A LFMCW radar Keystone transform distance walk correction and semi-blind velocity effect elimination method and device

Abstract

The application discloses a LFMCW radar Keystone transformation distance walking correction and semi-blind speed effect elimination method and device. In view of the energy defocusing and Doppler tearing problems of the semi-blind speed area caused by Sinc interpolation truncation when the conventional Keystone transformation processes high-speed maneuvering targets, a double-path parallel architecture is adopted. A conventional branch extracts a safe area spectrum; a blind speed branch constructs a time domain compensation factor containing a radar frequency modulation slope and a fast time variable, substitutes high calculation power interpolation by pure physical phase rotation, and realizes extreme focusing of target energy; then, based on a target absolute Doppler index, a point-to-point coordinate mapping mechanism is adopted to seamlessly recombine the focused main lobe into a basic spectrum. The application recovers the coherent accumulation loss caused by interpolation truncation, eliminates the ghost false peaks and speed measurement blind bias at the Doppler cross-border, greatly reduces the consumption of underlying hardware resources, and meets the real-time detection demand.

Description

Technical Field

[0001] This invention belongs to the field of radar signal processing and target detection technology, specifically relating to a method and apparatus for Keystone transform range migration correction and semi-blind speed effect elimination in LFMCW radar. Background Technology

[0002] Linear Frequency Modulated Continuous Wave (LFMCW) radar has been widely used in fields such as autonomous driving collision avoidance and low-altitude weak target (e.g., drone) detection due to its significant advantages, including small size, low power consumption, low probability of intercept, and high range resolution. However, because LFMCW radar typically has low transmit power and extremely low signal-to-noise ratio (SNR) of single-pulse echoes, it is difficult to effectively detect high-speed, weak targets. To effectively improve the detection range and SNR of high-speed, weak targets, radar systems usually need to employ long-term coherent accumulation techniques.

[0003] However, when the target performs high-speed maneuvers or the radar accumulation time is long, the target echo will cross multiple range cells within the coherent accumulation period, resulting in severe range migration (RM) and a sharp decline in coherent accumulation performance. Currently, the Keystone Transform (KT) is an effective means to eliminate range migration and decouple the range dimension (fast time) from the Doppler dimension (slow time). It requires no prior knowledge of target motion parameters and can achieve full Doppler domain compensation for linear range migration through blind correction, making it the most widely used range migration correction scheme in current engineering applications. Traditional KT typically uses Sinc interpolation or Chirp-Z Transform (CZT). However, in practical engineering applications, KT implemented through Sinc interpolation suffers significant performance loss at the boundaries of the Doppler compensation band. The physical essence of this problem is as follows: at the half-blind-veelocity point, the range travel slope corresponding to the target's Doppler frequency causes the spectrum of the fast-time sampling to fold to the truncation boundary of the Sinc interpolation kernel. The truncation error of the interpolation and the spectral aliasing effect are amplified sharply, ultimately leading to target energy defocusing and severe loss of coherent accumulation gain, forming a non-negligible half-blind-veelocity detection blind zone. Because these locations are close to the "half-blind-veelocity (HBV)" point, this problem is called the "half-blind-veelocity effect" (HBVE).

[0004] Existing solutions to the HBVE problem have significant limitations. The literature [JIA W, FENG Y, QIAOX, et al. Variable Doppler Starting Point Keystone Transform for RadarManeuvering Target Detection[J]. Remote Sensing, 2024, 16(12): 2129.] uses the Doppler frequency shift method or the blind velocity starting point search method to compensate for the interpolation error of the semi-blind velocity point by dividing the data into intervals. However, this doubles the number of interpolation or transformation calculations, significantly increasing the computational load and making it difficult to meet the stringent real-time requirements of LFMCW radar. On the other hand, although the literature [Hong Yongbin, Gao Meiguo, Wang Jianming, et al. Suppression and elimination of Keystone transform semi-blind velocity point effect [J]. Journal of Electronics and Information Technology, 2014, 36(1): 175-180.] proposed an interpolation-free approximate compensation method under the pulse Doppler (PD) radar system, this method still requires additional ambiguity compensation and Doppler filtering, and its compensation effect is not ideal for target points not located in the center of the HBV band. More importantly, PD radar achieves ranging based on pulse threshold sampling, while LFMCW radar achieves ranging based on deskewing processing + range dimension FFT, and their range-Doppler coupling mechanisms are completely different. Due to the unique "range-frequency" coupling mechanism of LFMCW radar, if the existing frequency domain compensation strategy is directly applied to the LFMCW system, it will not only produce serious residual movement and energy defocus for targets deviating from the blind velocity center, but also introduce systematic Doppler velocity apparent offset, which cannot meet the accuracy requirements of engineering applications.

[0005] In summary, under the LFMCW radar system, the industry currently lacks a semi-blind velocity point elimination scheme that is adapted to the deskewing processing architecture, has low computational complexity, requires no time-domain interpolation, and has no performance loss in the full Doppler domain. Therefore, there is an urgent need to design a novel coherent accumulation processing architecture to completely eliminate target energy loss, missed detections, and system velocity measurement errors caused by semi-blind velocity points in extreme maneuvering scenarios, recover coherent accumulation gain, and thus significantly improve the radar's detection capability and ranging and velocity measurement accuracy for high-speed, weak targets. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a method and apparatus for Keystone transform range travel correction and elimination of the half-blind velocity effect (HBVE) in high-speed weak target detection of LFMCW radar. It aims to solve the energy defocusing problem caused by Sinc interpolation truncation in the prior art and avoid the residual travel and velocity blind bias caused by traditional frequency domain approximation compensation, so as to achieve the recovery of coherent accumulation gain with low hardware computing power.

[0007] The technical solution to achieve the objective of this invention is as follows: Firstly, this invention provides a method for Keystone transform range migration correction and semi-blind speed effect elimination in LFMCW radar, comprising the following steps:

[0008] S1: Acquire the baseband difference frequency echo signal of the LFMCW radar for the detected target, and construct a fast-time-slow-time two-dimensional echo matrix;

[0009] S2: Apply the conventional Keystone transform based on Sinc interpolation to the two-dimensional echo matrix to filter out Doppler blind velocity boundary data and extract the basic range-Doppler spectrum of the safe zone;

[0010] S3: Construct a time-domain compensation factor that includes radar frequency modulation slope and fast time variables, perform interpolation-free phase correction on the two-dimensional echo matrix, eliminate range-travel coupling, and extract the focusing main lobe of the target located in the blind velocity zone after two-dimensional Fourier transform.

[0011] S4: Calculate the absolute Doppler index corresponding to the true boundary velocity of the target, and through discrete point-to-point coordinate mapping, reassemble the focused main lobe into the blind velocity dead zone of the base distance-Doppler spectrum to obtain the panoramic blind zone-Doppler spectrum;

[0012] S5: Perform two-dimensional peak detection on the panoramic blind-spot-free distance-Doppler spectrum and output the true distance and velocity parameters of the detected target.

[0013] Furthermore, the time-domain compensation factor containing the radar frequency modulation slope and fast time variables mentioned in step S3 is constructed and corrected as follows: extract the center frequency of the LFMCW radar. With frequency modulation slope and obtain fast time variables In the fast time domain, the phase of the target to be compensated is directly rotated, and its phase compensation function is similar to... They are positively correlated, thus eliminating the scale shift of Doppler frequencies without the need for time-domain interpolation.

[0014] The time-domain compensation factor The construction formula is:

[0015]

[0016] in, The preset blind speed compensation value, At the speed of light, The center frequency of the carrier. For frequency modulation slope, For fast time indexing, For fast sampling intervals, For slow time indexing, This is the pulse repetition period.

[0017] Furthermore, the discrete point-to-point coordinate mapping process described in step S4 includes: calculating the absolutely correct Doppler index based on the target's prior limit blind velocity; extracting the center peak index of the target's main lobe in the blind velocity zone; establishing an equal translation mapping relationship between the source peak index and the absolutely correct Doppler index; translating and copying the main lobe of the target pixel by pixel to the base distance-Doppler spectrum; and forcibly clearing the false alarm data in the blind velocity dead zone.

[0018] According to the preset blind speed point Calculate the absolute Doppler index offset of the target in the digital frequency domain, relative to the system velocity resolution. ; Obtain the centroid index of the main lobe of the target focusing path in step S3. ;according to The absolute true Doppler index of the target is derived by reverse engineering. ;by Using the physical coordinate center, the pixel energy blocks of the focused main lobe are mapped in parallel and overlaid onto the corresponding positions of the basic distance-Doppler spectrum.

[0019] Furthermore, the two-dimensional peak detection in step S5 adopts the two-dimensional cell average constant false alarm rate (2D-CA-CFAR) detection algorithm or the two-dimensional ordered statistical constant false alarm rate (2D-OS-CFAR) detection algorithm.

[0020] In a second aspect, the present invention provides an LFMCW radar Keystone transform range travel correction and semi-blind speed effect elimination system for implementing the method described in the first aspect, the system comprising:

[0021] The baseband echo acquisition module is used to acquire the baseband difference frequency echo signal and construct a two-dimensional echo matrix;

[0022] The conventional frequency domain processing module is used to perform conventional Keystone transform on the two-dimensional echo matrix and extract the fundamental distance-Doppler spectrum;

[0023] The fast time-domain compensation module is used to construct time-domain compensation factors for interpolation-free phase correction and main lobe extraction;

[0024] The frequency domain mapping and reconstruction module is used to perform discrete coordinate mapping based on the absolute Doppler index and to reconstruct the main lobe of the blind velocity region without bias.

[0025] The target detection output module is used to perform two-dimensional peak detection on the reconstructed panoramic blind-spot-free distance-Doppler spectrum to output target parameters.

[0026] Thirdly, the present invention provides an LFMCW radar Keystone transform range travel correction and semi-blind speed effect elimination device for implementing the method described in the first aspect, the device comprising:

[0027] The radar radio frequency front end is used to transmit linear frequency modulated continuous waves and receive echoes, and to obtain the baseband difference frequency echo signal through deskewing processing.

[0028] An analog-to-digital converter, closely positioned at the output of the RF front end, is used to sample baseband signals and construct a two-dimensional echo matrix;

[0029] The processor is configured to perform the following operations: perform Keystone transform on the two-dimensional echo matrix to extract the safe zone spectrum; construct a time-domain compensation factor to perform interpolation-free phase correction and extract the main lobe of the blind velocity zone; perform discrete coordinate mapping and reconstruction based on the absolute Doppler index; and perform peak detection on the reconstructed panoramic spectrum to output the target parameters.

[0030] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method described in the first aspect.

[0031] A computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the method described in the first aspect.

[0032] A computer program product includes a computer program that, when executed by a processor, implements the steps of the method described in the first aspect.

[0033] Compared with the prior art, the significant advantages of the present invention are:

[0034] This invention features low computational complexity, directly utilizing the time-domain compensation factor for phase rotation in the blind speed processing branch, eliminating the need for computationally expensive Sinc interpolation and redundant multiple Fourier transform operations. This architecture reduces the computational load of blind speed compensation by approximately 50%, significantly saving on-chip storage and multiply-accumulator resources on embedded platforms such as FPGAs / DSPs, perfectly meeting the requirements of LFMCW radar for small size, low power consumption, low cost, and microsecond-level real-time performance.

[0035] This invention eliminates energy collapse in the semi-blind speed zone. Addressing the inherent range-frequency difference coupling characteristics of LFMCW radar, it abandons the traditional pulse Doppler (PD) frequency domain approximation compensation approach and proposes a fast time-domain phase compensation model based on the radar's frequency modulation slope. This model achieves continuous and smooth elimination of range travel, avoiding spectral aliasing and energy leakage at truncation boundaries caused by traditional Sinc interpolation. Compared to conventional methods, it can recover 13.14 dB of coherent accumulation gain at the extreme blind speed point, significantly improving the detection probability of low-altitude, weakly maneuvering targets.

[0036] This invention achieves high-precision velocity measurement without blind bias. Addressing the problem of apparent velocity offset easily generated by existing dual-path stitching methods, it designs a discrete spectrum frequency shift-based inverse reconstruction mechanism based on the target's true absolute physical velocity. By employing a point-to-point coordinate precise mapping method instead of traditional rigid matrix stitching, it not only ensures a seamless alignment of the main lobe energy in the blind velocity region on the RD two-dimensional graph but also completely eliminates the tearing false alarms and ghost peaks generated by conventional Keystone transform at Doppler boundaries, achieving zero-error system output for target velocity measurement. Attached Figure Description

[0037] Figure 1 is a flowchart of a method for Keystone transform range movement correction and semi-blind speed effect elimination for LFMCW radar provided in an embodiment of the present invention.

[0038] Figure 2 is a schematic diagram of the hardware device structure provided in an embodiment of the present invention.

[0039] Figure 3 The range-Doppler spectrum obtained by directly performing two-dimensional FFT processing when the target is in a normal motion state (non-semi-blind speed zone) and no motion compensation measures are taken in the embodiments of the present invention.

[0040] Figure 4 This is the result after applying the standard Keystone transformation.

[0041] Figure 5 The two-dimensional distance-Doppler spectrum is processed using the conventional Keystone transform method based on Sinc interpolation.

[0042] Figure 6 This invention provides a panoramic blind-spot-free distance-Doppler spectrum diagram for applying the fast time-domain interpolation-free phase compensation and dual-path stitching reconstruction method proposed in this invention.

[0043] Figure 7 This is a velocity profile generated at the Doppler crossover point using the traditional dual-path splicing method.

[0044] Figure 8 This is a high-precision velocity measurement profile diagram after the discrete point-to-point absolute index mapping and reconstruction of the present invention. Detailed Implementation

[0045] This invention discloses a method and apparatus for range migration correction and semi-blind speed effect elimination in Keystone transform for LFMCW radar. Addressing the energy defocusing and Doppler tearing problems in the semi-blind speed zone caused by Sinc interpolation truncation when processing high-speed maneuvering targets using conventional Keystone transform, this invention employs a dual-path parallel architecture. The conventional branch extracts the spectrum of the safe zone; the blind speed branch constructs a time-domain compensation factor containing the radar frequency modulation slope and fast time variables, achieving extreme focus of target energy by replacing high-computational-power interpolation with pure physical phase rotation; subsequently, based on the target's absolute Doppler index, a discrete point-to-point coordinate mapping mechanism is used to seamlessly reassemble the focused main lobe into the basic spectrum. This invention recovers the coherent accumulation loss caused by interpolation truncation, eliminates phantom peaks and velocity blind bias at Doppler boundaries, and significantly reduces the consumption of underlying hardware resources, meeting real-time detection requirements.

[0046] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the embodiments described.

[0047] Example 1

[0048] Reference Figure 1 The present invention provides a method for Keystone transform range migration correction and semi-blind speed effect elimination for LFMCW radar, which specifically includes the following steps:

[0049] Step 1: Discrete-time modeling of LFMCW difference frequency echo

[0050] Let the period of the linear frequency modulated continuous wave signal transmitted by the LFMCW radar be... The frequency modulation slope is , The sweep bandwidth is given by the carrier center frequency. It contains M pulses within a single coherent accumulation period (CPI). For an initial distance of... Radial velocity is The high-speed maneuvering target, its instantaneous distance is The radar echo signal, after being amplified with low noise, is mixed with the transmitted local oscillator signal (de-chirp processing) and then low-pass filtered. Let the fast-time sampling interval be... (Quick Time Index) (Slow time is) (Slow Time Index) Ignoring the residual video phase (RVP) term, which does not affect the final envelope position, the baseband difference frequency signal matrix after two-dimensional discretization is... The mathematical model can be precisely represented as:

[0051]

[0052] Where A is the echo amplitude and the instantaneous two-way delay. Phase term of baseband signal Expanded to:

[0053]

[0054] The first term is the fixed initial phase, and the second term includes the distance. The information difference frequency term (fast time frequency), the third term is the Doppler frequency shift term caused by target motion (slow time frequency), and the fourth term... This is the "fast time-slow time" coupling term. The physical meaning of this term is that the difference frequency of the target drifts as the slow time m increases, which is called range migration (RM).

[0055] Step 2: Analysis of the Mechanism of Conventional Keystone Transformation and Half-Blind Velocity Point (HBVE)

[0056] To eliminate fast-time-slow-time coupling terms, the conventional Keystone Transform (KT) introduces a virtual slow time. After scaling, the timescale transformation relationship under the LFMCW regime is as follows:

[0057]

[0058] By transforming the formula, the Doppler term and the coupling term can be merged into one. This decouples the distance from the Doppler.

[0059] However, in discrete digital signal processing, virtual slow time... Located on a uniform integer grid, the actual pulse index m obtained by solving is often a non-integer, and must be achieved by one-dimensional Sinc interpolation:

[0060]

[0061] And when the target Doppler frequency When the radar pulse repetition frequency approaches half (i.e., PRF / 2, the half-blind velocity point), the phase rotation between adjacent pulses approaches π radians. At this point, the interpolation kernel fractional truncation deviation is amplified to the extreme, and the frequency response characteristics of the Sinc function cause severe attenuation and folding of signal energy in the high-frequency region (edge ​​band) (spectral aliasing), which in turn causes defocusing and splitting of the target's main lobe on the two-dimensional range-Doppler (RD) map.

[0062] Step 3: Time-domain phase compensation without interpolation

[0063] To avoid the truncation error of the Sinc interpolation at the semi-blind velocity point, this invention proposes to abandon the time-domain interpolation operation for blind velocity targets.

[0064] Preset blind speed value for areas at the boundary of the blind speed zone (Corresponding to semi-blind speed), this invention directly constructs a physical phase compensation factor on the fast-time-slow-time two-dimensional time domain matrix. :

[0065]

[0066] For the original echo matrix Multiplying by the compensation factor yields the new compensated matrix. its new phase At this point, the baseband signal phase term can be expanded and recombined with similar terms to obtain:

[0067]

[0068] The target's true speed at this time Compared with blind speed assumption value Let the residual velocity deviation between them be Because the target was near the blind spot, Extremely small.

[0069] At this point, the new distance-walking coupling term becomes Throughout the entire coherent accumulation period ( Within this range, the maximum distance offset caused by this item. The range resolution is much smaller than that of the LFMCW radar. After pure time-domain phase multiplication and rotation, the residual range travel has been compressed into a single range resolution cell, meaning that coupling is eliminated at the physical level.

[0070] Therefore, for By directly performing a two-dimensional FFT (without any Sinc interpolation), target energy focusing can be achieved, fundamentally recovering the gain loss caused by interpolation truncation.

[0071] Step 4: Discrete Spectrum Frequency Shift Inverse Reconstruction Mechanism

[0072] After step S3, although the energy of the target in the blind zone is focused, its apparent position on the Doppler axis (slow time frequency domain) is shifted. Direct fusion would produce phantom peaks and system velocity measurement bias. Therefore, this embodiment employs discrete point-to-point absolute index mapping: calculating the discrete index offset of the preset blind velocity point in the digital frequency domain: ,in Let be the system velocity resolution. Suppose the centroid index of the target detected in the two-dimensional FFT spectrum of the S3 compensation branch is . The absolute true Doppler index of the target is derived by reverse engineering: Within the two-dimensional RD frequency domain, a 3*3 or 5*5 pixel energy block of the focused main lobe is extracted and horizontally shifted to the coordinates of the base spectrum. Through this coordinate translation mapping, the reconstructed panoramic image is perfectly aligned, and the target velocity measurement result has no blind bias.

[0073] Step 5: Parameter Output

[0074] Two-dimensional constant false alarm rate (2D-CFAR) detection is performed on the reconstructed panoramic blind-spot-free range-Doppler spectrum. Since energy has been recovered and false alarms have been eliminated in step S4, the detector can easily extract the target's true range and velocity parameters.

[0075] Through the above steps, this invention constructs a complete and efficient LFMCW radar coherent accumulation signal processing link, realizing interpolation-free accurate compensation for target range movement in the semi-blind velocity zone, seamless and unbiased reconstruction of the two-dimensional spectrum, and complete elimination of Doppler false peaks. Ultimately, it achieves high-precision ranging and blind-bias-free velocity measurement output for high-speed and weak targets.

[0076] The proposed method for Keystone transform range travel correction and semi-blind speed effect elimination in LFMCW radar was verified by simulation data processing. The experimental results fully demonstrate the effectiveness of the method.

[0077] The simulation experiment employed a typical LFMCW radar difference frequency echo model. To compare and verify the effectiveness of the proposed method, comparative simulation experiments were conducted against the conventional Keystone transform method, the traditional approximate compensation method, and the time-domain interpolation-free compensation and reconstruction method proposed in this invention. The main system parameters for the simulation experiment were set as follows: the radar center frequency was located in the millimeter-wave band at 35 GHz, the frequency modulation bandwidth was 1 GHz, the single sweep period (fast time window) was 50 μs, the number of coherent accumulation pulses was 1024, and the target radial velocity was set near the critical value of the system's semi-blind velocity boundary.

[0078] To establish a clear benchmark, the effectiveness of conventional distance movement phenomena and the basic Keystone transformation was first verified. Figure 3 The range-Doppler spectrum obtained by directly performing two-dimensional FFT processing when the target is in normal motion (not in the semi-blind velocity zone) and no motion compensation measures are taken is presented. As shown in the figure, due to the high-speed radial motion of the target, its echo envelope spans multiple range cells within the coherent accumulation time, resulting in severe range migration. This causes significant diffusion of the target energy along the range axis, making it impossible to form an effective focused peak. Figure 4The results after applying the conventional Keystone transform are presented. Time-scaled resampling successfully decoupled the range dimension from the Doppler dimension, allowing the energy to coherently accumulate and converge into a sharp main lobe, demonstrating the Keystone transform's ability to correct for linear range travel in the conventional Doppler region.

[0079] Figure 5 The two-dimensional range-Doppler spectrum after processing with the conventional Keystone transform method based on Sinc interpolation is presented. It can be seen that near the semi-blind velocity point, the interpolation truncation error causes severe energy defocusing of the target echo, and the main lobe collapses sharply. Figure 6 The panoramic blind-spot-free distance-Doppler spectrum after applying the fast time-domain interpolation-free phase compensation and dual-path stitching reconstruction proposed in this invention is presented, along with... Figure 5 In comparison, it is clear that phase rotation smoothly eliminates distance travel, and the target energy is refocused at the blind velocity position. To further verify the system's velocity measurement accuracy, Figure 7 The velocity profile generated at the Doppler crossover using the traditional dual-path stitching method is presented. The figure shows severe energy collapse and phantom peaks resulting from spectral crossover tearing. Figure 8 A high-precision velocity profile is presented after reconstruction using the discrete point-to-point absolute index mapping of this invention. Figure 7 In comparison, Figure 8 In the recombined spectrum, the target recovers the gain loss caused by interpolation truncation, and the target exhibits a single focused main lobe on the velocity axis. Ghost peaks are eliminated, and the target projection position perfectly matches its true physical velocity.

[0080] In terms of quantitative evaluation, the target radial velocity in this simulation scenario is set at the system's limiting semi-blind velocity point of 42.857 m / s. Traditional dual-path splicing methods suffer severe energy collapse and cross-boundary leakage at this point, resulting in significant velocity measurement errors. However, the velocity measurement error is eliminated after processing using the method of this invention. Simultaneously, regarding coherent accumulation gain, the amplitude of the reconstructed single-peak signal (576731) achieved by this invention represents a significant gain improvement of approximately 13.14 dB compared to the peak value (127090) after collapse using the traditional method, thus recovering the system signal-to-noise ratio loss caused by interpolation truncation.

[0081] Based on the above comparison chart, it is evident that the algorithm of this invention is remarkably effective in eliminating energy collapse in the semi-blind velocity region, recovering coherent accumulation gain, and achieving high-precision velocity measurement without blind bias.

[0082] Example 2

[0083] Reference Figure 2This embodiment provides an LFMCW radar Keystone transform range movement correction and semi-blind speed effect elimination device. This device is integrated into the LFMCW radar hardware system and is used for high-precision detection, ranging and speed measurement of high-speed maneuvering weak targets under autonomous driving collision avoidance or low-altitude UAV detection.

[0084] The device mainly includes a radar radio frequency front-end, an analog-to-digital converter (ADC), and a core digital signal processor.

[0085] The radar radio frequency front end mainly consists of millimeter-wave transceiver antennas and de-chirp mixing links, which are installed on a carrier platform (such as a vehicle or detection base station) and oriented towards the target area to be measured.

[0086] The analog-to-digital converter (ADC) is preferably a high-speed, high-precision digital sampling chip, tightly configured at the baseband output of the RF front-end, with its sampling timing strictly controlled by the radar system's master clock. This compact hardware layout ensures that the echo analog signal can be accurately discretized into a fast-time-slow-time two-dimensional data matrix, providing reliable raw data support for subsequent high-precision, interpolation-free underlying phase compensation.

[0087] The core digital signal processor is typically a field-programmable gate array (FPGA) or a dedicated digital signal processing chip (DSP), responsible for running the core signal processing algorithm of this invention and communicating with the host computer or other display and control terminals regarding the target trajectory. The core DSP is specifically configured with: a baseband echo acquisition module for real-time acquisition of the ADC two-dimensional echo matrix; a conventional frequency domain processing module for performing conventional Keystone transform and extracting the safe zone spectrum; a fast time domain compensation module for constructing a time domain compensation factor based on the radar frequency modulation slope and performing interpolation-free phase rotation; a frequency domain mapping and reconstruction module for performing discrete coordinate mapping based on absolute Doppler index to achieve unbiased stitching of the panoramic spectrum; and a target detection output module for peak detection of the reconstructed blind-zone-free two-dimensional spectrum to output the final physical parameters.

[0088] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

[0089] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for Keystone transform range travel correction and semi-blind speed effect elimination in LFMCW radar, characterized in that, Includes the following steps: S1: Acquire the baseband difference frequency echo signal of the LFMCW radar for the detected target and construct a fast-time-slow-time two-dimensional echo matrix; S2: Apply the conventional Keystone transform based on Sinc interpolation to the two-dimensional echo matrix to filter out Doppler blind velocity boundary data and extract the base range-Doppler spectrum of the safe zone; S3: Construct a time-domain compensation factor that includes radar frequency modulation slope and fast time variables, perform interpolation-free phase correction on the two-dimensional echo matrix, eliminate range-travel coupling, and extract the focusing main lobe of the target located in the blind velocity zone after two-dimensional Fourier transform. S4: Calculate the absolute Doppler index corresponding to the true boundary velocity of the target, and through discrete point-to-point coordinate mapping, reassemble the focused main lobe into the blind velocity dead zone of the base distance-Doppler spectrum to obtain the panoramic blind zone-Doppler spectrum; S5: Perform two-dimensional peak detection on the panoramic blind-spot-free distance-Doppler spectrum and output the true distance and velocity parameters of the detected target.

2. The method for Keystone transform range migration correction and semi-blind speed effect elimination of LFMCW radar according to claim 1, characterized in that: The time-domain compensation factor mentioned in step S3 The construction formula is: ； in, The preset blind speed compensation value, At the speed of light, The center frequency of the carrier. For frequency modulation slope, For fast time indexing, For fast sampling intervals, For slow time indexing, This is the pulse repetition period.

3. The method for Keystone transform range migration correction and semi-blind speed effect elimination of LFMCW radar according to claim 2, characterized in that: The discrete point-to-point coordinate mapping in step S4 includes the following process: based on the preset blind speed point Calculate the absolute Doppler index offset of the target in the digital frequency domain, relative to the system velocity resolution. ; Obtain the centroid index of the main lobe of the target focusing path in step S3. ;according to The absolute true Doppler index of the target is derived by reverse engineering. ;by Using the physical coordinate center, the pixel energy blocks of the focused main lobe are mapped in parallel and overlaid onto the corresponding positions of the basic distance-Doppler spectrum.

4. The method for Keystone transform range migration correction and semi-blind speed effect elimination of LFMCW radar according to claim 1, characterized in that: The two-dimensional peak detection in step S5 uses either the two-dimensional unit average constant false alarm rate detection algorithm or the two-dimensional ordered statistical constant false alarm rate detection algorithm.

5. A Keystone transform range migration correction and semi-blind speed effect elimination system for LFMCW radar, used to implement the method described in any one of claims 1-4, characterized in that, include: The baseband echo acquisition module is used to acquire the baseband difference frequency echo signal and construct a two-dimensional echo matrix; The conventional frequency domain processing module is used to perform conventional Keystone transform on the two-dimensional echo matrix and extract the fundamental distance-Doppler spectrum; The fast time-domain compensation module is used to construct time-domain compensation factors for interpolation-free phase correction and main lobe extraction; The frequency domain mapping and reconstruction module is used to perform discrete coordinate mapping based on the absolute Doppler index and to reconstruct the main lobe of the blind velocity region without bias. The target detection output module is used to perform two-dimensional peak detection on the reconstructed panoramic blind-spot-free distance-Doppler spectrum to output target parameters.

6. A device for Keystone transform range migration correction and semi-blind speed effect elimination in LFMCW radar, used to implement the method described in any one of claims 1-4, characterized in that, include: The radar radio frequency front end is used to transmit linear frequency modulated continuous waves and receive echoes, and to obtain the baseband difference frequency echo signal through deskewing processing. An analog-to-digital converter, closely positioned at the output of the RF front end, is used to sample baseband signals and construct a two-dimensional echo matrix; The processor is configured to perform the following operations: perform Keystone transform on the two-dimensional echo matrix to extract the safe zone spectrum; construct a time-domain compensation factor to perform interpolation-free phase correction and extract the main lobe of the blind velocity zone; perform discrete coordinate mapping and reconstruction based on the absolute Doppler index; and perform peak detection on the reconstructed panoramic spectrum to output the target parameters.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method as described in any one of claims 1-4.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1-4.

9. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method described in any one of claims 1-4.

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