A real-time beam pointing correction method based on echo and difference ratio and carrier height

Abstract

The application provides a real-time beam pointing correction method based on echo and difference ratio and carrier height, and belongs to the technical field of radar control, and the method comprises the following steps: step one, obtaining sum path distance-Doppler data and pitch difference path distance-Doppler data after pulse compression and FFT processing respectively, and the current height of the carrier; step two, calculating the sum and difference amplitude ratio of the sum path distance-Doppler data and the pitch difference path distance-Doppler data, and determining the distance corresponding to the maximum sum and difference amplitude ratio; step three, calculating the actual pointing angle of the beam based on the distance corresponding to the maximum sum and difference amplitude ratio and the current height of the carrier, and obtaining the pointing angle deviation based on the actual pointing angle of the beam and the control pointing angle; step four, feeding back the pointing angle deviation to the radar beam control system, and adjusting the pointing of the radar beam based on the pointing angle deviation and the control pointing angle, so that the pointing angle of the radar beam approaches the actual pointing angle, and the pointing correction of the real-time beam of the radar is completed.

Description

Technical Field

[0001] This invention belongs to the field of radar control technology, and specifically relates to a real-time beam pointing correction method based on echo and difference ratio and aircraft altitude. Background Technology

[0002] In radar systems, pitch pointing deviation refers to the angular error between the actual pitch pointing of the antenna and the theoretical pitch pointing. This angular error is usually caused by mechanical installation errors, antenna deformation, carrier vibration, or changes in ambient temperature. This deviation will directly affect the accuracy of the radar system in measuring the target pitch angle, thereby reducing the accuracy of target positioning or the reliability of detection.

[0003] Traditional methods for correcting pitch pointing deviations involve leveling the aircraft platform on the ground, measuring the actual pitch axis pointing of the radar antenna using a high-precision angle meter, and then testing to eliminate the deviation. However, this method relies on manual operation, cannot compensate for deviations caused by dynamic environments (such as carrier vibration and changes in ambient temperature) in real time, and lacks sufficient sensitivity to correct minute deviations. Summary of the Invention

[0004] The purpose of this invention is to provide a real-time beam pointing correction method based on echo sum-difference ratio and aircraft altitude, so as to solve or alleviate at least one of the problems in the background art.

[0005] The technical solution of this invention is: 1. A real-time beam pointing correction method based on echo sum-difference ratio and aircraft altitude, comprising:

[0006] Step 1: Obtain the sum-Doppler distance and pitch difference distance-Doppler data after pulse compression and FFT processing, respectively, as well as the current altitude of the aircraft;

[0007] Step 2: Calculate the sum-difference ratio of the pitch difference path distance-Doppler data and the pitch difference path distance-Doppler data, and determine the distance corresponding to the largest sum-difference ratio;

[0008] Step 3: Calculate the actual beam pointing angle based on the distance corresponding to the maximum sum-difference amplitude ratio and the current altitude of the carrier aircraft; and obtain the pointing angle deviation based on the actual beam pointing angle and the control pointing angle.

[0009] Step four: Feedback the pointing angle deviation to the radar beam control system. The radar beam control system adjusts the pointing of the radar beam based on the pointing angle deviation and the control pointing angle, so that the pointing angle of the radar beam is close to the actual pointing angle, thus completing the real-time pointing correction of the radar beam.

[0010] In a preferred embodiment of the present invention, the method for calculating the sum-difference ratio is as follows:

[0011]

[0012] In the formula, γ(i) is the amplitude ratio of the sum path pulse voltage at the i-th frequency gate to the FFT-generated signal or data S(i,M) and the pitch difference path pulse voltage to the FFT-generated signal or data E(i,M). =1, 2, ..., N.

[0013] In a preferred embodiment of the present invention, the actual beam pointing angle θ d The calculation method is as follows:

[0014]

[0015] In the formula, R is the distance corresponding to the maximum sum-difference ratio, and H is the current altitude of the aircraft.

[0016] In a preferred embodiment of the present invention, the pointing angle deviation In the formula, θ is the control pointing angle.

[0017] In addition, the present invention also provides a radar system, the radar system including a radar control system, the radar control system employing the real-time beam pointing correction method based on echo sum-difference ratio and aircraft altitude as described above for radar elevation beam control.

[0018] The method of this invention is based on real-time radar-received main clutter echoes and aircraft altitude data. It features a short calculation cycle (milliseconds), strong real-time performance, and applicability to dynamic flight scenarios. This method relies solely on the radar's own sum and difference channels and altitude sensor, without depending on external equipment such as INS / GPS, making it interference-resistant and cost-effective. This invention directly reflects the physical nature of beam pointing deviation (energy distribution differences) through the sum and difference amplitude ratio. After correction, the beam pointing error is less than 0.2° (in typical scenarios), resulting in higher beam control precision. Attached Figure Description

[0019] To more clearly illustrate the technical solution provided by the present invention, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention.

[0020] Figure 1 This is a schematic diagram of the radar real-time beam pointing correction method of the present invention.

[0021] Figure 2 This is a schematic diagram of a pulse compression FFT according to an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of differential pulse compression FFT according to an embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the sum-difference amplitude ratio curve before compensation in one embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of the sum-difference amplitude ratio curve after compensation in one embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be described in more detail below with reference to the accompanying drawings.

[0026] This invention provides a method for calculating and correcting the actual beam pointing deviation in real time based on the ratio of the main clutter echo received by the airborne radar itself and the current altitude of the aircraft. This method can solve the problems of poor real-time performance, reliance on external references, and insufficient altitude adaptability in traditional technologies, thereby improving the beam pointing accuracy of airborne radar in dynamic flight and complex ground clutter environments.

[0027] Main clutter is a strong reflected signal generated when airborne radar illuminates the ground. Its echo intensity is strongly correlated with the downward angle of the radar beam pointing towards the ground (the angle between the beam axis and the horizontal plane). When there is a pointing deviation in the radar beam, the difference between the actual and theoretical downward angle will cause changes in the energy distribution of the main clutter in the sum and difference beam directions (manifested as a change in the amplitude ratio γ of the sum and difference channels). Combining the aircraft's current altitude H (which determines the geometry of the ground illumination area), a formula can be established: "sum and difference amplitude ratio γ - actual pitch angle θ". d The mapping model of "-height H" can deduce the actual beam pointing deviation angle in real time, thereby correcting the beam control parameters.

[0028] Based on the above, such as Figure 1 As shown, the radar real-time beam pointing correction method based on echo sum-difference ratio and aircraft altitude provided by the present invention includes:

[0029] Step 1: Obtain the sum-Doppler distance data, pitch difference-Doppler distance data, and the current altitude of the aircraft after pulse compression and FFT (Fourier Transform) processing.

[0030] In this invention, the signals or data received by the radar at a certain scanning azimuth include the sum path pulse compression and FFT-derived signal or data S(N,M) and the pitch difference path pulse compression and FFT-derived signal or data E(N,M), where M represents the range gate number in each reception cycle and N represents the FFT points in one frame. Simultaneously, the current altitude H of the aircraft is obtained through an onboard altitude sensor (radio altimeter or laser altimeter).

[0031] Step 2: Calculate the amplitude ratio of the pitch difference path distance-Doppler data to the pitch difference path distance-Doppler data, and determine the distance corresponding to the maximum amplitude ratio.

[0032] Assuming the main clutter of the current signal is at frequency gate n, the sum-difference amplitude ratio is calculated sequentially for the amplitudes of all distance gates of the signal or data S(N,M) and E(N,M) at that frequency gate. This ratio can characterize the energy focusing difference of the main clutter in the sum-difference direction. When the beam is precisely pointed to the target area, the difference channel amplitude is the smallest, and the sum-difference amplitude ratio γ approaches the maximum. When there is a pointing deviation of the beam, the difference channel captures part of the clutter energy, and the sum-difference amplitude ratio γ decreases.

[0033] In this invention, the method for calculating the sum-difference ratio is as follows: In the formula, γ(i) is the amplitude ratio of the sum path pulse voltage at the i-th frequency gate to the FFT-generated signal or data S(i,M) and the pitch difference path pulse voltage to the FFT-generated signal or data E(i,M). =1, 2, ..., N.

[0034] Step 3: Calculate the actual beam pointing angle based on the distance corresponding to the maximum amplitude ratio and the current altitude of the carrier aircraft, and obtain the pointing angle deviation based on the actual beam pointing angle and the control pointing angle;

[0035] In this invention, the actual pointing angle (pitch angle) of the wave speed is calculated according to the following formula. In the formula, R is the distance corresponding to the range gate when the maximum sum-difference amplitude ratio γ is reached (i.e., the slant distance of the beam center illuminating the ground), and H is the current altitude of the carrier aircraft.

[0036] Furthermore, based on the actual beam pointing angle The beam pointing angle deviation can be calculated. , In the formula, θ is the control pointing angle. Pointing angle deviation A positive value indicates that the actual beam deflects downwards, and a negative value indicates the opposite.

[0037] For example, in this embodiment of the invention, the main clutter frequency gate of the current signal is at position 14 of the pulse sequence, such as... Figure 2 As shown, the sum-path pulse voltage at this frequency gate is sequentially calculated with the amplitudes of all distance gates of the FFT-generated signal or data S(N,M) and pitch difference pulse voltage is sequentially calculated with the amplitudes of all distance gates of the FFT-generated signal or data E(N,M). .like Figure 3 As shown, the range gate corresponding to the maximum value of the sum-difference amplitude ratio γ(i) is 1925. At this time, the current altitude H of the carrier aircraft is approximately 250m. The actual beam pointing angle can be calculated according to the above formula. The value is -1.2565°, and the controlled beam pointing angle at this time is... It is -1.01°. This is determined by the pointing angle deviation. It can calculate the beam pointing angle deviation. The angle is 0.2465°, at which point the actual beam deflects downwards.

[0038] Step four: Feedback the pointing angle deviation to the radar beam control system. The radar beam control system adjusts the pointing of the radar beam based on the pointing angle deviation and the control pointing angle, so that the pointing angle of the radar beam is close to the actual pointing angle, thus completing the real-time pointing correction of the radar beam.

[0039] In this invention, by deviating the pointing angle Feedback is sent to the radar beam control system (such as the phase shifter control unit of a phased array antenna or the mechanical scanning drive mechanism), which then adjusts the theoretical pointing parameters of the beam (e.g., correcting the original theoretical beam pointing angle θ (elevation angle) to...). ±| |), making the actual beam angle approximate the actual beam pointing angle. This eliminates pointing deviation.

[0040] like Figure 4 and Figure 5 As shown, before correction, range gate 1925 was corrected according to the beam pointing angle; after correction, range gate 2209 corresponds to the beam pointing angle. The value is -0.7497°, while the controlled beam pointing angle θ is -0.69°. Calculate the beam pointing angle deviation. The angle is 0.0597°, which effectively improves pointing accuracy.

[0041] This invention calculates and corrects the actual beam pointing deviation in real time based on the ratio of the main clutter echo received by the airborne radar and the current altitude of the aircraft. It has been verified by actual flight test data of a certain type of millimeter-wave radar and has a good effect on pitch pointing deviation correction.

[0042] The method of this invention is based on real-time radar-received main clutter echoes and aircraft altitude data. It features a short calculation cycle (milliseconds), strong real-time performance, and applicability to dynamic flight scenarios. This method relies solely on the radar's own sum and difference channels and altitude sensor, without depending on external equipment such as INS / GPS, making it interference-resistant and cost-effective. This invention directly reflects the physical nature of beam pointing deviation (energy distribution differences) through the sum and difference amplitude ratio. After correction, the beam pointing error is less than 0.2° (in typical scenarios), resulting in higher beam control precision.

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A real-time beam pointing correction method based on echo sum-difference ratio and aircraft altitude, characterized in that, include: Step 1: Obtain the sum-Doppler distance and pitch difference distance-Doppler data after pulse compression and FFT processing, respectively, as well as the current altitude of the aircraft; Step 2: Calculate the sum-difference ratio of the pitch difference path distance-Doppler data and the pitch difference path distance-Doppler data, and determine the distance corresponding to the largest sum-difference ratio; Step 3: Calculate the actual beam pointing angle based on the distance corresponding to the maximum sum-difference amplitude ratio and the current altitude of the carrier aircraft; and obtain the pointing angle deviation based on the actual beam pointing angle and the control pointing angle. Step four: Feedback the pointing angle deviation to the radar beam control system. The radar beam control system adjusts the pointing of the radar beam based on the pointing angle deviation and the control pointing angle, so that the pointing angle of the radar beam is close to the actual pointing angle, thus completing the real-time pointing correction of the radar beam.

2. The real-time beam pointing correction method based on echo sum-difference ratio and aircraft altitude as described in claim 1, characterized in that, The method for calculating the sum-difference ratio is as follows: In the formula, γ(i) is the amplitude ratio of the sum path pulse voltage at the i-th frequency gate to the FFT-generated signal or data S(i,M) and the pitch difference path pulse voltage to the FFT-generated signal or data E(i,M). =1, 2, ..., N.

3. The real-time beam pointing correction method based on echo sum-difference ratio and aircraft altitude as described in claim 1, characterized in that, The actual pointing angle of the beam θ d The calculation method is as follows: In the formula, R is the distance corresponding to the maximum sum-difference ratio, and H is the current altitude of the aircraft.

4. The real-time beam pointing correction method based on echo sum-difference ratio and aircraft altitude as described in claim 3, characterized in that, The pointing angle deviation In the formula, θ is the control pointing angle.

5. A radar system, characterized in that, The radar system includes a radar control system, which employs a real-time beam pointing correction method based on echo sum-difference ratio and aircraft altitude as described in any one of claims 1 to 4 for radar elevation beam control.

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