A radar low-speed quasi-dynamic echo signal speed-increasing equivalent reconstruction method

Abstract

This invention relates to a method for equivalent reconstruction of radar low-speed quasi-dynamic echo signals with increased speed, comprising the following steps: S1, fast-time decoupling of range and velocity, including sampling and digital down-conversion of radar low-speed quasi-dynamic relative motion echo data to obtain zero-IF echo data, performing two-dimensional rearrangement of the zero-IF echo data in both fast and slow time domains, and decoupling the fast time corresponding to each two-dimensional rearranged signal; S2, performing fast-time fast Fourier transform and frequency domain phase compensation; S3, performing fast-time frequency domain scaling transformation and amplitude compensation; S4, performing slow-time scaling transformation; S5, performing fast-time frequency domain range travel compensation; S6, performing fast-time frequency domain inverse Fourier transform and phase compensation. The method provided by this invention can achieve equivalent reconstruction of velocities at arbitrary multiples and achieves good equivalent reconstruction performance for cross-range cell travel problems.

Description

Technical Field

[0001] This invention relates to the field of radar signal processing technology, and specifically to a method for equivalent reconstruction of low-speed quasi-dynamic echo signals from radar using speed-increasing technology. Background Technology

[0002] To address the challenges of simulating high-speed relative motion at full speed in field tests, particularly the difficulty and low accuracy of simulating high-speed dynamic rendezvous, this paper proposes a method that uses the echo signals from low-speed relative motion between the radar and the target. This method employs an equivalent reconstruction method by increasing the speed of the low-speed quasi-dynamic echo signals to convert them into echo signals from high-speed relative motion between the radar and the target. This enables a low-cost, high-precision equivalent simulation of high-speed dynamic rendezvous tests in the field.

[0003] Existing methods for simulating high-speed motion by using low-speed quasi-dynamic relative motion to achieve equivalent speed increase mainly rely on variable repetition frequency (RPF). However, these methods cannot address issues such as pulse scale scaling and distance shift that arise during the speed increase equivalence process for broadband signals. Currently, there are no effective methods for reconstructing equivalent speed increases for complex signals such as pulse Doppler signals with distance information or wide-bandwidth signals. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes an equivalent reconstruction method for accelerating low-speed quasi-dynamic echo signals from radar, characterized by the following:

[0005] S1. Fast time domain range and velocity decoupling, including sampling radar low-speed quasi-dynamic relative motion echo data and digital down-conversion to obtain zero intermediate frequency echo data, performing two-dimensional rearrangement of the zero intermediate frequency echo data in fast time domain and slow time domain, and decoupling the fast time corresponding to each two-dimensional rearranged signal.

[0006] S2. Perform fast time-domain fast Fourier transform and frequency-domain phase compensation on the decoupled pulse signal.

[0007] S3. Perform fast time-frequency domain scaling transformation and amplitude compensation on the signal that has undergone fast Fourier transform and frequency domain phase compensation in step S2.

[0008] S4. Perform a slow time-scale transformation on the signal that has undergone fast time-frequency domain scaling and amplitude compensation in step S3.

[0009] S5. Perform fast time-frequency domain distance travel compensation on the signal transformed by the slow time scale in step S4.

[0010] S6. Perform fast time-frequency domain inverse Fourier transform and phase compensation on the signal from step S5 for fast time-frequency domain distance travel compensation.

[0011] Further, the two-dimensional rearrangement signal in step S1 is represented as s r(t,t m ):

[0012]

[0013] In the formula, A1 is the echo signal amplitude; t = nT s For fast time-dimensional time domain, n is the nth sampling point within the pulse, T s t represents the sampling interval; m =mT r The time interval is slow, m is the m-th pulse between pulses, and T is slow. r The pulse repetition interval (PRI); f c c is the carrier frequency; c is the speed of light; p(·) is the pulse scale scaling factor; p(·) is the baseband signal waveform; For echo delay scaled to pulse width, r(t) m )=r0+v0mT r , where r0 and v0 are the initial radial distance of the target relative to the radar and the relative velocity during the low-speed quasi-dynamic motion process, respectively;

[0014] Decoupling is performed on the fast time corresponding to each two-dimensional rearranged signal, which is achieved through phase compensation. The process is represented as: s r1 (t,t m ) = s r (t,t m Q1(t,t) m );

[0015] Compensation factor Q1(t,t) m ) is represented as:

[0016] Furthermore, step S2, Fast Fourier Transform and Frequency Domain Phase Compensation, is expressed as follows:

[0017] s r2 (f,t m ) = FFT t {s r1 (t,t m )}Q2(f,t m )

[0018] In the formula, FFT t This represents a fast Fourier transform in the fast time domain; the frequency domain compensation factor Q2(f,t) m ) is represented as:

[0019]

[0020] In the formula, f = nB / N, where B is the signal bandwidth and N is the number of fast-time sampling points.

[0021] Furthermore, the signal obtained from step 2 via Fast Fourier Transform and frequency domain phase compensation is represented as follows:

[0022]

[0023] The signal after time-frequency domain scaling and amplitude compensation in step S3 is:

[0024]

[0025] Let f′ be the fast time-frequency domain after scaling transformation, f = f′κ0 / κ h ,in v is the pulse width scaling factor under high-speed relative motion. h The relative speed after the increase, κ0 / κ h This is the amplitude compensation factor.

[0026] Furthermore, the signal after the slow time-dimensional scaling transformation in step S4 is:

[0027]

[0028] Let t m =Kt' m ,t' m For the slower time domain after the acceleration, K = v H / v0 represents the speed increase factor.

[0029] Furthermore, the signal after fast time-frequency domain distance travel compensation in step S5 is:

[0030] s r3 (f′,t' m ) = s r2 (f′,t' m )Q3(f′,t' m )

[0031] In the formula, Q3(f′,t') m ) represents

[0032]

[0033] Furthermore, the signal after fast time-frequency domain inverse Fourier transform and phase compensation in step S6 is:

[0034] s r4 (t′,t' m =IFFT f′ {s r3 (f′,t' m )}Q4(t′,t' m )

[0035] In the formula, IFFT f′ This represents performing a fast inverse Fourier transform on f′; t′ is the time domain corresponding to f′; Q4(t′,t') m ) is represented as:

[0036]

[0037] The method provided by this invention can achieve equivalent reconstruction of any multiple of velocity and can achieve good equivalent reconstruction performance for cross-distance cell movement problems. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating the implementation of the radar low-speed quasi-dynamic echo signal amplification equivalent reconstruction method of the present invention. Figure 2 and Figure 3 Fast-time-slow-time two-dimensional zero-IF echo data for low-speed relative motion

[0039] Figure 4 and Figure 5 This is the equivalent reconstructed fast-time-slow-time two-dimensional zero-IF echo data of high-speed relative motion;

[0040] Figure 6 This is to reconstruct the distance change trajectory between the radar and the target before and after the equivalent reconstruction. Detailed Implementation

[0041] Please see Figure 1 The following is a flowchart illustrating the implementation of the radar low-speed quasi-dynamic echo signal amplification equivalent reconstruction method proposed in this invention. The specific implementation steps are as follows:

[0042] S1. Fast-time range-velocity decoupling in the time domain includes sampling and digital down-conversion of low-speed quasi-dynamic relative motion echo data from the radar to obtain zero-IF radar echo data. The zero-IF echo data is then rearranged in both fast and slow time domains (range-pulse two-dimensional space). The fast-time and slow-time domain rearranged signals of the zero-IF radar echo data are represented as follows:

[0043]

[0044] In the formula, A1 is the echo signal amplitude; t = nT s For fast time-dimensional time domain, n is the nth sampling point within the pulse, T s t represents the sampling interval; m =mT r The time interval is slow, m is the m-th pulse between pulses, and T is slow. r f is the pulse repetition interval; c Where c is the carrier frequency and c is the speed of light. is the pulse scale scaling factor, and p(·) is the baseband signal waveform; For echo delay scaled to pulse width, r(t) m )=r0+v0mT r , where r0 and v0 are the initial radial distance of the target relative to the radar and the relative velocity during the low-speed quasi-dynamic motion process, respectively;

[0045] In this process, the decoupling of the fast-time distance and velocity is achieved through phase compensation. The phase compensation process, which decouples the fast-time distance for each two-dimensional rearranged signal, is expressed as follows:

[0046] s r1 (t,t m ) = s r (t,t m Q1(t,t) m );

[0047] In the formula, the compensation factor Q1(t,t) m ) is represented as:

[0048]

[0049] S2. Fast-time Fast Fourier Transform in the Time Domain and Phase Compensation in the Frequency Domain. This process is expressed as:

[0050] s r2 (f,t m ) = FFT t {s r1 (t,t m )}Q2(f,t m );

[0051] In the formula, FFT t This represents a fast Fourier transform in the fast time domain; the frequency domain compensation factor Q2(f,t) m ) is represented as:

[0052]

[0053] In the formula, f = nB / N, where B is the signal bandwidth and N is the number of fast-time sampling points.

[0054] S3. Fast-time frequency domain scaling and amplitude compensation. The signal obtained after fast-time Fourier transform and frequency domain phase compensation in step S2 is represented as follows:

[0055]

[0056] Let f′ be the fast time-frequency domain after scaling transformation, f = f′κ0 / κ h ,in v is the pulse width scaling factor under high-speed relative motion. hThe relative speed after the increase is multiplied by the amplitude compensation factor κ0 / κ. h After amplitude compensation, we get:

[0057]

[0058] S4. Slow-time-dimensional scaling transformation:

[0059] Let t m =Kt' m ,t' m For the slower time domain after the acceleration, K = v H / v0 is the rate of increase of velocity, therefore, after the slow time dimension scaling transformation, we get:

[0060]

[0061] S5. Fast time-frequency domain distance travel compensation, the compensation process is expressed as follows:

[0062] s r3 (f′,t' m ) = s r2 (f′,t' m )Q3(f′,t' m )

[0063] In the formula, Q3(f′,t') m ) represents

[0064]

[0065] S6. Fast time-frequency domain inverse Fourier transform and phase compensation, the process is expressed as:

[0066] sr4(t′,t' m =IFFT f′ {s r3 (f′,t ' m)}Q4(t′,t' m )

[0067] In the formula, IFFT f′ This represents performing a fast inverse Fourier transform on f′; t′ is the time domain corresponding to f′; Q4(t′,t m ) represents

[0068]

[0069] Through the above steps, the radar and target's low-speed quasi-dynamic relative motion echo and the equivalent high-speed relative motion are reconstructed using the equivalent acceleration method. The reconstructed fast-time-slow-time two-dimensional data is then played back frame by frame according to the pulse repetition frequency interval Tr to obtain the equivalent high-speed relative motion echo signal between the radar and the target.

[0070] This implementation example sets the radar parameters as follows: carrier frequency f0, linear frequency modulated pulse signal bandwidth of 10MHz, sampling frequency of 30MHz, pulse width of 20μs, pulse repetition interval of 200μs, slow-time dimension pulse number of 1000, and sampling points of 800 per pulse. For a single moving target, the initial distance is 1km, the relative velocity between the radar and the target in low-speed quasi-dynamic motion is v0, and the equivalent relative velocity after acceleration and equivalent reconstruction is v. h .

[0071] Figure 2 and Figure 3 The fast-time-slow-time two-dimensional zero-IF echo data of low-speed relative motion v0 is presented. The method proposed in this invention can achieve equivalent reconstruction of any multiple of velocity. Figure 4 and Figure 5 The equivalent v after equivalent reconstruction is given. h High-speed relative motion fast-time-slow-time two-dimensional zero-IF echo data. Figure 6 The distance change trajectories between the radar and the target before and after equivalent reconstruction are given. It can be seen that the method of this invention can achieve good equivalent reconstruction performance for the problem of cross-range cell movement.

[0072] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for equivalent reconstruction of low-speed quasi-dynamic echo signals from radar using acceleration, characterized in that, Includes the following: S1. Fast time domain range and velocity decoupling, including sampling radar low-speed quasi-dynamic relative motion echo data and digital down-conversion to obtain zero intermediate frequency echo data, performing two-dimensional rearrangement of the zero intermediate frequency echo data in fast time domain and slow time domain, and decoupling the fast time corresponding to each two-dimensional rearranged signal. S2. Perform fast time-domain fast Fourier transform and frequency-domain phase compensation on the decoupled pulse signal. S3. Perform fast time-frequency domain scaling transformation and amplitude compensation on the signal that has undergone fast Fourier transform and frequency domain phase compensation in step S2. S4. Perform a slow time-scale transformation on the signal that has undergone fast time-frequency domain scaling and amplitude compensation in step S3. S5. Perform fast time-frequency domain distance travel compensation on the signal transformed by the slow time scale in step S4. S6. Perform fast time-frequency domain inverse Fourier transform and phase compensation on the signal of fast time-frequency domain distance travel compensation in step S5. The two-dimensional rearrangement signal in step S1 is represented as follows: : In the formula, in the formula A 1 represents the amplitude of the echo signal; t = nT s For the fast time dimension time domain, n For the first pulse n One sampling point, T s The sampling interval; t m =mT r For slow time, m For the interpulse m One pulse, and T r The pulse repetition interval (PRI) is used. f c For carrier frequency; c The speed of light; This is the pulse scale scaling factor; This is the baseband signal waveform; Echo delay for pulse width scaling ,in r 0 and v 0 represents the initial radial distance of the target relative to the radar and the relative velocity during the low-speed quasi-dynamic motion process, respectively; Decoupling is performed on the fast time corresponding to each two-dimensional rearranged signal, which is achieved through phase compensation. The process is represented as follows: ; Compensation factor Represented as: .

2. The radar low-speed quasi-dynamic echo signal speed-up equivalent reconstruction method as described in claim 1, characterized in that, The fast Fourier transform and frequency domain phase compensation in step S2 are expressed as follows: In the formula, FFT t This represents a fast Fourier transform in the fast time domain; frequency domain compensation factor. Represented as: In the formula, f=nB / N and B For signal bandwidth, N This represents the number of sampling points in the fast time.

3. The radar low-speed quasi-dynamic echo signal speed-up equivalent reconstruction method as described in claim 2, characterized in that, The signal obtained from step 2 via Fast Fourier Transform and frequency domain phase compensation is represented as follows: ; The signal after time-frequency domain scaling and amplitude compensation in step S3 is: make This is the fast time-frequency domain after scaling transformation. ,in This is the pulse width scaling factor under high-speed relative motion. The relative speed after the increase. This is the amplitude compensation factor.

4. The radar low-speed quasi-dynamic echo signal speed-up equivalent reconstruction method as described in claim 3, characterized in that, The signal after slow time-dimensional scaling transformation in step S4 is: ； make , For the slower time domain after the growth rate, It is the multiple by which the speed increases.

5. The radar low-speed quasi-dynamic echo signal speed-up equivalent reconstruction method as described in claim 4, characterized in that, The signal after fast time-frequency domain distance travel compensation in step S5 is: In the formula, Represented as 。 6. The radar low-speed quasi-dynamic echo signal speed-up equivalent reconstruction method as described in claim 5, characterized in that, The signal after fast time-frequency domain inverse Fourier transform and phase compensation in step S6 is: In the formula, Indicates to Perform a fast inverse Fourier transform; for The corresponding time domain; Represented as: 。

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