Sum-difference angle measurement method based on angle discrimination curve piecewise fitting

Abstract

The invention discloses a sum and difference angle measurement method based on angle discrimination curve piecewise fitting, which belongs to the field of signal processing, and comprises the following steps: firstly, carrying out digital beam synthesis on four-quadrant signals, synthesizing a sum beam, an azimuth difference beam and a pitch difference beam, and measuring the amplitude of the sum beam, the amplitude of the azimuth difference beam and the amplitude of the pitch difference beam; thirdly, according to a fixed frequency interval, completing beam pattern scanning of M frequency points of a target frequency band, calculating a sum-difference amplitude comparison result, and generating M groups of angle measurement parameters by adopting an angle discrimination curve segmentation fitting method; and finally, measuring signal frequency, sum beam amplitude, azimuth difference beam amplitude, pitch difference beam amplitude, azimuth sum difference phase difference and pitch sum difference phase difference in real time, selecting angle measurement parameters according to a frequency proximity principle, and calculating a target azimuth angle and a pitch angle in real time. According to the invention, sum-difference angle measurement of a wide-frequency-domain signal receiving system can be realized, the angle measurement precision is improved, and the engineering realization complexity is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of signal receiving recognition, and particularly relates to a sum-difference angle measurement method based on angle discriminator curve piecewise fitting. BACKGROUND

[0002] The function of the radiation source receiving recognition system is to intercept the enemy's radiation source signals in the target frequency domain and space domain and determine the parameter characteristics. The radiation source angle measurement is one of the important functions of the next generation of signal receiving recognition equipment, and whether the angle measurement result is accurate directly relates to the performance index of the signal receiving recognition system and will directly affect the interception effect of the radar. At present, the angle measurement technologies for the radar radiation source mainly include adjacent beam amplitude comparison angle measurement, interferometer angle measurement and the like. The sum-difference angle measurement method applied to the signal receiving recognition is not mentioned in the public literature.

[0003] The electromagnetic threat environment faced by the radar system is complex and changes in an instant, and the means of the traditional signal receiving recognition equipment relying only on the frequency information for the radiation source recognition has great limitations and cannot meet the application requirements of the radar. The angle measurement function can accurately obtain the spatial angle information of the target, provides another dimension information for the radiation source recognition in the spatial multi-radiation source background, and significantly improves the signal receiving recognition performance. SUMMARY

[0004] In view of the problem that the existing signal receiving recognition system lacks the angle measurement function, the limitation of the signal receiving recognition relying only on the frequency function, and the difficulty in adapting to the radar working requirements in the complex electromagnetic environment, the application provides an angle measurement method for the signal receiving recognition system. The method generates the angle measurement coefficient through the angle discriminator curve piecewise fitting, has high angle measurement accuracy, adopts the direct calculation mode, simplifies the table lookup calculation process, improves the calculation efficiency, has high real-time performance, has low engineering complexity, and has high engineering application value.

[0005] The technical solution of the application is as follows: a sum-difference angle measurement method based on angle discriminator curve piecewise fitting, comprising the following steps:

[0006] Step 1: performing digital beam synthesis on the four-quadrant signal to obtain a sum beam, an azimuth difference beam and an elevation difference beam, and measuring the sum beam amplitude, the azimuth difference beam amplitude and the elevation difference beam amplitude, and entering step 2.

[0007] Step 2: completing the beam pattern scanning of M frequency points in the target frequency band according to a fixed frequency interval FreqInter, calculating the sum-difference amplitude comparison result, generating M groups of angle measurement parameters by using the angle discriminator curve piecewise fitting method, and taking the target frequency band bandwidth as TargetBandW, so that the value of M is TargetBandW / FreqInter, and entering step 3.

[0008] Step 3, according to the real-time measured signal frequency, and beam amplitude, azimuth difference beam amplitude, elevation difference beam amplitude, azimuth and difference beam phase difference, elevation and difference beam phase difference, select the angle measurement parameter according to the frequency proximity principle, and real-time calculate the target azimuth angle and elevation angle.

[0009] Compared with the prior art, the present application has the following advantages:

[0010] 1) The present application realizes a sum-difference angle measurement engineering implementation method which can be used for wide frequency domain signal reception, and generates multiple sets of angle measurement coefficients in the target frequency band through fixed frequency interval, and selects the angle measurement coefficient corresponding to the nearest frequency point according to the real-time frequency measurement result, so as to cover a wide frequency domain and reduce the angle measurement error.

[0011] 2) The present application proposes an improved sum-difference angle measurement method, which generates angle measurement coefficients through piecewise fitting according to the slope change characteristics of the angle measurement curve, reduces the angle measurement error caused by curve fitting error compared with the conventional curve fitting method, improves the angle measurement precision, and reduces the engineering implementation complexity compared with the table lookup method. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The sum-difference angle measurement method based on piecewise fitting of the angle measurement curve according to the present application. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0014] The technical solutions of the various embodiments of the present application can be combined with each other, but it must be based on the fact that they can be realized by those skilled in the art. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection claimed by the present application.

[0015] The specific embodiments and the technical difficulties and points of the present application will be further introduced below with reference to the examples of the present application.

[0016] In combination with Figure 1The and-difference angle measurement method based on the segmented fitting of the angle-discrimination curve is suitable for the signal receiving and identification technology of receiving and identifying the enemy's radiation source. The and-difference angle measurement method based on the segmented fitting of the angle-discrimination curve has the characteristics of the simplicity of directly calculating the angle measurement and the improved fitting precision of the angle-discrimination curve through the segmented mode, thereby improving the angle measurement precision. The main processing flow is as shown in the figure Figure 1 The and-difference angle measurement method based on the segmented fitting of the angle-discrimination curve is suitable for the signal receiving and identification technology of receiving and identifying the enemy's radiation source. The and-difference angle measurement method based on the segmented fitting of the angle-discrimination curve has the characteristics of the simplicity of directly calculating the angle measurement and the improved fitting precision of the angle-discrimination curve through the segmented mode, thereby improving the angle measurement precision. The main processing flow is as shown in the figure

[0017] Step 1, the four-quadrant signals are subjected to digital beam synthesis to obtain the sum beam, the azimuth difference beam and the elevation difference beam, and the sum beam amplitude, the azimuth difference beam amplitude and the elevation difference beam amplitude are measured, and step 2 is entered.

[0018] Step 2, the beam pattern scanning of M frequency points in the target frequency band is completed according to the fixed frequency interval FreqInter, the sum-difference amplitude ratio result is calculated, and the segmented fitting method of the angle-discrimination curve is used to generate M groups of angle measurement parameters, the target frequency band bandwidth is TargetBandW, and the value of M is TargetBandW / FreqInter, and the specific steps are as follows:

[0019] Step 21, the target frequency is set as f1, the azimuth angle is set as Atheta0, and the elevation angle is set as Etheta0. The control azimuth beam is directed to step by step scanning according to the fixed angle interval detatheta, and a total of N angles are scanned, and the azimuth beam scanning sequence Atheta is represented as {Atheta1, Atheta2, …, AthetaN}. The sum beam amplitude value and the azimuth difference beam amplitude value corresponding to each angle are measured, and the sum beam pattern and the azimuth difference beam pattern are generated.

[0020] Step 22, the segmented fitting method of the angle-discrimination curve is used to generate the azimuth direction angle measurement parameter APara_1 of the frequency point f1, and the specific steps are as follows:

[0021] Step 22_1, the curve fitting sequence is extracted:

[0022] Due to the symmetry of the angle-discrimination curve about the normal line of the beam pointing direction, the sequence corresponding to the monotonous angle-discrimination curve needs to be selected for fitting;

[0023] The target azimuth angle sequence theta is represented as {theta1, theta2, …, thetaN}, wherein thethetan=Athetan-Atheta0, and the azimuth sum-difference beam amplitude ratio sequence K is represented as {K1, K2, …, KN}.

[0024] The fitting sequence extraction process is as follows:

[0025] 1) Find the maximum value Kzero of the K sequence, that is, the zero-depth position;

[0026] 2) Find the value greater than or equal to 0 degrees in {theta(Nzero), theta(Nzero+1), …, theta(N_Af1)} to generate the azimuth angle fitting sequence theta_nh as {theta_nh1, theta_nh2 … theta_nhL}, L is the number of elements that meet the conditions, and generate the corresponding azimuth and difference amplitude ratio fitting sequence K_nh as {K_nh1, K_nh2 … K_nhL}.

[0027] Wherein, Nzero is the index value of the element in the sequence K that meets the condition.

[0028] Step 22_2, calculate the curve segment threshold coefficient: find the minimum value Kmin and the maximum value Kmax in {K_nh1, K_nh2 … K_nhL} respectively, and take the threshold coefficient Athreshold1=(Kmin+Kmax) / 2;

[0029] Step 22_3, perform angle identification curve segment fitting: take the threshold coefficient Athreshold1 as the limit, and perform one-time curve fitting on the L1 angle corresponding to the group of sum-difference amplitude ratio value sequence {K_nh1, K_nh2 … K_nhL1} and the angle sequence {theta_nh1, theta_nh2 … theta_nhL1} whose difference ratio value is greater than Athreshold1, the fitting formula is theta_nhl=AK1*K_nhl+AP1, and the curve slope AK1 and the constant AP1 are the first segment angle measurement coefficient Apara1_1 of the azimuth direction of the frequency point; Perform one-time curve fitting on the L2(L=L1+L2) angle corresponding to the group of sum-difference amplitude ratio value sequence {K_nhL1+1, K_nhL1+2 … K_nhL} and the angle sequence {theta_nhL1+1, theta_nhL1+2 … theta_nhL} whose difference ratio value is less than Athreshold1, the fitting formula is theta_nhl=AK2*K_nhl+AP2, and the curve slope AK2 and the constant AP2 are the second segment angle measurement coefficient Apara1_2 of the azimuth direction of the frequency point.

[0030] Step 22_4, calculating the zero-depth overbound protection parameter: the zero-depth overbound protection parameter AZeroPara_1 is set as -AP1 / AK1; the azimuth angle parameter APara_1 of the frequency point f1 is expressed as {Athreshold_1, Apara_11, Apara_12, AZeroPara_1}; the azimuth angle parameter APara_m of the frequency point fm is expressed as {Athreshold_m, Apara_m1, Apara_m2, AZeroPara_m}, and fm represents any one of f1, f2, …, and fM.

[0031] Step 23, repeating step 22 to generate the azimuth angle parameters APara_2, APara_3, …, and APara_M of f2, f3, …, and fM in sequence.

[0032] Step 24, repeating steps 21 to 23 to generate the elevation angle parameters EPara_1, EPara_2, …, and EPara_M of each frequency point.

[0033] Step 25, storing the angle parameters in sequence according to the frequency points, and expressing APara_1 and EPara_1 as the angle parameters Para_1, expressing APara_2 and EPara_2 as the angle parameters Para_2, and so on, to generate the full-band angle parameter table as Para_1, Para_2, …, and Para_M.

[0034] Go to step 3.

[0035] Step 3, selecting the angle parameters according to the frequency proximity principle based on the real-time measured signal frequency, and the beam amplitude, the azimuth difference beam amplitude, the elevation difference beam amplitude, the azimuth sum difference beam phase difference, and the elevation sum difference beam phase difference, and real-time calculating the target azimuth angle and the elevation angle;

[0036] Step 31, measuring the signal frequency Fmeasure in real time, and selecting a group of angle parameters Para_m corresponding to the frequency point most adjacent to Fmeasure.

[0037] Step 32, calculating the azimuth sum difference amplitude ratio AKmeasure, and if AKmeasure is greater than AZeroPara_m, the absolute value DetaA of the target deviation from the beam normal angle is 0; otherwise, if AKmeasure is greater than Athreshold_m, the angle parameter Apara_m1 is selected, DetaA = AKmeasure*AK1+AP1, otherwise the angle parameter Apara_m2 is selected, DetaA = AKmeasure*AK2+AP2.

[0038] Step 33: Calculate the phase difference Detafai between the azimuth difference beam and the sum beam, and determine the sign of DetaA based on the value of Detafai. The tolerance is deta. If the range of Detafai is [270-deta, 270+deta], DetaA is negative. If the range of Detafai is [90-deta, 90+deta], DetaA is positive. Otherwise, DetaA is set to 0.

[0039] Step 34: Calculate the target azimuth angle TthetaA according to the current beam azimuth Atheta0 and DetaA, where TthetaA=Atheta0+DetaA.

[0040] Step 35: Repeat steps 31 to 34 to calculate the target pitch angle TthetaE.

[0041] Based on engineering application results, compared to traditional lookup tables, which require a large storage space for angle measurement parameters, which increases with increasing beamwidth, this method requires a fixed storage space for angle measurement parameters. Based on the problem of increased angle measurement error near zero degrees due to zero-depth variations in angle measurement curves with different signal-to-noise ratios, a zero-depth protection threshold was proposed, effectively addressing the increased angle measurement error near zero degrees. Compared to single curve fitting methods, this method effectively reduces the angle measurement error caused by curve fitting and improves angle measurement accuracy. The measured root mean square error of angle measurement was reduced from 0.5302° to 0.4378°.

Claims

1. A method for sum and difference angle measurement based on segmented fitting of angle detection curves, characterized in that: The following steps are involved: Step 1: Perform digital beam synthesis on the four-quadrant signals to obtain a sum beam, an azimuth difference beam, and an elevation difference beam, and measure the sum beam amplitude, azimuth difference beam amplitude, and elevation difference beam amplitude, and then proceed to step 2. Step 2: Scan the beam pattern at M frequency points within the target frequency band at a fixed frequency interval FreqInter, calculate the sum-difference ratio, and generate M sets of angle measurement parameters using a piecewise fitting method for the angle detection curve. The target frequency band bandwidth is TargetBandW, so the value of M is TargetBandW / FreqInter. Then proceed to Step 3. Step 3: Based on the real-time measured signal frequency, sum beam amplitude, azimuth difference beam amplitude, elevation difference beam amplitude, azimuth sum difference beam phase difference, and elevation sum difference beam phase difference, select angle measurement parameters according to the frequency proximity principle and calculate the target azimuth and elevation angles in real time.

2. The method for sum and difference angle measurement based on segmented fitting of angle detection curves according to claim 1, characterized in that: In step 2, the beam pattern scan of M frequency points in the target frequency band is completed according to the fixed frequency interval FreqInter, the sum and difference amplitude ratio results are calculated, and the segmented fitting method of the angle detection curve is used to generate M groups of angle measurement parameters. The bandwidth of the target frequency band is TargetBandW, and the value of M is TargetBandW / FreqInter. The following steps are included: Step 21. Set the target frequency to f1, the azimuth angle to Atheta0, and the elevation angle to Etheta0. Control the azimuth beam pointing to scan at a fixed angle interval detatheta, scanning a total of N_Af1 angles. The azimuth beam scanning sequence Atheta is expressed as {Atheta1, Atheta2...AthetaN_Af1}. Measure the sum beam amplitude value and azimuth difference beam amplitude value corresponding to each angle respectively to generate the sum beam pattern and azimuth difference beam pattern. The sum beam azimuth width is AbeamWidth_f1, and the value of N_Af1 is AbeamWidth_f1 / detatheta. Step 22: Use the segmented fitting method of the angle detection curve to generate the azimuth angle measurement parameter APara_1 of the frequency point f1; Step 23: Repeat step 22 to generate azimuth angle measurement parameters APara_2, APara_3, ... APara_M of frequency points f2, f3, ... fM in sequence; Step 24: Repeat steps 21 to 23 to generate the elevation angle measurement parameters of each frequency point, i.e., EPara_1, Epara_2, ..., Epara_M. Step 25: Store the angle measurement parameters in sequence according to the frequency points. APara_1 and EPara_1 are expressed as angle measurement parameters Para_1, APara_2 and EPara_2 are expressed as angle measurement parameters Para_2, and so on. Generate a full-band angle measurement parameter table as Para_1, Para_2...Para_M.

3. The method for sum and difference angle measurement based on segmented fitting of angle detection curves according to claim 2, characterized in that: In step 21, the maximum detatheta does not exceed 1 / 10 of the theoretical beam width.

4. The method for sum and difference angle measurement based on segmented fitting of angle detection curves according to claim 3, characterized in that: In step 22, a segmented fitting method of the angle detection curve is used to generate the azimuth angle measurement parameter APara_1 of the frequency point f1, which includes the following steps: Step 22_1, extract the curve fitting sequence: Due to the symmetry of the angle detection curve about the beam normal, it is necessary to select a sequence corresponding to a monotonic angle detection curve for fitting; The target azimuth angle sequence theta is expressed as {theta1, theta2, ... thetaN_Af1}, where theta1 = Atheta1-Atheta0, theta2 = Atheta2-Atheta0, thetaN_Af1 = AthetaN_Af1-Atheta0, and the corresponding azimuth and difference beam amplitude ratio sequence K is expressed as {K1, K2, ... KN_Af1}; The fitting sequence extraction process is as follows: 1) Find the maximum value KNzero of the K sequence, that is, the zero depth position; 2) Find the values ​​greater than or equal to 0 degrees in {theta(Nzero), theta(Nzero+1), ... theta(N_Af1)}, generate the azimuth angle fitting sequence theta_nh as {theta_nh1, theta_nh2 ... theta_nhL}, where L is the number of elements that meet the conditions, and generate the corresponding azimuth and difference amplitude ratio fitting sequence K_nh as {K_nh1, K_nh 2 ... K_nh L}; Step 22_2, calculate the curve segment threshold coefficient: respectively find the minimum value Kmin and the maximum value Kmax in {K_nh1, K_nh 2, ..., K_nh L}, and take the threshold coefficient Athreshold1 = (Kmin + Kmax) / 2; Step 22_3, perform segmented fitting of the angle detection curve: using the threshold coefficient Athreshold1 as the boundary, a set of sum-difference amplitude ratio sequences {K_nh1, K_nh2, ..., K_nh L1} corresponding to the L1 angles whose sum-difference ratio amplitudes are greater than Athreshold1 are subjected to a curve fitting with the angle sequence {theta_nh1, theta_nh2, ..., theta_nhL1}. The fitting formula is theta_nhl = AK1 * K_nhl + AP1. The curve slope AK1 and the constant AP1 are the first segment angle measurement coefficient Apara1_1 in the azimuth direction of the frequency point; a set of sum-difference amplitude ratio sequences {{K_nhL1+1, {K_nh L1+2, ..., {K_nh L1}} corresponding to the L2 angles (L = L1 + L2) whose sum-difference ratios are less than Athreshold1 are subjected to a curve fitting with the angle sequence {{K_nhL1+1, {K_nh L1+2, ..., {K_nh L1}}}. L} and the angle sequence {theta_nhL1+1, theta_nhL1+2...theta_nhL} are subjected to a curve fitting, and the fitting formula is theta_nhl=AK2*K_nhl+AP2. The curve slope AK2 and the constant AP2 are the second-segment angular measurement coefficient Apara1_2 of the azimuth direction of the frequency point; Step 22_4. Calculate the zero-depth out-of-bounds protection parameters: the zero-depth out-of-bounds protection parameter AZeroPara_1 is set to -AP1 / AK1; the azimuth angle measurement parameter APara_1 of the frequency point f1 is expressed as {Athreshold_1, Apara_11, Apara_12, AZeroPara_1}; the azimuth angle measurement parameter Apara_m of the frequency point fm is expressed as {Athreshold_m, Apara_m1, Apara_m2, AZeroPara_m}, where fm represents any value among f1, f2, ..., fM.

5. The method for sum and difference angle measurement based on segmented fitting of angle detection curves according to claim 4, characterized in that: In step 3, according to the real-time measured signal frequency, sum beam amplitude, azimuth difference beam amplitude, elevation difference beam amplitude, azimuth sum difference phase difference, and elevation sum difference phase difference, angle measurement parameters are selected according to the frequency proximity principle to calculate the target azimuth and elevation angles in real time, including the following steps: Step 31: Measure the signal frequency Fmeasure in real time, and select a set of angular measurement coefficients Para_m corresponding to the frequency point closest to Fmeasure; Step 32: Calculate the azimuth difference amplitude ratio AKmeasure. If AKmeasure is greater than AZeroParal_m, the absolute value of the target deviation from the beam normal angle DetaA is 0. Otherwise, if AKmeasure is greater than Athreshold_m, select the angle measurement coefficient Apara_m1, DetaA = AKmeasure * AK1 + AP1; otherwise, select the angle measurement coefficient Apara_m2, DetaA = AKmeasure * AK2 + AP2. Step 33: Calculate the phase difference Detafai between the azimuth difference beam and the sum beam, and determine the sign of DetaA based on the value of Detafai. The tolerance is deta. If the range of Detafai is [270-deta, 270+deta], then DetaA is a negative number. If the range of Detafai is [90-deta, 90+deta], then DetaA is a positive number. Otherwise, DetaA is set to 0. Step 34: Calculate the target azimuth angle TthetaA according to the current beam azimuth Atheta0 and DetaA, where TthetaA = Atheta0 + DetaA. Step 35: Repeat steps 31 to 34 to measure the target pitch angle TthetaE.

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