Radar signal distance alignment implementation method based on envelope correlation

Abstract

The invention relates to a radar signal distance alignment implementation method based on envelope correlation, and belongs to the technical field of radar signal processing. Comprising the following steps: calculating an original signal envelope of each pulse in the same pulse group; envelope cross-correlation between original signal envelopes is calculated; obtaining a peak value position of envelope cross-correlation of the original signal; performing N-time interpolation on the original signal, and calculating the envelope of the interpolated signal; acquiring the corresponding position of the envelope cross-correlation peak position of the original signal after interpolation, and calculating the envelope cross-correlation within the range of N / 2 + 1 sampling points near the left and right by taking the position as the center; obtaining a peak value position of envelope cross-correlation of the interpolated signal; compensating the interpolated signal according to the envelope cross-correlation peak position of the interpolated signal; and performing N-time extraction on the compensated signal. The problem that the processing performance is low due to the fact that the calculated amount is too large in the broadband radar signal distance alignment processing based on envelope correlation is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar signal processing, and in particular to range alignment processing of radar broadband signals, and specifically to an efficient implementation method for range alignment of radar signals based on envelope correlation. Background Art

[0002] One of the functions of broadband signals is to provide a good basis for radar target identification. Conventional narrowband radars have very low range resolution, so general targets (such as airplanes) appear as "point" targets. Although their waveforms also contain certain target information, they are very rough. For radars with a bandwidth of more than 100 MHz to several hundred MHz, the target echo is a high range resolution (HRR) signal with a resolution of sub-meter level. The HRR echo signal of a general target appears as a one-dimensional range image. However, the high range resolution of broadband signals also brings some inconveniences in application, mainly because the distance movement of the target echo between pulses can easily cause the distance units of the image to be staggered, making it difficult to achieve coherent accumulation of a series of echoes.

[0003] In view of the cross-range unit migration of high-resolution range images, algorithms can be used to remedy it under certain conditions. Commonly used algorithms include envelope correlation method, overall correlation method, minimum entropy method, etc. Among them, envelope correlation method and overall correlation method are both cross-correlation methods, which use the maximum cross-correlation of the real envelope of the echo as the criterion for alignment, and the minimum entropy method uses the minimum entropy of the real envelope of the echo as the criterion for alignment. The envelope correlation method uses the cross-correlation method to compensate for the time delay corresponding to the peak value of the real envelope of two adjacent echoes. In fact, radar signals are sampled in discrete time, and the sampling interval is generally slightly smaller than the pulse width. The envelope alignment accuracy is required to reach 1 / 8 of the range unit. Therefore, when calculating the cross-correlation function, the time discrete value is usually interpolated 8 times, which can achieve good alignment of adjacent real envelopes. At the same time, it will undoubtedly greatly increase the amount of calculation of the algorithm, making it difficult to apply in engineering. Summary of the invention

[0004] The technical problems to be solved by the present invention are:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides an efficient implementation method for radar signal distance alignment based on envelope correlation, which is used to solve the problems of large amount of calculation and insufficient processing performance when using the envelope correlation method to perform distance alignment on radar broadband signals.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] An efficient method for implementing radar signal range alignment based on envelope correlation, characterized by comprising:

[0008] Calculate the original signal envelope of each pulse in the same pulse group;

[0009] Selecting the first pulse as a reference pulse, calculating the envelope cross-correlation between the remaining pulse envelope and the reference pulse envelope;

[0010] Obtain the peak position of the envelope cross-correlation of the original signal;

[0011] Perform N-fold interpolation on the original signal and calculate the envelope of the interpolated signal;

[0012] Get the peak position of the envelope cross-correlation of the original signal at the corresponding position after interpolation, and calculate the envelope cross-correlation within the range of N / 2+1 sampling points around the position;

[0013] Obtain the peak position of the envelope cross-correlation of the interpolated signal;

[0014] The interpolated signal is compensated according to the peak position of the envelope cross-correlation of the interpolated signal;

[0015] The compensated signal is decimate by N times.

[0016] A further technical solution of the present invention: the step of calculating the envelope cross-correlation between the residual pulse envelope and the reference pulse envelope comprises:

[0017] Do 2N on the reference pulse envelope u1(n) r -1 point Fourier transform to get U1(k), k∈[1,2N r -1];

[0018] For the i-th residual pulse envelope u i (n),i∈[2,N d ]Do 2N r -1 point Fourier transform to get U i (k),k∈[1,2N r -1];

[0019] For U1 and U i The result of the conjugate vector dot multiplication operation is inverse Fourier transformed to obtain the envelope cross-correlation result R 1i ,i∈[2,N d ].

[0020] A further technical solution of the present invention is as follows: the peak position of the envelope cross-correlation of the original signal is obtained, specifically:

[0021] By traversing the envelope cross-correlation R of the i-th residual pulse and the reference pulse 1i Get its peak position a i ,a i ∈[-N r +1,N r -1],i∈[2,N d ].

[0022] A further technical solution of the present invention is: performing N-fold interpolation on the original signal and calculating the envelope of the interpolated signal is specifically as follows:

[0023] For the original signal s i (n),n∈[1,N r ],i∈[1,N d ] Perform Fourier transform to get S i (k),k∈[1,N r ],i∈[1,N d ];

[0024] From S i (k)ceil(N r / 2+1) insert NN continuously r 0 to get S i '(k'),k'∈[1,(N+1)N r ];

[0025] Perform inverse Fourier transform on S'(k') to obtain the interpolated signal s'(n'), n'∈[1,(N+1)N r ];

[0026] The signal envelope u'(n') after interpolation is obtained by taking the modulus of s'(n'), n'∈[1,(N+1)N r ].

[0027] A further technical solution of the present invention is as follows: the peak position of the envelope cross-correlation of the original signal is obtained at the corresponding position after interpolation, and the envelope cross-correlation is calculated within the range of N / 2+1 sampling points around the position, specifically:

[0028] By envelope cross-correlation R 1i The peak position a i , and its corresponding position after interpolation is a' i =(N+1)a i ,i∈[2,N d ];

[0029] With a' i The envelope cross-correlation result R' within the range of N / 2+1 sampling points around the center 1i ,i∈[2,N d ] is obtained by the following formula

[0030] R' 1i (m)=∑u'1(n')u' i (n'-m),m∈[a' i -N / 2-1,a' i +N / 2+1]

[0031] Among them, u'1 is the envelope of the reference pulse after interpolation, u' i is the interpolated envelope of the ith pulse.

[0032] A further technical solution of the present invention is: compensating the interpolated signal according to the peak position of the envelope cross-correlation of the interpolated signal, specifically:

[0033] By envelope cross-correlation R 1i 'The peak position b i , then the frequency domain result X after the compensation of the pulse signal after the i-th interpolation i ' can be obtained by the following formula

[0034]

[0035] Among them, S i '(k) is the frequency domain result before the pulse signal compensation after the i-th interpolation, i∈[2,N d ].

[0036] A further technical solution of the present invention is to perform N-fold decimation on the compensated signal, specifically:

[0037] Intercept X i The first ceil(N r / 2) data and the last N r -ceil(N r / 2) data are combined into X i (k),k∈[1,N r ],i∈[2,N d ];

[0038] X i (k) Perform inverse Fourier transform to obtain the distance aligned signal x i (n),n∈[1,N r ]; where N r is the number of sampling points, ceil(.) means rounding up.

[0039] A computer system, characterized in that it comprises: one or more processors, and a computer-readable storage medium for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned method.

[0040] A computer-readable storage medium, characterized in that it stores computer-executable instructions, which are used to implement the above method when executed.

[0041] A computer program product, characterized by comprising computer executable instructions, wherein the instructions are used to implement the above method when executed.

[0042] The beneficial effects of the present invention are:

[0043] The present invention provides an efficient implementation method for radar signal distance alignment based on envelope correlation. The method optimizes cross-correlation operations and compensation operations to achieve the purpose of improving algorithm processing performance, including: performing signal interpolation, correlation, compensation and extraction operations in the frequency domain, and accelerating using efficient scientific computing libraries, such as FFTW, OpenBlas libraries, etc.; optimizing correlation operations to avoid envelope cross-correlation operations of the full length after interpolation; optimizing compensation operations to avoid complete compensation coefficient calculations after interpolation, and only compensating for the sampling points required for the final extraction. Since the method of the present invention avoids envelope cross-correlation and compensation of the signal after the complete interpolation, the calculation amount of the entire algorithm is greatly reduced, thereby improving the processing performance of the algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0045] Figure 1 The present invention is implemented as a flow chart.

[0046] Figure 2 is the signal envelope before distance alignment processing.

[0047] Figure 3 It is the signal envelope processed by the distance alignment method of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0049] Reference Figure 1 This embodiment provides an efficient method for implementing radar signal range alignment based on envelope correlation, including the following steps:

[0050] S101, calculating the original signal envelope of each pulse in the same pulse group, and selecting the first pulse as a reference pulse;

[0051] S102, calculating the envelope cross-correlation between the residual pulse and the reference pulse;

[0052] S103, obtaining the peak position of the envelope cross-correlation;

[0053] S104, performing N-fold interpolation on the original signal, and calculating the envelope of the interpolated signal;

[0054] S105, obtaining the position corresponding to the result of S103 after interpolation, and calculating the envelope cross-correlation within the range of N / 2+1 sampling points around the position;

[0055] S106, obtaining the peak position of the envelope cross-correlation after interpolation;

[0056] S107, compensating the interpolated signal according to the peak position of S106.

[0057] The above steps are implemented as follows:

[0058] In step S101, each pulse s in the pulse group is i (n),n∈[1,N r ],i∈[1,N d ] Perform modulo operation to obtain the original signal envelope u i (n),n∈[1,N r ],i∈[1,N d ], where N r is the number of sampling points, N d is the number of pulses in the pulse group, and the first pulse is selected as the reference pulse;

[0059] In step S102, the envelope cross-correlation between the residual pulse and the reference pulse is calculated, and the specific implementation steps are as follows:

[0060] 2a) Do 2N on the reference pulse envelope u1(n) r -1 point Fourier transform to get U1(k), k∈[1,2N r -1];

[0061] 2b) For the i-th pulse envelope u i (n),i∈[2,N d ]Do 2N r -1 point Fourier transform to get U i (k),k∈[1,2N r -1];

[0062] 2c) For U1 and U i The result of the conjugate vector dot multiplication operation is inverse Fourier transformed to obtain the envelope cross-correlation result R 1i ,i∈[2,N d ];

[0063] In step S103, by traversing the envelope cross-correlation R of the i-th pulse and the reference pulse 1i Get its peak position a i ,a i ∈[-N r +1,N r -1],i∈[2,N d ];

[0064] In step S104, the original signal is interpolated N times to calculate the envelope of the interpolated signal. The specific implementation steps are as follows:

[0065] 4a) For the original signal s i (n),n∈[1,N r ],i∈[1,N d ] Perform Fourier transform to get S i (k),k∈[1,N r ],i∈[1,N d ];

[0066] 4b) From S i (k)ceil(N r / 2+1) insert NN continuously r 0 to get S i '(k'),k'∈[1,(N+1)N r ];

[0067] 4c) Perform inverse Fourier transform on S'(k') to obtain the interpolated signal s'(n'), n'∈[1,(N+1)N r ];

[0068] 4d) Take the modulus of s'(n') to obtain the interpolated signal envelope u'(n'), n'∈[1,(N+1)N r ];

[0069] In step S105, the position corresponding to the result of step S103 after interpolation is obtained, and the envelope cross-correlation is calculated within the range of N / 2+1 sampling points around the position as the center. The specific implementation steps are as follows:

[0070] 5a) Through step (3), we can get the envelope cross-correlation R 1i The peak position a i , and its corresponding position after interpolation is

[0071] a' i =(N+1)a i ,i∈[2,N d ];

[0072] 5b) With a' iThe envelope cross-correlation result R' within the range of N / 2+1 sampling points around the center 1i ,i∈[2,N d ] is obtained by the following formula

[0073] R' 1i (m)=∑u'1(n')u' i (n'-m),m∈[a' i -N / 2-1,a' i +N / 2+1]

[0074] Among them, u'1 is the envelope of the reference pulse after interpolation, u' i is the envelope of the i-th pulse after interpolation;

[0075] In step S106, by traversing the interpolated envelope cross-correlation R of the i-th pulse and the reference pulse 1i 'Get its peak position b i ,b i ∈[-(N+1)N r +1,(N+1)N r -1],i∈[2,N d ];

[0076] In step S107, the interpolated signal is compensated according to the peak position in step S106. The specific implementation steps are as follows:

[0077] Through step S106, the envelope cross-correlation R 1i 'The peak position b i , then the frequency domain result X after the compensation of the pulse signal after the i-th interpolation i ' can be obtained by the following formula

[0078]

[0079] Among them, S i '(k) is the frequency domain result before the pulse signal compensation after the i-th interpolation, i∈[2,N d ];

[0080] In step S108, the compensated signal is decimated N times, and the specific implementation steps are as follows:

[0081] 8a) Intercept X i The first ceil(N r / 2) data and the last N r -ceil(N r / 2) data are combined into X i (k),k∈[1,N r ],i∈[2,N d ];

[0082] 8b) For X i (k) Perform inverse Fourier transform to obtain the distance aligned signal x i (n),n∈[1,N r ]; where N r is the number of sampling points, N is the interpolation multiple, and ceil(.) means rounding up.

[0083] The effect of the present invention is further illustrated by the following comparative test:

[0084] 1. Experimental parameters

[0085] The CPU model used in the server is Feiteng 2000+, Kylin V10 system, FFTW computing library version 3.3.8, OpenBLAS computing library version 3.20.1, local test data is used as the input source, the number of radar beams is 1, the number of pulse accumulations is 1024, the number of sampling points of the echo signal is 4000, and 8x interpolation.

[0086] 2. Experimental content

[0087] 2a) Signal envelope before distance alignment, such as Figure 2 shown.

[0088] 2b) The signal envelope processed by the distance alignment method of the present invention, such as Figure 3 shown.

[0089] 2c) 16 threads were used to perform envelope cross-correlation processing in parallel, and the processing time of 1000 operations before and after optimization was counted. The average results are shown in Table 1:

[0090] Table 1 Comparison of processing time before and after cross-correlation operation optimization

[0091] Envelope cross-correlation processing time before optimization (ms) Optimized envelope cross-correlation processing time (ms) 10.271 0.232

[0092] 2d) 16 threads were used to perform signal compensation processing in parallel, and the processing time of 1000 operations before and after optimization was counted. The average results are shown in Table 2:

[0093] Table 2 Comparison of processing time before and after compensation calculation optimization

[0094] Compensation calculation processing time before optimization (ms) Compensation calculation processing time after optimization (ms) 1.225 0.0274

[0095] 2e) 16 threads are used to perform distance alignment in parallel. The processing time of 1000 operations before and after optimization is counted. The average results are shown in Table 3:

[0096] Table 3 Comparison of processing time before and after optimization of distance alignment module

[0097] Optimization pre-processing time (ms) Optimized post-processing time (ms) 909.937 190.296

[0098] 3. Result analysis:

[0099] from Figure 2 It can be seen that the envelopes between pulses are not aligned;

[0100] from Figure 3 It can be seen that the envelopes between pulses are aligned;

[0101] As can be seen from Table 1, under the same hardware platform, the performance of the optimized envelope cross-correlation processing is improved by about 17.9 times;

[0102] As can be seen from Table 2, under the same hardware platform, the optimized compensation processing performance is improved by about 44.3 times;

[0103] It can be seen from Table 3 that the optimization of cross-correlation and compensation calculations improves the overall envelope alignment performance by about 4.7 times, greatly improving the processing performance.

[0104] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.

Claims

1. A radar signal distance alignment implementation method based on envelope correlation, characterized in that: include: Calculate the original signal envelope of each pulse in the same pulse group; Selecting the first pulse as a reference pulse, calculating the envelope cross-correlation between the remaining pulse envelope and the reference pulse envelope; Obtain the peak position of the envelope cross-correlation of the original signal; Perform N-fold interpolation on the original signal and calculate the envelope of the interpolated signal; Get the peak position of the envelope cross-correlation of the original signal at the corresponding position after interpolation, and calculate the envelope cross-correlation within the range of N / 2+1 sampling points around the position; Obtain the peak position of the envelope cross-correlation of the interpolated signal; The interpolated signal is compensated according to the peak position of the envelope cross-correlation of the interpolated signal; The compensated signal is decimate by N times.

2. According to claim 1, a radar signal distance alignment implementation method based on envelope correlation is characterized in that: The calculating the envelope cross-correlation between the residual pulse envelope and the reference pulse envelope comprises: Do 2N on the reference pulse envelope u1(n) r -1 point Fourier transform to get U1(k), k∈[1,2N r -1]; For the i-th residual pulse envelope u i (n),i∈[2,N d ]Do 2N r -1 point Fourier transform to get U i (k),k∈[1,2N r -1]; for U1 and U i The result of the conjugate vector dot multiplication operation is inverse Fourier transformed to obtain the envelope cross-correlation result R 1i ,i∈[2,N d ].

3. According to claim 2, a radar signal distance alignment implementation method based on envelope correlation is characterized in that: The peak position of the envelope cross-correlation of the original signal is obtained, specifically: By traversing the envelope cross-correlation R of the i-th residual pulse and the reference pulse 1i Get its peak position a i ,a i ∈[-N r +1,N r -1],i∈[2,N d ].

4. According to claim 1, a radar signal distance alignment implementation method based on envelope correlation is characterized in that: The original signal is interpolated N times to calculate the envelope of the interpolated signal, specifically: For the original signal s i (n),n∈[1,N r ],i∈[1,N d ] Perform Fourier transform to get S i (k),k∈[1,N r ],i∈[1,N d ]; From S i (k)ceil(N r / 2+1) insert NN continuously r 0 to get S i '(k'),k'∈[1,(N+1)N r ]; Perform inverse Fourier transform on S'(k') to obtain the interpolated signal s'(n'), n'∈[1,(N+1)N r ]; The signal envelope u'(n') after interpolation is obtained by taking the modulus of s'(n'), n'∈[1,(N+1)N r ].

5. According to claim 3, a radar signal distance alignment method based on envelope correlation is characterized in that: The peak position of the envelope cross-correlation of the original signal is obtained at the corresponding position after interpolation, and the envelope cross-correlation is calculated within the range of N / 2+1 sampling points around the position, specifically: By envelope cross-correlation R 1i The peak position a i , and its corresponding position after interpolation is a i '=(N+1)a i ,i∈[2,N d ]; With a i 'Centered, the envelope cross-correlation result R1 within the range of N / 2+1 sampling points around it' i ,i∈[2,N d ] is obtained by the following formula R1' i (m)=∑u1'(n')u i '(n'-m),m∈[a i '-N / 2-1,a i '+N / 2+1] Among them, u1' is the envelope of the reference pulse after interpolation, u i ' is the envelope of the i-th pulse after interpolation.

6. According to claim 5, a radar signal distance alignment implementation method based on envelope correlation is characterized in that: The interpolation signal is compensated according to the peak position of the envelope cross-correlation of the interpolation signal, specifically: By envelope cross-correlation R 1i 'The peak position b i , then the frequency domain result X after the compensation of the pulse signal after the i-th interpolation i ' can be obtained by the following formula Among them, S i '(k) is the frequency domain result before the pulse signal compensation after the i-th interpolation, i∈[2,N d ].

7. The method for implementing radar signal range alignment based on envelope correlation according to claim 6, characterized in that: The compensated signal is extracted N times, specifically: Intercept X i The first ceil(N r / 2) data and the last N r -ceil(N r / 2) data are combined into X i (k),k∈[1,N r ],i∈[2,N d ]; X i (k) Perform inverse Fourier transform to obtain the distance aligned signal x i (n),n∈[1,N r ]; where N r is the number of sampling points, ceil(.) means rounding up.

8. A computer system, characterized in that include: One or more processors, and a computer-readable storage medium for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors are enabled to implement the method of claim 1.

9. A computer-readable storage medium, characterized in that Computer executable instructions are stored, and when the instructions are executed, they are used to implement the method of claim 1.

10. A computer program product, characterized in that The invention comprises computer executable instructions, which are used to implement the method of claim 1 when being executed.

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