A radar beam-based electronic warfare angle of arrival ambiguity resolution method

Abstract

The present application relates to airborne fire control radar technical field, disclose a kind of electronic warfare angle measurement ambiguity confirmation method based on radar beam, first according to the phase difference of obtaining angle measurement element receiving echo, the phase angle transformation relationship is used to accurately solve target angle, to the angle of part existing phase ambiguity, using radar and with protection beam to suspected angle target is again detected signal, confirm whether target truly exists in the angle, eliminate angle ambiguity, judge the actual target angle, to realize accurate angle measurement.The method is not restricted by antenna size and other hardware conditions, the implementation method is more feasible, and the calculation method is simple, under the premise of not affecting the normal work of radar, can realize active detection to the initially estimated target angle, more real-time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of airborne fire control radar, and particularly relates to an electronic warfare angle measurement ambiguity confirmation method based on a radar beam. BACKGROUND

[0002] With the development of science and technology, electromagnetic space as an important carrier of information has become increasingly important in the battlefield of airborne radar and electronic warfare equipment. Controlling the electromagnetic spectrum is the core issue of gaining the initiative of both sides in the war. Modern fighter aircraft are generally equipped with fire control radar and electronic warfare equipment. In order to detect long-range targets, radar signal processing of reflected echoes can accurately locate and track targets, but the transmitted signals are easily intercepted and jammed by enemy electronic warfare systems. The means of battlefield information acquisition based on active radar and other active detection systems are increasingly affected by low-altitude and ultra-low-altitude penetration, anti-radiation missiles, stealth targets, and integrated electronic jamming, and the use scenarios are greatly limited.

[0003] Unlike active phased array radars, electronic warfare is a passive and concealed sensor that provides target detection and accurate angular positioning by receiving and processing electromagnetic waves from radars. In complex electromagnetic interference battlefield environments, electronic warfare equipment has the ability to obtain enemy radiation source parameter information and location information while remaining concealed and safe. It does not emit electromagnetic waves and relies on receiving electromagnetic wave signals from targets to detect and locate targets. Compared to active detection equipment that detects targets by radiating electromagnetic waves and receiving target reflection signals, passive detection systems have the advantages of long range, strong concealment, good flexibility in battlefield use, and strong survivability. Modern electronic warfare technologies, represented by integrated electronic intelligence acquisition, electronic jamming, and electronic deception, have improved the survivability and combat capability of concealed attacks, and have played an increasingly significant role in modern warfare.

[0004] One of the important links in the field of electronic warfare is to measure the angle information of the radiation source signal. In existing direction-finding systems, phase interferometers have the advantages of high direction-finding accuracy, simple algorithm, fast processing speed, stable system operation, and wide working frequency band. Interferometer direction-finding equipment mainly uses a multi-element antenna and uses the phase difference between the signals received by the antenna elements to solve the azimuth and elevation angles of the signal.

[0005] In order to improve the accuracy of interferometer angle measurement, existing interferometers usually use a multi-baseline system. The baseline lengths are selected according to a certain staggered relationship, and the phase difference is de-ambiguously processed using the ratio characteristics of different baseline lengths of different phase interferometers. It is usually required that the combination of different baseline lengths results in a virtual "shortest" baseline length less than λ / 2. This greatly limits the element spacing, which is not conducive to flexible antenna element arrangement.

[0006] The modern most advanced fighter aircraft radar and electronic warfare system can realize radar and electronic warfare function antenna aperture synthesis, realize the complementation of both sides. But through the above analysis, when designing the antenna aperture synthesis which satisfies the radar and electronic warfare function, the demand of both sides for the element spacing is contradictory, and an accurate solution method for angle ambiguity is needed under the condition of sparse element spacing. SUMMARY

[0007] Therefore, the present application provides a radar beam based electronic warfare interferometric angle ambiguity confirmation method, which verifies the multiple ambiguous target angles of multi-baseline angle measurement by radar beam, judges the actual target angle, and realizes accurate angle measurement.

[0008] A radar beam based electronic warfare interferometric angle ambiguity confirmation method, comprising the following steps:

[0009] Step 1: obtain the phase difference of the angle measurement element received echo when interferometric angle measurement is performed;

[0010] Step 2: according to the obtained phase difference, the target angle is calculated by using the phase angle transformation relationship, the target angle in the radar scanning range is obtained, and whether there is ambiguity is judged according to the target angle size;

[0011] Step 3: if there is ambiguous angle, the radar and beam are used to point to the ambiguous angle to be confirmed, and it is judged whether the target is in the main lobe range of the antenna, if there is target at the angle, the angle is the real angle of the target, and then the result is output; otherwise, the ambiguous angle is corrected, the accurate angle is calculated and output.

[0012] Further, before the phase difference of the angle measurement element received echo in step 1, radar channel calibration is performed in advance to compensate the phase error between channels and improve the accuracy of the measured phase difference.

[0013] Further, in step 2, the long-short baseline method is used to calculate the target angle, which specifically includes the following process:

[0014] The phase difference between the elements is respectively:

[0015]

[0016]

[0017] Wherein, d1 is the length of the short baseline, d1=kλ, λ is the wavelength of the received signal, d2 is the length of the long baseline, when the distance between the target and the angle measurement radar antenna array is far away, the received signal of the antenna array can be considered as parallel, and the phase of each received signal is θ is the target angle;

[0018] The target angle estimate is corrected using a long baseline to obtain an accurate target angle.

[0019] Furthermore, the specific process for determining whether there is blurriness based on the target angle in step 2 is as follows:

[0020] Based on the short baseline length, the unambiguous range of the target angle is calculated, and it is determined whether the target angle is within the unambiguous range. The unambiguous range of the angle is...

[0021] Furthermore, the phased array radar antenna has a scanning angle range of ±60° and a short baseline length of 0.5774λ.

[0022] Furthermore, since the target angle in step 3 is within the fuzzy range, the fuzzy multiplicity needs to be confirmed; specifically:

[0023] If the target angle observation value exist If the target angle is within the maximum scanning range, the actual short baseline ambiguity multiplicity is N1 = -1 or 0. The calculated target angle is then illuminated using radar and a beam. If the sum of the detected signal power at the illumination angle exceeds the protection channel, the target angle is located in the main lobe region of the current radar beam illumination, and the corresponding measured angle for that region is output. Otherwise, the actual short baseline ambiguity multiplicity is N1 = -1, and the target angle value is corrected to...

[0024] If the target angle observation value From the minimum value of the scan range to If the actual short baseline ambiguity multiplicity is N1 = 1 or 0, then the calculated target angle is tested using radar and beam illumination. If the sum of the detected signal and channel power of the illumination angle exceeds the protection channel, the target angle is located in the main lobe region of the current radar beam illumination, and the measured angle corresponding to that illumination region is output; otherwise, the actual short baseline ambiguity multiplicity is N1 = 1, and the target angle value is corrected to...

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. This invention achieves accurate angle measurement by first obtaining the phase difference of the echo received by the angle measuring array element under phase ambiguity conditions, and then using the phase angle transformation relationship to accurately calculate the target angle. For some angles with phase ambiguity, radar and guard beams are used to re-receive signals of suspected angle targets to confirm whether the target actually exists at that angle, eliminate angle ambiguity, and determine the actual target angle.

[0027] 2. The method is not restricted by hardware conditions such as antenna size, the implementation method is more feasible, the calculation method is simple, the preliminary estimated target angle can be actively detected without affecting the normal operation of the radar, and the method is more real-time. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0029] Figure 1 Flowchart of the radar beam-based electronic warfare angle ambiguity resolution method in embodiment 1 or 2;

[0030] Figure 2 Schematic diagram of the long-short baseline angle measurement principle in embodiment 2;

[0031] Figure 3 Relationship diagram of the short baseline incidence angle and the phase difference observation value in embodiment 2;

[0032] Figure 4 Relationship diagram of the incidence angle and the phase difference observation value when the baseline length d = 3λ in embodiment 2;

[0033] Figure 5 Relationship diagram of the incidence angle and the phase difference observation value when the baseline length d = 2λ in embodiment 2;

[0034] Figure 6 Relationship diagram of the incidence angle and the phase difference observation value when the baseline length d = 3λ in embodiment 2;

[0035] Figure 7 Relationship diagram of the incidence angle and the phase difference observation value when the baseline length d = 4λ in embodiment 2;

[0036] Figure 8 Schematic diagram of the radar and electronic warfare joint angle measurement connection relationship in embodiment 2;

[0037] Figure 9 Schematic diagram of the short baseline in the angle measurement in embodiment 2;

[0038] Figure 10 Relationship diagram of the gain of the and channel antenna and the protection channel antenna in embodiment 2. DETAILED DESCRIPTION

[0039] The embodiments of the present application will be described in detail below with reference to the drawings.

[0040] Following make the application's implementation through specific concrete example, the person skilled in the art can easily understand the other advantages and efficacy of the application from the disclosure of this specification. Obviously, the described embodiments are only a part of the embodiments of the application, not all the embodiments. The application can also be implemented or applied by another different specific implementation, and the details in the specification can be based on different views and applications, various modifications or changes are made without departing from the spirit of the application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the application, all other embodiments obtained by the person skilled in the art without creative labor belong to the scope of protection of the application.

[0041] Embodiment 1

[0042] Reference Figure 1 A radar beam-based electronic warfare angle-of-arrival ambiguity confirmation method, comprising the following steps:

[0043] Step 1: When the angle of arrival is interfered, the phase difference of the received echo of the angle measurement element is obtained;

[0044] Step 2: According to the obtained phase difference, the target angle is calculated using the phase angle transformation relationship, the target angle in the radar scanning range is obtained, and whether there is ambiguity is judged according to the target angle size;

[0045] Step 3: If there is an ambiguous angle, the radar and the beam are pointed to the ambiguous angle to be confirmed, and it is judged whether the target is in the main lobe range of the antenna. If there is a target at this angle, the angle is the real angle of the target, and the result is output. Otherwise, the ambiguous angle is corrected, and the accurate angle is calculated and output.

[0046] In this embodiment, under the condition of phase ambiguity, the phase difference of the received echo of the angle measurement element is obtained, the target angle is accurately calculated using the phase angle transformation relationship, and for the angle with partial phase ambiguity, the radar and the protection beam are used to detect the signal of the suspected angle target again, to confirm whether the target really exists at this angle, eliminate the angle ambiguity, and judge the actual target angle, so as to realize accurate angle measurement. The method is not restricted by the hardware conditions such as antenna size, the implementation method is more feasible, the calculation method is simple, the preliminary estimated target angle can be detected actively without affecting the normal work of the radar, and the method is more real-time.

[0047] Before the phase difference of the echo received by the angle measurement array element in step 1 of the embodiment, radar channel calibration can be performed in advance to compensate for the phase error between channels and improve the accuracy of the measured phase difference.

[0048] Embodiment 2:

[0049] Referring to Figures 1-7 In the embodiment, based on the integration of the active phased array radar and the electronic warfare aperture, most of the multi-baseline interferometers are used to measure the angle of the incoming signal. The long-short baseline method is used to illustrate the effect of the present application.

[0050] The long-short baseline angle measurement principle is shown in Figure 2 A0, A1, A2 are three interference angle measurement elements, the short baseline length is d1, and the long baseline length is d2. When the target is far away from the angle measurement radar antenna array, the incoming signal received by the antenna array can be considered as parallel. According to the distance between the antennas, the phases of the signals received by A0, A1, and A2 are When the active electronic scanning antenna, rectangular array or triangular array of the airborne active phased array radar is used, the element spacing is usually designed to be greater than or equal to λ / 2 under the premise of meeting the maximum frequency ±60° angle coverage range detection requirement, λ is the wavelength of the received signal, in order to reduce the cost of the antenna. Therefore, in the embodiment, the scanning angle range of the active phased array radar antenna is ±60°, and the phase difference between the adjacent elements in the scanning angle range must not be ambiguous, that is, the range of the real phase difference is [-π, π], and the element spacing of the radar is ≤0.5774λ. The scanning angle range of the active phased array radar antenna is ±60°, and if the common aperture design of the radar and electronic warfare is realized, that is, the short baseline spacing of the interference angle measurement is 0.5774λ.

[0051] Let the phase difference between the elements be:

[0052]

[0053]

[0054]

[0055]

[0056] The phase angle transformation relationship of the short baseline is shown in Figure 3 In the range of [-90°, 90°], the real phase difference φ1 of the adjacent elements of the short baseline of the interference angle measurement is in the range of [-1.1547π, 1.1547π]. In order to improve the angle measurement accuracy, the long baseline is used to correct the target angle estimation value. The phase angle transformation relationship of the long baseline under different baseline lengths is shown in Figures 4-7 ​

[0057] The interferometric angle range is generally required to be [-90°, 90°], and if the short baseline angle measurement is not ambiguous in the angle range, the short baseline distance is required to be <0.5λ. In the condition of large bandwidth and high frequency application, the array element distance of radar and electronic warfare co-aperture design is inevitably in conflict with the short baseline requirement of interferometric angle, so the radar beam is used for interferometric angle ambiguity confirmation. The specific implementation steps are as follows:

[0058] Step 1: The hardware relationship of interferometric angle ambiguity confirmation under the condition of radar and electronic warfare co-aperture is shown in Figure 8 After the radar is turned on, channel calibration and noise test are first performed to reduce the error of the antenna receiving channel phase and then reduce the angle measurement error.

[0059] Step 2: When the interferometric angle is measured, the phase difference of the received echo of the angle measurement array element is calculated, the phase angle transformation relationship is used, and the target angle of the target echo is calculated by using the traditional long-short baseline method

[0060] Step 3: If the target angle observation value calculated in step 2 is in the range of that is , that is, in the lightest color shadow area in Figure 9 , the angle measurement is not ambiguous, and the calculated value is output. Otherwise, step 4 is executed.

[0061] Step 4: If step 3 is not true, the ambiguity number needs to be further confirmed. If the target angle observation value obtained in step 2 is , there may also be an ambiguous target angle , that is, in the second darkest color shadow area in Figure 9 , and if the target angle observation value obtained in step 2 is , there may also be an ambiguous target angle , that is, in the second darkest color shadow area in Figure 9 .

[0062] Step 5: The radar beam is used to test or , and when the sum channel power of the illumination angle detection signal exceeds the protection channel (such as Figure 10 ), it indicates that the target is located in the main lobe area of the current radar beam illumination, and the measurement angle corresponding to the illumination area is output or Otherwise, step 6 is executed.

[0063] Step 6: If step 5 is not true, the angle verified at present needs to be corrected and output. The specific correction method is as follows:

[0064] If: , the actual short baseline ambiguity number is N1=-1, and the target angle value is corrected to

[0065] If: then the actual short baseline ambiguity number is N1=1 and the target angle value is corrected to

[0066] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for ambiguity confirmation of electronic warfare interferometric angle measurement based on radar beams, characterized in that, Includes the following steps: Step 1: When performing interferometric angle measurement, obtain the phase difference of the echo received by the angle measurement array element; Step 2: Based on the obtained phase difference, calculate the target angle using the phase angle transformation relationship to obtain the target angle within the radar scanning range, and determine whether there is ambiguity based on the target angle magnitude; Step 3: If there is an ambiguous angle, use radar and beam pointing to the ambiguous angle to determine whether the target is within the main lobe range of the antenna. If the target exists at that angle, the angle is the true angle of the target, and the result is output; otherwise, correct the ambiguous angle, calculate and output the accurate angle. In step 3, if the target angle is within the fuzzy range, the fuzzy multiplicity is confirmed; specifically: If the target angle observation value exist Within the maximum value of the scanning range, the actual short baseline ambiguity multiplicity is: N 1 = -1 or 0; The target angle is illuminated by radar and beam to test the calculated angle. When the sum of the detected signal and channel power of the illumination angle exceeds the protection channel, the target angle is located in the main lobe region of the current radar beam. Then the measured angle corresponding to the illumination region is output. Otherwise, the actual short baseline fuzzy multiplicity is N 1 = -1, the target angle value is corrected to , d 1 represents the short baseline length. d 1= k λ, where λ is the wavelength of the received signal. k It is a positive integer; If the target angle observation value From the minimum value of the scan range Within this range, the actual short baseline fuzzy multiplicity is: N 1=1 or 0; The radar and beam are used to test the calculated target angle. When the sum of the detected signal and the channel power of the illumination angle exceed the protection channel, the target angle is located in the main lobe region of the current radar beam illumination. Then the measured angle corresponding to the illumination region is output. Otherwise, the actual short baseline fuzzy multiplicity is N 1 = 1, target angle value corrected to .

2. The electronic warfare interferometric angle measurement ambiguity confirmation method based on radar beams according to claim 1, characterized in that, Before the phase difference of the echo received by the angle measuring array element in step 1, radar channel calibration is performed in advance to compensate for the phase error between channels and improve the accuracy of the measured phase difference.

3. The electronic warfare interferometric angle measurement ambiguity confirmation method based on radar beams according to claim 1, characterized in that, Step 2 uses the long and short baseline method to calculate the target angle, which includes the following process: The phase differences between the array elements are as follows: in, d 2 represents the long baseline length. When the target is far from the angle-measuring radar antenna array, the incoming wave signals received by the antenna array can be considered parallel, and the phases of each received signal are respectively... , , θ is the target angle; The target angle estimate is corrected using a long baseline to obtain an accurate target angle.

4. The electronic warfare interferometric angle measurement ambiguity confirmation method based on radar beams according to claim 3, characterized in that, The specific process for determining whether there is blurriness based on the target angle in step 2 is as follows: Based on the short baseline length, the unambiguous range of the target angle is calculated, and it is determined whether the target angle is within the unambiguous range. The unambiguous range of the angle is... .

5. The electronic warfare interferometric angle measurement ambiguity confirmation method based on radar beams according to claim 4, characterized in that, The phased array radar antenna has a scanning angle range of ±60°, and a short baseline length of 0.5774. λ .

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