A 2-bit imaging method and related equipment for synthetic aperture radar

Abstract

The present invention discloses a 2-bit imaging method and related equipment for synthetic aperture radar, including: obtaining a target echo signal received by the radar, sampling and extracting symbol information to obtain a first single-bit signal, imaging the first single-bit signal to obtain a first imaging result; performing phase shifting processing on the target echo signal, sampling and extracting symbol information from the phase-shifted signal to obtain a second single-bit signal, imaging the second single-bit signal to obtain a second imaging result; and adding and merging the first imaging result and the second imaging result to obtain a target imaging result. By phase shifting and imaging the signal, and then adding the two to obtain the target imaging result, the influence of harmonics in the obtained target image is suppressed. In addition, the present invention adopts a simple signal quantization method and does not use a large number of loop iterative operations based on methods such as compressed sensing, so that the implementation requirements are low and complex calculations are not required.

Description

Technical Field

[0001] The present invention relates to the field of signal processing technology, and in particular to a 2-bit imaging method and related equipment for synthetic aperture radar. Background Art

[0002] Synthetic Aperture Radar (SAR), with its all-weather, long-range, high-resolution detection capabilities, plays a vital role in a wide range of fields, including remote sensing mapping, regional monitoring, geological exploration, and disaster relief. With the increasing demand for SAR imaging, signals with higher wavelengths and wider bandwidths are being used to achieve finer image resolution. However, this increased signal bandwidth places a heavier computational burden on SAR systems. To reduce the costs of SAR data acquisition, storage, transmission, and processing, research is currently underway on single-bit sampling and quantization of SAR data.

[0003] At present, single-bit sampling quantization has great advantages in simplifying system architecture and improving efficiency. However, the current method of applying single-bit sampling quantization in synthetic aperture radar imaging systems still has the problems of high computational complexity caused by combining single-bit sampling quantization theory with compressed sensing theory and the harmonics caused by the nonlinear effect of single-bit quantization leading to false targets.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] The technical problem to be solved by the present application is to provide a 2-bit imaging method and related equipment for synthetic aperture radar in response to the shortcomings of the existing technology. The present invention can phase-shift the signal and sample it separately to obtain corresponding imaging results, and add the imaging results to obtain the target imaging result. Since the target imaging result is obtained by imaging the signal before and after the phase shift, the influence of harmonics in the final target image is suppressed by the phase shift. At the same time, the present invention adopts a simple signal quantization method and does not have a large number of loop iterative operations based on methods such as compressed sensing, so that it has lower implementation requirements during the implementation process and does not require complex calculations.

[0006] In order to address the deficiencies of the above-mentioned prior art problems, the first aspect of the embodiments of the present application provides a 2-bit imaging method for synthetic aperture radar, the method comprising:

[0007] Acquire a target echo signal received by a radar, sample the signal and extract symbol information to obtain a first single-bit signal, and perform imaging processing on the first single-bit signal to obtain a first imaging result;

[0008] performing phase shift processing on the target echo signal received by the radar, sampling the phase-shifted signal and extracting symbol information to obtain a second single-bit signal, and performing imaging processing on the second single-bit signal to obtain a second imaging result;

[0009] The first imaging result and the second imaging result are added and combined to obtain a target imaging result.

[0010] The acquiring of a target echo signal received by the radar, sampling the signal and extracting symbol information to obtain a first single-bit signal, and performing imaging processing on the first single-bit signal to obtain a first imaging result specifically includes:

[0011] The process of obtaining the first single-bit signal comprises sampling at a constant first time interval, retaining only the sign information of the sampled signal after sampling, and forming the first single-bit signal according to the sign information;

[0012] The first single-bit signal is processed using a range Doppler algorithm to obtain a first imaging result.

[0013] The method of performing phase shift processing on the target echo signal received by the radar, sampling the phase-shifted signal and extracting symbol information to obtain a second single-bit signal, and performing imaging processing on the second single-bit signal to obtain a second imaging result specifically includes:

[0014] performing phase shift processing on a target echo signal received by the radar, sampling the phase-shifted signal at a constant first time interval, retaining only sign information of the sampled signal after sampling, and forming a second single-bit signal based on the sign information;

[0015] The second single-bit signal is processed using a range Doppler algorithm to obtain a second imaging result.

[0016] The phase shifting process specifically includes:

[0017] The target echo signal received by the radar is phase delayed according to the preset phase shift amount.

[0018] The preset phase shift specifically includes:

[0019] The preset phase shift is set according to the false target to be suppressed, and the influence of the phase shift on the target imaging result is: where α k is the amplitude gain coefficient of the target imaging result relative to the first imaging result, k is the order of the harmonic, and θ is the phase shift.

[0020] The step of adding and merging the first imaging result and the second imaging result to obtain a target imaging result specifically includes:

[0021] Calculate the amplitude gain coefficients of the fundamental wave and harmonics corresponding to the target image in the combined target imaging result to determine whether the output target imaging result suppresses false targets of harmonics;

[0022] If the output target imaging result suppresses the false target of harmonics, the corresponding target imaging result is output;

[0023] If the output target imaging result cannot suppress the false target of harmonics, the phase is re-shifted, and the target imaging result obtained after the re-phase shift is output;

[0024] The relationship between the amplitude gain coefficient and the phase shift is: where α k is the amplitude gain coefficient of the target imaging result relative to the first imaging result, k is the order of the harmonic, and θ is the phase shift.

[0025] The calculating of the amplitude gain coefficients of the fundamental wave and harmonics corresponding to the target image in the combined target imaging result and determining whether the output target imaging result suppresses false targets of harmonics specifically includes:

[0026] If α1>1, α1>α k , k = 3, 5..., k takes the preset order corresponding to the harmonic to be suppressed, then the output target imaging result suppresses the false target of the harmonic;

[0027] If the output target imaging result does not satisfy α1>1 and α1>α k , k=3, 5..., k takes the preset order corresponding to the harmonic to be suppressed, then the output target imaging result does not suppress the false target of the harmonic.

[0028] A second aspect of an embodiment of the present application provides a 2-bit imaging system for synthetic aperture radar, the device comprising:

[0029] A first imaging result generating module acquires a target echo signal received by the radar, samples the signal and extracts symbol information to obtain a first single-bit signal, and performs imaging processing on the first single-bit signal to obtain a first imaging result;

[0030] A second imaging result generating module performs phase shift processing on the target echo signal received by the radar, samples the phase-shifted signal and extracts symbol information to obtain a second single-bit signal, and performs imaging processing on the second single-bit signal to obtain a second imaging result;

[0031] The target imaging result generating module adds and combines the first imaging result and the second imaging result to obtain the target imaging result.

[0032] A third aspect of an embodiment of the present application provides a radar device, characterized in that the radar device includes a memory, a processor, and a 2-bit imaging method for synthetic aperture radar stored in the memory and executable on the processor. When the processor executes the 2-bit imaging method for synthetic aperture radar, the steps of the 2-bit imaging method for synthetic aperture radar as described in any one of the above items are implemented.

[0033] A fourth aspect of an embodiment of the present application provides a storage medium, characterized in that the storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the 2-bit imaging method for synthetic aperture radar as described in any one of the above items.

[0034] Beneficial effects: Compared with the prior art, the present application provides a 2-bit imaging method and related equipment for synthetic aperture radar, the method comprising obtaining a target echo signal received by the radar, sampling the signal and extracting symbol information to obtain a first single-bit signal, imaging the first single-bit signal to obtain a first imaging result; performing phase shifting processing on the target echo signal received by the radar, sampling the phase-shifted signal and extracting symbol information to obtain a second single-bit signal, imaging the second single-bit signal to obtain a second imaging result; and adding and merging the first imaging result and the second imaging result to obtain a target imaging result. The present invention can phase shift the signal and sample it separately, obtain corresponding imaging results, and add the imaging results to obtain the target imaging result. Since the target imaging result is obtained by imaging the signal before and after the phase shift, the phase shift suppresses the influence of harmonics in the final target image. At the same time, the present invention adopts a simple signal quantization method and does not use a large number of loop iterative operations based on methods such as compressed sensing, so that complex calculations are not required during the implementation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] Figure 1 A flow chart of the 2-bit imaging method for synthetic aperture radar provided by the present invention;

[0037] Figure 2 A signal processing flow chart corresponding to the 2-bit imaging method for synthetic aperture radar provided in an embodiment of the present invention;

[0038] Figure 3 A schematic diagram of a one-dimensional range image result of high-precision imaging provided by an embodiment of the present invention;

[0039] Figure 4 A schematic diagram of a one-dimensional range image result of single-bit imaging provided by an embodiment of the present invention;

[0040] Figure 5 A schematic diagram of a one-dimensional range image obtained by a 2-bit imaging method for synthetic aperture radar provided in an embodiment of the present invention;

[0041] Figure 6 This is a functional block diagram of a 2-bit imaging system for synthetic aperture radar provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] This application provides a 2-bit imaging method and related equipment for synthetic aperture radar. To make the objectives, technical solutions, and effects of this application more clear and explicit, the application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate this application and are not intended to limit this application.

[0043] It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of this application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when an element is said to be "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, "connected" or "coupled" as used herein may include wireless connections or wireless couplings. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0044] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0045] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0046] Synthetic Aperture Radar (SAR), with its all-weather, all-day, long-range, high-resolution detection capabilities, plays a vital role in numerous fields, including remote sensing mapping, regional monitoring, geological exploration, and disaster relief. With the increasing demand for SAR imaging, signals with higher wavelengths and wider bandwidths are being used to achieve finer image resolution. However, this increase in signal bandwidth places a heavier computational burden on SAR systems. To reduce the costs of SAR data acquisition, storage, transmission, and processing, research on single-bit sampling quantization (SQ) has been conducted on SAR data. While SQ offers significant advantages in simplifying system architecture and improving efficiency, current methods for applying SQ in SAR imaging systems still face challenges, such as high computational complexity resulting from combining SQ theory with compressed sensing theory, and the appearance of false targets due to harmonics caused by the nonlinear effects of SQ.

[0047] In response to the shortcomings of the existing technology, the present invention provides a 2-bit imaging method and related equipment for synthetic aperture radar. The present invention can phase-shift the signal and sample it separately to obtain corresponding imaging results, and add the imaging results to obtain a target imaging result. Since the target imaging result is obtained by imaging the signal before and after the phase shift, the phase shift suppresses the influence of harmonics in the final target image. At the same time, the present invention adopts a simple signal quantization method and does not require a large number of loop iterative operations based on methods such as compressed sensing, so that the implementation requirements are low during the implementation process and no complex calculations are required.

[0048] Example Method

[0049] First embodiment

[0050] like Figure 1As shown in FIG, a flow chart of a 2-bit imaging method for synthetic aperture radar provided by an embodiment of the present invention is provided. The 2-bit imaging method for synthetic aperture radar can be applied to radar equipment. In an embodiment of the present invention, the method includes the following steps:

[0051] Step S10: Acquire a target echo signal received by the radar, sample the signal and extract symbol information to obtain a first single-bit signal, and perform imaging processing on the first single-bit signal to obtain a first imaging result;

[0052] Specifically, after obtaining the target echo signal received by the radar, the received target echo signal is sampled at a constant time interval to obtain a sampling signal, and the sign information of the sampling value in the sampling signal is taken out, that is, the sign information of each sampling value is retained to convert the sampling value information into information formed by +1 or -1, thereby forming a single-bit signal, that is, a first single-bit signal. After obtaining the first single-bit signal, imaging is performed to obtain a first imaging result.

[0053] Furthermore, the acquiring of the target echo signal received by the radar, sampling the signal and extracting symbol information to obtain a first single-bit signal, and performing imaging processing on the first single-bit signal to obtain a first imaging result specifically includes:

[0054] The process of obtaining the first single-bit signal comprises sampling at a constant first time interval, retaining only the sign information of the sampled signal after sampling, and forming the first single-bit signal according to the sign information;

[0055] The first single-bit signal is processed using a range Doppler algorithm to obtain a first imaging result.

[0056] Specifically, in the process of obtaining the first single-bit signal, sampling is performed at a constant time interval, and only the sign information of the sampled signal is retained after sampling, thereby obtaining a sampled signal containing only the sign information +1 and -1, thereby obtaining the corresponding first single-bit signal;

[0057] The operation of retaining only the sign information of the sampled signal after sampling can be implemented by a comparator. In addition, it can also be implemented by various devices or methods that convert analog signals into 1-bit digital signals, such as a single-bit quantizer; a lower implementation cost is adopted in the sampling and quantization link, and only the sign of the sampled value needs to be retained, thereby making the complexity of the present invention lower.

[0058] Specifically, after obtaining the first single-bit signal, imaging processing is performed on the signal to obtain a corresponding first imaging result, wherein the first imaging result is obtained by sampling and extracting symbol information from the originally received target echo signal.

[0059] When using the range Doppler algorithm to image a single-bit signal, the range Doppler algorithm is used for imaging. That is, based on the large magnitude difference in the time variable in the distance and azimuth, the range migration correction is used between the two one-dimensional operations to approximately separate the range dimension and the azimuth dimension. Specifically, after the first single-bit signal is subjected to fast Fourier transform in the range dimension, the range dimension matched filtering is performed in the range frequency domain, wherein the range dimension matched filtering Then, the distance compression is completed by the inverse fast Fourier transform of the distance; the first single-bit signal is transformed into the range-Doppler domain by the azimuth fast Fourier transform, and the range migration curve is straightened to the direction parallel to the azimuth frequency axis by the range migration correction in the range-Doppler domain; then, matched filtering is performed in the azimuth frequency domain, wherein the azimuth dimension matched filtering Complete azimuth pulse compression; finally, perform azimuth-dimensional inverse fast Fourier transform on the signal and transform the data back to the two-dimensional time domain to obtain the first imaging result matrix I a ; where R MF and A MF are the distance dimension and azimuth dimension matched filters, t r and t a Fast time and slow time, T r and T a The fast time and slow time signal widths, K r and K a are the modulation rates of the fast time and slow time dimensions respectively.

[0060] Step S20: performing phase shift processing on the target echo signal received by the radar, sampling the phase-shifted signal and extracting symbol information to obtain a second single-bit signal, and performing imaging processing on the second single-bit signal to obtain a second imaging result;

[0061] Specifically, the target echo signal received by the radar is phase-shifted by a phase shifter, the phase-shifted signal is sampled and symbol information is extracted to obtain a second single-bit signal, and a second imaging result is obtained based on the corresponding imaging of the second single-bit signal.

[0062] Furthermore, performing phase shift processing on the target echo signal received by the radar, sampling the phase-shifted signal and extracting symbol information to obtain a second single-bit signal, and performing imaging processing on the second single-bit signal to obtain a second imaging result specifically includes:

[0063] performing phase shift processing on a target echo signal received by the radar, sampling the phase-shifted signal at a constant first time interval, retaining only sign information of the sampled signal after sampling, and forming a second single-bit signal based on the sign information;

[0064] The second single-bit signal is processed using a range Doppler algorithm to obtain a second imaging result.

[0065] Specifically, after performing phase shift processing on the target echo signal received by the radar, the phase-shifted signal is sampled using the same constant first time interval as the first single-bit signal acquisition process. After sampling, only the sign information of the obtained sampled signal is retained, thereby obtaining a sampled signal containing only sign information +1 and -1, thereby obtaining a corresponding second single-bit signal. The second single-bit signal is processed using a range Doppler algorithm to obtain a second imaging result, wherein the imaging operation process for the second single-bit signal is the same as the imaging operation process for the first single-bit signal, and a second imaging result matrix I is obtained. b .

[0066] Furthermore, the phase shifting process specifically includes:

[0067] The target echo signal received by the radar is phase delayed according to the preset phase shift amount.

[0068] When performing phase shifting, the target signal received by the radar is phase-delayed according to the phase shift amount set in advance. The preset phase shift amount is set according to the false target to be suppressed. The relationship between the phase shift amount and the target imaging result is: where α k is the amplitude gain coefficient of the target imaging result relative to the first imaging result, k is the order of the harmonic, and θ is the phase shift.

[0069] When setting the phase shift amount, the phase shift amount may be optionally set according to the false target to be suppressed. Specifically, when an appropriate phase shift amount is selected, the false image in the final imaging result is suppressed. The relationship between the phase shift amount and the final target imaging result is as follows:

[0070]

[0071] where α k is the amplitude gain coefficient of the target imaging result relative to the first imaging result, k is the order of the harmonic, and θ is the phase shift. In the imaging process, since false targets are mainly caused by odd harmonics, the present invention suppresses false targets generated by odd harmonics. The amplitude of the image composed of the fundamental wave in the target imaging result is When α1>1, the target image is enhanced in the final imaging. At the same time, for odd harmonics, k=3, 5, etc., when setting the corresponding phase shift, the phase shift is set to meet α1>1 and α1>α k , select in the obtained phase shift interval, and the target imaging result corresponding to the obtained phase shift amount achieves the suppression effect on the false target of the k-order harmonic; in one implementation method, if the false target generated by the 3rd order harmonic is to be suppressed, then Then the 3rd order harmonic after phase shift can be suppressed relative to the fundamental wave; in another implementation method, when suppressing the false target generated by the 5th order harmonic, let α1>1 and α1>α5, and take θ as the corresponding phase shift amount, so that the 5th order harmonic after phase shift can be suppressed relative to the fundamental wave; in another implementation method, when suppressing the false targets generated by the 3rd and 5th order harmonics, set the corresponding phase shift amount, let α1>1, α1>α3 and α1>α5, so that the 3rd order harmonic and 5th order harmonic after phase shift can be suppressed relative to the fundamental wave; in addition, when suppressing the k-order harmonic, not only the false target corresponding to a certain odd-order harmonic can be suppressed, but also the false targets corresponding to multiple odd-order harmonics can be suppressed.

[0072] The corresponding phase shift amount is pre-set according to the false target to be suppressed, so that the phase of the target echo signal received by the radar is delayed by a phase shifter using the preset phase shift amount.

[0073] Step S30: Add and combine the first imaging result and the second imaging result to obtain a target imaging result.

[0074] After obtaining the corresponding first imaging result matrix and second imaging result matrix, the corresponding elements of the obtained imaging results are added together to obtain and output the target imaging result. Specifically, in this process, by adding the first imaging result and the phase-shifted second imaging result, the corresponding false targets can be suppressed in the obtained target imaging result.

[0075] Furthermore, the adding and merging of the first imaging result and the second imaging result to obtain the target imaging result specifically includes:

[0076] Calculate the amplitude gain coefficients of the fundamental wave and harmonics corresponding to the target image in the combined target imaging result to determine whether the output target imaging result suppresses false targets of harmonics;

[0077] If the output target imaging result suppresses the false target of harmonics, the corresponding target imaging result is output;

[0078] If the output target imaging result cannot suppress the false target of harmonics, the phase is re-shifted, and the target imaging result obtained after the re-phase shift is output;

[0079] The relationship between the amplitude gain coefficient and the phase shift is: where α k is the amplitude gain coefficient of the target imaging result relative to the first imaging result, k is the order of the harmonic, and θ is the phase shift.

[0080] Specifically, the target imaging result is obtained by adding the first imaging result and the second imaging result. Since the first imaging result is subjected to a phase shift addition operation in the target imaging result, the target amplitude of the obtained target imaging result will change, which is specifically reflected by the amplitude gain coefficient, wherein the amplitude gain coefficient represents the multiple of the amplitude increase of the target imaging result relative to the first imaging result; the relationship between the amplitude gain coefficient and the phase shift is: where α k is the amplitude gain coefficient of the target imaging result relative to the first imaging result, k is the order of the harmonic, and θ is the phase shift.

[0081] The calculating of the amplitude gain coefficients of the fundamental wave and harmonics corresponding to the target image in the combined target imaging result and determining whether the output target imaging result suppresses false targets of harmonics specifically includes:

[0082] If α1>1, α1>α k , k = 3, 5..., k takes the preset order corresponding to the harmonic to be suppressed, then the output target imaging result suppresses the false target of the harmonic;

[0083] If the output target imaging result does not satisfy α1>1 and α1>α k , k=3, 5..., k takes the preset order corresponding to the harmonic to be suppressed, then the output target imaging result does not suppress the false target of the harmonic.

[0084] Specifically, after obtaining the target imaging result, the amplitude gain coefficients of the fundamental wave and harmonic waves corresponding to the target image in the combined target imaging result are calculated to determine whether the output target imaging result suppresses the false targets of the harmonics, wherein the amplitude gain coefficient α1 of the image composed of the fundamental wave is calculated, and the amplitude gain coefficient α of the false targets to be suppressed is calculated. k , k=3, 5......, k takes the preset order corresponding to the harmonic to be suppressed, when α1>1, α1>α k It can be seen that at this time, α1>1 means that the amplitude gain coefficient of the non-false target formed by the fundamental wave is greater than 1 and is enhanced. k It indicates that the amplitude gain coefficient of the false target is smaller than the amplitude gain coefficient of the non-false target formed by the fundamental wave. Compared with the amplitude gain coefficient of the non-false target formed by the fundamental wave, the amplitude gain coefficient of the false target is lower, which indicates that the target imaging result output at this time suppresses the false target of the harmonic. When α1>1 and α1>α are not satisfied, k When α1>1 is not established, the non-false target formed by the fundamental wave itself is suppressed, and it is determined that the output target imaging result cannot suppress the false target of the harmonic. If α1>1, α1<α k, the amplitude gain effect of the false target exceeds that of the non-false target, then it is determined that the output target imaging result cannot suppress the false target of harmonics. If α1>1, α1>α k If neither of them holds true, it is determined that the output target imaging result cannot suppress the false targets of harmonics.

[0085] If the output target imaging result suppresses the false target of harmonics, the corresponding target imaging result is output;

[0086] If the output target imaging result cannot suppress the false target of the harmonic, the phase is shifted again, and the target imaging result obtained after the phase shift is output; specifically, the phase shift amount is reset, and a new target imaging result is obtained through the reset phase shift amount. It is judged whether the new target imaging result suppresses the false target of the harmonic. If it is suppressed, the corresponding target imaging result is output; if it cannot be suppressed, the phase shift amount is reset again until the target imaging result obtained suppresses the false target of the harmonic, outputs the corresponding target imaging result, or inputs a stop operation instruction.

[0087] In addition, the present invention sets an appropriate phase shift when suppressing false targets caused by a certain order of harmonics, and at the same time, it also produces a weaker suppression effect on false targets generated by multiple order harmonics. Therefore, when setting an appropriate phase shift, it is possible to suppress false targets caused by multiple order harmonics, thereby achieving a better imaging effect. At the same time, for single-bit sampling quantization, when the sampling rate is infinite, the position of the false target is in a multiple relationship with the origin, that is, the imaging amplitude will decrease with increasing distance. However, when considering the specific cost, the sampling rate will be reduced as much as possible, so that false targets farther away will be folded near the origin, and the amplitude of these targets will not be affected by the sampling rate. In the present invention, because the phase shift operation is performed on the entire received target echo signal, when suppressing false targets, the corresponding false targets in all cycles can be suppressed. That is, it is effective whether at high or low sampling rates, and can better suppress the false target problem.

[0088] The present invention implements the overall process of the 2-bit imaging method for synthetic aperture radar by Figure 2 To reflect, specifically, Figure 2 As shown in the figure, after receiving the target echo signal, it is sampled, signed, and imaged using range Doppler. After phase shifting, the target echo signal is also sampled, signed, and imaged using range Doppler. The images before and after the phase shift are obtained, and then summed to obtain the target imaging result. This process is relatively convenient and generates less data, which is conducive to the lightweight design of future digital receivers and their application on small, mobile, and unmanned platforms.

[0089] In the second embodiment, the present invention performs imaging on a specific case. Specifically, the target at a distance of 20 km is imaged and processed using the method of the present invention. Figure 3 This is a schematic diagram of the one-dimensional range image result of high-precision imaging. Figure 4 This is a schematic diagram of the one-dimensional range imaging result of single-bit imaging. Figure 5 The figure is a schematic diagram of the one-dimensional range image obtained by the 2-bit imaging method for synthetic aperture radar. Figure 3 It can be seen that under high-precision imaging conditions, the target can be well focused at 20km; Figure 3 It can be seen that when the single-bit imaging method is used for processing, a false target at -60 km will appear in the imaging result; Figure 4 It can be seen that when the 2-bit imaging method proposed in the present invention is used for imaging processing, the false target at -60 km is well suppressed. Therefore, it can be concluded that the present invention achieves a high degree of comprehensive effect in terms of computing cost and processing performance.

[0090] In the third embodiment, when it is necessary to suppress the false target generated by the third-order harmonic, it is preferred to set the phase shift to π / 3 and perform a phase delay of π / 3 on the signal. Then, in the target imaging result obtained, Right now That is, α3 = 0, then in the target image result obtained, the image gain coefficient of the image corresponding to the third-order harmonic is 0, which can well eliminate the false target of the third-order harmonic; in addition, Right now That is, when the phase shift is set to π / 3 at this time, the fifth-order harmonic is not changed relative to the fundamental wave, but the false target of the third-order harmonic is suppressed, thereby achieving accurate suppression of the third-order harmonic.

[0091] In the fourth embodiment, when it is necessary to suppress the false targets generated by the 3rd and 5th order harmonics, optionally, α1>1, α1>α3 and α1>α5, and the phase shift amount that meets the conditions can be taken to suppress the false targets generated by the 3rd and 5th order harmonics.

[0092] Exemplary devices

[0093] like Figure 6 As shown in , based on the above-mentioned 2-bit imaging method for synthetic aperture radar, an embodiment of the present invention provides a 2-bit imaging system for synthetic aperture radar, which includes:

[0094] The first imaging result generating module 61 acquires the target echo signal received by the radar, samples the signal and extracts the symbol information to obtain a first single-bit signal, performs phase shift processing on the target echo signal received by the radar, samples the phase-shifted signal and extracts the symbol information to obtain a second single-bit signal;

[0095] The second imaging result generating module 62 performs imaging processing on the first single-bit signal to obtain a first imaging result; and performs imaging processing on the second single-bit signal to obtain a second imaging result;

[0096] The target imaging result generating module 63 adds and combines the first imaging result and the second imaging result to obtain a target imaging result.

[0097] Based on the above embodiments, the present invention further provides a radar device. The radar device includes a memory, a processor, and a 2-bit imaging method for synthetic aperture radar (SAR) stored in the memory and executable on the processor. When the processor executes the 2-bit imaging method for SAR, the steps of the 2-bit imaging method for SAR are implemented as described above.

[0098] Based on the above embodiments, the present invention also provides a storage medium, characterized in that the storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the 2-bit imaging method for synthetic aperture radar as described above.

[0099] In summary, the present invention provides a 2-bit imaging method and related equipment for synthetic aperture radar. The method includes obtaining a target echo signal received by the radar, sampling the signal and extracting symbol information to obtain a first single-bit signal, imaging the first single-bit signal to obtain a first imaging result; performing phase shifting on the target echo signal received by the radar, sampling the phase-shifted signal and extracting symbol information to obtain a second single-bit signal, imaging the second single-bit signal to obtain a second imaging result; and adding and merging the first imaging result and the second imaging result to obtain a target imaging result. The present invention can obtain a target imaging result by phase shifting and sampling the signal separately, obtaining corresponding imaging results, and adding the imaging results. Since the target imaging result is obtained by imaging the signal before and after the phase shift, the phase shift suppresses the influence of harmonics in the final target image. At the same time, the present invention adopts a simple signal quantization method and does not use a large number of loop iterative operations based on methods such as compressed sensing, so that complex calculations are not required during implementation.

[0100] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0101] Those skilled in the art will appreciate that all or part of the processes in the above-described embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a storage medium. When the computer program is executed, it can include the processes of the above-described embodiments. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), memory bus (Ram bus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0102] It should be understood that the application of the present invention is not limited to the above examples. Those skilled in the art can make improvements or changes based on the above description. All these improvements and changes fall within the scope of protection of the claims attached to the present invention.

Claims

1. A 2-bit imaging method for synthetic aperture radar, characterized in that: The method comprises: Acquire a target echo signal received by a radar, sample the signal and extract symbol information to obtain a first single-bit signal, and perform imaging processing on the first single-bit signal to obtain a first imaging result; performing phase shift processing on the target echo signal received by the radar, sampling the phase-shifted signal and extracting symbol information to obtain a second single-bit signal, and performing imaging processing on the second single-bit signal to obtain a second imaging result; Adding and merging the first imaging result and the second imaging result to obtain a target imaging result; The phase shifting process specifically includes: According to the preset phase shift amount, the target echo signal received by the radar is phase delayed; The preset phase shift amount specifically includes: The preset phase shift is set according to the false target to be suppressed, and the influence of the phase shift on the target imaging result is: where α k is the amplitude gain coefficient of the target imaging result relative to the first imaging result, k is the order of the harmonic, and θ is the phase shift.

2. The 2-bit imaging method for synthetic aperture radar according to claim 1, characterized in that: The acquiring of a target echo signal received by the radar, sampling the signal and extracting symbol information to obtain a first single-bit signal, and performing imaging processing on the first single-bit signal to obtain a first imaging result specifically includes: The process of obtaining the first single-bit signal comprises sampling at a constant first time interval, retaining only the sign information of the sampled signal after sampling, and forming the first single-bit signal according to the sign information; The first single-bit signal is processed using a range Doppler algorithm to obtain a first imaging result.

3. The 2-bit imaging method for synthetic aperture radar according to claim 2, characterized in that: The method of performing phase shift processing on the target echo signal received by the radar, sampling the phase-shifted signal and extracting symbol information to obtain a second single-bit signal, and performing imaging processing on the second single-bit signal to obtain a second imaging result specifically includes: performing phase shift processing on a target echo signal received by the radar, sampling the phase-shifted signal at a constant first time interval, retaining only sign information of the sampled signal after sampling, and forming a second single-bit signal based on the sign information; The second single-bit signal is processed using a range Doppler algorithm to obtain a second imaging result.

4. The 2-bit imaging method for synthetic aperture radar according to claim 1, characterized in that: The step of adding and merging the first imaging result and the second imaging result to obtain a target imaging result specifically includes: Calculate the amplitude gain coefficients of the fundamental wave and harmonics corresponding to the target image in the combined target imaging result to determine whether the output target imaging result suppresses false targets of harmonics; If the output target imaging result suppresses the false target of harmonics, the corresponding target imaging result is output; If the output target imaging result cannot suppress the false target of harmonics, the phase is re-shifted, and the target imaging result obtained after the re-phase shift is output; The relationship between the amplitude gain coefficient and the phase shift is: where α k is the amplitude gain coefficient of the target imaging result relative to the first imaging result, k is the order of the harmonic, and θ is the phase shift.

5. The 2-bit imaging method for synthetic aperture radar according to claim 4, characterized in that: The calculating of the amplitude gain coefficients of the fundamental wave and harmonics corresponding to the target image in the combined target imaging result and determining whether the output target imaging result suppresses false targets of harmonics specifically includes: If α1>1, α1>α k , k = 3, 5..., k takes the preset order corresponding to the harmonic to be suppressed, then the output target imaging result suppresses the false target of the harmonic; If the output target imaging result does not satisfy α1>1 and α1>α k , k=3, 5..., k takes the preset order corresponding to the harmonic to be suppressed, then the output target imaging result does not suppress the false target of the harmonic.

6. A 2-bit imaging system for synthetic aperture radar, characterized in that: The system comprises: A first imaging result generating module acquires a target echo signal received by the radar, samples the signal and extracts symbol information to obtain a first single-bit signal, and performs imaging processing on the first single-bit signal to obtain a first imaging result; A second imaging result generating module performs phase shift processing on the target echo signal received by the radar, samples the phase-shifted signal and extracts symbol information to obtain a second single-bit signal, and performs imaging processing on the second single-bit signal to obtain a second imaging result; A target imaging result generating module is configured to add and combine the first imaging result and the second imaging result to obtain a target imaging result; The phase shifting process specifically includes: According to the preset phase shift amount, the target echo signal received by the radar is phase delayed; The preset phase shift amount specifically includes: The preset phase shift is set according to the false target to be suppressed, and the influence of the phase shift on the target imaging result is: where α k is the amplitude gain coefficient of the target imaging result relative to the first imaging result, k is the order of the harmonic, and θ is the phase shift.

7. A radar device, characterized in that: The radar device includes a memory, a processor, and a 2-bit imaging method for synthetic aperture radar stored in the memory and executable on the processor. When the processor executes the 2-bit imaging method for synthetic aperture radar, the steps of the 2-bit imaging method for synthetic aperture radar as described in any one of claims 1 to 5 are implemented.

8. A storage medium, characterized in that: The storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the 2-bit imaging method for synthetic aperture radar as described in any one of claims 1-5.

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