Method for recovering original echo signal of target
By using an interpolation function based on Fast Fourier Transform and a spectral position index based on scaling transformation, along with inverse stolt mapping, the problem of insufficient accuracy in Doppler phase history recovery of moving targets in high-resolution SAR imaging is solved, and efficient recovery of the original echo signal is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN INSTITUE OF SPACE RADIO TECH
- Filing Date
- 2025-12-12
- Publication Date
- 2026-04-17
AI Technical Summary
Existing technologies struggle to efficiently recover the Doppler phase history of moving targets in high-resolution SAR imaging processing, especially in data processed by RMA algorithms, where existing methods suffer from insufficient accuracy.
Upsampling is performed using an interpolation function based on Fast Fourier Transform, and combined with the spectral position index after scaling transformation, inverse stolt mapping is completed. Subsequently, inverse uniform compression and inverse range pulse compression are performed to recover the original echo signal of the target.
It achieves high-precision recovery of the target's Doppler phase history, obtains the original echo signal of moving targets in a high-resolution SAR system, and improves computational efficiency.
Smart Images
Figure CN121878632A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of space microwave radar signal processing technology, and specifically relates to a method for recovering the original echo signal of a target, which is applied to high-resolution SAR / ISAR imaging processing. Background Technology
[0002] The Range Migration Algorithm (RMA) is widely used in high-resolution SAR imaging processing because its derivation involves almost no approximations. The RMA algorithm mainly consists of a two-dimensional Fourier transform, uniform compression, stolt mapping, and a two-dimensional inverse Fourier transform. Uniform compression and stolt mapping are the two most critical processing steps in the RMA algorithm. Uniform compression corrects the entire echo signal through reference function phase correction, ensuring that the residual phase of the target at the reference slant range (usually the scene center) is zero, thus achieving complete target focus. Stolt mapping compensates for the residual coupling phase using interpolation operations, completing residual range migration correction, residual secondary range compression, and residual azimuth compression, thereby achieving complete focus on all other targets within the scene.
[0003] However, in many practical signal processing processes (such as refocusing of moving targets), it is necessary to recover the Doppler phase history of the target of interest in order to facilitate subsequent re-imaging and refocusing. Therefore, it is necessary to perform inverse RMA processing on the imaging results of the target of interest to obtain the original echo signal of the target. Summary of the Invention
[0004] To overcome the shortcomings of existing technologies, the inventors have conducted intensive research and proposed a method for recovering the original echo signal of a target after RMA algorithm processing. This method first uses an interpolation function based on Fast Fourier Transform (FFT) for upsampling, and then combines it with the spectral position index after scale transformation to complete the inverse stolt mapping processing based on scale transformation. Compared to sinc interpolation, using an interpolation function based on FFT and the spectral position index after scale transformation to complete the inverse stolt mapping processing based on scale transformation is more computationally efficient. Subsequent inverse uniform compression and inverse range pulse compression processing ultimately achieve high-precision recovery of the target's Doppler phase history, obtaining the original echo signal of the target before RMA processing, thus completing this invention. The technical solution provided by this invention is as follows: Firstly, a method for recovering the original echo signal of a target includes: A two-dimensional fast Fourier transform is performed on the imaging results containing the target of interest to transform the signal into the two-dimensional frequency domain; The two-dimensional spectrum of the signal is upsampled pulse by pulse using an interpolation function based on Fast Fourier Transform to obtain the upsampled two-dimensional spectrum. The scaling factor is calculated pulse-by-pulse for the upsampled two-dimensional spectrum. By combining the scaling factor, the spectral position index after scaling is determined; Based on the upsampled two-dimensional spectrum and the spectrum position index after scaling transformation, the two-dimensional spectrum after inverse stol mapping is obtained, thus completing the inverse stol mapping process based on scaling transformation. Perform inverse uniform compression on the two-dimensional spectrum after inverse stol mapping; Inverse range pulse compression is performed on the two-dimensional spectrum after inverse uniform compression. The two-dimensional spectrum after inverse range pulse compression is subjected to a two-dimensional fast inverse Fourier transform and transformed to the two-dimensional time domain to obtain the original echo signal of the target.
[0005] Secondly, a device for recovering the original echo signal of a target includes: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the method for recovering the target original echo signal as described in the first aspect.
[0006] Thirdly, a readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for recovering the target original echo signal as described in the first aspect.
[0007] Fourthly, a computer program product comprising: a computer program (also referred to as code or instructions) that, when run, performs the method for recovering the target original echo signal as described in the first aspect.
[0008] The method for recovering the original echo signal of a target provided by the present invention has the following beneficial effects: Existing methods for recovering the original echo signal of a moving target during refocusing are mostly designed for imaging algorithms such as RD, CS, and SPECAN. However, these algorithms suffer from insufficient accuracy in high-resolution SAR systems. Thanks to rigorous theoretical derivation, the RMA algorithm is widely used in high-resolution SAR imaging processing. Therefore, to recover the Doppler phase history of a moving target in a high-resolution system, inverse processing of the RMA algorithm is required. This invention provides a method for recovering the original echo signal of a target. This method first uses an interpolation function based on Fast Fourier Transform (FFT) for upsampling, then combines it with the spectral position index after scale transformation to complete the inverse stolt mapping based on scale transformation. Subsequent inverse uniform compression and inverse range pulse compression processes ultimately achieve high-precision recovery of the target's Doppler phase history and obtain the original echo signal. Compared to sinc interpolation, using an interpolation function based on FFT and the spectral position index after scale transformation to complete the inverse stolt mapping based on scale transformation is computationally more efficient. Attached Figure Description
[0009] Figure 1 A flowchart of a method for recovering the original echo signal of a target; Figure 2 The image is a simulation result of the target data. Figure 3 This is a two-dimensional spectrum result after inverse stolt mapping. Figure 4 This is a diagram of the original echo signal of the target after two-dimensional IFFT transformation. Detailed Implementation
[0010] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.
[0011] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.
[0012] This invention provides a method for recovering the original echo signal of a target, such as... Figure 1 As shown, it includes the following steps: S1. Perform a two-dimensional Fast Fourier Transform (FFT) on the imaging results containing the target of interest to transform the signal into the two-dimensional frequency domain.
[0013] S2. The two-dimensional spectrum of the signal is upsampled pulse by pulse using an interpolation function based on Fast Fourier Transform to obtain the upsampled two-dimensional spectrum.
[0014] S3. Calculate the scaling factor pulse by pulse for the two-dimensional spectrum after upsampling.
[0015] In this step, the scaling factor is calculated pulse-by-pulse on the upsampled two-dimensional spectrum. Represented as:
[0016] in, This is the scaling factor. c At the speed of light, f c For carrier frequency, f r For faster time frequency, f a For slow time frequency, V r This is the radar equivalent velocity.
[0017] S4. Combine the scaling factor to determine the spectral position index after scaling.
[0018] In this step, the spectral position index after scaling is determined by combining the scaling factor. The formula for calculating the spectral position index is as follows:
[0019] in, I nd For spectral location index, To increase the sampling factor, f r (1) is the initial fast time frequency.
[0020] S5. Based on the upsampled two-dimensional spectrum and the spectrum position index after scaling transformation, obtain the two-dimensional spectrum after inverse stol mapping, and complete the inverse stol mapping processing based on scaling transformation.
[0021] In this step, the two-dimensional spectrum after the inverse stolt mapping is represented as follows:
[0022] in, The two-dimensional spectrum after inverse stolt mapping. This is the two-dimensional spectrum after upsampling.
[0023] S6. Perform inverse uniform compression on the two-dimensional spectrum after inverse stol mapping.
[0024] In this step, the inverse consistent compression process is represented as follows:
[0025] in, The two-dimensional spectrum after inverse uniform compression. R c This is the reference slope distance.
[0026] S7. Perform inverse distance pulse compression on the two-dimensional spectrum after inverse uniform compression.
[0027] In this step, the inverse distance pulse compression process is represented as follows:
[0028] in, The two-dimensional spectrum after inverse distance pulse compression. K r This represents the frequency modulation slope.
[0029] S8. Perform a two-dimensional inverse fast fourier transform (IFFT) on the two-dimensional spectrum after inverse range pulse compression processing to transform it to the two-dimensional time domain and obtain the original echo signal of the target.
[0030] The following is an illustrative example through specific embodiments.
[0031] A method for recovering the original echo signal of a target includes the following steps: (1) Two-dimensional FFT For the imaging results containing the target of interest, see [image]. Figure 2 Perform a two-dimensional FFT to transform the signal into a two-dimensional frequency domain, thus obtaining a two-dimensional spectrum.
[0032] (2) Interpolation upsampling The two-dimensional spectrum of the signal is upsampled pulse by pulse using an interpolation function based on Fast Fourier Transform to obtain the upsampled two-dimensional spectrum.
[0033] (3) Calculation of scaling factor The scaling factor is calculated pulse-by-pulse for the upsampled two-dimensional spectrum. The scaling factor is expressed as:
[0034] in, This is the scaling factor. c At the speed of light, f c For carrier frequency, f r For faster time frequency, f a For slow time frequency, V r This is the radar equivalent velocity.
[0035] (4) Calculation of Spectrum Position Index By combining the scaling factor, the spectral position index after scaling is determined. The formula for calculating the index is as follows:
[0036] in, I nd For location index, To increase the sampling factor, f r (1) is the initial fast time frequency.
[0037] S5, inverse stol mapping spectrum acquisition Based on the upsampled 2D spectrum and the spectral position index after scaling, the 2D spectrum after inverse stolt mapping is obtained, completing the inverse stolt mapping process based on scaling. See [link to documentation]. Figure 3 The two-dimensional spectrum after inverse stol mapping is represented as:
[0038] in, The two-dimensional spectrum after inverse stolt mapping. This is the two-dimensional spectrum after upsampling.
[0039] (6) Inverse uniform compression The two-dimensional spectrum after inverse stol mapping is subjected to inverse uniform compression. The inverse uniform compression process is represented as follows:
[0040] in, The two-dimensional spectrum after inverse uniform compression. R c This is the reference slope distance.
[0041] S7, Reverse Distance Pulse Compression The inverse range pulse compression is performed on the two-dimensional spectrum after inverse uniform compression. The inverse range pulse compression is expressed as follows:
[0042] in, The two-dimensional spectrum after inverse distance pulse compression. K r This represents the frequency modulation slope.
[0043] S8, Two-dimensional IFFT By performing a two-dimensional IFFT on the two-dimensional spectrum after inverse range pulse compression and transforming it to the two-dimensional time domain, the Doppler history of the target can be recovered, thus obtaining the original echo signal of the target. (See...) Figure 4 .
[0044] The present invention also provides a device for recovering the original echo signal of a target, comprising: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the above-described method for recovering the target original echo signal.
[0045] The present invention also provides a readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method for recovering the target original echo signal.
[0046] The readable storage media include, but are not limited to, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.
[0047] The present invention also provides a computer program product comprising: a computer program (also referred to as code or instructions), which, when the computer program is run, executes the above-described method for recovering the target original echo signal.
[0048] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, microwave, etc.) means.
[0049] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.
[0050] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0051] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.
[0052] The contents not described in detail in this specification are common knowledge to those skilled in the art.
Claims
1. A method for recovering the original echo signal of a target, characterized in that, include: A two-dimensional fast Fourier transform is performed on the imaging results containing the target of interest to transform the signal into the two-dimensional frequency domain; The two-dimensional spectrum of the signal is upsampled pulse by pulse using an interpolation function based on Fast Fourier Transform to obtain the upsampled two-dimensional spectrum. The scaling factor is calculated pulse-by-pulse for the upsampled two-dimensional spectrum. By combining the scaling factor, the spectral position index after scaling is determined; Based on the upsampled two-dimensional spectrum and the spectrum position index after scaling transformation, the two-dimensional spectrum after inverse stol mapping is obtained, thus completing the inverse stol mapping process based on scaling transformation. Perform inverse uniform compression on the two-dimensional spectrum after inverse stol mapping; Inverse range pulse compression is performed on the two-dimensional spectrum after inverse uniform compression. The two-dimensional spectrum after inverse range pulse compression is subjected to a two-dimensional fast inverse Fourier transform and transformed to the two-dimensional time domain to obtain the original echo signal of the target.
2. The method for recovering the original echo signal of the target according to claim 1, characterized in that, The scaling factor is calculated pulse-by-pulse on the upsampled two-dimensional spectrum, and the scaling factor is expressed as follows: in, The scaling factor. c At the speed of light, f c For carrier frequency, f r For faster time frequency, f a For slow time frequency, V r This is the radar equivalent velocity.
3. The method for recovering the original echo signal of the target according to claim 1, characterized in that, In the step of determining the scale-transformed spectral position index by combining the scaling factor, the spectral position index is represented as: in, I nd For spectral location index, To increase the sampling factor, f r (1) is the initial fast time frequency.
4. The method for recovering the original echo signal of the target according to claim 1, characterized in that, In the step of obtaining the inverse stolt-mapped two-dimensional spectrum based on the upsampled two-dimensional spectrum and the spectral position index after scaling, thus completing the inverse stolt mapping processing step based on scaling, the inverse stolt-mapped two-dimensional spectrum is represented as follows: in, The two-dimensional spectrum after inverse stolt mapping. This is the two-dimensional spectrum after upsampling.
5. The method for recovering the original echo signal of the target according to claim 1, characterized in that, In the step of performing inverse uniform compression on the two-dimensional spectrum after inverse stol mapping, the inverse uniform compression process is represented as follows: in, The two-dimensional spectrum after inverse uniform compression. R c This is the reference slope distance.
6. The method for recovering the original echo signal of the target according to claim 1, characterized in that, In the step of performing inverse range pulse compression on the inverse uniformly compressed two-dimensional spectrum, the inverse range pulse compression is expressed as follows: in, The two-dimensional spectrum after inverse distance pulse compression. K r This represents the frequency modulation slope.
7. A device for recovering the original echo signal of a target, characterized in that, include: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the method for recovering the target original echo signal as described in any one of claims 1 to 6.
8. A readable storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the method for recovering the target original echo signal as described in the first aspect.
9. A computer program product, characterized in that, The computer program product includes: a computer program that, when the computer program is run, performs the method for recovering the target original echo signal as described in any one of claims 1 to 6.