Broadband signal amplitude-phase correction method based on joint error compensation

Abstract

The invention discloses a broadband signal amplitude and phase correction method based on joint error compensation, which is characterized in that waveform nonlinearity caused by a hardware circuit is compensated by using a reference channel technology, amplitude and phase errors are estimated and compensated in a broadband synthesis process by using a joint error compensation method, and finally distortion correction is performed through a frequency domain correction algorithm. Amplitude and phase correction processing of broadband signals is achieved, the imaging resolution is improved, amplitude distortion and phase distortion are reduced, and a clearer and more accurate target image is obtained.

Description

Technical Field

[0001] The invention relates to the field of aerospace technology, and in particular to a broadband signal amplitude and phase correction method for combined error compensation. Background Art

[0002] Facing the application requirements of high-resolution imaging, traditional optical radar cannot work properly under complex environmental conditions such as strong backlight, and has certain limitations. Microwave imaging radar has the characteristics of all-day and all-weather, and can obtain target images without being affected by light. To obtain high-resolution images of targets, especially space targets, it is necessary to perform high-precision amplitude and phase compensation on radar echoes, improve imaging resolution, reduce amplitude distortion and phase distortion, and obtain clearer and more accurate target images.

[0003] Therefore, it is necessary to propose a broadband signal amplitude and phase correction method with joint error compensation. Summary of the invention

[0004] The present invention provides a broadband signal amplitude and phase correction method for joint error compensation, so as to perform high-precision amplitude and phase compensation on radar echoes, improve imaging resolution, reduce amplitude distortion and phase distortion, and obtain clearer and more accurate target images.

[0005] To achieve the above object, the present invention provides a wideband signal amplitude and phase correction method with joint error compensation, comprising:

[0006] The reference channel technology is used to estimate and compensate the phase error caused by the non-ideality of the circuit in the radar waveform generation system based on the sharpening function.

[0007] According to the actual radar echo signal model received in each sub-band, a compensation function is designed to compensate for the linear phase error introduced by multi-channel transmission;

[0008] The echo signal after linear phase error compensation is processed by range pulse compression, and the range spectrum is obtained by superposition along the azimuth. The spectrum is extracted by error fitting based on the filter function, and the spectrum amplitude error compensation function is constructed.

[0009] The high-order phase error of the signal is extracted through the internal calibration loop, and the high-order phase error of the signal after the range pulse compression is compensated;

[0010] Perform inverse Fourier transform on the signal, rearrange and splice each stepped frequency sub-band in the order of carrier frequency, and move each sub-band signal to its respective center frequency point;

[0011] In the frequency domain, the frequency domain distortion coefficient is obtained through the baseband linear frequency modulation signal, and the correction coefficient is obtained by taking the inverse method to perform distortion correction.

[0012] Optionally, the method of using a reference channel technology to estimate and compensate for a phase error caused by non-ideality of a circuit in a radar waveform generation system based on a sharpening function includes:

[0013] The target channel signal model and the reference channel signal model after heterodyning in the time domain are calculated, and the error phase ratio is obtained by taking the logarithm of their phases:

[0014]

[0015] Among them, τ tar is the target delay, τ tar_lo is the target local oscillator delay, τ ref is the reference delay, τ ref_lo is the reference local oscillator delay;

[0016] The error phase ratio of each order is estimated based on the sharpening function, and the phase error of the target channel is compensated using the information of the reference channel.

[0017] Optionally, the designing of a compensation function according to an actual radar echo signal model received in each sub-band to compensate for a linear phase error introduced by multi-channel transmission includes:

[0018] In the frequency domain broadband synthesis, the linear phase error introduced by multi-channel transmission is obtained according to the calculated actual radar echo model received in each sub-band, and a compensation function is constructed to compensate the low-order linear phase error.

[0019] Optionally, performing error fitting extraction on the spectrum based on the filter function to construct a spectrum amplitude error compensation function includes:

[0020] The wavelet filter function is used to perform error fitting extraction on the non-flat distance spectrum to obtain the error curve A after filtering. w (f r ), the spectrum amplitude error compensation function is constructed:

[0021]

[0022] in, is the mean value of the error curve after filtering, using H w (f r ; k), compensate the distance frequency domain signal to obtain an approximately flat distance spectrum characteristic.

[0023] Optionally, extracting a high-order phase error of a signal through an internal calibration loop and performing high-order phase error compensation on the signal after range pulse compression includes:

[0024] The calibration signal is used to record the radar system link information close to the real echo signal, forming an internal calibration loop, from which the high-order phase error of the signal is extracted and the internal calibration compensation term is constructed:

[0025] H high (k) = exp(jφ high (k))

[0026] Among them, φ high (k) represents the high-order phase error of the signal, and the high-order phase error of the sub-band signal is compensated using the internal calibration compensation term.

[0027] Optionally, obtaining a frequency domain distortion coefficient in the frequency domain through a baseband linear frequency modulation signal and obtaining a correction coefficient by taking an inverse method to perform distortion correction may include:

[0028] The distortion function is multiplied by the baseband linear frequency modulation signal and converted to the frequency domain by Fourier transform;

[0029] Calculate the spectrum derivative of the baseband linear frequency modulation signal and deduce the spectrum of the distortion coefficient;

[0030] The distortion correction coefficient is obtained by taking the inverse method and the correction is performed in the frequency domain.

[0031] Optionally, the method further comprises: obtaining a frequency domain distortion coefficient in the frequency domain by using a baseband linear frequency modulation signal, and performing distortion correction by obtaining a correction coefficient by taking an inverse method.

[0032] After correction, an inverse Fourier transform is performed to obtain a distortion-corrected echo signal;

[0033] The corrected signal is pulse compressed to obtain the final imaging result.

[0034] Optionally, the moving each sub-band signal to its respective center frequency point includes:

[0035] Perform Fourier transform on the signal so that the multi-subband signals are distributed within their respective corresponding frequency spectrum ranges.

[0036] On the other hand, the present invention provides an electronic device, including a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, the above-mentioned wideband signal amplitude and phase correction method with joint error compensation is implemented.

[0037] On the other hand, the present invention provides a readable storage medium, wherein the readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned wideband signal amplitude and phase correction method with joint error compensation is implemented.

[0038] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0039] 1. A broadband signal amplitude and phase correction method with joint error compensation of the present invention realizes high-precision compensation of the amplitude and phase of broadband signals.

[0040] 2. The broadband signal amplitude and phase correction method of the present invention uses reference channel technology to compensate for the phase error caused by the non-ideality of the circuit, thereby improving the accuracy of image interpretation and subsequent analysis.

[0041] 3. The broadband signal amplitude and phase correction method of the present invention estimates and compensates the amplitude and phase errors introduced by the system in the frequency domain based on a joint error compensation method to achieve multi-subband coherent synthesis.

[0042] 4. The present invention can perform distortion correction through a frequency domain correction algorithm, thereby overcoming the influence of time delay and the sensitivity of traditional distortion algorithms to the position of the target scattering point relative to the receiving window.

[0043] 5. The frequency domain correction algorithm designed by the present invention has simple implementation steps and is relatively easy to apply to radar systems.

[0044] The invention discloses a broadband signal amplitude and phase correction method for joint error compensation, which has the advantages of simple compensation algorithm, obvious error compensation and imaging effect, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A framework diagram of a wideband signal amplitude and phase correction method for joint error compensation according to an embodiment of the present invention;

[0046] Figure 2 Output waveform diagram for heterodyne experiment;

[0047] Figure 3 is the nonlinear error phase diagram;

[0048] Figure 4 This is the effect diagram before and after phase error compensation;

[0049] Figure 5 It is a curve diagram before and after compensation of the range spectrum amplitude within the sub-band;

[0050] Figure 6 It is a schematic diagram of the frequency shift distortion correction algorithm;

[0051] Figure 7 It is the one-dimensional range image of the simulation data before and after distortion correction. DETAILED DESCRIPTION

[0052] The following is a further detailed description of the broadband signal amplitude and phase correction method for joint error compensation proposed by the present invention in combination with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects that can be produced by the present invention and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention.

[0053] See also Figure 1 , Figure 1 The present invention is a framework diagram of a wideband signal amplitude and phase correction method with joint error compensation according to an embodiment of the present invention. The present embodiment provides a wideband signal amplitude and phase correction method with joint error compensation. Due to the non-ideality of the circuits in each link of the radar waveform generation system, the generated signal is not an ideal linear frequency modulation signal, and each sub-band signal inevitably has certain errors introduced during the transmission and reception process. The present method implements a high-precision amplitude and phase correction compensation technology through a frequency nonlinear compensation algorithm, a joint error compensation method of amplitude compensation and phase compensation for each sub-band, and a distortion correction algorithm based on the frequency domain.

[0054] This embodiment provides a broadband signal amplitude and phase correction method with joint error compensation, including:

[0055] The reference channel technology is used to estimate and compensate the phase error caused by the non-ideality of the circuit in the radar waveform generation system based on the sharpening function.

[0056] According to the actual radar echo signal model received in each sub-band, a compensation function is designed to compensate for the linear phase error introduced by multi-channel transmission;

[0057] The echo signal after linear error compensation is processed by range pulse compression, and the range spectrum is obtained by superposition along the azimuth. The spectrum is extracted by error fitting based on the filter function, and the spectrum amplitude error compensation function is constructed.

[0058] The high-order phase error of the signal is extracted through the internal calibration loop, and the high-order phase error of the signal after the range pulse compression is compensated;

[0059] Perform inverse Fourier transform on the signal, rearrange and splice each stepped frequency sub-band in the order of carrier frequency, and move each sub-band signal to its respective center frequency point;

[0060] In the frequency domain, the frequency domain distortion coefficient is obtained through the baseband linear frequency modulation signal, and the correction coefficient is obtained by taking the inverse method to perform distortion correction.

[0061] Specifically, first, the heterodyned target channel signal model and the reference channel signal model are obtained by calculation in the time domain, and the error phase ratio can be obtained by taking the logarithm of the phases of the two:

[0062]

[0063] Among them, τ tar is the target delay, τ tar_lo is the target local oscillator delay, τ ref is the reference delay, τ ref_lo is the reference local oscillator delay. Then, the phase ratio of each order error is estimated based on the sharpening function, so as to use the information of the reference channel to compensate the phase error of the target channel. Figure 2 This is the waveform diagram of the heterodyne experiment output. It can be seen that the signal displayed by the oscilloscope is not a standard sinusoidal signal. The signal is sparse and dense, which means that the transmitted signal has a high-order phase. After the de-interlacing frequency modulation, the signal still has a high-order phase. Pulse compression cannot be completed using only de-interlacing frequency modulation. Figure 3 The nonlinear error phase diagram is shown in Figure 2. Using the sharpening function curve to estimate p for compensation, the effect diagram before and after the phase error compensation can be obtained as shown in Figure 2. Figure 4 As shown, the wide pulse on the top is the effect diagram without error compensation, and the narrow pulse on the bottom is the effect diagram after error compensation, which verifies the effectiveness of the method.

[0064] In the frequency domain broadband synthesis, according to the calculated actual radar echo model received in each sub-band, the linear phase error introduced by multi-channel transmission can be obtained, and the corresponding compensation function can be constructed to compensate for the low-order linear phase error. After compensation, the signal is Fourier transformed to obtain the frequency domain signal after range pulse compression processing.

[0065] Due to the influence of the hardware circuit, the amplitude in the sub-band is not flat. If it is not corrected in advance, the side lobe of the pulse compression signal will be raised. The range frequency domain signal is superimposed along the azimuth, and the range spectrum distribution is obtained by statistics. Figure 5 The image on the left shows that the distance spectrum is not flat. Then the wavelet filter function is used to extract the error fitting of the non-flat spectrum to obtain the error curve A after filtering. w (f r ), and finally construct the spectrum amplitude error compensation function H w (f r ; k) as follows

[0066]

[0067] in, is the mean value of the error curve after filtering, using H w (f r k). Compensate the distance frequency domain signal to obtain an approximately flat distance spectrum characteristic, such as Figure 5 Shown in the image on the right.

[0068] Considering that radar ultra-wideband signals are affected by the nonlinearity of the radar link, an internal calibration loop system is designed when designing the radar system. The calibration signal records the radar system link information that is close to the real echo signal, forming an internal calibration loop, from which the high-order phase error of the signal can be extracted to construct the internal calibration compensation term H high (k) as follows

[0069] H high (k) = exp(jφ high (k))

[0070] Among them, φ high (k) represents the high-order phase error of the signal. The high-order phase error of the sub-band signal can be compensated by using the internal calibration compensation term.

[0071] After the precise estimation and compensation of the amplitude and phase errors within the sub-band, a relatively ideal sub-band amplitude and phase characteristic can be obtained. Next, the frequency shift processing is performed, that is, each stepped frequency sub-band is rearranged and spliced ​​in the order of carrier frequency. First, the two ends of each sub-band signal are padded with zeros to obtain the range spectrum amplitude of k sub-bands; then each sub-band signal is moved to its respective center frequency point, so that the multi-sub-band signals are distributed within their respective corresponding spectrum ranges.

[0072] The broadband signal amplitude and phase correction method for joint error compensation provided in this embodiment includes frequency domain distortion correction. The algorithm diagram of frequency domain distortion correction is as shown in FIG. Figure 6 As shown. From the conversion relationship between the time and frequency domains, it can be seen that the delay in the time domain is equivalent to the frequency exponential term related to the delay in the frequency domain. Therefore, if distortion correction is performed in the frequency domain, the influence of delay on the correction performance can be avoided. First, multiply the distortion function with the baseband linear frequency modulation signal and convert it to the frequency domain through Fourier transform; then, by calculating the spectral derivative of the baseband linear frequency modulation signal, the spectrum of the distortion coefficient is calculated; the distortion correction coefficient is obtained by taking the inverse method and correcting it in the frequency domain; after correction, an inverse Fourier transform is performed to obtain the echo signal after distortion correction. The corrected signal is pulse compressed to obtain the final imaging result. Through simulation experiments, it is obtained Figure 7 The one-dimensional range image of the simulation data before and after distortion correction shows that the distortion raises the range sidelobe of the one-dimensional range image of the echo. After correction by this method, the focusing effect of the one-dimensional range image is improved.

[0073] This method is mainly aimed at practical engineering applications. It only selects one reference channel and compensates for the errors caused by non-ideal circuits based on the sharpening function. This method only obtains high-order phase compensation through an internal calibration loop, which is simple to operate and easier to implement in engineering applications. In addition, this method proposes a distortion correction algorithm in the frequency domain. According to the nature of time-frequency domain conversion, the delay in the time domain is equivalent to a fixed phase term in the frequency domain. Therefore, if correction is made in the frequency domain, the influence of the delay can be ignored, which can avoid the influence of the delay on the correction performance and overcome the sensitivity of the traditional distortion correction algorithm to the position of the target scattering point relative to the receiving window.

[0074] This embodiment also provides an electronic device, including a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the wideband signal amplitude and phase correction method for joint error compensation described in this embodiment is implemented.

[0075] This embodiment further provides a readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the wideband signal amplitude and phase correction method with joint error compensation described in this embodiment is implemented.

[0076] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0077] It should be noted that the devices and methods disclosed in the embodiments of this article can also be implemented in other ways. The device implementation described above is only schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of this article. In this regard, each box in the flowchart or block diagram can represent a part of a module, program or code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented by a dedicated hardware-based system for performing a specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0078] In addition, the functional modules in the various embodiments of this document may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0079] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A broadband signal amplitude and phase correction method with joint error compensation, characterized in that: include: The reference channel technology is used to estimate and compensate the phase error caused by the non-ideality of the circuit in the radar waveform generation system based on the sharpening function. According to the actual radar echo signal model received in each sub-band, a compensation function is designed to compensate for the linear phase error introduced by multi-channel transmission; The echo signal after linear error compensation is processed by range pulse compression, and the range spectrum is obtained by superposition along the azimuth. The spectrum is extracted by error fitting based on the filter function, and the spectrum amplitude error compensation function is constructed. The high-order phase error of the signal is extracted through the internal calibration loop, and the high-order phase error of the signal after the range pulse compression is compensated; Perform inverse Fourier transform on the signal, rearrange and splice each stepped frequency sub-band in the order of carrier frequency, and move each sub-band signal to its respective center frequency point; In the frequency domain, the frequency domain distortion coefficient is obtained through the baseband linear frequency modulation signal, and the correction coefficient is obtained by taking the inverse method to perform distortion correction.

2. The broadband signal amplitude and phase correction method with joint error compensation as claimed in claim 1, characterized in that: The reference channel technology is used to estimate and compensate for the phase error caused by the non-ideality of the circuit in the radar waveform generation system based on the sharpening function, including: The target channel signal model and the reference channel signal model after heterodyning in the time domain are calculated, and the error phase ratio is obtained by taking the logarithm of their phases: Among them, τ tar is the target delay, τ tar_lo is the target local oscillator delay, τ ref is the reference delay, τ ref_lo is the reference local oscillator delay; The error phase ratio of each order is estimated based on the sharpening function, and the phase error of the target channel is compensated using the information of the reference channel.

3. The broadband signal amplitude and phase correction method with joint error compensation as claimed in claim 1, characterized in that: The method of designing a compensation function based on the actual radar echo signal model received in each sub-band to compensate for the linear phase error introduced by multi-channel transmission includes: In the frequency domain broadband synthesis, the linear phase error introduced by multi-channel transmission is obtained according to the calculated actual radar echo model received in each sub-band, and a compensation function is constructed to compensate the low-order linear phase error.

4. The broadband signal amplitude and phase correction method with joint error compensation as claimed in claim 1, characterized in that: The error fitting and extraction of the spectrum based on the filter function to construct the spectrum amplitude error compensation function includes: The wavelet filter function is used to perform error fitting extraction on the non-flat distance spectrum to obtain the error curve A after filtering. w (f r ), the spectrum amplitude error compensation function is constructed: in, is the mean value of the error curve after filtering, using H w (f r ; k), compensate the distance frequency domain signal to obtain an approximately flat distance spectrum characteristic.

5. The broadband signal amplitude and phase correction method with joint error compensation as claimed in claim 1, characterized in that: The method of extracting the high-order phase error of the signal through the internal calibration loop and compensating the high-order phase error of the signal after the range pulse compression includes: The calibration signal is used to record the radar system link information close to the real echo signal, forming an internal calibration loop, from which the high-order phase error of the signal is extracted and the internal calibration compensation term is constructed: H high (k)=exp(jφ high (k)) Among them, φ high (k) represents the high-order phase error of the signal, and the high-order phase error of the sub-band signal is compensated using the internal calibration compensation term.

6. The broadband signal amplitude and phase correction method with joint error compensation as claimed in claim 1, characterized in that: The method of obtaining a frequency domain distortion coefficient in the frequency domain by using a baseband linear frequency modulation signal and obtaining a correction coefficient by taking an inverse method for distortion correction includes: The distortion function is multiplied by the baseband linear frequency modulation signal and converted to the frequency domain by Fourier transform; Calculate the spectrum derivative of the baseband linear frequency modulation signal and deduce the spectrum of the distortion coefficient; The distortion correction coefficient is obtained by taking the inverse method and the correction is performed in the frequency domain.

7. The broadband signal amplitude and phase correction method with joint error compensation as claimed in claim 6, characterized in that: After obtaining the frequency domain distortion coefficient in the frequency domain through the baseband linear frequency modulation signal and obtaining the correction coefficient by taking the inverse method for distortion correction, the method further includes: After correction, an inverse Fourier transform is performed to obtain a distortion-corrected echo signal; The corrected signal is pulse compressed to obtain the final imaging result.

8. The broadband signal amplitude and phase correction method with joint error compensation as claimed in claim 1, characterized in that: The step of moving each sub-band signal to its respective center frequency point includes: Perform Fourier transform on the signal so that the multi-subband signals are distributed within their respective corresponding frequency spectrum ranges.

9. An electronic device, characterized in that: The method comprises a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method according to any one of claims 1 to 8 is implemented.

10. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

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