Three-dimensional rotating baseline direction finding method, system and device, medium and terminal

Abstract

The invention belongs to but not limited to the technical field of radio detection, and particularly relates to a three-dimensional rotating baseline direction finding method, system, equipment, medium and terminal, the system is composed of three antennas which are respectively marked as an antenna A, an antenna B and an antenna C. The antenna A and the antenna B form a linear array which is connected through a cross rod, the distance is adjustable, the maximum is X m, and the midpoint of the A and B linear arrays is the position of a rotating shaft; a vertical rod is arranged at the center of the AB along a rotating shaft, the length of the vertical rod is adjustable, the longest length is Y meters, and the antenna C is located at the upper end of the vertical rod. During working, a base line where the antenna AB is located is driven by the rotating mechanism or the rotating platform to rotate anticlockwise, and the antenna C is located on the rotating shaft and does not rotate; the three antennas are respectively connected to the three receiving channels and synchronously start to collect data during working to form a base line AB, a base line AC and a base line BC, and phase differences of the base line AC, the base line BC and the base line AC are measured.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the field of radio detection technology, and in particular relates to a three-dimensional rotating baseline direction finding method, system, equipment, medium and terminal. Background Art

[0002] Passive direction finding and positioning are important technologies in the field of electromagnetic spectrum monitoring and control. At present, the most commonly used passive direction finding technology system is a multi-baseline interferometer based on a combination of long baseline and short baseline, such as a 5-element array and a 7-element array interferometer. In order to make up for the shortcomings of traditional interferometers, such as complex systems, high costs, large volume and weight, and poor frequency band adaptability, a rotating baseline direction finding system based on time-varying baseline technology has emerged. Compared with the traditional system, which increases antennas and receiving channels and uses complex processing algorithms to resolve phase difference ambiguity and then find the direction, the spinning baseline direction finding system requires at least two antennas and receiving channels, which effectively solves the contradiction between system complexity and positioning accuracy. It has broad application prospects in passive detection, especially in the development of miniaturized passive detection equipment.

[0003] At present, the most common form of rotating baseline direction finding system is that two omnidirectional antennas form a one-dimensional linear array. The equipment is driven to rotate around the center of the linear array by the rotation of the platform (such as a drone) or a rotating mechanism (such as a motor). This rotating baseline structure composed of two antennas has the characteristics of simple system design and low volume cost. Li Teng et al. discussed the feasibility, calculation method and performance limit of the rotating baseline direction finding technology based on the dual-antenna one-dimensional linear array in the article "Multi-hypothesis NLS positioning algorithm based on the fuzzy phase difference of the rotating interferometer [J]. Journal of Electronics and Information Technology, 2012, 34(4): 956-962.", and Zhang Min et al. discussed in detail the feasibility, calculation method and performance limit of the rotating baseline direction finding technology based on the dual-antenna one-dimensional linear array in the article "Method for improving the direction finding accuracy of the rotating baseline phase interferometer [J]. Telecommunication Technology, 2022, 62(7): 936-940."

[0004] In view of the above analysis, the technical problems that need to be solved urgently in the prior art are:

[0005] 1) The theoretical measurement range of the pitch angle of the rotating baseline direction finding system based on a dual-antenna one-dimensional linear array is 0 to 90°, that is, it is impossible to effectively distinguish whether the measured target is above or below the rotating plane, which greatly limits the application scope of the system. When the rotating plane has a significant height (such as the rotating baseline direction finding system on an unmanned aerial vehicle), serious errors will occur.

[0006] 2) The theoretical measurement range of the elevation angle of the dual-antenna one-dimensional linear array rotating direction finding technology is 0 to 90°. However, when the elevation angle approaches 90° (counterclockwise deviation from the rotation plane is positive), the theoretical phase difference asymptotically approaches 0. At this time, the random measurement error will greatly affect the direction finding accuracy. Therefore, there is a problem that the direction finding performance drops sharply when the elevation angle approaches 90°. Summary of the invention

[0007] In view of the problems existing in the prior art, in order to expand the pitch angle measurement range of the rotating baseline direction finding system and improve the measurement accuracy at high pitch angles, and fully considering the difficulty and cost of engineering, the present invention provides a three-dimensional rotating baseline direction finding method, system, equipment, medium and terminal.

[0008] The present invention is implemented in this way: a three-dimensional rotating baseline direction finding method comprises:

[0009] 1) The system consists of 3 antennas, denoted as antenna A, B, and C. Antennas A and B form a linear array connected by a crossbar, with an adjustable spacing of up to X meters. The midpoint of the AB linear array is the location of the rotation axis;

[0010] 2) A vertical rod is set at the center of AB along the rotation axis. The length of the vertical rod is adjustable and the maximum length is Y meters. Antenna C is located at the upper end of the vertical rod;

[0011] 3) During operation, the baseline where antenna AB is located is driven by the rotating mechanism or rotating platform to rotate counterclockwise, and antenna C is located on the rotating axis and does not rotate;

[0012] 4) The three antennas are connected to three receiving channels respectively, and start to collect data synchronously when working to form baseline AB, baseline AC and baseline BC, and measure the phase difference of baseline AC, BC and AC.

[0013] Furthermore, it is defined that the pitch angle above the rotation plane is positive, and the pitch angle below the rotation plane is negative.

[0014] Further, the implementation steps are as follows:

[0015] 1) The phase deviation between channels is compensated in advance. Before working, the phase deviation between the three measurement channels is measured in the full working frequency band to form channel phase deviation compensation tables AC, BC and AB, which are used to compensate for the inherent phase deviation between channels A and C, channels B and C, and channels A and B respectively;

[0016] 2) Assume that the length of baseline AB is 2d and the height of the vertical rod is h. After starting work, baseline AB rotates counterclockwise at an angular velocity Ω. The three receiving channels collect data synchronously and calculate the phase differences corresponding to baselines AC, BC and AB.

[0017] Furthermore, the phase differences corresponding to the baselines AC, BC and AB are calculated as follows:

[0018] a) Assuming the target azimuth angle is α and the pitch angle is β, the phase deviation compensation table generated in advance is used to perform phase deviation compensation. Hereinafter, n(t) is used to represent the random error measured at different times;

[0019] b) The phase difference of baseline AB is: Where f is the signal frequency, Ω is the baseline rotation angular velocity, t is the time, and n is the AB (t) is the random noise when measuring the baseline AB phase difference, mod is the modulo operation;

[0020] c) The phase difference of the baseline AC is: Where n AC (t) is the random noise when measuring the baseline AC phase difference;

[0021] d) The phase difference of the baseline BC is: Where n BC (t) is the random noise when measuring the baseline BC phase difference;

[0022] e) Sum the phase difference between baseline AC and baseline BC and perform mod-2π operation. From the above phase difference calculation formula, we can see that the first term cos(Ωt-α)cosβ caused by the rotation can be eliminated, and the result is: Obviously, there is no positive or negative ambiguity in the pitch angle at this time, only 2π periodic ambiguity exists, and the value range of the integer k covers twice the range of the ambiguity number: -2N MaxAmbCount ≤k≤2N MaxAmbCount ;

[0023] f) The maximum fuzzy number is defined as: λ is the wavelength corresponding to the signal center frequency;

[0024] g) Traverse k in the range of fuzzy numbers, record k n is the k value corresponding to the nth fuzzy number, when Calculate the pitch angle: β(j) represents the estimated result corresponding to the j-th k value, and finally a set of potential pitch angle sets β(j) (the number is assumed to be M) is obtained;

[0025] h) Based on the potential pitch angle sequence, solve the true azimuth and pitch angle.

[0026] Further, the method for solving the true azimuth and elevation angle is as follows:

[0027] h1) The potential set of pitch angles is β(j)∈[β(1),β(2),…,β(M)], and the azimuth traversal accuracy parameter N is set, and the potential set of azimuth angles is obtained as α(i) represents the i-th azimuth;

[0028] h2) By traversing the combination of azimuth and elevation angles, the candidate set Δφ(t,i,j)=Δφ is calculated at different times, that is, at different rotation angles AC (t,i,j)+Δφ AB (t,i,j)+Δφ BC (t,i,j), where the sum can reduce the impact of random measurement noise and improve the direction finding performance near ±90;

[0029] h3) Calculate the joint search metric F(i,j) = sum[abs(Δφ(t)-Δφ(t,i,j))];

[0030] h4) Find the i corresponding to the minimum F(i,j) min , j min , then the azimuth estimation result is α(i min ), the pitch angle estimation result is β(j min );

[0031] h5) In order to reduce the amount of calculation and improve the estimation accuracy, in step h1, a smaller N value can be preferred to preliminarily determine the azimuth angle range, and then gradually refine the estimate, iteratively executing steps h1 to h4 until a result with sufficient accuracy is estimated.

[0032] Another object of the present invention is to provide a three-dimensional rotating baseline direction finding system for implementing the three-dimensional rotating baseline direction finding method, comprising:

[0033] Inter-channel phase deviation table making module: This module is responsible for measuring the phase deviation between different channels of the 3D direction finding system at fixed frequency intervals through the signal source and power divider in the indoor test environment to obtain the phase deviation compensation table between different channels;

[0034] Phase difference measurement module: This module is responsible for calculating the phase difference of different baselines;

[0035] Pitch angle estimation module: This module is responsible for estimating the pitch angle based on the baseline AC and baseline BC phase difference measurement results to obtain a potential pitch angle set;

[0036] Azimuth and elevation joint estimation module: This module uses a joint search method to achieve fast estimation of azimuth and elevation angles with the support of a potential pitch angle set.

[0037] Another object of the present invention is to provide a computer device, the computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the three-dimensional rotating baseline direction finding method.

[0038] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to execute the steps of the three-dimensional rotating baseline direction finding method.

[0039] Another object of the present invention is to provide an information data processing terminal, which includes the three-dimensional rotating baseline direction finding system.

[0040] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0041] First, in view of the technical problems and defects existing in the above-mentioned prior art, a number of creative technical effects are brought about after solving the problems. The specific description is as follows:

[0042] (1) The present invention designs a new rotating baseline direction finding system, taking full account of the difficulty and cost of implementation, and by adding only one fixed antenna, the rotating array is expanded from a one-dimensional array to a three-dimensional antenna array, thus solving the shortcomings and defects of the existing system;

[0043] (2) The azimuth and elevation angle estimation method of the present invention transforms the nonlinear estimation problem into a rough estimation of the elevation angle and a joint search problem of the azimuth and elevation angles. The algorithm is stable, the amount of calculation is small, the estimation accuracy is high, and it is simple and practical.

[0044] Second, the method and system design of the present invention have achieved significant technical progress in solving the problems and defects of the prior art, and greatly expanded the reliability and direction-finding range of the traditional rotating baseline direction-finding system.

[0045] Extended direction-finding range: By extending the one-dimensional baseline system (which can be viewed as a two-dimensional baseline system after rotation) to a three-dimensional baseline system, the theoretical elevation angle direction-finding range of the traditional rotating baseline system is extended from 0 to 90° to -90 to 90°.

[0046] Enhance system reliability: This method reduces the impact of random measurement errors by summing up multiple measurement results, and can effectively improve the direction-finding performance when the pitch angle is close to ±90 degrees.

[0047] Improving the stability and robustness of the system: Through rough estimation of the pitch angle and joint search of the azimuth and pitch angles, the present invention enhances the stability and robustness of the system under various conditions.

[0048] Third, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0049] (1) The expected benefits and commercial value of the technical solution of the present invention after transformation are:

[0050] At present, rotating baseline direction finding technology is widely used in military and civilian fields such as electronic reconnaissance, electronic countermeasures, UAV control, and radio management due to its favorable factors such as cost, volume, and power consumption. The technical solution proposed in the present invention greatly expands the direction finding range and reliability of the traditional system, while the cost and volume increase is very small, which can promote the large-scale application of this technical system.

[0051] (2) Whether the technical solution of the present invention solves the technical problems that people have been eager to solve but have never been able to solve successfully:

[0052] The traditional dual-antenna rotating baseline direction-finding system has the problem of limited elevation angle observation range, which makes it impossible to be effectively applied in many scenarios. The technical solution of the present invention proposes a new system design and calculation method to effectively solve this problem.

[0053] Third, the existing 3D direction finding technology lacks accuracy and stability in dealing with complex environments and high noise conditions, especially when dealing with pitch angles close to ±90 degrees, where direction finding ambiguity and reduced accuracy often occur. In addition, the traditional method does not adequately compensate for phase deviation, resulting in inaccurate measurement results, large computational complexity, and poor real-time performance.

[0054] The present invention proposes a three-dimensional rotating baseline direction finding method to solve the above technical problems. The specific technical solution includes the following parameters, algorithms and mathematical models:

[0055] 1) System structure parameters:

[0056] The rotating baseline consists of three antenna systems (antennas A, B, and C). Antennas A and B are connected by a horizontal rod with adjustable spacing. The maximum spacing is X meters. Antenna C is located on a vertical rod with adjustable length up to Y meters.

[0057] The rotation axis of the baseline AB is set at the center position, and the antenna C does not participate in the rotation.

[0058] 2) Algorithm and steps:

[0059] Phase deviation compensation: The phase deviation between the three measurement channels is measured in full frequency band in advance to form compensation tables AC, BC and AB to compensate for the inherent phase deviation.

[0060] Phase difference calculation: During operation, the baseline AB rotates counterclockwise at an angular velocity Ω, and the three receiving channels collect data synchronously to calculate the phase differences of the baselines AC, BC, and AB.

[0061] Phase difference formula: Use the phase deviation compensation table to compensate for the phase deviation, and use mod-2π operation to eliminate the influence of rotation to obtain an accurate phase difference.

[0062] Fuzzy number traversal: traverse k within the fuzzy number range, calculate the potential pitch angle set, and eliminate the positive and negative ambiguity and 2π periodic ambiguity of the pitch angle.

[0063] Joint search metric: By traversing the combination of azimuth and elevation angles, the joint search metric value is calculated to find the true azimuth and elevation angle corresponding to the minimum metric value.

[0064] 3) Mathematical model:

[0065] Phase difference formula: By accurately calculating the phase difference of baselines AC, BC and AB, correction is made in combination with the compensation table to ensure the accuracy of the measurement results.

[0066] Fuzzy number range: The maximum fuzzy number is defined as λ is the wavelength corresponding to the center frequency of the signal, which ensures accurate calculation of the pitch angle when traversing over different k value ranges.

[0067] Through the above technical solution, the present invention has achieved significant technical progress, which is specifically reflected in the following aspects:

[0068] 1) Improve direction finding accuracy: Through phase deviation compensation and fuzzy number traversal algorithm, the phase deviation and pitch angle ambiguity problems in the traditional method are solved, and the direction finding accuracy is improved.

[0069] 2) Enhanced stability: The joint search metric and iterative refinement estimation are used to enhance the stability of the system in high noise environments, especially when the pitch angle is close to ±90 degrees, the measurement results are more accurate.

[0070] 3) Reduce the amount of calculation: Through the coarse-first-fine-later iterative estimation method, the amount of calculation is effectively reduced and the real-time performance of the system is improved.

[0071] 4) Wide applicability: The system parameters are adjustable and suitable for application scenarios of different sizes and different environments, with strong flexibility and adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 Schematic diagram of a typical ground three-dimensional rotating baseline direction finding system provided by an embodiment of the present invention;

[0073] Figure 2 Schematic diagram of a typical unmanned aerial vehicle three-dimensional rotating baseline direction finding system provided by an embodiment of the present invention;

[0074] Figure 3 It is a schematic diagram of a typical process of ground rotating baseline direction finding provided by an embodiment of the present invention;

[0075] Figure 4 It is the measurement result of different baseline phase differences when the elevation angle is 60 degrees and the azimuth angle is 30 degrees provided by the embodiment of the present invention;

[0076] Figure 5 It is a schematic diagram of comparison between pitch angle estimation results and true values ​​corresponding to different fuzzy periods when the pitch angle is 60 degrees and the azimuth angle is 30 degrees provided by the embodiment of the present invention;

[0077] Figure 6 This is the azimuth and pitch angle estimation result obtained by joint search when the pitch angle is 60 degrees and the azimuth angle is 30 degrees provided by an embodiment of the present invention.

[0078] Figure 7 This is a schematic diagram of a typical process of rotating baseline direction finding onboard an unmanned aerial vehicle provided by an embodiment of the present invention;

[0079] Figure 8 It is the measurement result of different baseline phase differences when the elevation angle is -60 degrees and the azimuth angle is 30 degrees provided by the embodiment of the present invention;

[0080] Fig. 9 It is a schematic diagram of comparison between pitch angle estimation results and true values ​​corresponding to different fuzzy periods when the pitch angle is -60 degrees and the azimuth angle is 30 degrees provided by the implementation of the present invention;

[0081] Fig.10 This is the azimuth and pitch angle estimation result obtained by joint search when the pitch angle is -60 degrees and the azimuth angle is 30 degrees provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0082] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0083] The following are two specific embodiments for illustrating the application of the above three-dimensional rotating baseline direction finding method:

[0084] Embodiment 1:

[0085] 1) System configuration:

[0086] The three-dimensional direction finding system is composed of antennas A, B and C, wherein the spacing between the linear arrays formed by antennas A and B is adjustable, with a maximum of 5 meters (X=5m).

[0087] The length of the vertical pole is adjustable, with a maximum length of 10 meters (Y=10m), and the antenna C is located at the upper end of the vertical pole.

[0088] The signal center operating frequency is 3GHz, and the corresponding wavelength is 0.1 meter.

[0089] 2) Working steps:

[0090] The phase deviations among the three measurement channels are measured over the entire working frequency band to form channel phase deviation compensation tables AC, BC and AB.

[0091] The baseline AB rotates counterclockwise at an angular velocity Ω = π / 2rad / s, and the three receiving channels collect data synchronously.

[0092] The phase differences corresponding to the baselines AC, BC, and AB are calculated, and phase deviation compensation is performed.

[0093] By traversing the combinations of azimuth and elevation angles, the joint search metric is calculated, and the azimuth and elevation angle corresponding to the minimum value are found.

[0094] Initially set the azimuth traversal accuracy parameter N = 10, and gradually refine the estimate until sufficient accuracy is achieved.

[0095] 3) Results:

[0096] The estimated azimuth angle is 45° and the elevation angle is 30°, which are consistent with the true values.

[0097] Embodiment 2:

[0098] 1) System configuration:

[0099] The three-dimensional direction finding system is composed of antennas A, B and C, wherein the spacing between the linear arrays formed by antennas A and B is adjustable, with a maximum of 8 meters (X=8m).

[0100] The length of the vertical pole is adjustable, with a maximum length of 15 meters (Y=15m), and the antenna C is located at the upper end of the vertical pole.

[0101] The signal center operating frequency is 5GHz, and the corresponding wavelength is 0.06 meters.

[0102] 2) Working steps:

[0103] The phase deviations among the three measurement channels are measured over the entire working frequency band to form channel phase deviation compensation tables AC, BC and AB.

[0104] The baseline AB rotates counterclockwise at an angular velocity Ω = πrad / s, and the three receiving channels collect data synchronously.

[0105] The phase differences corresponding to the baselines AC, BC, and AB are calculated, and phase deviation compensation is performed.

[0106] By traversing the combinations of azimuth and elevation angles, the joint search metric is calculated, and the azimuth and elevation angle corresponding to the minimum value are found.

[0107] The azimuth traversal accuracy parameter N is initially set to 15, and the estimation is gradually refined until sufficient accuracy is achieved.

[0108] 3) Results:

[0109] The estimated azimuth is 60° and the pitch is -45°, which is consistent with the true value. Note that the pitch is negative in this example, indicating that the target is below the rotation plane.

[0110] These two embodiments show how to use the above three-dimensional rotating baseline direction finding method to estimate the azimuth and elevation angles. By adjusting the system configuration and parameters in the working steps, it can adapt to different direction finding requirements and environments.

[0111] An embodiment of the present invention provides a three-dimensional rotating baseline direction finding method, comprising:

[0112] 1) The system consists of 3 antennas, denoted as antenna A, B, and C. Antennas A and B form a linear array connected by a crossbar, with an adjustable spacing of up to X meters. The midpoint of the AB linear array is the location of the rotation axis;

[0113] 2) A vertical rod is set at the center of AB along the rotation axis. The length of the vertical rod is adjustable and the maximum length is Y meters. Antenna C is located at the upper end of the vertical rod;

[0114] 3) During operation, the baseline where antenna AB is located is driven by the rotating mechanism or rotating platform to rotate counterclockwise, and antenna C is located on the rotating axis and does not rotate;

[0115] 4) The three antennas are connected to three receiving channels respectively, and start to collect data synchronously when working to form baseline AB, baseline AC and baseline BC, and measure the phase difference of baseline AC, BC and AC.

[0116] Furthermore, it is defined that the pitch angle above the rotation plane is positive, and the pitch angle below the rotation plane is negative.

[0117] Further, the implementation steps are as follows:

[0118] 1) The phase deviation between channels is compensated in advance. Before working, the phase deviation between the three measurement channels is measured in the full working frequency band to form channel phase deviation compensation tables AC, BC and AB, which are used to compensate for the inherent phase deviation between channels A and C, channels B and C, and channels A and B respectively;

[0119] 2) Assume that the length of baseline AB is 2d and the height of the vertical rod is h. After starting work, baseline AB rotates counterclockwise at an angular velocity Ω. The three receiving channels collect data synchronously and calculate the phase differences corresponding to baselines AC, BC and AB.

[0120] Furthermore, the phase differences corresponding to the baselines AC, BC and AB are calculated as follows:

[0121] a) Assuming the target azimuth angle is α and the pitch angle is β, the phase deviation compensation table generated in advance is used to perform phase deviation compensation. Hereinafter, n(t) is used to represent the random error measured at different times;

[0122] b) The phase difference of baseline AB is: Where f is the signal frequency, Ω is the baseline rotation angular velocity, t is the time, and n is the AB (t) is the random noise when measuring the baseline AB phase difference, mod is the modulo operation;

[0123] c) The phase difference of the baseline AC is: Among them, n AC (t) is the random noise when measuring the baseline AC phase difference;

[0124] d) The phase difference of the baseline BC is: Where n BC (t) is the random noise when measuring the baseline BC phase difference;

[0125] e) Sum the phase difference between baseline AC and baseline BC and perform mod-2π operation. From the above phase difference calculation formula, we can see that the first term cos(Ωt-α)cosβ caused by the rotation can be eliminated, and the result is: Obviously, there is no positive or negative ambiguity in the pitch angle at this time, only 2π periodic ambiguity exists, and the value range of k covers twice the range of ambiguity numbers: -2N MaxAmbCount ≤k≤2N MaxAmbCount ;

[0126] f) The maximum fuzzy number is defined as: λ is the wavelength corresponding to the signal center frequency;

[0127] g) Traverse k within the fuzzy number range, when Calculate the pitch angle: β(j) represents the estimated result corresponding to the j-th k value, and finally a set of potential pitch angle sets β(j) (the number is assumed to be M) is obtained;

[0128] h) Based on the potential pitch angle sequence, solve the true azimuth and pitch angle.

[0129] Further, the method for solving the true azimuth and elevation angle is as follows:

[0130] h1) The potential set of pitch angles is β(j)∈[β(1),β(2),…,β(M)], and the azimuth traversal accuracy parameter N is set, and the potential set of azimuth angles is obtained as α(i) represents the i-th azimuth;

[0131] h2) By traversing the combination of azimuth and elevation angles, the candidate set Δφ(t,i,j)=Δφ is calculated at different times, that is, at different rotation angles AC (t,i,j)+Δφ AB (t,i,j)+Δφ BC(t,i,j), where the sum can reduce the impact of random measurement noise and improve the direction finding performance near ±90;

[0132] h3) Calculate the joint search metric F(i,j) = sum[abs(Δφ(t)-Δφ(t,i,j))];

[0133] h4) Find the i corresponding to the minimum F(i,j) min , j min , then the azimuth estimation result is α(i min ), the pitch angle estimation result is β(j min );

[0134] h5) In order to reduce the amount of calculation and improve the estimation accuracy, in step h1, a smaller N value can be preferred to preliminarily determine the azimuth angle range, and then gradually refine the estimate, iteratively executing steps h1 to h4 until a result with sufficient accuracy is estimated.

[0135] Another object of the present invention is to provide a three-dimensional rotating baseline direction finding system for implementing the three-dimensional rotating baseline direction finding method, comprising:

[0136] Inter-channel phase deviation table making module: This module is responsible for measuring the phase deviation between different channels of the 3D direction finding system at fixed frequency intervals through the signal source and power divider in the indoor test environment to obtain the phase deviation compensation table between different channels;

[0137] Phase difference measurement module: This module is responsible for calculating the phase difference of different baselines;

[0138] Pitch angle estimation module: This module is responsible for estimating the pitch angle based on the baseline AC and baseline BC phase difference measurement results to obtain a potential pitch angle set;

[0139] Azimuth and elevation joint estimation module: This module uses a joint search method to achieve fast estimation of azimuth and elevation angles with the support of a potential pitch angle set.

[0140] Example 1: A ground-based three-dimensional rotating baseline direction-finding system measures the direction of an aerial radiation source (such as a drone). The target azimuth is 30°, the pitch is 60°, the phase difference measurement error is 20°, the horizontal rod is 10 times the wavelength, and the vertical rod is 5 times the wavelength.

[0141] A schematic diagram of a ground three-dimensional rotating baseline direction finding system in an embodiment of the present invention is shown in FIG. Figure 1 As shown, it includes a rotating mechanism, a receiving antenna array, a receiver and a signal processing board, and a display and control module, etc., to realize the estimation of the azimuth and elevation angle of the radiation source of the aerial target.

[0142] In this embodiment, Figure 1As shown, the antenna array consists of three omnidirectional antennas, typically fiberglass antennas, marked as antennas A, B, and C. Antennas A and B are connected by a horizontal bar with an adjustable spacing. The specific length is determined according to the wavelength of the monitoring frequency band and is at least greater than one time the wavelength of the monitoring frequency band. The midpoint of the AB line array is the location of the rotation axis. At the center of AB, an adjustable vertical bar is set along the rotation axis. The specific length is determined according to the wavelength of the monitoring frequency band and is at least greater than one time the wavelength of the monitoring frequency band. Antenna C is located at the upper end of the vertical bar.

[0143] In this embodiment, the rotating mechanism is typically a motor (theoretically, the higher the rotation speed, the more conducive to measurement, but too high a rotation speed may easily cause the crossbar to break, so a suitable motor should be selected according to needs), which is used to drive the baseline where the antenna AB is located to rotate counterclockwise at a set angular velocity such as 2π radians per second. Antenna C does not rotate.

[0144] In this embodiment, the receiver is composed of three receiving channels with synchronization function (such as an ADRV9026 chip receiver with 4 receiving channels).

[0145] In this embodiment, the signal processing board is composed of two programmable devices, FPGA and DSP, which digitally processes the signal, calculates the phase difference of the baselines AC, AB and BC, and realizes the target angle estimation.

[0146] In this embodiment, the display and control module is composed of a microprocessor, a display screen, etc., and is connected to the signal processing board through a network port. Its main functions include result display, user control command sending, etc.

[0147] The system direction finding process in the present invention is as follows: Figure 3 As shown:

[0148] (1) Generate a phase deviation compensation table between the three receiving channels in advance through actual measurement;

[0149] (2) The motor drives the antenna to start rotating, collects data synchronously, and measures the phase difference between the AB, AC, and BC channels. The results are as follows: Figure 4 As shown;

[0150] (3) Based on the sum of AC and BC phase differences, Figure 4 neutron Figure 4 As shown, the pitch angle is estimated and a potential pitch angle set is obtained, such as Figure 5 As shown;

[0151] (4) The azimuth and elevation angles are accurately estimated by the joint search method of azimuth and elevation. The results are as follows: Figure 6 As shown;

[0152] (5) The processing results are reported and displayed.

[0153] Example 2: The UAV-mounted three-dimensional rotating baseline direction-finding system locates the interference source, the target azimuth is 30°, the pitch is -60°, the phase difference measurement error is 20°, the horizontal rod is 10 times the wavelength, and the vertical rod is 5 times the wavelength.

[0154] In this embodiment, the schematic diagram of the UAV-mounted three-dimensional rotating baseline system is as follows: Figure 2 , consists of a receiving antenna, a UAV system, a receiver and signal processing board, a data transmission module and a ground display and control system.

[0155] In this embodiment, the receiving antenna adopts a 360-degree omnidirectional antenna. Three antennas are fixed on the drone through an adjustable horizontal rod and an adjustable vertical rod, which are marked as antenna A, B, and C respectively. Antenna C is placed at the top of the vertical rod at the midpoint of AB.

[0156] In this embodiment, the UAV is a rotor-type UAV (typically such as the Tianying M8-240 eight-rotor UAV, etc.), and the base line composed of antennas A and B is driven to rotate by the rotation of the UAV itself.

[0157] In this embodiment, the receiver is composed of three receiving channels with synchronization function (such as an ADRV9026 chip receiver with 4 receiving channels).

[0158] In this embodiment, the signal processing board is composed of two programmable devices, FPGA and DSP, which digitally processes the signal, including filtering, amplification, A / D conversion, and calculates the phase difference of the baselines AC, AB and BC to achieve target angle estimation.

[0159] In this embodiment, the data transmission module (such as the Huazhiyi V21 digital image transmission) is responsible for transmitting the data collected and processed by the system to the ground display and control system. The module adopts high-reliability wireless communication technology to ensure the stability and real-time performance of data transmission.

[0160] When finding the direction, the drone takes off and hovers at a set altitude, collecting and processing data during the spin. The direction finding process is as follows: Figure 7 As shown:

[0161] (1) Determine whether there is a phase deviation compensation table on the ground. If not, generate the phase deviation compensation table between the three receiving channels through actual measurement;

[0162] (2) The drone takes off and hovers, collecting data during the spin process and measuring the phase difference between the AB, AC, and BC channels. The results are as follows: Figure 8 As shown;

[0163] (3) The pitch angle is estimated based on the sum of the AC and BC phase differences. Figure 7 As shown, the potential pitch angle set is obtained, such as Fig. 9 As shown;

[0164] (4) The azimuth and elevation angles are accurately estimated by the joint search method of azimuth and elevation. The results are as follows: Fig.10 As shown;

[0165] (5) The processing results are reported and displayed.

[0166] Combining the processing results of Example 1 (pitch angle +60°) and Example 2 (pitch angle -60°), it can be seen that the method of the present invention expands the measurement range of the pitch angle to [-90° to 90°].

[0167] An application embodiment of the present invention provides a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor executes the steps of a three-dimensional rotating baseline direction finding method.

[0168] An application embodiment of the present invention provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of a three-dimensional rotating baseline direction finding method.

[0169] An application embodiment of the present invention provides an information data processing terminal, which includes a three-dimensional rotating baseline direction finding system.

[0170] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0171] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0172] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A three-dimensional rotating baseline direction finding method, characterized in that: By setting up a three-antenna system and combining the design of a rotating baseline, accurate measurement of the target azimuth and elevation angles can be achieved. This method solves the phase deviation and ambiguity problems in traditional methods by introducing a phase deviation compensation table and an fuzzy number traversal algorithm, thereby improving the direction finding accuracy. At the same time, this method further enhances the direction finding performance in a high noise environment through joint search metric value calculation and iterative refinement estimation, especially when the elevation angle is close to ±90 degrees, significantly improving the accuracy and reliability of the measurement results.

2. The three-dimensional rotating baseline direction finding method according to claim 1, characterized in that: include: 1) The system consists of 3 antennas, denoted as antenna A, B, and C. Antennas A and B form a linear array connected by a crossbar, with an adjustable spacing of up to X meters. The midpoint of the AB linear array is the location of the rotation axis; 2) A vertical rod is set at the center of AB along the rotation axis. The length of the vertical rod is adjustable and the maximum length is Y meters. Antenna C is located at the upper end of the vertical rod; 3) During operation, the baseline where antenna AB is located is driven by the rotating mechanism or rotating platform to rotate counterclockwise, and antenna C is located on the rotating axis and does not rotate; 4) The three antennas are connected to the three receiving channels respectively, and start to collect data synchronously when working, forming baseline AB, baseline AC and baseline BC, and measuring the phase difference of baseline AC, BC and AC.

3. The three-dimensional rotating baseline direction finding method according to claim 1, characterized in that: Define the pitch angle above the rotation plane as positive, and the pitch angle below the rotation plane as negative.

4. The three-dimensional rotating baseline direction finding method according to claim 1, characterized in that: The implementation steps are as follows: 1) The phase deviation between channels is compensated in advance. Before working, the phase deviation between the three measurement channels is measured in the full working frequency band to form channel phase deviation compensation tables AC, BC and AB, which are used to compensate for the inherent phase deviation between channels A and C, channels B and C, and channels A and B respectively; 2) Assume that the length of baseline AB is 2d and the height of the vertical rod is h. After starting work, baseline AB rotates counterclockwise at an angular velocity Ω. The three receiving channels collect data synchronously and calculate the phase differences corresponding to baselines AC, BC and AB.

5. The three-dimensional rotating baseline direction finding method according to claim 4, characterized in that: The method for calculating the phase difference corresponding to the baselines AC, BC and AB is as follows: a) Assuming the target azimuth angle is α and the pitch angle is β, the phase deviation compensation table generated in advance is used to perform phase deviation compensation. Hereinafter, n(t) is used to represent the random error measured at different times; b) The phase difference of baseline AB is: c) The phase difference of the baseline AC is: d) The phase difference of the baseline BC is: e) Sum the phase difference between baseline AC and baseline BC and perform mod-2π operation. From the above phase difference calculation formula, we can see that the first term cos(Ωt-α)cosβ caused by the rotation can be eliminated, and the result is: Obviously, there is no positive or negative ambiguity in the pitch angle at this time, only 2π periodic ambiguity exists, and the value range of k covers twice the range of ambiguity numbers: -2N MaxAmbCount ≤k≤2N MaxAmbCount ; f) The maximum fuzzy number is defined as: λ is the wavelength corresponding to the signal center frequency; g) Traverse k within the fuzzy number range, when Calculate the pitch angle: β(i) represents the estimated result corresponding to the i-th k value, and finally a set (the number is assumed to be M) of potential pitch angle sets β(i) is obtained; h) Based on the potential pitch angle sequence, solve the true azimuth and pitch angle.

6. The three-dimensional rotating baseline direction finding method according to claim 5, characterized in that: The method to solve the true azimuth and elevation angle is as follows: h1) The potential set of pitch angles is β∈[β(1),β(2),…,β(M)], and the azimuth traversal accuracy parameter N is set, and the potential set of azimuth angles is obtained as h2) By traversing the combination of azimuth and elevation angles, the candidate set Δφ(t,i,j)=Δφ is calculated at different times, that is, at different rotation angles AC (t,i,j)+Δφ AB (t,i,j)+Δφ BC (t,i,j), where the sum can reduce the impact of random measurement noise and improve the direction finding performance near ±90; h3) Calculate the joint search metric F(i,j) = sum[abs(Δφ(t)-Δφ(t,i,j))]; h4) Find the i corresponding to the minimum F(i,j) min , j min , then the azimuth estimation result is α(i min ), the pitch angle estimation result is β(j min ); h5) In order to reduce the amount of calculation and improve the estimation accuracy, in step h1, a smaller N value can be preferred to preliminarily determine the azimuth angle range, and then gradually refine the estimate, iteratively executing steps h1 to h4 until a result with sufficient accuracy is estimated.

7. A three-dimensional rotating baseline direction finding system for implementing the three-dimensional rotating baseline direction finding method according to any one of claims 1 to 6, characterized in that: include: Inter-channel phase deviation table making module: This module is responsible for measuring the phase deviation between different channels of the 3D direction finding system at fixed frequency intervals through the signal source and power divider in the indoor test environment to obtain the phase deviation compensation table between different channels; Phase difference measurement module: This module is responsible for calculating the phase difference of different baselines; Pitch angle estimation module: This module is responsible for estimating the pitch angle based on the baseline AC and baseline BC phase difference measurement results to obtain a potential pitch angle set; Azimuth and elevation joint estimation module: This module uses a joint search method to achieve fast estimation of azimuth and elevation angles with the support of a potential pitch angle set.

8. A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the three-dimensional rotating baseline direction finding method according to any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to execute the steps of the three-dimensional rotating baseline direction finding method according to any one of claims 1 to 6.

10. An information data processing terminal, comprising the three-dimensional rotating baseline direction finding system according to claim 7.

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