Airborne radar non-positive lateral array space-time combined constraint sum-difference angle measurement method in clutter environment

Abstract

The invention discloses an airborne radar non-positive-side array space-time combined constraint sum-difference angle measurement method in a clutter environment, and solves the problems that in the prior art, complex changes of clutter characteristics in a non-positive-side view array cannot be effectively handled, and universality is poor. The method comprises the following steps: judging the working mode of a current radar, and determining space-time joint constraint conditions corresponding to different working modes; constructing a joint optimization model by using a linear constraint minimum variance criterion to obtain adaptive difference weights corresponding to different working modes, and determining a sum weight based on a space-time optimal weight of a maximum signal to interference plus noise ratio criterion; a Bayliss weight is distributed to the self-adaptive difference weight, a Taylor weight is distributed to the sum weight, a single pulse ratio is obtained through calculation, and then an angle estimation value is obtained through calculation according to the single pulse ratio; according to the method, different constraint schemes are provided according to different clutter spectrum characteristics, constraint points are dynamically adjusted to suppress the influence of clutter spectrum broadening, and shape preservation of an angle discrimination curve is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of airborne phased array radars, and in particular to a space-time joint constraint and difference angle measurement method for a non-frontal array of an airborne radar in a clutter environment. Background Art

[0002] Radar target detection and angle measurement in clutter environments have always faced severe challenges, with clutter being a key constraint affecting angle measurement accuracy. In a monostatic radar system, different array antenna placement patterns exhibit different clutter characteristics: Since the beam of a straight-looking array is perpendicular to the direction of the aircraft's motion, its clutter Doppler shift is symmetrically distributed on both sides of the zero frequency, and the spectrum broadening is relatively small. Since the beam of a forward-looking array is aligned with the direction of the aircraft's motion, the clutter exhibits distinct asymmetric characteristics, with a severely skewed Doppler shift distribution and significant spectrum broadening. Squint-looking arrays fall somewhere in between, with clutter exhibiting specific offset characteristics and a unique coupling relationship between Doppler shift and angle. These differentiated clutter characteristics pose significant challenges to traditional sum-and-difference beam angle measurement technology: on the one hand, angle measurement algorithms with fixed constraint point distributions struggle to adapt to the changing clutter characteristics under different array layouts; on the other hand, the broadening and offset of the clutter spectrum distort the Doppler-angle coupling relationship, severely affecting the linear characteristics of the difference-and-ratio curve. Especially in forward-looking and oblique-looking arrays, the severe broadening of the clutter spectrum significantly reduces the target signal-to-clutter ratio, sharply deteriorating the accuracy of traditional angle measurement methods. Furthermore, with the increasing real-time requirements of modern radar systems, how to ensure angle measurement accuracy while reducing computational complexity has become a key technical challenge that needs to be addressed.

[0003] Existing technical solutions: In their journal paper "STAP Single Pulse Angle Estimation Method for Airborne Radar Based on Joint Space-Time Constraints", Chen Gong et al. proposed a STAP single pulse angle estimation method based on a joint space-time constraint of a positive side-view array. The method extends the single pulse curve into a single pulse surface, and significantly improves the accuracy and robustness of target angle estimation through joint space-time constraints.

[0004] Existing algorithms are primarily optimized for orthogonal and side-viewing arrays, with uniformly distributed constraint points. This makes them ineffective in addressing the complex variations in clutter characteristics found in non-orthogonal and side-viewing arrays (such as front-view and oblique-view arrays), resulting in poor versatility. This limitation results in significant distortion in the angle detection curves of existing technologies, leading to significant performance degradation in non-orthogonal and side-viewing array applications. Summary of the Invention

[0005] The present invention provides a space-time joint constraint and difference angle measurement method for a non-side-view array of an airborne radar in a clutter environment, thereby solving the problems of the prior art in being unable to effectively cope with the complex changes in clutter characteristics under non-side-view arrays and having poor versatility. Different constraint schemes are proposed according to different clutter spectrum characteristics, and the constraint points are dynamically adjusted to suppress the influence of clutter spectrum broadening, thereby achieving conformal angle detection curve.

[0006] The present invention provides a method for space-time joint constraint and difference angle measurement of an airborne radar non-frontal array in a clutter environment, the method comprising: Determine the current radar operating mode and determine the space-time joint constraints corresponding to different operating modes; wherein the operating modes include: front-view mode, front-view mode, and oblique-view mode; Using the linear constrained minimum variance criterion, a joint optimization model is constructed based on the space-time joint constraints corresponding to different operating modes. Clutter suppression is performed on the main beam position, and adaptive difference weights corresponding to different operating modes are obtained. The sum weight is then determined based on the space-time optimal weights of the maximum signal-to-interference-and-noise ratio criterion. A Bayliss weight is assigned to the adaptive difference weight, a Taylor weight is assigned to the sum weight, a single pulse ratio is calculated based on the confirmed difference weight, the confirmed sum weight, and the actual received radar data vector, and then an angle estimate is calculated based on the single pulse ratio.

[0007] In a possible implementation, determining the space-time joint constraint conditions corresponding to different operating modes includes: Determine a clutter power spectrum of a positive side-view mode corresponding to the positive side-view mode, a clutter power spectrum of a forward-view mode corresponding to the forward-view mode, and a clutter power spectrum of a squint mode corresponding to the squint mode; The corresponding space-time joint constraints are determined according to the clutter power spectra of different modes.

[0008] In one possible implementation, constructing a joint optimization model based on the joint space-time constraints corresponding to different operating modes, performing clutter suppression on clutter at the main beam position, and obtaining adaptive difference weights corresponding to different operating modes includes: Determine the constraint matrix and constraint response vector corresponding to different working modes; Based on the criterion of linear constrained minimum variance, a joint optimization model is constructed according to the constraint matrix and the constraint response vector; The joint optimization model is solved using the Lagrange multiplier method to obtain the adaptive difference weight.

[0009] In a possible implementation, the space-time joint constraint condition is expressed as: ; in, represents the constraint matrix; represents the constraint response vector; represents the adaptive difference weight; represents the conjugate transpose.

[0010] In a possible implementation, the joint optimization model is expressed as: ; in, represents the adaptive difference weight; represents the clutter covariance matrix; represents the constraint response vector; represents the constraint matrix; represents the conjugate transpose.

[0011] In a possible implementation, the adaptive difference weight is expressed as: ; in, represents the clutter covariance matrix; represents the constraint matrix; represents the constraint response vector; represents the inverse of a matrix; represents the adaptive difference weight.

[0012] In a possible implementation, the sum weight is expressed as: ; in, represents the clutter covariance matrix; express The corresponding space-time steering vector; Indicates the pointing angle of the radar airspace main beam; Indicates the center frequency of the Doppler filter corresponding to the target; Representation and power.

[0013] In a possible implementation, the single pulse ratio is expressed as: ; in, Indicates the difference in rights after confirmation of ownership; Represents the actual received data vector; It means the right after the title is confirmed; represents the real part; represents the conjugate transpose.

[0014] One or more technical solutions provided in the present invention have at least the following technical effects or advantages: This invention deeply integrates space-time joint adaptive processing with single-pulse angle measurement technology. It dynamically adjusts space-time constraints for the three radar operating modes—front, side, and oblique—to generate adaptive difference weights and construct a joint optimization model. This significantly improves clutter suppression and main-beam signal-to-interference-noise ratio. Furthermore, by assigning Bayliss weights to the difference beam and Taylor weights to the sum beam, and using single-pulse ratios to calculate angles, it achieves high-precision angle measurement and strong anti-interference performance. Its core advantage lies in the organic combination of multi-mode adaptive processing, space-time joint optimization, and intelligent weight allocation. This balances clutter suppression depth, angle estimation accuracy, and real-time performance in complex environments, significantly improving the robustness and detection performance of radar systems compared to traditional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flowchart of the steps of a method for space-time joint constraint and difference angle measurement of an airborne radar non-frontal array in a clutter environment provided by an embodiment of the present invention; Figure 2 A geometric diagram of a moving platform array radar and ground clutter blocks provided by an embodiment of the present invention; Figure 3 A schematic diagram of the clutter power spectrum of the front-side looking array provided in an embodiment of the present invention; Figure 4 A schematic diagram of the clutter power spectrum of the forward-looking array provided in an embodiment of the present invention; Figure 5 A schematic diagram of the clutter power spectrum of a squint array provided in an embodiment of the present invention; Figure 6 A schematic diagram of the distribution of space-time joint constraint points of the front and side view array provided by an embodiment of the present invention; Figure 7 A schematic diagram of a single pulse curved surface of a positive side-view array provided in an embodiment of the present invention; Figure 8 A schematic diagram of the distribution of space-time joint constraint points of the forward-looking array provided in an embodiment of the present invention; FIG9( a ) is a schematic diagram of a single pulse surface of a forward-looking array with uniformly distributed constraint points provided by an embodiment of the present invention; FIG9( b ) is a schematic diagram of a single pulse surface of a forward-looking array with high-frequency dense distribution of constraint points provided by an embodiment of the present invention; Figure 10 A schematic diagram of the distribution of space-time joint constraint points of a squint array provided by an embodiment of the present invention; FIG11( a ) is a schematic diagram of a single pulse surface of a squint array when the constraint points are uniformly distributed according to an embodiment of the present invention; FIG11( b ) is a schematic diagram of a single pulse surface of a squint array with oblique strip distribution of constraint points provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0017] The present invention provides a method for joint space-time constraint and difference angle measurement of non-frontal array of airborne radar in clutter environment. Figure 1 The method includes the following steps S101 to S103.

[0018] S101, judging the current working mode of the radar, and determining the space-time joint constraint conditions corresponding to different working modes; wherein the working modes include: a front-view mode, a front-view mode, and a side-view mode.

[0019] Specifically, in step S101, the space-time joint constraint conditions corresponding to different working modes are determined, including the following S1011 to S1012.

[0020] S1011, determining a clutter power spectrum of a front-side-view mode corresponding to a front-side-view mode, a clutter power spectrum of a front-view mode corresponding to a front-view mode, and a clutter power spectrum of a squint mode corresponding to a squint mode; S1012: Determine corresponding space-time joint constraints according to clutter power spectra of different modes.

[0021] Here, the space-time joint constraint is expressed as: (1.1) in, represents the constraint matrix; represents the constraint response vector; represents the adaptive difference weight; represents the conjugate transpose.

[0022] For example, see Figure 2 , analyze the general array position form, the platform speed is , is the angle between the antenna axis and the direction of aircraft movement (also called yaw angle), are the spatial cone angles between the target and the antenna direction and the platform velocity direction, respectively. are the Doppler frequency domain and the maximum Doppler frequency, respectively, where .

[0023] From the geometric relationship in the figure, we can deduce: (1.2) when When the aircraft's motion direction is perpendicular to the array beam, it is a positive side-view array. Substituting it into formula (1.2) we can get the positive side-view array clutter power spectrum, which is expressed as: (1.3) Formula (1.3) can be rewritten as: (1.4) It can be seen that the clutter power spectrum of the positive side-view array is on the space-time two-dimensional plane ( ) is distributed in a straight line, and formula (1.4) is consistent with the azimuth angle. Therefore, the clutter power spectra at different distance units coincide, that is, the clutter is uniform along the distance direction. The simulation results show that the clutter power spectrum of the front side view array is as follows: Figure 3 shown.

[0024] when When , it is the forward-looking array, Substituting into formula (1.2) we can get the forward-looking mode clutter power spectrum, which is expressed as: (1.5) Formula (1.5) can be rewritten as: (1.6) Formula (1.6) presents an elliptical characteristic in the space-time two-dimensional plane coordinate system, and its elliptical parameters will change with the radar viewing angle. changes due to changes in the.

[0025] This geometric characteristic indicates that the distribution of clutter spectrum will be significantly different at different distance units, thus showing distance-dependent clutter spectrum characteristics. Figure 4 The actual distribution of the clutter power spectrum of the forward-looking array airborne radar is shown, and the spectrum broadening phenomenon caused by this distance dependence can be clearly observed. As the distance increases, the ratio of the major and minor axes of the ellipse changes significantly, causing the clutter spectrum of the close-range unit to be significantly wider than that of the far-range unit. This distance dependence directly affects the performance of space-time adaptive processing.

[0026] when When it is equal to other values, it is a squint array. At this time, the clutter spectrum is a slant ellipse on the two-dimensional plane, and the squint mode clutter power spectrum is expressed as formula (1.2).

[0027] See also Figure 5 , Figure 5 Give It can be seen that for a general squint array, the clutter spectrum is distributed in a slanted ellipse, the clutter is distance-dependent, and the clutter spectrum is broadened.

[0028] The clutter of the airborne radar shows a significant space-time coupling characteristic due to the movement of the carrier aircraft. In view of this characteristic, the present invention adopts the space-time joint domain ( The multi-constraint point optimization method of the plane is used to build an adaptive processing architecture through reasonably distributed constraint points. Figure 6 As shown, this method sets a series of optimization constraint points on the space-time two-dimensional plane.

[0029] exist Figure 6 middle, Indicates the pointing angle of the radar airspace main beam, The center frequency of the Doppler filter corresponding to the target, and They represent the distance between constraint points in the spatial and temporal directions respectively. and The value of is matched with the space-time resolution of the radar system and is usually set to 3dB beam width. ( is the number of constraint points in the beam direction) to ensure complete coverage of the main lobe clutter area.

[0030] The conditions of the space-time joint constraint can be written in the matrix form of formula (1.1). In formula (1.1), the constraint matrix and the constraint response vector They are: (1.7) Among them, the subscript " "" "" " represents the three different Doppler frequencies above and below the constraint point, is the static single pulse ratio slope.

[0031] In order to make the angle estimation method still have good robustness in the case of Doppler mismatch, the three Doppler frequencies should satisfy and The linear ratio between them is: (1.8) The single pulse ratio surface obtained by simulation is The projection on Figure 7 shown.

[0032] The forward-looking array beam is pointed in the same direction as the carrier's motion. The clutter spectrum is elliptical in distribution on a two-dimensional plane, and the spectrum is significantly broadened. This is due to the distance dependence of the clutter. Since short-range clutter is more dependent on distance, dense constraints are applied in the high-frequency region and sparse constraints are applied in the low-frequency region to constrain the difference beam. The constraint diagram is shown in the figure below. Figure 8 shown.

[0033] The space-time joint constraint conditions are the same as those for the front and side view arrays. The constraint matrix and the constraint response vector They are: (1.9) Among them, the subscript " "" "" " represents the three different Doppler frequencies above and below the constraint point, is the static single pulse slope ratio. The vectors are as follows: (1.10) in: .

[0034] After simulation analysis, the linearity of the angle detection curve is improved to a certain extent after the position of the forward-looking array constraint points is corrected. The simulation results are shown in Figures 9(a) and 9(b). Figure 9(a) is a schematic diagram of the single-pulse surface of the forward-looking array with uniformly distributed constraint points, and Figure 9(b) is a schematic diagram of the single-pulse surface of the forward-looking array with densely distributed constraint points at high frequencies.

[0035] Squint array, for general squint array, the clutter spectrum is oblique elliptical distribution, the clutter has distance dependence, the clutter spectrum is broadened, and the yaw angle The larger the value, the stronger the distance dependence of the clutter. The clutter has specific bias characteristics. The Doppler frequency shift forms a unique coupling relationship with the angle. From the clutter power spectrum, it can be seen that the clutter spectrum is distributed in an oblique elliptical pattern. According to the distribution of the oblique ellipse, the constraint points are distributed obliquely in the vicinity of the clutter spectrum according to the inclination of the ellipse. The constraint diagram is shown in the figure below. Figure 10 shown.

[0036] The space-time joint constraint can be written as formula (1.1). Constraint matrix and the constraint response vector They are: (1.11) The vectors are as follows: (1.12) After simulation analysis, the linearity of the angle detection curve is improved to a certain extent after the position of the forward-looking array constraint points is corrected. The simulation results are shown in Figures 11(a) and 11(b). Figure 11(a) is a schematic diagram of the single-pulse surface of the squint array when the constraint points are evenly distributed; Figure 11(b) is a schematic diagram of the single-pulse surface of the squint array when the constraint points are obliquely distributed in a strip-like pattern.

[0037] S102: Using the linear constrained minimum variance criterion, a joint optimization model is constructed based on the space-time joint constraints corresponding to different operating modes to suppress clutter from the main beam position. Adaptive difference weights corresponding to different operating modes are obtained, and sum weights are determined based on the space-time optimal weights of the maximum signal-to-interference-and-noise ratio criterion. Specifically, in step S102, a joint optimization model is constructed according to the space-time joint constraints corresponding to different working modes, clutter suppression is performed on the clutter at the main beam position, and adaptive difference weights corresponding to different working modes are obtained, including the following steps S1021 to S1023.

[0038] S1021, determining the constraint matrix and constraint response vector corresponding to different working modes; it should be noted that this result is obtained from step S101.

[0039] S1022: Based on the linear constrained minimum variance criterion, a joint optimization model is constructed according to the constraint matrix and the constraint response vector.

[0040] Here, the joint optimization model is expressed as: (1.13) in, represents the adaptive difference weight; represents the clutter covariance matrix; represents the constraint response vector; represents the constraint matrix; represents the conjugate transpose.

[0041] S1023: Solve the joint optimization model using a Lagrange multiplier method to obtain an adaptive difference weight.

[0042] Here, the adaptive difference weight is expressed as: (1.14) in, represents the clutter covariance matrix; represents the constraint matrix; represents the constraint response vector; represents the inverse of a matrix; represents the adaptive difference weight.

[0043] Specifically, the sum weight in step S102 is expressed as: (1.15) in, represents the clutter covariance matrix; express The corresponding space-time steering vector; Indicates the pointing angle of the radar airspace main beam; Indicates the center frequency of the Doppler filter corresponding to the target; Representation and power.

[0044] For example, although This ensures that the monopulse ratio maintains ideal linearity, but it does not fully address the need for clutter suppression. To further improve angle estimation accuracy, it is necessary to simultaneously optimize the clutter suppression performance of the difference beam. Based on the linear constrained minimum variance (LCMV) criterion, the following joint optimization model is constructed. Here, the joint optimization model is represented by Equation (1.13).

[0045] Joint optimization model maintains constraints This ensures that the ratio of the difference beam to the sum beam is linearly related to the deflection angle; and minimizes the difference beam output power to achieve optimal clutter suppression.

[0046] This optimization problem can be solved using the Lagrange multiplier method to obtain adaptive difference weights. This solution can maximize the suppression of clutter power while maintaining the linearity of the single pulse ratio, thereby significantly improving the accuracy and robustness of angle estimation.

[0047] S103, assigning Bayliss weights to the adaptive difference weights, assigning Taylor weights to the sum weights, calculating a single pulse ratio based on the weighted difference weights, the weighted sum weights, and the actual received radar data vector, and then calculating an angle estimate based on the single pulse ratio.

[0048] Here, the single pulse ratio is expressed as: (1.16) in, Indicates the difference in rights after confirmation of ownership; Represents the actual received data vector; It means the right after the title is confirmed; represents the real part; represents the conjugate transpose.

[0049] For example, since the target signal detection is performed in the sum beam, in order to ensure the detection performance, only the difference weight is considered to be constrained, and the adaptive sum weight adopts the space-time optimal weight based on the maximum signal-to-interference-and-noise ratio (MSINR) criterion, that is, the sum weight formula (1.15).

[0050] Finally, add Taylor weight to the sum weight , difference weight plus Bayliss weight , we get the final difference and sum of the rights, that is, the difference and sum of the rights after confirmation: (1.17) The single pulse ratio is calculated based on the sum and difference weights and is expressed as formula (1.16).

[0051] Since the single pulse ratio and the deflection angle Satisfies the linear relationship: , from which the deflection angle can be obtained , and finally calculate the angle estimate: (1.18) Compared with the existing technology, the present invention has achieved all-round performance breakthroughs: 1. Through the dynamic space-time constraint mechanism, adaptive processing of three array layouts: side view, front view and oblique view is realized for the first time; 2. To address the Doppler mismatch problem, high-frequency dense constraint distribution and oblique strip constraint distribution are used to improve the linearity of single pulse ratio, effectively suppressing the angle measurement jump caused by the high-speed movement of the carrier aircraft; 3. There is no need to develop special algorithms for different array layouts. One system can meet diverse deployment needs, greatly reducing the research and development and maintenance costs of equipment.

[0052] The various embodiments in this specification are described in a progressive manner. References to the same or similar parts between the various embodiments are sufficient. Each embodiment focuses on the differences from other embodiments. All or part of the present invention can be used in a variety of general or specialized computer system environments or configurations. For example, personal computers, server computers, handheld or portable devices, tablet devices, mobile communication terminals, multiprocessor systems, microprocessor-based systems, programmable electronic devices, network PCs, minicomputers, mainframe computers, and distributed computing environments that include any of the above systems or devices.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it should be understood by those skilled in the art that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the present invention.

Claims

1. A method for joint space-time constraint and difference angle measurement of non-frontal array of airborne radar in clutter environment, characterized by: include: Determine the current radar operating mode and determine the space-time joint constraints corresponding to different operating modes; wherein the operating modes include: front-view mode, front-view mode, and oblique-view mode; Using the linear constrained minimum variance criterion, a joint optimization model is constructed based on the space-time joint constraints corresponding to different operating modes. Clutter suppression is performed on the main beam position, and adaptive difference weights corresponding to different operating modes are obtained. The sum weight is then determined based on the space-time optimal weights of the maximum signal-to-interference-and-noise ratio criterion. A Bayliss weight is assigned to the adaptive difference weight, a Taylor weight is assigned to the sum weight, a single pulse ratio is calculated based on the confirmed difference weight, the confirmed sum weight, and the actual received radar data vector, and then an angle estimate is calculated based on the single pulse ratio.

2. The method for joint space-time constraint and difference angle measurement of non-frontal array of airborne radar in clutter environment according to claim 1 is characterized in that: Determining the space-time joint constraint conditions corresponding to different working modes includes: Determine a clutter power spectrum of a positive side-view mode corresponding to the positive side-view mode, a clutter power spectrum of a forward-view mode corresponding to the forward-view mode, and a clutter power spectrum of a squint mode corresponding to the squint mode; The corresponding space-time joint constraints are determined according to the clutter power spectra of different modes.

3. The method for joint space-time constraint and difference angle measurement of non-frontal array of airborne radar in clutter environment according to claim 1 is characterized in that: The joint optimization model is constructed according to the space-time joint constraints corresponding to different working modes, clutter suppression is performed on the clutter at the main beam position, and adaptive difference weights corresponding to different working modes are obtained, including: Determine the constraint matrix and constraint response vector corresponding to different working modes; Based on the criterion of linear constrained minimum variance, a joint optimization model is constructed according to the constraint matrix and the constraint response vector; The joint optimization model is solved using the Lagrange multiplier method to obtain the adaptive difference weight.

4. The method for joint space-time constraint and difference angle measurement of non-frontal array of airborne radar in clutter environment according to claim 1 is characterized in that: The space-time joint constraint condition is expressed as: ； in, represents the constraint matrix; represents the constraint response vector; represents the adaptive difference weight; represents the conjugate transpose.

5. The method for joint space-time constraint and difference angle measurement of non-frontal array of airborne radar in clutter environment according to claim 1 is characterized in that: The joint optimization model is expressed as: ； in, represents the adaptive difference weight; represents the clutter covariance matrix; represents the constraint response vector; represents the constraint matrix; represents the conjugate transpose.

6. The method for joint space-time constraint and difference angle measurement of non-frontal array of airborne radar in clutter environment according to claim 1 is characterized in that: The adaptive difference weight is expressed as: ； in, represents the clutter covariance matrix; represents the constraint matrix; represents the constraint response vector; represents the inverse of a matrix; represents the adaptive difference weight.

7. The method for joint space-time constraint and difference angle measurement of non-frontal array of airborne radar in clutter environment according to claim 1 is characterized in that: The sum is expressed as: ； in, represents the clutter covariance matrix; express The corresponding space-time steering vector; Indicates the pointing angle of the radar airspace main beam; Indicates the center frequency of the Doppler filter corresponding to the target; Representation and power.

8. The method for joint space-time constraint and difference angle measurement of non-frontal array of airborne radar in clutter environment according to claim 1 is characterized in that: The single pulse ratio is expressed as: ； in, Indicates the difference in rights after confirmation of ownership; Represents the actual received data vector; It means the right after the title is confirmed; represents the real part; represents the conjugate transpose.

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