All-digital array low-altitude early warning radar

Abstract

The invention relates to a low-altitude radar, in particular to an all-digital array low-altitude early warning radar, which comprises a digital beam forming module, realizes rapid pointing adjustment of beams and simultaneous formation of multiple beams by digitally controlling the amplitude and phase of each array element in an antenna array, and supports omni-directional scanning of a low-altitude airspace and residence in a key area; the broadband signal processing module is used for generating a high-resolution linear frequency modulation LFM signal, completing pulse compression and Doppler processing of an echo signal, realizing distance-speed joint resolution and meeting a low-speed low-altitude target detection requirement; the self-adaptive interference suppression module is used for dynamically suppressing interference in a low-altitude environment and improving the signal-to-noise ratio of a target; the multi-target tracking and decision-making module is used for realizing multi-target state estimation and trajectory prediction and supporting threat level evaluation and alarm decision-making; according to the technical scheme provided by the invention, the defects that the low-speed low-altitude target is difficult to accurately monitor and the low-altitude safety prevention and control capability is insufficient in the prior art can be effectively overcome.

Description

Technical Field

[0001] This invention relates to low-altitude radar, and more specifically to a fully digital array low-altitude early warning radar. Background Technology

[0002] With the increasing openness of low-altitude airspace, the number of low-altitude aircraft such as drones and light aircraft has increased dramatically. These aircraft are characterized by low flight altitude, slow speed, and high maneuverability, and are easily obstructed by complex terrain (such as urban buildings and mountains), posing numerous challenges to traditional radar in low-altitude detection. On the one hand, mechanically scanned radars, limited by their physical rotation speed, struggle to achieve rapid, all-around coverage of low-altitude airspace, easily missing fast-moving targets. On the other hand, the beamforming methods of traditional radars are less flexible, making it impossible to conduct long-term surveillance of key areas (such as the area around airports and above sensitive facilities), resulting in insufficient target tracking continuity. Furthermore, the low-altitude environment is filled with ground clutter and human interference (such as communication base stations and electronic countermeasures equipment). Traditional radars have limited anti-jamming capabilities, resulting in low target signal-to-noise ratios and difficulty in effectively extracting slow-moving low-altitude target signals from strong clutter backgrounds.

[0003] At the signal processing level, the Doppler frequencies of low-altitude targets overlap with the spectra of ground clutter, making it difficult for traditional pulse compression and Doppler processing techniques to achieve joint high resolution of range and velocity, resulting in a decline in the detection performance of slow-moving low-altitude targets. Simultaneously, in low-altitude multi-target scenarios, traditional radars lack efficient multi-target state estimation and trajectory prediction capabilities, and threat level assessment relies on manual intervention, making it difficult to meet real-time decision-making requirements.

[0004] Therefore, developing a low-altitude early warning radar with capabilities such as rapid beamforming, high-resolution signal processing, strong interference suppression, and intelligent multi-target tracking has become crucial for improving the level of low-altitude airspace security surveillance. All-digital array low-altitude early warning radar, through the integration of technologies such as digital beamforming, broadband signal processing, adaptive interference suppression, and multi-target tracking decision-making, provides an effective approach to solving these problems. Summary of the Invention

[0005] (a) Technical problems to be solved In view of the above-mentioned shortcomings of the existing technology, the present invention provides a fully digital array low-altitude early warning radar, which can effectively overcome the shortcomings of the existing technology in that it is difficult to accurately monitor slow-moving low-altitude targets and the lack of low-altitude security control capabilities.

[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: A fully digital array low-altitude early warning radar, including: The digital beamforming module achieves rapid beam pointing adjustment and simultaneous multi-beam formation by digitally controlling the amplitude and phase of each element in the antenna array, supporting all-around scanning and key area stationary in the low-altitude airspace. The broadband signal processing module generates a high-resolution linear frequency modulated (LFM) signal, performs pulse compression and Doppler processing on the echo signal, and achieves joint range-velocity resolution to meet the requirements for slow-speed, low-altitude target detection. An adaptive interference suppression module dynamically suppresses interference in low-altitude environments, improving the target signal-to-noise ratio; The multi-target tracking and decision-making module enables multi-target state estimation and trajectory prediction, and supports threat level assessment and alarm decision-making.

[0007] Preferably, the digital beamforming module achieves rapid beam pointing adjustment and simultaneous multi-beam formation by digitally controlling the amplitude and phase of each element in the antenna array, supporting omnidirectional scanning and focused area coverage in low-altitude airspace, including: The beam pointing can be quickly adjusted by digitally controlling the amplitude and phase of each element in the antenna array, and the beam direction is determined by the weighted vector. Multiple independent beams are formed simultaneously by orthogonal weighted vector groups, covering different airspaces and supporting all-round scanning of low-altitude airspace and stationing in key areas.

[0008] Preferably, the method of rapidly adjusting the beam direction by digitally controlling the amplitude and phase of each element in the antenna array, wherein the beam direction is determined by a weighted vector, includes: Beam direction is determined by weighted vector Let N be the number of array elements, and the complex weighting coefficient of the i-th array element be determined. for: ; Among them, A i The magnitude weighting of the complex weighting coefficients of the i-th array element is applied. The phase weighting of the complex weighting coefficients of the i-th array element. , The beam azimuth angle, λ is the wavelength, and d is the element spacing.

[0009] Preferably, the method of simultaneously forming multiple independent beams through orthogonal weighted vector groups to cover different airspaces and support omnidirectional scanning and focused area coverage in low-altitude airspace includes: Using orthogonal weighted vector groups Simultaneously, M independent beams are formed, covering different airspaces, supporting all-round scanning of low-altitude airspace and stationing in key areas.

[0010] Preferably, the broadband signal processing module generates a high-resolution linear frequency modulated (LFM) signal, performs pulse compression and Doppler processing on the echo signal, achieves joint range-velocity resolution, and meets the requirements for detecting slow-moving, low-altitude targets, including: Generate a high-resolution linear frequency modulated (LFM) signal s(t): ; Where t is time, T is the pulse width (i.e., the effective duration of the signal), rect is the rectangular window function, and f c Where is the carrier frequency, i.e., the center frequency of the signal, and K is the frequency modulation slope. B represents bandwidth.

[0011] Preferably, the broadband signal processing module generates a high-resolution linear frequency modulated (LFM) signal, performs pulse compression and Doppler processing on the echo signal, achieves joint range-velocity resolution, and meets the requirements for detecting slow-moving, low-altitude targets, including: After the echo signal is pulse-compressed and then subjected to matched filtering to improve signal performance, the pulse compression ratio CR is: ; Among them, the pulse compression ratio CR reflects the ratio between the peak power of the output signal and the average power of the input signal after matched filtering; Distance resolution for: ; Where c is the speed of light.

[0012] Preferably, the adaptive interference suppression module dynamically suppresses interference in the low-altitude environment and improves the target signal-to-noise ratio, including: To address ground clutter, multipath interference, and intentional interference in low-altitude environments, the space-time adaptive processing (STAP) technique is employed to dynamically suppress interference in low-altitude environments and improve the target signal-to-noise ratio.

[0013] Preferably, the method of dynamically suppressing interference in the low-altitude environment by employing space-time adaptive processing (STAP) technology to address ground clutter, multipath interference, and intentional interference includes: In the filter design of STAP (Spatial-Time Adaptive Processing), the optimal weight vector The solution is obtained by jointly minimizing the filter's output power and the constraints: ; in, For weight vectors, weight vector The conjugate transpose of R xx Let covariance matrix be the variance matrix. This represents the filter's response power to the input signal, i.e., the filter's output power. `st` indicates that the power is limited by... Target azimuth angle The steering vector defines the filter's desired response to the target signal. , The spatial guidance vector represents the direction of the target within the array plane. Let f be the time-guided vector, representing the target's Doppler frequency. d , The Kronecker product represents the space-time joint processing.

[0014] Preferably, the multi-target tracking and decision-making module realizes multi-target state estimation and trajectory prediction, supports threat level assessment and alarm decision-making, including: Based on Kalman filtering and data association algorithms, multi-target state estimation and trajectory prediction are achieved, supporting threat level assessment and alarm decision-making.

[0015] Preferably, the Kalman filter and data association algorithm for multi-target state estimation and trajectory prediction, supporting threat level assessment and alarm decision-making, includes: The state equation for Kalman filtering is: ; Where, x k x k+1 Let w be the state vector at time step k and time step k+1, respectively, F be the state transition matrix, and w be the state vector at time step k+1. k This is process noise; The observation equation for Kalman filtering is: ; Among them, z k Let v be the observation vector at time step k, H be the observation matrix, and v be the observation vector. k To observe noise; The target threat index TI is calculated using the following formula to assess the threat level: ; Where v is the target's normalized velocity, and h is the target's normalized altitude. From the perspective of normalization of the objective, A, B, and C are all weighting coefficients.

[0016] (III) Beneficial Effects Compared with existing technologies, the all-digital array low-altitude early warning radar provided by this invention has the following advantages: 1) Flexible beam control enhances low-altitude detection performance The digital beamforming module achieves rapid beam pointing adjustment and simultaneous multi-beam formation by digitally controlling the amplitude and phase of each element in the antenna array. This feature enables the radar to support all-around rapid scanning of the low-altitude airspace, significantly shortening target search time and improving the monitoring coverage of the low-altitude airspace. At the same time, it can conduct long-term surveillance of key areas, ensuring continuous monitoring of critical areas and effectively avoiding the target miss problem caused by the mechanical scanning speed limitation of traditional radar. For example, in complex urban environments, low-altitude targets are easily obscured by buildings. The flexible beam adjustment capability of this module can quickly adjust the beam direction to accurately capture low-altitude targets hidden between buildings, achieving accurate monitoring of low-altitude targets. 2) Intelligent signal processing and anti-interference to enhance target processing and security control capabilities. The broadband signal processing module generates high-resolution linear frequency modulated (LFM) signals and performs pulse compression and Doppler processing on the echo signals, achieving high-resolution range-velocity joint processing. This enables the radar to clearly distinguish targets at different distances and speeds, especially meeting the need for precise monitoring of slow-moving low-altitude targets (such as UAVs and airships), effectively solving the problem of traditional radar in detecting slow-moving low-altitude targets. Simultaneously, the adaptive interference suppression module dynamically suppresses various types of interference in the low-altitude environment, significantly improving the target signal-to-noise ratio and enhancing the radar's operational stability in complex electromagnetic environments. The multi-target tracking and decision-making module further realizes multi-target state estimation and trajectory prediction, supporting threat level assessment and alarm decision-making. It can track multiple low-altitude targets in real time, accurately predict their trajectories, and assess their threat level based on parameters such as speed, altitude, and direction, promptly issuing alarm information. This provides strong decision support for low-altitude security and effectively ensures the safety of the low-altitude airspace. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 This is a schematic diagram of the system of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] The following describes the specific functional modules of the all-digital array low-altitude early warning radar provided by this invention, using concrete examples (such as...). Figure 1 As shown in the figure, and considering the technical effects, the system functional modules include: The digital beamforming module achieves rapid beam pointing adjustment and simultaneous multi-beam formation by digitally controlling the amplitude and phase of each element in the antenna array, supporting all-around scanning and key area stationary in the low-altitude airspace. The broadband signal processing module generates a high-resolution linear frequency modulated (LFM) signal, performs pulse compression and Doppler processing on the echo signal, and achieves joint range-velocity resolution to meet the requirements for slow-speed, low-altitude target detection. An adaptive interference suppression module dynamically suppresses interference in low-altitude environments, improving the target signal-to-noise ratio; The multi-target tracking and decision-making module enables multi-target state estimation and trajectory prediction, and supports threat level assessment and alarm decision-making.

[0021] I. Digital Beamforming Module The digital beamforming module achieves rapid beam pointing adjustment and simultaneous multi-beam formation by digitally controlling the amplitude and phase of each element in the antenna array. It supports omnidirectional scanning and focused area coverage in low-altitude airspace, including: Rapid beam pointing is achieved by digitally controlling the amplitude and phase of each element in the antenna array. The beam direction is determined by a weighted vector, including: Beam direction is determined by weighted vector Let N be the number of array elements, and the complex weighting coefficient of the i-th array element be determined. for: ; Among them, A i The magnitude weighting of the complex weighting coefficients of the i-th array element is applied. The phase weighting of the complex weighting coefficients of the i-th array element. , The beam azimuth angle, λ is the wavelength, and d is the element spacing. Multiple independent beams are simultaneously formed using orthogonal weighted vector groups, covering different airspaces and supporting omnidirectional scanning and focused area coverage in low-altitude airspace, including: Using orthogonal weighted vector groups Simultaneously, M independent beams are formed, covering different airspaces, supporting all-round scanning of low-altitude airspace and stationing in key areas.

[0022] The aforementioned technical solution utilizes a digital beamforming module that digitally controls the amplitude and phase of each element in the antenna array to achieve rapid beam pointing adjustment and simultaneous multi-beam formation. This feature enables the radar to support omnidirectional rapid scanning of low-altitude airspace, significantly shortening target search time and improving the monitoring coverage of low-altitude airspace. Simultaneously, it allows for long-term surveillance of key areas, ensuring continuous monitoring of critical regions and effectively avoiding target misses caused by the mechanical scanning speed limitations of traditional radars. For example, in complex urban environments, low-altitude targets are easily obstructed by buildings; the module's flexible beam control capability can quickly adjust the beam direction to accurately capture low-altitude targets hidden among buildings, achieving precise monitoring of low-altitude targets.

[0023] II. Broadband Signal Processing Module The broadband signal processing module generates a high-resolution linear frequency modulated (LFM) signal, performs pulse compression and Doppler processing on the echo signal, and achieves joint range-velocity resolution to meet the requirements for detecting slow-moving, low-altitude targets, including: Generate a high-resolution linear frequency modulated (LFM) signal s(t): ; Where t is time, T is the pulse width (i.e., the effective duration of the signal), rect is the rectangular window function, and f c Where is the carrier frequency, i.e., the center frequency of the signal, and K is the frequency modulation slope. B represents bandwidth.

[0024] The broadband signal processing module generates a high-resolution linear frequency modulated (LFM) signal, performs pulse compression and Doppler processing on the echo signal, and achieves joint range-velocity resolution to meet the requirements for detecting slow-moving, low-altitude targets, including: After the echo signal is pulse-compressed and then subjected to matched filtering to improve signal performance, the pulse compression ratio CR is: ; Among them, the pulse compression ratio CR reflects the ratio between the peak power of the output signal and the average power of the input signal after matched filtering; Distance resolution for: ; Where c is the speed of light.

[0025] III. Adaptive Interference Suppression Module The adaptive interference suppression module dynamically suppresses interference in low-altitude environments and improves the target signal-to-noise ratio, including: To address ground clutter, multipath interference, and intentional interference in low-altitude environments, the space-time adaptive processing (STAP) technique is employed to dynamically suppress interference in low-altitude environments and improve the target signal-to-noise ratio, including: In the filter design of STAP (Spatial-Time Adaptive Processing), the optimal weight vector The solution is obtained by jointly minimizing the filter's output power and the constraints: ; in, For weight vectors, weight vector The conjugate transpose of R xx Let covariance matrix be the variance matrix. This represents the filter's response power to the input signal, i.e., the filter's output power. `st` indicates that the power is limited by... Target azimuth angle The steering vector defines the filter's desired response to the target signal. , The spatial guidance vector represents the direction of the target within the array plane. Let f be the time-guided vector, representing the target's Doppler frequency. d , The Kronecker product represents the space-time joint processing.

[0026] IV. Multi-target tracking and decision-making module The multi-target tracking and decision-making module enables multi-target state estimation and trajectory prediction, supports threat level assessment and alarm decision-making, including: Based on Kalman filtering and data association algorithms, multi-target state estimation and trajectory prediction are achieved, supporting threat level assessment and alarm decision-making, including: The state equation for Kalman filtering is: ; Where, x k x k+1 Let w be the state vector at time step k and time step k+1, respectively, F be the state transition matrix, and w be the state vector at time step k+1. k This is process noise; The observation equation for Kalman filtering is: ; Among them, z k Let v be the observation vector at time step k, H be the observation matrix, and v be the observation vector. k To observe noise; The target threat index TI is calculated using the following formula to assess the threat level: ; Where v is the target's normalized velocity, and h is the target's normalized altitude. From the perspective of normalization of the objective, A, B, and C are all weighting coefficients.

[0027] The aforementioned technical solution utilizes a broadband signal processing module to generate a high-resolution linear frequency modulated (LFM) signal and performs pulse compression and Doppler processing on the echo signal, achieving joint range-velocity high resolution. This enables the radar to clearly distinguish targets at different distances and speeds, particularly meeting the need for precise monitoring of slow-moving low-altitude targets (such as UAVs and airships), effectively solving the challenges of traditional radar in detecting slow-moving low-altitude targets. Simultaneously, the adaptive interference suppression module dynamically suppresses various types of interference in the low-altitude environment, significantly improving the target signal-to-noise ratio and enhancing the radar's operational stability in complex electromagnetic environments. The multi-target tracking and decision-making module further realizes multi-target state estimation and trajectory prediction, supporting threat level assessment and alarm decision-making. It can track multiple low-altitude targets in real time, accurately predict their trajectories, and assess their threat level based on parameters such as speed, altitude, and direction, promptly issuing alarm information. This provides strong decision support for low-altitude security and effectively ensures the safety of the low-altitude airspace.

[0028] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fully digital array low altitude warning radar, characterized in that: The application relates to a low-altitude air defense radar system, which comprises the following modules: A digital beam forming module, which realizes rapid directional adjustment of a beam and simultaneous formation of multiple beams by digitally controlling the amplitude and phase of each array element in an antenna array, supports omnidirectional scanning and key area residence in a low-altitude airspace, and comprises the following parts: A wideband signal processing module, which generates a high-resolution linear frequency modulation (LFM) signal, completes pulse compression and Doppler processing of echo signals, realizes joint distance-velocity resolution, and meets the detection requirements of slow low-altitude targets; An adaptive interference suppression module, which dynamically suppresses interference in a low-altitude environment and improves the signal-to-noise ratio of targets; A multi-target tracking and decision module, which realizes multi-target state estimation and trajectory prediction and supports threat level evaluation and alarm decision.

2. The all-digital array low altitude warning radar of claim 1, wherein: The digital beam forming module realizes rapid directional adjustment of a beam and simultaneous formation of multiple beams by digitally controlling the amplitude and phase of each array element in an antenna array, supports omnidirectional scanning and key area residence in a low-altitude airspace, and comprises the following parts: Rapid directional adjustment of a beam is realized by digitally controlling the amplitude and phase of each array element in an antenna array, and the direction of the beam is determined by a weighted vector; Multiple independent beams are simultaneously formed by an orthogonal weighted vector group, different airspaces are covered, and omnidirectional scanning and key area residence in a low-altitude airspace are supported.

3. The all-digital array low altitude warning radar of claim 2, wherein: The rapid directional adjustment of a beam by digitally controlling the amplitude and phase of each array element in an antenna array and the determination of the direction of the beam by a weighted vector comprise the following parts: The beam direction is determined by a weighting vector N is the number of array elements, and the complex weighting coefficient of the i-th array element is is ； where A i is the amplitude weighting of the complex weighting coefficient of the i-th array element, is the phase weighting of the complex weighting coefficient of the i-th array element, , is the beam azimuth angle, is the wavelength, and d is the array element spacing.

4. The all-digital array low altitude warning radar of claim 3, wherein: The simultaneous formation of multiple independent beams by an orthogonal weighted vector group, the covering of different airspaces, and the support of omnidirectional scanning and key area residence in a low-altitude airspace comprise the following parts: By orthogonal weighting vector sets M independent beams are formed at the same time, covering different spaces, supporting all-around scanning and key area residence in low-altitude airspace.

5. The all-digital array low altitude warning radar of claim 1, wherein: The wideband signal processing module generates a high-resolution linear frequency modulation (LFM) signal, completes pulse compression and Doppler processing of echo signals, realizes joint distance-velocity resolution, and meets the detection requirements of slow low-altitude targets, and comprises the following parts: A high-resolution linear frequency modulation (LFM) signal s(t) is generated: ； where t is time, T is the pulse width, i.e. the effective duration of the signal, rect is a rectangular window function, f c is the carrier frequency, i.e. the center frequency of the signal, K is the frequency modulation slope, and B is the bandwidth.

6. The all-digital array low altitude warning radar of claim 5, wherein: The wideband signal processing module generates a high-resolution linear frequency modulation (LFM) signal, completes pulse compression and Doppler processing of echo signals, realizes joint distance-velocity resolution, and meets the detection requirements of slow low-altitude targets, and comprises the following parts: After the echo signal is pulse compressed and the signal performance is improved through a matching filter technology, the pulse compression ratio CR is: ； Wherein, the pulse compression ratio CR reflects the ratio between the peak power of the output signal after the matching filter and the average power of the input signal; Distance resolution is: ； Wherein, c is the speed of light.

7. The all-digital array low altitude warning radar of claim 1, wherein: The adaptive interference suppression module dynamically suppresses interference in a low-altitude environment and improves the signal-to-noise ratio of targets, and comprises the following parts: For ground clutter, multipath interference and intentional interference in a low-altitude environment, a space-time adaptive processing (STAP) technology is adopted to dynamically suppress interference in a low-altitude environment and improve the signal-to-noise ratio of targets.

8. The all-digital array low altitude warning radar of claim 7, wherein: For ground clutter, multipath interference and intentional interference in a low-altitude environment, a space-time adaptive processing (STAP) technology is adopted to dynamically suppress interference in a low-altitude environment and improve the signal-to-noise ratio of targets, and comprises the following parts: In the filter design of space-time adaptive processing (STAP), the optimal weight vector The filter is jointly solved by minimizing the output power and the constraint condition: ； wherein is a weight vector, is a weight vector is a conjugate transpose of R xx is a covariance matrix, denotes the response power of the filter to the input signal, i.e. the output power of the filter, s.t. denotes subject to, is a steering vector of the target expected azimuth defines the desired response of the filter to the target signal, , is a spatial steering vector, denoting the direction of the target within the array plane, is a temporal steering vector, denoting the Doppler frequency f d , is a Kronecker product, denoting a joint space-time processing.

9. The all-digital array low altitude warning radar of claim 1, wherein: The multi-target tracking and decision module realizes multi-target state estimation and trajectory prediction and supports threat level evaluation and alarm decision, and comprises the following parts: Based on a Kalman filter and a data association algorithm, multi-target state estimation and trajectory prediction are realized, and threat level evaluation and alarm decision are supported.

10. The all-digital array low altitude warning radar of claim 9, wherein: The Kalman filter and data association algorithm realizes multi-target state estimation and trajectory prediction, supports threat level evaluation and alarm decision, and comprises the following steps: The state equation of the Kalman filter is as follows: ； where x k , x k+1 are state vectors at time step k, k+1, respectively, F is a state transition matrix, w k is process noise; The observation equation of the Kalman filter is as follows: ； where z k is the observation vector at time step k, H is the observation matrix, v k is the observation noise; The target threat index TI is calculated by the following formula to evaluate the threat level: ； where v is the normalized speed of the target, h is the normalized height of the target, is the normalized angle of the target, and A, B, and C are weight coefficients.

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