence is formed in the frequency domain, and then transferred to the time domain for data fusion through inverse Fourier transform. The first synthesized time domain data is shown in Figure 5 From the synthesized data, it can be seen that the layer interface reflection signal appears at about 36ns, corresponding to a depth of 2.0394m, which is consistent with the interface set by the model at a depth of 2m. The Bscan image synthesized by the data fused from 194 scanning track positions is shown in Figure 6 In order to compare with the forward modeling results of pulse signals commonly used in ground penetrating radar, Ricker wavelet with a center frequency of 200MHz is used as the source signal for forward modeling. The Bscan image synthesized by collecting 194 data is shown in Figure 2. Figure 8 .

[0089] In order to compare the step frequency data fusion results and the pulse signal forward modeling results under noise conditions, the same degree of noise is added to the forward modeling process of both. For the Ricker wavelet signal, noise is added to each reflection signal, and then the Bscan image is synthesized (see Fig. 9 ); For SFCW (stepped frequency continuous wave) signal, add the same degree of noise to the continuous wave reflection signal at each frequency point, and then press Figure 1 In the process (3)→(4)→(5)→(6), the data are processed and converted into single-channel data in the time domain, and then the fused 194-channel data are synthesized into a Bscan image (see Figure 7 ). Comparison of the Bscan results obtained by the two methods before and after adding noise shows that the signal-to-noise ratio of the results corresponding to the Ricker wavelet signal is significantly reduced after adding noise, and the radar echoes reflected by the layer interface and abnormal body are difficult to identify (such as Fig. 9 ); the multi-frequency data fusion result of the stepped frequency signal still maintains a high signal-to-noise ratio under the condition of adding noise, and the echo characteristics are clear (such as Figure 7 ). The above results show that the proposed multi-frequency data fusion method for stepped frequency radar signals has better noise resistance performance.

[0090] Example 2

[0091] This embodiment provides a data fusion device for stepped frequency radar signals, including:

[0092] The transmission signal acquisition module is used to obtain sinusoidal continuous wave transmission signals of different frequencies and express them as Tx(f1), Tx(f2)...Tx(f n ), where f n Indicates the nth frequency of the step frequency;

[0093] A reflection signal acquisition module is used to acquire reflection signals corresponding to sinusoidal continuous wave transmission signals of different frequencies, and express them as Rx(f1), Rx(f2)...Rx(fn);

[0094] The orthogonal decomposition module is used to perform orthogonal decomposition on the reflected signal of each frequency to obtain the corresponding in-phase component I n and the quadrature component Q n ;

[0095] Filter module, used for each frequency f n The corresponding in-phase component and quadrature component adopt cutoff frequency f n The low-pass filter is used to process the difference frequency component I' in the in-phase component and the orthogonal component results. n and Q' n ;

[0096] Multi-frequency data fusion module is used to combine the reflected signals of each frequency in the frequency domain through I′ n +jQ′ n The conjugate symmetric sequence composed of the reflected signals of all frequencies in the frequency domain is transformed into the time domain through inverse Fourier transformation for signal fusion.

[0097] Example 3

[0098] This embodiment provides a computer-readable storage medium storing a computer program. The computer program is suitable for being loaded by a processor and executing the data fusion method for stepped frequency radar signals as described above.

[0099] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0100] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0101] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0102] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0103] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0104] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0105] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A data fusion method for stepped frequency radar signals, characterized in that: include: Obtain sinusoidal continuous wave transmission signals of different frequencies and express them as Tx(f1), Tx(f2)...Tx(f n ), where f n Indicates the nth frequency of the step frequency; Obtain the reflected signals corresponding to the sinusoidal continuous wave transmission signals of different frequencies and express them as Rx(f1), Rx(f2)...Rx(fn); Perform orthogonal decomposition on the reflected signal of each frequency to obtain the corresponding in-phase component I n and the quadrature component Q n ; For each frequency f n The corresponding in-phase component and quadrature component adopt cutoff frequency f n The low-pass filter is used to process the difference frequency component I' in the in-phase component and the orthogonal component results. n and Q' n ; The reflected signal of each frequency is transmitted in the frequency domain through I n ′+jQ n ′ in the form of; The conjugate symmetric sequence composed of the reflected signals of all frequencies in the frequency domain is transformed into the time domain through inverse Fourier transformation for signal fusion; The reflection signal is obtained by forward modeling based on the constructed two-dimensional geological model and a forward modeling program based on the finite difference method, specifically including: A two-dimensional geological model for forward modeling is constructed. The two-dimensional geological model is set as a layered model, including upper and lower layers of medium. A circular cavity is set in the middle of the layered model, and the relative dielectric constant of the cavity is 1 and the conductivity is 0. The 2D geological model was meshed using a ground penetrating radar forward modeling program based on a finite difference algorithm. The step frequency range was 100 MHz to 300 MHz with a step length of 1 MHz. The transmitting and receiving points were selected, and the moving step length of the transmitting and receiving points was 0.05 m. Then data was collected to obtain the reflected signal. The transmission signal is expressed as: Among them, t is the duration, k is a constant less than 1; through kf n t to control the amplitude of the early transmission signal. n When t<1, the amplitude of the transmitted signal increases with the time length t. The smaller k is, the slower the amplitude increases. n When t>1, the amplitude of the transmitted signal is 1.

2. The data fusion method for stepped frequency radar signals according to claim 1, characterized in that: The transmission signal is obtained by the following method: Select the bandwidth range of the stepped frequency continuous wave signal; Sine continuous wave signals with different frequencies are generated as transmission signals based on the bandwidth range.

3. The data fusion method for stepped frequency radar signals according to claim 1, characterized in that: The orthogonal decomposition of the reflected signal of each frequency to obtain the corresponding in-phase component and orthogonal component specifically includes: The reflected signal Rx(f n ) and the transmitting signal Tx(f n ) are multiplied to obtain the in-phase component; The reflected signal Rx(f n ) is multiplied with a cosine signal of the same frequency to obtain a quadrature component; wherein the cosine signal is the same as the transmission signal Tx(f n ) Same frequency but different phase signal.

4. The data fusion method for stepped frequency radar signals according to claim 1, characterized in that: The reflection signal is obtained by forward modeling based on the constructed two-dimensional geological model and by using a forward modeling program based on the finite difference method. The reflection signal is expressed as follows: Among them, A n is the echo amplitude; f n =f0+(n-1)Δf, f0 is the step start frequency, n represents the nth frequency point of the step frequency, Δf is the frequency step length; is the phase change of the reflected signal relative to the transmitted signal, v is the propagation speed of the transmitted signal or the reflected signal in the medium to be tested, and d is the position of the detection point and the target to be detected.

5. The data fusion method for stepped frequency radar signals according to claim 4, characterized in that: The in-phase component I n and the quadrature component Q n They are obtained by the following formulas: For each frequency f n The corresponding in-phase component I n and the quadrature component Q n The cut-off frequency is f n The low-pass filter is used to process the difference frequency component I' in the in-phase component and the orthogonal component results. n and Q' n , expressed as: Then, the reflected signal of each frequency is expressed in the frequency domain as: Rx(n)=I n ′+jQ n ′。 6. A data fusion device for stepped frequency radar signals, characterized in that: include: The transmission signal acquisition module is used to obtain sinusoidal continuous wave transmission signals of different frequencies and express them as Tx(f1), Tx(f2)...Tx(f n ), where f n Indicates the nth frequency of the step frequency; A reflection signal acquisition module is used to acquire reflection signals corresponding to sinusoidal continuous wave transmission signals of different frequencies, and express them as Rx(f1), Rx(f2)...Rx(fn); The orthogonal decomposition module is used to perform orthogonal decomposition on the reflected signal of each frequency to obtain the corresponding in-phase component I n and the quadrature component Q n ; Filter module, used for each frequency f n The corresponding in-phase component and quadrature component adopt cutoff frequency f n The low-pass filter is used to process the difference frequency component I' in the in-phase component and the orthogonal component results. n and Q' n ; Multi-frequency data fusion module is used to combine the reflected signals of each frequency in the frequency domain through I n ′+jQ n ′; the conjugate symmetric sequence composed of the reflected signals of all frequencies in the frequency domain is transformed into the time domain through inverse Fourier transformation for signal fusion; The reflection signal is obtained by forward modeling based on the constructed two-dimensional geological model and a forward modeling program based on the finite difference method, specifically including: A two-dimensional geological model for forward modeling is constructed. The two-dimensional geological model is set as a layered model, including upper and lower layers of medium. A circular cavity is set in the middle of the layered model, and the relative dielectric constant of the cavity is 1 and the conductivity is 0. The 2D geological model was meshed using a ground penetrating radar forward modeling program based on a finite difference algorithm. The step frequency range was 100 MHz to 300 MHz with a step length of 1 MHz. The transmitting and receiving points were selected, and the moving step length of the transmitting and receiving points was 0.05 m. Then data was collected to obtain the reflected signal. The transmission signal is expressed as: Among them, t is the duration, k is a constant less than 1; through kf n t to control the amplitude of the early transmission signal. n When t<1, the amplitude of the transmitted signal increases with the time length t. The smaller k is, the slower the amplitude increases. n When t>1, the amplitude of the transmitted signal is 1.

7. A computer-readable storage medium storing a computer program, characterized in that: The computer program is suitable for being loaded by a processor and executing the data fusion method for stepped frequency radar signals according to any one of claims 1 to 5.

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