A method and device for direction finding based on multiple antennas and amplitude and phase comparison

Abstract

This invention relates to the field of radio direction finding technology, and discloses a direction finding method and apparatus based on multiple antennas and amplitude and phase comparison. The direction finding method includes: using multiple directional antennas with identical performance to form an antenna array; acquiring amplitude and phase information of a standard signal within the main lobe beam range of the antennas at predetermined steps; calculating the amplitude difference and phase difference, and fitting and discretizing them to form an amplitude comparison curve table and a phase difference curve table, which are then stored; synchronously receiving a target signal through the antenna array; acquiring the amplitude and phase information of the target signal and calculating the amplitude difference and phase difference; constructing a total cost function combining the amplitude difference and phase difference; traversing the amplitude comparison curve table and the phase difference curve table to search for the azimuth angle corresponding to the minimum value of the total cost function; comparing the minimum total cost function with a preset threshold; and outputting the corresponding azimuth angle as the signal azimuth of the main lobe region only when the total cost function is not greater than the preset threshold. This invention can achieve high-precision, omnidirectional signal direction finding.

Description

Technical Field

[0001] This invention relates to the field of radio direction finding technology, and in particular to a direction finding method and apparatus based on multiple antennas and amplitude and phase comparison. Background Technology

[0002] Radio direction finding technology is a key technology for determining the incident direction of a target by receiving its signal, and it is widely used in communication detection, electronic warfare, navigation and positioning. Currently, the mainstream direction finding technologies are mainly divided into two categories: amplitude comparison direction finding and phase comparison direction finding. Both types of technologies face the core problem of sidelobe signal interference in practical applications.

[0003] Amplitude comparison direction finding technology determines direction by comparing the amplitude differences of signals received by different antennas and combining this with a preset amplitude-azimuth correspondence. The core principle of this technology is to use the characteristic that the received signal amplitude in the main lobe region of an antenna is significantly higher than that in the sidelobes region to determine azimuth. However, when a signal is incident from the sidelobes region, its received amplitude can be confused with the amplitude characteristics of the azimuth in the main lobe region, directly leading to significant deviations or even errors in the direction finding angle. To solve this problem, amplitude comparison direction finding systems in engineering applications, in addition to the core direction finding antenna array, must additionally design and deploy a dedicated sidelobe suppression antenna. Through signal comparison and cancellation between the sidelobe suppression antenna and the direction finding antenna, the influence of the sidelobe incident signal is weakened. This complicates the system's hardware structure and signal processing flow, while also increasing the equipment's size, cost, and power consumption.

[0004] Phase comparison direction finding (PCD) calculates azimuth based on the phase difference of the same signal received by different antennas. While offering relatively high accuracy, it places stringent requirements on antenna array precision and the stability of the phase detection circuit. Similar to amplitude comparison PCD, when a signal is incident from the sidelobe region of an antenna, the phase difference between antennas deviates from the phase difference-azimuth correspondence model of the main lobe region, leading to distortion in the calculated azimuth. Therefore, practical PCD systems also require independent sidelobe suppression antennas and corresponding signal processing modules to distinguish between main lobe and sidelobe incident signals and avoid direction finding errors. This design also increases the system's hardware complexity, hindering miniaturization and integrated deployment.

[0005] In summary, existing amplitude and phase comparison direction finding technologies cannot solve the direction finding error caused by sidelobe signal interference by relying on their own direction finding antennas. They must rely on additional sidelobe suppression antennas to ensure direction finding reliability. Ultimately, this results in technical defects such as complex structure, high cost, and reduced real-time performance of the direction finding system, making it difficult to meet the high-precision and lightweight direction finding requirements in complex electromagnetic environments. Summary of the Invention

[0006] To address the technical problem that existing amplitude comparison and phase comparison direction finding systems both require independent sidelobe suppression antennas to effectively suppress sidelobe incident signals, resulting in complex system structures, high costs, and difficult integration, this invention proposes a direction finding method and device based on multiple antennas and amplitude and phase comparison, combining amplitude and phase comparison techniques to achieve high-precision, omnidirectional signal direction finding.

[0007] The technical solution adopted in this invention is as follows: A direction finding method based on multiple antennas and amplitude and phase comparison includes: Calibration phase: Multiple directional antennas with consistent performance are used to form an antenna array. Within the main lobe beam range of the antenna, the amplitude and phase information of the standard signal are collected in a set step. The amplitude difference and phase difference are calculated and fitted to form a ratio curve table and a phase difference curve table, which are then stored. Direction finding phase: The target signal is received synchronously through the antenna array, the amplitude and phase information of the target signal is collected, and the amplitude difference and phase difference are calculated to construct the total cost function of the combined amplitude difference and phase difference; the amplitude ratio curve table and the phase difference curve table are traversed to search for the azimuth angle corresponding to the minimum value of the total cost function, and the minimum total cost function is compared with a preset threshold. Only when the total cost function is not greater than the preset threshold is the corresponding azimuth angle output as the signal azimuth of the main lobe region.

[0008] Furthermore, an antenna array is formed by using multiple directional antennas with consistent performance, including: selecting three directional antennas with matched performance to form an antenna array, wherein the directional antennas are arranged at equal intervals on a circle with radius r, the center angle between adjacent antennas is 45°, and the main lobes of the three directional antennas point to -45°, 0° and 45° respectively.

[0009] Furthermore, during the calibration phase, the amplitude and phase information of the standard signal are acquired in predetermined steps within the antenna main lobe beam range, including: Set calibration parameters: Within the antenna main lobe beam range, select several calibration points according to the preset step angle; Signal transmission and acquisition: Place the standard signal source at each calibration point, transmit the test signal to the antenna array, and simultaneously acquire the received amplitude of the three antennas. A 1 、A 2 、A 3 and phase F 1 、F 2 、F 3. Record the current calibration azimuth angle. i .

[0010] Furthermore, in the calibration phase, the amplitude difference and phase difference are calculated and fitted discretely to form a ratio curve table and a phase difference curve table, which are then stored. Difference calculation: for each calibrated azimuth angle iCalculate the amplitude difference between adjacent antennas. A 1 、D.A. 2 、D.A. 3 and phase difference DF 1 、DF 2 、DF 3; Curve fitting and table generation: based on the amplitude difference of each calibration point A 1 、D.A. 2 、D.A. 3. respectively fitted to obtain A 1 -θ、ΔA 2 -θ、ΔA 3 -θ A total of three amplitude difference-azimuth curves were generated and discretized into a data table with preset step angles to form an amplitude comparison curve table, which was then stored. The phase difference at each calibration azimuth point was also used as the basis for the comparison. DF 1 、DF 2 、DF 3. respectively fitted to obtain DF 1 -θ、ΔΦ 2 -θ、ΔΦ 3 -θ There are a total of three phase difference-azimuth curves, which are discretized into a data table with preset step angles to form a phase difference curve table and store it.

[0011] Furthermore, in the direction finding phase, the target signal is synchronously received through the antenna array, and the amplitude and phase information of the target signal is collected and the amplitude difference and phase difference are calculated, including: Signal reception and acquisition: Multiple directional antennas simultaneously receive target signals and simultaneously acquire the amplitude of three target signals. A 1 ’、A 2 ’、A 3 ’ and phase F 1 '、F 2 '、F 3 ’ ; Amplitude and Phase Difference Calculation: Calculate the amplitude difference between adjacent antennas. A 1 ’=A 1 ’-A 2 ’ , A 2 ’=A 2 ’-A 3 ’ , D A 3 ’=A 1 ’-A 3 ’ And calculate the phase difference between adjacent antennas. DF 1 '=Φ 1 '-F 2 ’ , DF 2 '=Φ 3 '-F 2 ’ , DF 3 '=Φ 3 ’- F 1 ’ .

[0012] Furthermore, in the direction finding phase, the total cost function for the joint amplitude difference and phase difference is constructed, including: Constructing the amplitude difference cost function Its expression is:

[0013] In the formula, i Let be the azimuth angle to be searched. A i (i) The azimuth angle obtained from the amplitude comparison curve table i The corresponding standard amplitude difference; Constructing the phase difference cost function Its expression is:

[0014] In the formula, DF i (i) The azimuth angle obtained from the phase difference curve table i The corresponding standard phase difference; The total cost function is obtained by weighted summation of the amplitude difference cost function and the phase difference cost function. J(θ) The total cost function J(θ) The expression is: J(θ)=α J_A(θ)+β J_Φ(θ) In the formula, α and β These are the preset weighting coefficients.

[0015] Furthermore, in the direction finding phase, the azimuth angle corresponding to the minimum value of the total cost function is searched by traversing the amplitude ratio curve table and the phase difference curve table. This includes: calling the stored amplitude ratio curve table and phase difference curve table, traversing all azimuth points within the main lobe beam range, and calculating the total cost function corresponding to each azimuth point. J(θ) The total cost function is obtained through the search. J (i) The azimuth angle corresponding to the minimum value θ_min This serves as the initial orientation of the target signal.

[0016] Furthermore, in the direction-finding phase, the method for determining the preset threshold includes: The total cost function was determined by statistical analysis of the sidelobe region data during the calibration phase. J(θ) preset threshold J_th The total cost function corresponding to the signal in the main lobe region. J(θ) All are less than the preset threshold. J_th And the total cost function corresponding to the sidelobe region signal J(θ) All are greater than the preset threshold. J_th .

[0017] Furthermore, in the direction-finding phase, the minimum total cost function is compared with a preset threshold. Only when the total cost function is not greater than the preset threshold is the corresponding azimuth angle output as the signal azimuth of the main lobe region, including: The minimum total cost function obtained from the search J(θ_min) With preset threshold J_th Comparison: like J(θ_min) ≤J_th If the target signal is incident from the main lobe region, the azimuth angle is determined to be... θ_min Output the direction finding result to indicate the true azimuth of the target signal; like J(θ_min)>J_th If the target signal is incident from the sidelobe region, the direction finding result is invalid, no direction finding result is output, and the re-direction finding process can be triggered.

[0018] A direction-finding device based on multiple antennas and amplitude and phase comparison includes: Antenna array module: An antenna array composed of multiple directional antennas with consistent performance; Signal receiving module: Connected to the antenna array module, it is used to condition the signals received synchronously by multiple directional antennas and eliminate the influence of noise and interference signals; Signal processing module: It synchronously acquires multiple signals through analog-to-digital converter, extracts amplitude and phase information, calculates the amplitude difference and phase difference between signals, transmits the calculation results and compares them with the pre-stored amplitude ratio curve table and phase difference curve table, calculates the amplitude difference, phase difference data and cost function operation results, searches for the optimal azimuth angle, determines whether the signal comes from the sidelobe region and outputs the final direction finding result.

[0019] The beneficial effects of this invention are as follows: 1. High direction finding accuracy of main lobe signal: This invention effectively avoids the azimuth ambiguity problem of single amplitude or phase comparison direction finding by using the combined cost function calculation of amplitude and phase comparison and the complementarity of amplitude and phase information.

[0020] 2. Reliable sidelobe suppression effect: This invention requires no additional hardware and can accurately identify the sidelobe incident signal through the cost function threshold. The sidelobe signal suppression rate is ≥95%, avoiding direction finding errors caused by sidelobe signals and ensuring the reliability of direction finding results in complex electromagnetic environments. Its suppression effect is no less than that of existing systems that rely on additional sidelobe suppression antennas.

[0021] 3. Simplified system structure and reduced integration difficulty: This invention adopts a simplified multi-antenna architecture, eliminating the need for additional sidelobe suppression antennas and corresponding signal processing modules. Compared to existing direction-finding systems that require independent sidelobe suppression antennas, the number of hardware components is reduced by more than 30%, and the size is reduced by more than 40%, significantly reducing system complexity, cost, and integration difficulty, making it more suitable for lightweight and miniaturized deployment scenarios. Attached Figure Description

[0022] Figure 1 This is a flowchart of a direction finding method based on multiple antennas and amplitude and phase comparison according to the present invention.

[0023] Figure 2 This is a schematic diagram of a direction finding device based on multiple antennas and amplitude and phase comparison according to the present invention.

[0024] Figure 3 This is a schematic diagram of the layout of an antenna array according to the present invention.

[0025] Figure 4 This is an example diagram illustrating the correspondence between amplitude difference and azimuth curves in this invention.

[0026] Figure 5 This is an example diagram illustrating the phase difference-azimuth curve correspondence of the present invention. Detailed Implementation

[0027] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments are now described. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] Example 1 This embodiment provides a direction finding method based on multiple antennas and amplitude and phase comparison, including: Calibration phase: Multiple directional antennas with consistent performance are used to form an antenna array. Within the main lobe beam range of the antenna, the amplitude and phase information of the standard signal are collected in a set step. The amplitude difference and phase difference are calculated and fitted to form a ratio curve table and a phase difference curve table, which are then stored. Direction finding phase: The target signal is received synchronously through the antenna array, the amplitude and phase information of the target signal is collected and the amplitude difference and phase difference are calculated, and the total cost function of the combined amplitude difference and phase difference is constructed; the amplitude ratio curve table and the phase difference curve table are traversed to search for the azimuth angle corresponding to the minimum value of the total cost function, and the minimum total cost function is compared with the preset threshold. Only when the total cost function is not greater than the preset threshold is the corresponding azimuth angle output as the signal azimuth of the main lobe region.

[0029] It should be noted that this method combines the principles of amplitude and phase comparison in direction finding, enabling high-precision direction finding of incident signals within the main lobe region of the antenna, while simultaneously resolving the azimuth ambiguity problem inherent in single direction finding techniques. This method does not rely on additional sidelobe suppression antennas; by constructing a joint cost function of amplitude difference and phase difference and setting reasonable threshold values, it can effectively identify and suppress incident signals in the sidelobe region, simplifying the system hardware structure. Furthermore, this method optimizes the direction finding data processing flow, reduces the computational load of a single direction finding, improves the real-time performance of direction finding, and simultaneously reduces the overall system size and cost, meeting the requirements of lightweight and integrated engineering applications.

[0030] Preferably, this embodiment uses three performance-matched directional antennas as array units. A fixed circumferential radius is determined, and the three directional antennas are arranged on the circumference at equal intervals to ensure that the central angles between adjacent antennas are consistent. Simultaneously, the beam pointing of the three directional antennas is adjusted so that their main lobes correspond to different preset azimuths. After the antenna array is constructed, the performance parameters of each antenna are verified and ensured to have no significant deviations. More preferably, the central angle between adjacent antennas is 45°, and the main lobes of the three directional antennas point to -45°, 0°, and 45° respectively.

[0031] It should be noted that the simplified array structure is constructed using three directional antennas, eliminating the need for additional sidelobe suppression antennas and significantly simplifying the hardware architecture. The equally spaced circular arrangement and fixed main lobe pointing allow the antenna array to accurately cover the specified direction-finding range, improving the uniformity and accuracy of amplitude and phase information acquisition.

[0032] In this embodiment, before formal direction finding, calibration must be completed in a standard test environment to establish an amplitude ratio curve table and a phase difference curve table covering the main lobe beam range, so as to ensure direction finding accuracy.

[0033] Preferably, during the calibration phase, the amplitude and phase information of the standard signal is acquired in a set step within the main lobe beam range of the antenna, including: first setting calibration parameters to select the calibration azimuth point, then transmitting the test signal through the standard signal source, and simultaneously acquiring the amplitude and phase information of the antenna array and recording the corresponding azimuth angle.

[0034] Specifically, first, the coverage area of ​​the antenna main lobe beam is defined. Within this area, multiple calibration points are selected according to a preset step angle (preferably 1° step, balancing calibration accuracy and table storage capacity) to complete the setting of calibration parameters. A standard signal source is placed at each calibration point, and a test signal is transmitted from the standard signal source to the completed antenna array. The amplitude of the received signals from the three antennas is collected simultaneously. A 1 、A 2 、A 3 and phase F 1 、F 2 、F 3. Simultaneously record the azimuth angle corresponding to each calibration azimuth point. i .

[0035] It should be noted that selecting calibration azimuth points according to the set steps balances the coverage and accuracy of the calibration operation; synchronous signal transmission and acquisition ensure the timeliness and consistency of amplitude and phase information, and the recorded azimuth angles provide accurate azimuth references for subsequent curve table construction, effectively improving the data reliability of the calibration stage.

[0036] Preferably, the calibration phase involves calculating the amplitude difference and phase difference, fitting and discretizing them to form an amplitude ratio curve table and a phase difference curve table, and storing them. This includes: first, calculating multiple sets of amplitude differences and phase differences between adjacent antennas for each calibration azimuth angle; then, fitting curves based on the difference data and discretizing them into data tables; and finally storing the two types of curve tables. Specifically, this can be achieved using the following steps: Difference calculation: for each calibrated azimuth angle i Calculate the amplitude difference between adjacent antennas. A 1 、D.A. 2 、D.A. 3 and phase difference DF 1 、DF 2 、DF 3; Curve fitting and table generation: based on the amplitude difference of each calibration point A 1 、D.A. 2 、D.A. 3. respectively fitted to obtain A 1 -θ、ΔA 2 -θ、ΔA 3 -θ A total of three amplitude difference-azimuth curves were generated and discretized into a data table with preset step angles to form an amplitude comparison curve table, which was then stored. The phase difference at each calibration azimuth point was also used as the basis for the comparison. DF 1 、DF 2 、DF 3. respectively fitted to obtain DF 1 -θ、ΔΦ 2 -θ、ΔΦ 3 -θ There are a total of three phase difference-azimuth curves, which are discretized into a data table with preset step angles to form a phase difference curve table and store it.

[0037] It should be noted that calculating the difference for each azimuth angle makes the correspondence between data and azimuth more accurate; curve fitting integrates discrete calibration data, improving the continuity of data; discretization into a data table facilitates quick retrieval and comparison during the direction finding stage; storage operations allow calibration results to be reused without repeating calibration work, thus improving the overall efficiency of direction finding.

[0038] Preferably, in the direction finding phase, the target signal is synchronously received via an antenna array, and the amplitude and phase information of the target signal is collected and the amplitude difference and phase difference are calculated. This includes: first, completing the synchronous reception of the target signal and the acquisition of amplitude and phase information, and then calculating multiple sets of amplitude differences and phase differences between adjacent antennas. Specifically, this can be achieved using the following steps: Signal reception and acquisition: Multiple directional antennas simultaneously receive target signals and simultaneously acquire the amplitude of three target signals. A 1 ’、A 2 ’、A 3 ’ and phase F 1 '、F 2 '、F 3 ’ ; Amplitude and Phase Difference Calculation: Calculate the amplitude difference between adjacent antennas. A 1 ’=A 1 ’-A 2 ’ , A 2 ’=A 2 ’-A 3 ’ , D A 3 ’=A 1 ’-A 3 ’ And calculate the phase difference between adjacent antennas. DF 1 '=Φ 1 '-F 2 ’ , DF 2 '=Φ 3 '-F 2 ’ , DF 3 '=Φ 3 ’- F 1 ’ .

[0039] It should be noted that the antenna array synchronously receives the target signal, avoiding errors caused by the signal reception time difference; after signal conditioning, amplitude and phase information is collected, effectively eliminating the influence of noise and interference; multiple sets of amplitude differences and phase differences are accurately calculated, providing complete and accurate basic data for the subsequent construction of the total cost function.

[0040] Preferably, the construction of the combined amplitude difference and phase difference total cost function in the direction finding phase includes: to quantify the deviation between the measured difference and the calibration curve data, firstly, an amplitude difference cost function and a phase difference cost function are constructed separately, and then the two cost functions are weighted and summed using preset weighting coefficients to obtain the total cost function, thus fully utilizing the complementarity of amplitude and phase information to improve the accuracy of azimuth determination. Specifically, this can be achieved using the following steps: Construct the amplitude difference cost function using the mean square error form. Its expression is:

[0041] In the formula, i Let be the azimuth angle to be searched. A i (i) The azimuth angle obtained from the amplitude comparison curve table i The corresponding standard amplitude difference; The phase difference cost function is constructed using the mean square error form. Its expression is:

[0042] In the formula, DF i (i) The azimuth angle obtained from the phase difference curve table i The corresponding standard phase difference; The total cost function is obtained by weighted summation of the amplitude difference cost function and the phase difference cost function. J(θ) The total cost function J(θ) The expression is: J(θ)=α J_A(θ)+β J_Φ(θ) In the formula, α and β These are preset weighting coefficients, which can be optimized and determined based on the actual direction-finding scenario. Preferably, α=0.5 , β= 0.5 This is to achieve a balanced utilization of amplitude and phase information.

[0043] It should be noted that constructing two cost functions separately can accurately quantify the deviation between the actual data and the standard data in the amplitude and phase dimensions; the weighted summation method realizes the joint use of amplitude and phase information, giving full play to the complementarity of the two types of information, so that the total cost function can more comprehensively reflect the degree of deviation between the actual signal and the standard signal, thereby improving the accuracy of azimuth determination.

[0044] Preferably, in the direction finding stage, the azimuth angle corresponding to the minimum value of the total cost function is searched by traversing the amplitude ratio curve table and the phase difference curve table. This includes: retrieving the two types of curve tables from storage, traversing all azimuth points within the main lobe beam range and calculating the total cost function value, and determining the azimuth angle corresponding to the minimum value as the initial direction finding azimuth of the target signal.

[0045] Specifically, the stored amplitude ratio curve table and phase difference curve table are invoked, and all azimuth points are traversed within the main lobe beam range to calculate the total cost function corresponding to each azimuth point. J(θ) The total cost function is obtained through the search. J(θ) The azimuth angle corresponding to the minimum value θ_min This serves as the initial orientation of the target signal.

[0046] It should be noted that traversing the azimuth points within the main lobe beam range ensures the specificity of the direction finding range and avoids invalid azimuth calculations; calculating the total cost function value by looking up standard data makes the correspondence between azimuth and cost function value more accurate; using the azimuth angle corresponding to the minimum value as the initial direction finding azimuth can quickly lock the azimuth that best matches the actual signal, improving the efficiency of direction finding and the accuracy of preliminary judgment.

[0047] Preferably, the method for determining the preset threshold in the direction finding stage is to determine the preset threshold of the total cost function by statistically analyzing the sidelobe region data during the calibration stage, so that the total cost function values ​​corresponding to the main lobe region and the sidelobe region signals are respectively located on both sides of the threshold.

[0048] Specifically, the total cost function is determined through statistical analysis of sidelobe region data during the calibration phase. J(θ) preset threshold J_th The total cost function corresponding to the signal in the main lobe region. J(θ) All are less than the preset threshold. J_th And the total cost function corresponding to the sidelobe region signal J(θ) All are greater than the preset threshold. J_th .

[0049] It should be noted that by relying on the statistical analysis of the sidelobe region data during the calibration phase to determine the threshold, the threshold setting is more in line with the actual equipment and signal environment, ensuring the rationality of the threshold division. This allows the signals in the main lobe and sidelobe regions to be accurately distinguished by comparing the total cost function value with the threshold, providing a reliable basis for subsequent sidelobe signal suppression.

[0050] Preferably, in the direction finding stage, the minimum total cost function is compared with a preset threshold, and the corresponding azimuth angle is output as the signal azimuth of the main lobe region only when the total cost function is not greater than the preset threshold. This includes: comparing the minimum total cost function value obtained by the search with the preset threshold, determining the signal incident area based on the comparison result, and determining whether to output the direction finding result.

[0051] Specifically, the minimum total cost function obtained through the search... J(θ_min) With preset threshold J_th Comparison: like J(θ_min) ≤J_th If the target signal is incident from the main lobe region, the azimuth angle is determined to be... θ_min Output the direction finding result to indicate the true azimuth of the target signal; like J(θ_min)>J_th If the target signal is incident from the sidelobe region, the direction finding result is invalid, no direction finding result is output, and the re-direction finding process can be triggered.

[0052] It should be noted that the numerical comparison enables accurate determination of the signal incident area, outputs only the direction finding results of the main lobe area, effectively suppresses the incident signal of the side lobe area, avoids direction finding errors caused by the side lobe signal, and improves the reliability of the direction finding results; when invalid, the re-direction finding process is triggered to ensure the continuity of the direction finding work.

[0053] like Figure 1 The diagram illustrates the two main stages (calibration stage and direction finding stage) of the direction finding method in this embodiment, along with the core steps of each stage. The calibration stage outputs amplitude ratio and phase difference curve tables, while the direction finding stage, through signal acquisition, difference calculation, cost function construction, optimal azimuth search, and sidelobe determination, ultimately outputs the true azimuth of the main lobe signal or triggers a re-direction finding process, highlighting the sidelobe suppression procedure without additional hardware.

[0054] Accordingly, this embodiment also provides a direction finding device based on multiple antennas and amplitude and phase comparison, including an antenna array module, a signal receiving module, and a signal processing module.

[0055] like Figure 2 As shown, the antenna array module consists of multiple directional antennas with identical performance, serving as the basic unit for signal reception and enabling synchronous reception of target and standard signals. The signal receiving module is connected to the antenna array module and performs conditioning processing such as amplification, filtering, and down-conversion on various signals received by the antennas to eliminate noise and interference. The signal processing module synchronously acquires multiple conditioned signals through an analog-to-digital converter, extracts amplitude and phase information, calculates the amplitude and phase differences between signals, retrieves pre-stored amplitude ratio curves and phase difference curves for data comparison, performs cost function calculations, searches for the optimal azimuth angle, determines the signal incident area, and finally outputs the direction finding results.

[0056] It should be noted that the direction finding device adopts a modular structural design, with clear functional division of each module, which works together to realize the entire direction finding process, facilitating equipment integration, debugging and maintenance. Each module completes signal reception, conditioning and processing, making each step of the operation more targeted and effectively improving the overall working efficiency and direction finding accuracy of the direction finding device. At the same time, the streamlined modular structure reduces the size of the equipment and the integration difficulty, meeting the requirements of lightweight and integrated engineering applications.

[0057] Preferably, the antenna array module consists of three directional antennas with matched performance, denoted as antenna 1, antenna 2, and antenna 3; the three antennas are arranged at equal intervals on a circle of radius r, with the center angle between adjacent antennas being 45°, and the main lobes of the three antennas pointing to -45°, 0°, and 45° respectively. Figure 3 As shown in the figure, 1, 2, and 3 represent three directional antennas. The three antennas are arranged at equal intervals on an arc with a radius of r. The central angle between adjacent antennas is 45°. The arrows point in the direction of the main lobe of the antennas (the three points are -45°, 0°, and 45° respectively).

[0058] Preferably, the signal processing module synchronously acquires three signals via a high-speed ADC and extracts amplitude information. A 1 、A 2 、A 3) and phase information ( F 1 、F 2 、F 3), and calculate the amplitude difference between antennas. (D.A.) 1 =A 2 -A 1 、D.A. 2 =A 3 -A 2 、D.A. 3 =A 3 -A 1) and phase difference ( DF 1 =Φ 2 -F 1 、DF 2 =Φ 3 -F 2 、DF 3 =Φ 3 -F 1) The calculation results are transmitted and compared with the amplitude ratio curve table and phase difference curve table established in the pre-stored calibration stage. The amplitude difference, phase difference data and cost function calculation results are obtained, the optimal azimuth is searched, it is determined whether the signal comes from the sidelobe region, and the final direction finding result is output.

[0059] like Figure 4The example shown is an amplitude difference-azimuth curve. The horizontal axis represents the azimuth angle (-45° to +45°), and the vertical axis represents the amplitude difference between adjacent antennas (ΔA1, ΔA2, ΔA3). The three curves correspond to the variation of ΔA1, ΔA2, and ΔA3 with the azimuth angle, respectively. The discrete points on the curves are calibration data, which correspond to the stored content in the amplitude difference curve table, clearly showing the relationship between amplitude difference and azimuth.

[0060] like Figure 5 The image shows an example of a phase difference-azimuth curve. The horizontal axis represents the azimuth angle (-45° to +45°), and the vertical axis represents the phase difference between adjacent antennas (ΔΦ1, ΔΦ2, ΔΦ3). The two curves correspond to the variation of ΔΦ1, ΔΦ2, and ΔΦ3 with the azimuth angle, respectively. Figure 4 Similarly, the discrete points on the curve correspond to the stored data in the phase difference curve table, providing a basis for phase difference comparison in the direction finding stage.

[0061] Example 2 This embodiment is based on embodiment 1: This embodiment provides a direction finding method and apparatus based on multiple antennas and amplitude and phase comparison, which are described in detail below.

[0062] I. Setting Parameters for Direction Finding Device In this embodiment, the specific parameters of the direction-finding device are set as follows: 1. Antenna array module: It adopts three planar helical antennas, which are deployed on a circle with a diameter of 0.18m. The central angle between adjacent antennas is 45°. The antenna 3dB main lobe width is 90°, and the side lobe level is -20dB to -40dB.

[0063] 2. Signal receiving module: adopts 3-channel frequency conversion receiver, RF input range 2GHz~3GHz, intermediate frequency 70MHz, bandwidth 20MHz.

[0064] 3. Signal processing module: It adopts a 12-bit ADC acquisition chip with a sampling rate of 100MSps, an FPGA model of Xilinx XC7K325T, an ARM model of STM32H743, and a clock frequency of 100MHz to ensure the real-time performance of data processing and algorithm operation.

[0065] 4. Calibration and Direction Finding Parameters: Calibration azimuth step 1° (91 points in total, -45° to 45°), weighting coefficients. α=0.5、β= 0.5 Cost function threshold J_th=1.25 (Determined through statistical optimization of sidelobe region data during the calibration phase).

[0066] II. Implementation Process of Calibration Phase 1. In a standard microwave anechoic chamber, place a standard signal source (a continuous wave signal with an output frequency of 2000MHz and a power of 0dBm) on an azimuth turntable and adjust the turntable to the azimuth positions of -45°, -44°, -43°, ..., 45° in sequence.

[0067] 2. Control the signal receiving module and signal processing module to simultaneously acquire the received amplitude of the three antennas at various locations. A 1 、A 2 、A 3 and phase F 1 、F 2 、F 3.

[0068] 3. Calculate the amplitude difference at each location. A 1 、D.A. 2 、D.A. 3 and phase difference DF 1 、DF 2 、DF 3. Based on these data, we obtained the following fitting results. A 1 -θ、ΔA 2 -θ、ΔA 3 -θ、ΔΦ 1 -θ、ΔΦ 2 -θ、ΔΦ 3 -θ Six curves.

[0069] 4. Discretize the six curves into data tables with 1° increments, forming amplitude ratio curve tables and phase difference curve tables, and store them in the storage medium of the signal processing module. The calibration is then complete.

[0070] III. Implementation Process of Direction Finding Phase 1. Target signal setting: Continuous wave signal with a frequency of 2000MHz and a power of -10dBm, with an incident azimuth of 42° (within the antenna main lobe area).

[0071] 2. Signal Acquisition and Difference Calculation: The antenna array synchronously receives the target signal, and after signal conditioning, it is acquired. A 1 =40dB、A 2 =48.1dB、A 3 =48.6dB , F 1 =0.00rad、Φ 2 =-0.06rad、Φ 3 =-0.10rad ;Calculation obtained A 1 =-8.1dB、ΔA 2 =-0.5dB、ΔA 3 =-8.6dB、DIF 1 =0.06rad、ΔΦ 2 =-0.04rad、ΔΦ 3 =-0.10rad .

[0072] 3. Cost function calculation: The signal processing module calls the amplitude ratio curve table and the phase difference curve table, and iterates through the range of -45~45° to calculate the total cost function J(θ)=0.5J_A(θ)+0.5J_Φ(θ).

[0073] 4. Optimal Azimuth Search and Sidelobe Judgment: The azimuth angle corresponding to the minimum value of the total cost function is obtained through the search. θ_min= 42° Minimum cost function value J(θ_min)=0.33≤J_th=1.25 It was determined to be an incident signal from the central main lobe region.

[0074] 5. Results Output: The signal processing module outputs a direction finding result of 42° through the network interface. The single direction finding takes 0.8ms and the direction finding error is 0°, which verifies the high accuracy and real-time performance of the main lobe signal direction finding.

[0075] IV. Verification of the Sidelobe Suppression Effect Adjust the target signal incident azimuth to 120° (antenna sidelobe region), and repeat the above direction finding steps: 1. Collected A 1 =18dB、A 2 =18.1dB、A 3 =35.1dB,Φ 1 =0.00rad、Φ 2 =0.37rad、Φ 3 = 1.12rad ;Calculation obtained A 1 =-0.1dB、ΔA 2 =-17.0dB、ΔA 3 =-17.1dB、DIF 1 =-0.37rad、ΔΦ 2 = 0.75rad、DF 3 =1.12rad .

[0076] 2. After iterating through and calculating the total cost function, the minimum cost function value is obtained. J(θ_min)=8.47>J_th=1.25 The signal processing module determines that it is a sidelobe incident signal, does not output the direction finding result, and triggers the re-direction finding process.

[0077] 3. The incident signal in the sidelobe region was continuously tested 100 times, and all of them were accurately identified and suppressed, with a sidelobe suppression rate of 100%, which verifies that the present invention can achieve reliable sidelobe suppression without the need for an additional sidelobe suppression antenna.

[0078] This embodiment demonstrates that the direction finding method and device of the present invention have a simple structure, high direction finding accuracy, and reliable sidelobe suppression. They can effectively solve the system complexity problem caused by the need for additional sidelobe suppression antennas in the prior art and have good engineering application value.

[0079] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

[0080] It should be noted that, for the sake of simplicity, the foregoing method embodiments are described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

Claims

1. A direction-finding method based on multiple antennas and amplitude / phase comparison, characterized in that, include: Calibration phase: Multiple directional antennas with consistent performance are used to form an antenna array. Within the main lobe beam range of the antenna, the amplitude and phase information of the standard signal are collected in a set step. The amplitude difference and phase difference are calculated and fitted to form a ratio curve table and a phase difference curve table, which are then stored. Direction finding phase: The target signal is received synchronously through the antenna array, the amplitude and phase information of the target signal is collected, and the amplitude difference and phase difference are calculated to construct the total cost function of the combined amplitude difference and phase difference; the amplitude ratio curve table and the phase difference curve table are traversed to search for the azimuth angle corresponding to the minimum value of the total cost function, and the minimum total cost function is compared with a preset threshold. Only when the total cost function is not greater than the preset threshold is the corresponding azimuth angle output as the signal azimuth of the main lobe region.

2. The direction finding method based on multiple antennas and amplitude and phase comparison according to claim 1, characterized in that, The method of using multiple directional antennas with consistent performance to form an antenna array includes: selecting three directional antennas with matched performance to form an antenna array, wherein the directional antennas are arranged at equal intervals on a circle with radius r, the center angle between adjacent antennas is 45°, and the main lobes of the three directional antennas point to -45°, 0° and 45° respectively.

3. The direction finding method based on multiple antennas and amplitude and phase comparison according to claim 2, characterized in that, During the calibration phase, amplitude and phase information of a standard signal are acquired in predetermined steps within the antenna main lobe beam range, including: Set calibration parameters: Within the antenna main lobe beam range, select several calibration points according to the preset step angle; Signal transmission and acquisition: Place the standard signal source at each calibration point, transmit the test signal to the antenna array, and simultaneously acquire the received amplitude of the three antennas. A 1 、A 2 、A 3 and phase Φ 1 Φ 2 Φ 3. Record the current calibration azimuth angle. θ .

4. The direction finding method based on multiple antennas and amplitude and phase comparison according to claim 3, characterized in that, In the calibration phase, the amplitude difference and phase difference are calculated, and the discretized data are fitted to form a ratio curve table and a phase difference curve table, which are then stored. Difference calculation: for each calibrated azimuth angle θ Calculate the amplitude difference between adjacent antennas. ΔA 1 ΔA 2 ΔA 3 and phase difference Δ Φ 1 , ΔΦ 2 , ΔΦ 3; Curve fitting and table generation: based on the amplitude difference of each calibration point ΔA 1 ΔA 2 ΔA 3. Obtained by fitting respectively Δ A 1 -θ、ΔA 2 -θ、ΔA 3 -θ A total of three amplitude difference-azimuth curves were generated and discretized into a data table with preset step angles to form an amplitude comparison curve table, which was then stored. The phase difference at each calibration azimuth point was also used as the basis for the comparison. ΔΦ 1 , ΔΦ 2 , ΔΦ 3. respectively fitted to obtain Δ Φ 1 -θ、ΔΦ 2 -θ、ΔΦ 3 -θ There are a total of three phase difference-azimuth curves, which are discretized into a data table with preset step angles to form a phase difference curve table and store it.

5. The direction finding method based on multiple antennas and amplitude and phase comparison according to claim 4, characterized in that, During the direction finding phase, the target signal is synchronously received via the antenna array, and the amplitude and phase information of the target signal is collected and the amplitude difference and phase difference are calculated, including: Signal reception and acquisition: Multiple directional antennas simultaneously receive target signals and simultaneously acquire the amplitude of three target signals. A 1 ’、A 2 ’、A 3 ’ and phase Φ 1 '、Φ 2 '、Φ 3 ’ ; Amplitude and Phase Difference Calculation: Calculate the amplitude difference between adjacent antennas. ΔA 1 ’=A 1 ’-A 2 ’ , ΔA 2 ’=A 2 ’-A 3 ’ , ΔA 3 ’= A 1 ’-A 3 ’ And calculate the phase difference between adjacent antennas. ΔΦ 1 '=Φ 1 '-Φ 2 ’ , ΔΦ 2 '=Φ 3 '-Φ 2 ’ , ΔΦ 3 '=Φ 3 '-Φ 1 ’ .

6. The direction finding method based on multiple antennas and amplitude and phase comparison according to claim 5, characterized in that, In the direction finding phase, a total cost function combining the combined amplitude difference and phase difference is constructed, including: Constructing the amplitude difference cost function Its expression is: In the formula, θ Let be the azimuth angle to be searched. ΔA i (θ) The azimuth angle obtained from the amplitude comparison curve table θ The corresponding standard amplitude difference; Constructing the phase difference cost function Its expression is: In the formula, ΔΦ i (θ) The azimuth angle obtained from the phase difference curve table θ The corresponding standard phase difference; The total cost function is obtained by weighted summation of the amplitude difference cost function and the phase difference cost function. J(θ) The total cost function J(θ) The expression is: J(θ)=α J_A(θ)+β J_Φ(θ) In the formula, α and β These are the preset weighting coefficients.

7. The direction finding method based on multiple antennas and amplitude and phase comparison according to claim 1, characterized in that, In the direction finding phase, the azimuth angle corresponding to the minimum value of the total cost function is searched by traversing the amplitude ratio curve table and the phase difference curve table. This includes: calling the stored amplitude ratio curve table and phase difference curve table, traversing all azimuth points within the main lobe beam range, and calculating the total cost function corresponding to each azimuth point. J(θ) The total cost function is obtained through the search. J(θ) The azimuth angle corresponding to the minimum value θ_min This serves as the initial orientation of the target signal.

8. The direction finding method based on multiple antennas and amplitude and phase comparison according to claim 1, characterized in that, In the direction finding phase, the method for determining the preset threshold includes: The total cost function was determined by statistical analysis of the sidelobe region data during the calibration phase. J(θ) preset threshold J_th The total cost function corresponding to the signal in the main lobe region. J(θ) All are less than the preset threshold. J_th And the total cost function corresponding to the sidelobe region signal J(θ) All are greater than the preset threshold. J_th .

9. A direction finding method based on multiple antennas and amplitude and phase comparison according to claim 8, characterized in that, In the direction finding phase, the minimum total cost function is compared with a preset threshold. Only when the total cost function is not greater than the preset threshold is the corresponding azimuth angle output as the signal azimuth of the main lobe region, including: The minimum total cost function obtained from the search J(θ_min) With preset threshold J_th Comparison: like J(θ_min) ≤ J_th If the target signal is incident from the main lobe region, the azimuth angle is determined to be... θ_min Output the direction finding result to indicate the true azimuth of the target signal; like J(θ_min)>J_th If the target signal is incident from the sidelobe region, the direction finding result is invalid, no direction finding result is output, and the re-direction finding process can be triggered.

10. A direction-finding device based on multiple antennas and amplitude / phase comparison, applied to the direction-finding method as described in claim 1, characterized in that, The direction-finding device includes: Antenna array module: An antenna array composed of multiple directional antennas with consistent performance; Signal receiving module: Connected to the antenna array module, it is used to condition the signals received synchronously by multiple directional antennas and eliminate the influence of noise and interference signals; Signal processing module: It synchronously acquires multiple signals through analog-to-digital converter, extracts amplitude and phase information, calculates the amplitude difference and phase difference between signals, transmits the calculation results and compares them with the pre-stored amplitude ratio curve table and phase difference curve table, calculates the amplitude difference, phase difference data and cost function operation results, searches for the optimal azimuth angle, determines whether the signal comes from the sidelobe region and outputs the final direction finding result.

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