Dual-band broadband direction finding system and method based on antenna group gating

Abstract

The invention discloses a dual-band broadband direction finding system and method based on antenna group gating. The dual-band broadband direction finding system comprises an antenna array, a signal conversion unit, a channel gating unit, a digital processing unit and a control and interaction unit, the antenna array is used for integrally covering the first antenna group and the second antenna group based on unified geometric framework arrangement, and realizing unified output of cross-band direction finding results; the signal conversion unit is used for converting a radio frequency signal into a signal which can be processed by the digital processing unit; the channel gating unit is used for realizing configurable connection between the first antenna group or the second antenna group and a receiving channel of the digital processing unit; the digital processing unit is used for completing signal sampling, feature extraction and direction estimation operation and outputting a direction finding result; and the control and interaction unit is used for outputting parameters and results. According to the invention, the high-frequency direction-finding antenna group and the low-frequency direction-finding antenna group are respectively constructed under a unified hexagonal geometric framework, so that the system gives consideration to omnidirectional coverage, direction-finding sensitivity and engineering implementation feasibility under the condition of a wide frequency band.

Description

Technical Field

[0001] This invention relates to the field of direction finding technology, and in particular to a dual-band broadband direction finding system and method based on antenna group gating. Background Technology

[0002] In modern electronic warfare and reconnaissance missions, the need for direction finding of wide-band signals (especially 2-18 GHz) is increasingly urgent. This band covers most military and civilian radio frequency signals and is the core operating frequency band for electronic reconnaissance and jamming. Current mainstream direction finding technologies are mainly divided into two categories: amplitude comparison direction finding (amplitude comparison method) and interferometric phase direction finding (phase comparison method). However, both types of technologies have inherent defects in wide-band applications: The amplitude comparison method determines the target's azimuth by comparing the amplitude differences of the signals received by different antenna array elements. It has a simple structure and low hardware cost, but the direction finding accuracy is limited by the antenna beamwidth. The theoretical accuracy can only reach about one-tenth of the antenna beamwidth, which is difficult to meet the requirements of high-precision direction finding. Moreover, in the low frequency band (2-6GHz), the long signal wavelength leads to a wide antenna pattern, which further reduces the ability to distinguish amplitude differences and makes the accuracy defect more prominent.

[0003] Phase comparison method calculates azimuth based on the phase difference of signals received by different antenna elements, achieving much higher direction-finding accuracy than amplitude comparison method. However, it suffers from significant phase ambiguity: to improve accuracy, the antenna baseline length needs to be increased. When the baseline length exceeds half the signal wavelength, ambiguity angles are introduced, leading to multiple uncertain azimuth solutions. Existing technologies typically eliminate ambiguity by using multiple baselines of varying lengths, which undoubtedly increases the hardware complexity, size, and cost of the system, hindering engineering deployment.

[0004] To balance direction finding accuracy and system complexity, existing high-precision direction finding systems often employ a combination of "amplitude comparison for coarse measurement + phase comparison for fine measurement." This involves determining the approximate target azimuth range through amplitude comparison, and then using this range to assist in phase comparison for de-ambiguity resolution and fine measurement. However, this approach still faces engineering challenges in the 2-18GHz wideband coverage scenario: Firstly, high-frequency signals (6-18GHz) have short wavelengths, making interferometric direction finding prone to multiple ambiguity cycles, significantly increasing the difficulty of de-ambiguity resolution. Secondly, to reduce hardware size, most systems use a single-channel RF switch to poll multiple antenna elements to collect data, requiring multiple switches to gather a set of direction finding data. This leads to increased direction finding delay and complex switching control. Furthermore, in scenarios with pulse or agile signals, "non-simultaneous sampling" can cause phase consistency issues, further affecting direction finding accuracy.

[0005] In summary, existing direction-finding technologies struggle to simultaneously achieve the comprehensive performance requirements of 360° omnidirectional coverage, high sensitivity, high accuracy, and fast response across a wide frequency band of 2-18 GHz. Furthermore, they generally suffer from high hardware complexity and poor engineering feasibility. Therefore, there is an urgent need for a direction-finding system architecture and supporting implementation methods that can balance wideband adaptability, fast direction-finding capability, and high-precision calculation under limited receiving channel conditions. This would resolve the contradiction between latency, accuracy, and complexity in existing wideband direction-finding technologies, and improve the real-time performance, stability, and engineering feasibility of broadband direction-finding systems.

[0006] The disclosure of the above background technical content is only for the purpose of assisting in understanding the concept and technical solution of this application, and does not necessarily provide technical instruction. Summary of the Invention

[0007] The purpose of this invention is to provide a dual-band broadband direction finding system and method based on antenna group gating. Under a unified hexagonal geometric framework, a high-frequency direction finding antenna group and a low-frequency direction finding antenna group are constructed respectively, so that the system can take into account omnidirectional coverage, direction finding sensitivity and engineering feasibility under broadband conditions.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A dual-band broadband direction finding system based on antenna array gating includes an antenna array, a signal conversion unit, a channel gating unit, a digital processing unit, and a control and interaction unit. The antenna array is used to be arranged based on a unified geometric framework, integrating a first antenna group covering the first frequency band and a second antenna group covering the second frequency band, so as to achieve unified output of cross-frequency band direction finding results; The signal conversion unit is used to convert the radio frequency signal received by the antenna array into a signal that can be processed by the digital processing unit; The channel selection unit is used to enable configurable connection between the first antenna group or the second antenna group and the receiving channel of the digital processing unit based on mapping rules. The digital processing unit is used to perform signal sampling, feature extraction and direction estimation calculations, and generate and output the initial direction finding results to the control and interaction unit. The control and interaction unit is used for working mode configuration, antenna group selection, calibration data management, and receives the initial direction finding results output by the digital processing unit, processes them, and outputs the final direction finding results to the outside.

[0009] Furthermore, based on any or a combination of the aforementioned technical solutions, the unified geometric framework is a uniform hexagonal structure with six facets arranged around the same central coordinate system; The first frequency band is 6-18GHz, and the first antenna group arranges at least one array element on each of the adjacent array surfaces on both sides of each apex, forming 12 high-frequency array elements distributed circumferentially. The second frequency band is 2-6GHz. The second antenna group has at least one array element at the center of each array surface, forming 6 low-frequency array elements distributed circumferentially.

[0010] Furthermore, based on any or a combination of the aforementioned technical solutions, the digital processing unit is a radio frequency system-on-a-chip or an FPGA digital receiver, providing no less than 6 synchronous receiving channels; The channel selection unit is a switch and interface network, and the mapping rules are stored in the form of a static mapping table, which predefines the antenna access combinations and corresponding control words for different working modes.

[0011] Furthermore, based on any or a combination of the aforementioned technical solutions, the feature extraction of the digital processing unit includes amplitude extraction and phase difference extraction, and outputs unified format feature data containing amplitude, phase difference, frequency point identifier and time information; The orientation estimation of the digital processing unit is achieved in a combined manner: coarse measurement determines the azimuth range based on amplitude response differences, and fine measurement combines amplitude and phase difference characteristics to complete the accurate angle calculation.

[0012] Furthermore, following any one or a combination of the aforementioned technical solutions, the calibration data managed by the control and interaction unit is an amplitude and phase feature library. The amplitude and phase feature library is established by the system through anechoic chamber calibration or turntable calibration, and is organized by frequency band, frequency point index, antenna group, channel combination and angle to form a feature table containing amplitude ratio and phase difference information.

[0013] Furthermore, based on any or a combination of the aforementioned technical solutions, the digital processing unit is implemented using FPGA modular design, which is divided into data path and control path. The data path processing flow is as follows: AD sampling, digital channelization, FFT operation, amplitude and phase extraction, feature data generation, amplitude-power mapping and attenuation compensation, antenna repositioning mapping, coarse amplitude comparison, fine phase comparison, angle mapping and output; The processing flow of the control path is as follows: configuration management of local oscillator, frequency point and attenuation, loading and selection of calibration table and lookup table data, array amplitude determination, channel gating control, area decision and direction finding mapping, and external interface interaction.

[0014] Furthermore, based on any or a combination of the aforementioned technical solutions, the six low-frequency array elements of the second antenna group can be directly connected to the six synchronous receiving channels of the digital processing unit without additional selection or switching. The first antenna group connects the target area antenna and the receiving channel through the channel selection unit, and only one selection switch is needed to complete the acquisition of precision measurement data.

[0015] According to another aspect of the present invention, the present invention provides a dual-band broadband direction finding method based on antenna group gating, applied to the dual-band broadband direction finding system based on antenna group gating as described in any of the preceding claims, comprising the following steps: S1: The control and interaction unit sends out the monitoring frequency band and working mode, and the channel selection unit completes the configurable connection between the first antenna group or the second antenna group and the receiving channel of the digital processing unit according to the static mapping table. S2: The signal conversion unit converts the radio frequency signal received by the antenna array into a signal that can be processed by the digital processing unit. The digital processing unit completes signal sampling and amplitude and phase difference feature extraction, and outputs feature data in a unified format. S3: If the signal belongs to the first frequency band of 6-18GHz, the azimuth is limited to a certain apex region by comparing the amplitude of the 6 arrays. The channel selection unit only needs to switch once to connect the high-frequency array elements in the apex region to the receiving channel. After extracting the amplitude and phase characteristics, the phase ambiguity of the interferometer is removed by using the amplitude coarse measurement result, and then the accurate angle estimation is achieved by the interferometer method. S4: If the signal belongs to the second frequency band of 2-6GHz, the target's apex sector is determined by comparing the six amplitudes. The two low-frequency array elements corresponding to the apex sector are selected, and amplitude or phase comparison is performed directly based on the direct channel data for direction finding. S5: The digital processing unit completes amplitude matching based on the amplitude and phase feature library and outputs the direction finding results under the unified coordinate definition to the control and interaction unit.

[0016] Furthermore, following any one or a combination of the aforementioned technical solutions, in step S3, the determination of the apex region of the first frequency band is achieved through a six-sided parallel amplitude search. The amplitude data of the six array surfaces are compared to determine the array surface with the largest amplitude. The corresponding azimuth region is the range of the hexagonal apex where the largest array surface is located, and the channel switching time is ≤20ns.

[0017] Furthermore, following any one or a combination of the aforementioned technical solutions, in step S5, before the direction finding result is output, the control and interaction unit verifies the calculation result of the digital processing unit and, in conjunction with the validity judgment of the calibration data, if the error exceeds a preset threshold, returns to step S2 to re-extract features and calculate direction finding.

[0018] The beneficial effects of the technical solution provided by this invention are as follows: a. High real-time performance of direction finding; in high-frequency mode, precise measurement can be completed with only one switch, avoiding time delay and phase consistency issues caused by multiple switch cycles; b. It has strong broadband adaptability and excellent direction finding accuracy. Through the collaboration of dual-band antenna groups and the combination logic of "coarse measurement and ambiguity resolution + fine angle measurement", it covers the 2-18GHz frequency band and ensures omnidirectional direction finding robustness. c. The project is highly feasible, based on static mapping tables and FPGA modular design, with low hardware complexity, convenient calibration, and support for high-throughput real-time processing. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of a dual-band broadband direction finding system based on antenna group gating provided in an exemplary embodiment of the present invention; Figure 2 A schematic diagram of a dual-band broadband direction finding system based on antenna group gating is provided as an exemplary embodiment of the present invention; Figure 3 A schematic diagram of a 6-18GHz antenna array mapping provided as an exemplary embodiment of the present invention; Figure 4 A schematic diagram of a 2-6GHz antenna array mapping provided as an exemplary embodiment of the present invention; Figure 5 A schematic diagram of a dual-band broadband direction finding method based on antenna group gating, provided as an exemplary embodiment of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0023] In one embodiment of the present invention, such as Figure 1 and 2 As shown, a dual-band broadband direction finding system based on antenna group gating is provided, including an antenna array, a signal conversion unit, a channel gating unit, a digital processing unit, and a control and interaction unit. The antenna array is arranged based on a unified geometric framework, integrating a first antenna group covering a first frequency band and a second antenna group covering a second frequency band, achieving unified output of cross-band direction finding results. The signal conversion unit converts the radio frequency signals received by the antenna array into signals that can be processed by the digital processing unit. The channel gating unit, based on mapping rules, enables configurable connections between the first or second antenna group and the receiving channel of the digital processing unit. The digital processing unit performs signal sampling, feature extraction, and direction estimation calculations, generating and outputting initial direction finding results to the control and interaction unit. The control and interaction unit configures the operating mode, selects antenna groups, manages calibration data, receives the initial direction finding results output by the digital processing unit, processes them, and outputs the final direction finding results externally. In one embodiment of the present invention, such as Figure 3 and 4 As shown, the first frequency band is 6-18GHz, and the first antenna group arranges at least one array element on each of the adjacent array surfaces on both sides of each vertex, forming 12 high-frequency array elements distributed circumferentially. The second frequency band is 2-6GHz. The second antenna group has at least one array element arranged at the center of each array surface, forming 6 low-frequency array elements distributed in a circumferential direction. In one embodiment of the present invention, the digital processing unit is a radio frequency system-on-a-chip or an FPGA digital receiver, providing no less than 6 synchronous receiving channels; In one embodiment of the present invention, the channel selection unit is a switch and interface network, and the mapping rules are stored in the form of a static mapping table, predefining antenna access combinations and corresponding control words under different working modes; In one embodiment of the present invention, the feature extraction of the digital processing unit includes amplitude extraction and phase difference extraction, and outputs unified format feature data containing amplitude, phase difference, frequency point identifier and time information; In one embodiment of the present invention, the orientation estimation of the digital processing unit is achieved by a combination of methods: coarse measurement determines the azimuth range based on the difference in amplitude response, and fine measurement combines amplitude and phase difference characteristics to complete the accurate angle calculation.

[0024] In one embodiment of the present invention, the calibration data managed by the control and interaction unit is an amplitude and phase feature library. The amplitude and phase feature library is established by the system through anechoic chamber calibration or turntable calibration, and is organized by frequency band, frequency point index, antenna group, channel combination and angle to form a feature table containing amplitude ratio and phase difference information.

[0025] In one embodiment of the present invention, the digital processing unit is implemented using FPGA modular design, which is divided into data path and control path. In one embodiment of the present invention, the data path processing flow is as follows: AD sampling, digital channelization, FFT operation, amplitude and phase extraction, feature data generation, amplitude-power mapping and attenuation compensation, antenna repositioning mapping, coarse amplitude comparison, fine phase comparison, angle mapping and output. In one embodiment of the present invention, the processing flow of the control path is as follows: configuration management of local oscillator, frequency point and attenuation, loading and selection of calibration table and lookup table data, array amplitude determination, channel gating control, region decision and direction finding mapping, and external interface interaction.

[0026] In one embodiment of the present invention, the six low-frequency array elements of the second antenna group can be directly connected to the six synchronous receiving channels of the digital processing unit without additional selection and switching. The first antenna group connects the target area antenna and the receiving channel through the channel selection unit, and only one selection switch is needed to complete the acquisition of precision measurement data.

[0027] The present invention's embodiment demonstrates significant technical advantages through its collaborative design of a "dual-band hexagonal integrated antenna structure + limited channel gating + amplitude and phase joint direction finding." The antenna array integrates dual-band antenna groups based on a unified geometric framework. Both types of antenna groups share the same coordinate definition, ensuring consistent output of cross-band direction finding results, simplifying structural installation and maintenance, and achieving omnidirectional coverage and direction finding adaptation for different frequency bands. The signal conversion unit efficiently converts RF signals into signals that can be processed by the digital processing unit, providing a stable and reliable signal source for subsequent sampling and feature extraction, laying the foundation for accurate direction finding. The channel gating unit, through flexible mapping rules, enables configurable connections between the dual-band antenna groups and the receiving channel. This eliminates the need for additional channel hardware, meeting antenna access requirements for different frequency bands and operating stages, significantly reducing system hardware complexity and cost. The digital processing unit integrates signal sampling, feature extraction, and direction estimation functions. Through standardized feature extraction and computational logic, it ensures the efficiency of the direction finding process and the accuracy of the results, adapting to wideband signal processing requirements. The control and interaction unit coordinates the configuration of working modes, antenna group selection, calibration data management and result output, realizing orderly collaboration among all parts of the system. The calibration data it manages ensures the accuracy of direction finding, while simplifying the system operation and maintenance process.

[0028] With each component working closely together, it achieves a seamless integration of wideband adaptability, efficient direction finding, and convenient operation and maintenance without requiring complex hardware upgrades. This effectively resolves the contradictions between broadband coverage, hardware complexity, and direction finding performance inherent in traditional direction finding systems, demonstrating significant practical value and potential for widespread adoption. Furthermore, by managing the connection relationships between antenna groups and channels using a static mapping table and employing a unified format for feature data output, it reduces hardware complexity and calibration and maintenance costs. Under limited ADC channels, it achieves a harmonious balance of wideband direction finding, high precision, fast response, and easy deployment, making it highly valuable for practical applications.

[0029] To facilitate understanding, the following specific examples will be used for illustration: Figure 1-4 As shown, Example 1, System Hardware Components Antenna array: It adopts a uniform hexagonal structure, with an external metal frame as the mounting carrier. Six array surfaces are symmetrically arranged around the central coordinate system, and the angle between adjacent array surfaces is 60°.

[0030] High-frequency antenna array (6-18GHz): Microstrip patch antennas are selected as array elements. One array element is welded on each of the adjacent array surfaces on both sides of each vertex, forming a total of 12 high-frequency array elements at the 6 vertexes. The spacing between array elements is 0.8 times the center wavelength of the corresponding frequency band, which facilitates the formation of effective amplitude and phase characteristic differences within the vertex range for high-precision direction finding in the high-frequency band and ensures the angular sensitivity of high-frequency signals.

[0031] Low-frequency antenna array (2-6GHz): Symmetrical array elements are selected as array elements. One array element is fixed at the center of each array surface, for a total of 6 low-frequency array elements. The distance from the array element to the center of the array is 30cm, achieving 360° omnidirectional coverage and maintaining sufficient reception margin and engineering feasibility with a relatively small number of array elements.

[0032] RF / Microwave Front-End: Employs a 6-channel independent RF design. Each channel includes a low-noise amplifier, bandpass filter (switchable between 2-6GHz and 6-18GHz), digitally controlled attenuator (0-30dB attenuation range, 1dB increments), and mixer. The front-end down-converts the RF signal received by the antenna to an intermediate frequency (IF) signal with an instantaneous bandwidth of 2GHz and a frequency range of 2.6-4.6GHz, and outputs it to the switch and interface network.

[0033] Switch and interface network: A 16-to-6 RF switch matrix (isolation ≥60dB, switching time ≤10ns) is selected, and an FPGA control chip is used to realize switch state switching. The static mapping table is stored in the Flash memory of the switch matrix, and three types of mapping relationships and corresponding control words are predefined: "high frequency search mode", "high frequency precision measurement mode" and "low frequency pass-through mode".

[0034] Digital processing board: Uses commercially available chips, integrating a 6-channel 12-bit ADC and FPGA logic unit. The FPGA logic resources are used to implement digital channelization, amplitude and phase extraction, direction finding algorithms, and switch control, while the ARM core is used for communication with the control / host computer unit and calibration data management.

[0035] Control / Host computer unit: Adopts an industrial computer, equipped with Windows operating system and dedicated control software, supports frequency band configuration, mode switching, calibration data import / export and direction finding result display (including azimuth angle, frequency point, signal strength and other information).

[0036] System calibration process The system needs to be calibrated in a microwave anechoic chamber before leaving the factory. The specific steps are as follows: The antenna array is fixed on an electric turntable with an accuracy of 0.1°. A 2-18GHz signal generator is placed in the dark room to output continuous wave signals with different frequencies (100MHz intervals) and different powers.

[0037] The control turntable rotates in 1° increments, covering azimuth angles from 0 to 360°. With each rotation, the system switches operating modes in the order of "low frequency band (2-6GHz) → high frequency band (6-18GHz)" to collect amplitude and phase data from each antenna group.

[0038] The host computer software processes the acquired data, organizes the data according to the structure of "frequency band / frequency point index - antenna group / channel combination - angle", and generates an amplitude ratio and phase difference feature table. Each data item in the feature table has a bit width of 16 bits and is stored in the DDR4 memory of the digital processing board.

[0039] After calibration is completed, a calibration report is generated, recording the direction finding error correction values ​​for each frequency point, which serve as the basis for compensation during online operation.

[0040] Direction finding workflow (1) High-frequency mode (6-18GHz) The host computer issues commands for monitoring frequency bands (such as 10-12GHz) and operating modes, and the digital processing board configures the bandpass filter, local oscillator frequency, and ADC sampling rate of the RF / microwave front end.

[0041] The switch and interface network uses a high-frequency search mode mapping table to connect the high-frequency array elements of the six arrays to the six ADC channels respectively, and the FPGA acquires the amplitude data of the six signals in real time.

[0042] The FPGA uses an amplitude comparison module to determine the array surface with the largest amplitude, identifies the apex region where the target is located (such as the 3rd apex, corresponding to the 60-120° range), and generates a switch control word.

[0043] After receiving the control word, the switch and interface network switch the channel connection according to the high-frequency precision measurement mode mapping table, and connect the four high-frequency array elements of the two adjacent arrays at the third vertex to the four ADC channels (the remaining two channels are reserved).

[0044] The FPGA extracts the amplitude and phase difference data of the four signals, combines them with the corresponding entries in the calibration feature table, uses the amplitude coarse measurement results to remove the phase ambiguity of the interferometer, and then calculates the precise azimuth angle (accuracy ≤ 0.5°) using the correlation interferometer method.

[0045] The digital processing board packages information such as azimuth angle, frequency point, and signal strength into PDW format data and uploads it to the control / host computer unit for display.

[0046] (2) Low frequency mode (2-6GHz) The host computer issues commands for monitoring frequency bands (such as 3-4GHz) and low-frequency operating modes. The RF / microwave front end switches to the corresponding bandpass filter, and the switches and interface networks are mapped according to the low-frequency pass-through mode mapping table, directly connecting the 6 low-frequency array elements to the 6 ADC channels.

[0047] The FPGA acquires the amplitude data of 6 signals in real time, and determines the vertices sector where the target is located (e.g., the 5th vertices sector, corresponding to the 240-300° range) by comparison.

[0048] The FPGA selects the low-frequency array data of the two arrays corresponding to the apex angle, calculates the accurate azimuth angle using the amplitude comparison method, and uploads the result to the control / host computer unit.

[0049] Example 2: Simplified System Hardware Design Antenna array: A lightweight plastic frame (external diameter 60cm) is used. The high-frequency antenna group uses a miniaturized patch antenna (12 elements), and the low-frequency antenna group uses a folded array antenna (6 elements). The array element arrangement is the same as in Example 1.

[0050] RF / Microwave Front End: An integrated RF module is used, with each channel containing a low-noise amplifier and a fixed attenuator (10dB attenuation). The mixer outputs an intermediate frequency signal at 1GHz, simplifying circuit design.

[0051] Switch and interface network: An 8-to-6 RF switch matrix (isolation ≥50dB, switching time ≤20ns) is selected, and only two types of mapping relationships, "high frequency mode" and "low frequency mode", are predefined to reduce control complexity.

[0052] Digital processing board: It uses commercially available chips (with 6-channel 10-bit ADC, sampling rate 1GSps) and only implements the core amplitude and phase extraction, direction finding algorithm and switch control functions. The calibration data is stored on the SD card.

[0053] Control / Host computer unit: It adopts an embedded touch screen, runs on a Linux operating system, and supports basic mode switching, parameter configuration and direction finding result display.

[0054] Direction finding workflow optimization In high-frequency mode, the switching and precise measurement data acquisition are carried out simultaneously, reducing the switching waiting time and the direction finding delay is ≤5ms.

[0055] In low-frequency mode, the amplitude and phase difference data of 6 signals are directly used for phase comparison and direction finding, simplifying the algorithm logic and meeting the needs of low-cost and low-complexity application scenarios.

[0056] The calibration data is simplified and organized by "frequency band - angle". Each set of feature entries is shared by 10 frequency points, which reduces storage pressure and is suitable for scenarios with low direction finding accuracy requirements (≤1.5°).

[0057] Example 3: Dual-band hexagonal array broadband direction finding system based on FPGA+DSP System hardware composition The digital processing board adopts an "FPGA+DSP" architecture. The FPGA is responsible for digital channelization, amplitude and phase extraction and switching control, while the DSP chip is responsible for direction finding algorithm calculation and data interaction.

[0058] The spacing between high-frequency elements in the antenna array is optimized to 1.0 times the center wavelength of the corresponding frequency band, improving the directivity of high-frequency signals; the low-frequency elements adopt a dual-polarization design to enhance signal reception sensitivity.

[0059] The RF / microwave front end adopts a pluggable module design, supporting the individual replacement of 2-6GHz and 6-18GHz frequency band modules to adapt to the frequency band requirements of different application scenarios.

[0060] It supports pulse signal direction finding. The FPGA identifies the rising / falling edge of the pulse signal through the pulse detection module and synchronously collects the amplitude and phase data within the pulse, avoiding the phase consistency problem caused by "non-simultaneous sampling".

[0061] The calibration feature library supports online updates. When system hardware (such as antennas and RF modules) is replaced, new calibration data can be imported through the host computer without having to recalibrate the entire frequency band.

[0062] With the addition of multi-signal sorting function, the DSP can process three signals at different frequencies simultaneously through spectrum analysis and signal feature extraction, and output the azimuth angle of each signal, making it suitable for complex electromagnetic environments.

[0063] Example 4: A dual-band broadband direction finding method based on antenna group gating, such as... Figure 5 As shown: Method Preconditions The system has completed anechoic chamber calibration and established an amplitude and phase feature library for the 2-18GHz frequency band. The feature table is organized according to "frequency band (2-6GHz / 6-18GHz) - frequency point (50MHz interval) - antenna group / channel combination - azimuth angle (0-360°, step size 0.1°)" and stores amplitude ratio (16-bit precision) and phase difference (16-bit precision) data.

[0064] The digital processing board (RFSoC) has been loaded with FPGA logic, including an amplitude comparison module, a phase difference calculation module, a deblurring module, and a lookup table matching module.

[0065] The control / host computer unit has issued the monitoring frequency band (e.g., 4-10GHz), direction finding mode (automatic frequency band identification), and accuracy threshold (≤0.8°).

[0066] Specific direction finding steps (S1) Frequency band identification and antenna group selection The RF / microwave front-end receives the RF signal collected by the antenna array, performs preliminary frequency band filtering through the bandpass filter bank (2-6GHz / 6-18GHz), and outputs it to the ADC channel of the digital processing board.

[0067] The digital processing board performs fast spectrum analysis on the ADC sampled data (1024 FFT points, 2GSps sampling rate), extracts the signal center frequency, and determines the frequency band to which the signal belongs: the center frequency is 2-6GHz, which is the low frequency band, and 6-18GHz, which is the high frequency band.

[0068] Based on the frequency band determination result, the control unit calls the corresponding static mapping table: for the low frequency band, it calls the "low frequency direct mapping table" to connect the 6 low frequency array elements to the 6 ADC channels; for the high frequency band, it calls the "high frequency search mapping table" to connect the high frequency array elements of the 6 arrays to the 6 ADC channels.

[0069] (S2) Coarse amplitude measurement and azimuth area limitation The digital processing board acquires the signal amplitude data of 6 channels in real time, removes noise interference through sliding window filtering (window length 16), and obtains stable amplitude values ​​A1-A6 (corresponding to 6 arrays / low-frequency array elements).

[0070] The amplitude comparison module calculates the maximum value A of A1-A6. max And the corresponding array face number N (N=1-6), determine the azimuth area based on the array face number: Low frequency band: The apex sector corresponding to array N is [N×60°-30°, N×60°+30°] (e.g., N=3 corresponds to 150°-210°); High frequency band: The apex region corresponding to array N is [(N-1)×60°, N×60°] (e.g., N=3 corresponds to 120°-180°).

[0071] (S3) Amplitude and phase feature extraction Low frequency band: Directly extract the amplitude data A1-A6 from 6 channels and the phase difference between any two adjacent array elements. ( (This refers to the signal phase).

[0072] High-frequency band: The control unit sends a switching control word to the switch and interface network, calls the "high-frequency precision measurement mapping table", connects the four high-frequency array elements of the two adjacent arrays in the apex region to the four ADC channels, and extracts the amplitude data B1-B4 and phase difference of the four signals. ( 1-3).

[0073] (S4) Defuzzification and Precise Angle Calculation Low frequency band: A method combining amplitude and ratio is adopted, with the maximum amplitude A as the criterion. max Using the corresponding array element as the reference, calculate the amplitude ratio R1-R5 (Ri=Ai / A) of other array elements relative to the reference array element. max ), combined with phase difference Query the low-frequency amplitude and phase feature table to obtain the precise azimuth angle. (Accuracy ≤ 1°).

[0074] High frequency band: De-ambiguity: Using the vertices region defined by the coarse amplitude measurement as the constraint range, combined with the phase difference corresponding to the shortest baseline of the interferometer (the distance between adjacent high-frequency array elements). Calculate fuzzy numbers K =round[( +360°× K 0) / 360°]( K 0 represents the initial blur number (based on the feature table preset), thus removing phase blur; Precise calculation: the phase difference after deblurring ( Substituting the amplitude ratio S1-S3 (Sj=Bj / Bmax) into the correlation interferometer algorithm, the matching formula using cosine summation is obtained: The accurate azimuth angle is calculated. (Accuracy ≤ 0.5°), and corrected to 0-360° omnidirectional angle by combining the apex region.

[0075] (S5) Result Verification and Output The digital processing board will calculate the azimuth angle / Compare the data with the standard data of the corresponding frequency and angle in the amplitude and phase characteristic table. If the error is less than or equal to the accuracy threshold (0.8°), the result is valid. If the error exceeds the threshold, return to step S2 to perform a coarse measurement again.

[0076] The valid results are packaged in PDW format, including information such as azimuth, center frequency, signal amplitude, and direction finding timestamp, and uploaded to the control host computer unit via Ethernet interface to complete the direction finding process.

[0077] Example 5: Simplified direction finding method This embodiment is designed for low-cost, low-complexity application scenarios. It simplifies the algorithm logic and calibration process, ensuring the core direction finding function while reducing hardware and software overhead.

[0078] Simplified calibration: Anechoic chamber calibration is performed only for the center frequencies (4GHz and 12GHz) of the 2-6GHz and 6-18GHz bands, generating two sets of simplified amplitude and phase characteristic tables, eliminating the need for full coverage at interval frequencies.

[0079] Algorithm simplification: In the high-frequency band, only the amplitude and phase difference of two adjacent high-frequency array elements are extracted, and the single baseline interferometer method is used in combination with coarse measurement area de-ambiguity; in the low-frequency band, the amplitude comparison method is directly used for direction finding, without the need for phase difference calculation.

[0080] Simplified switching: The high-frequency band only has two states, "search" and "precision measurement", and the switch switching control words are fixed to two groups, reducing the complexity of the control logic.

[0081] Specific direction finding steps Frequency band identification: The frequency band is determined by a simple frequency threshold (center frequency ≤ 6 GHz is low frequency band, > 6 GHz is high frequency band), omitting the spectrum analysis step.

[0082] Coarse measurement limitations: Only the maximum values ​​of the 6 channels' amplitudes are compared, directly corresponding to the top corner region, without the need for sliding window filtering.

[0083] Precise measurement calculation: Low frequency band: Taking the array element with the maximum amplitude as the center, select the amplitude ratio of the two adjacent array elements on the left and right, and look up the simplified feature table to obtain the azimuth angle (accuracy ≤ 1.5°). High frequency band: Switch to 2 high frequency array element channels, extract the phase difference, use the coarse measurement area to limit the range of ambiguity numbers (K=0 or 1), and calculate the azimuth angle after deambiguation (accuracy ≤1°).

[0084] Output results: Directly output azimuth angle and frequency band information, omitting the result verification step, and the direction finding delay is ≤8ms.

[0085] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Appropriate adjustments can be made to hardware selection, algorithm details, workflow, etc., without departing from the core technical solution of the present invention, and all such adjustments should be covered within the scope of protection of the claims of the present invention.

[0086] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0087] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A dual-band broadband direction finding system based on antenna group gating, characterized in that, It includes an antenna array, a signal conversion unit, a channel gating unit, a digital processing unit, and a control and interaction unit; The antenna array is used to be arranged based on a unified geometric framework, integrating a first antenna group covering the first frequency band and a second antenna group covering the second frequency band, so as to achieve unified output of cross-frequency band direction finding results; The signal conversion unit is used to convert the radio frequency signal received by the antenna array into a signal that can be processed by the digital processing unit; The channel selection unit is used to enable configurable connection between the first antenna group or the second antenna group and the receiving channel of the digital processing unit based on mapping rules. The digital processing unit is used to perform signal sampling, feature extraction and direction estimation calculations, and generate and output the initial direction finding results to the control and interaction unit. The control and interaction unit is used for working mode configuration, antenna group selection, calibration data management, and receives the initial direction finding results output by the digital processing unit, processes them, and outputs the final direction finding results to the outside.

2. The dual-band broadband direction finding system based on antenna group gating according to claim 1, characterized in that, The unified geometric framework is a uniform hexagonal structure with six arrays arranged around the same central coordinate system. The first frequency band is 6-18GHz, and the first antenna group arranges at least one array element on each of the adjacent array surfaces on both sides of each apex, forming 12 high-frequency array elements distributed circumferentially. The second frequency band is 2-6GHz. The second antenna group has at least one array element at the center of each array surface, forming 6 low-frequency array elements distributed circumferentially.

3. The dual-band broadband direction finding system based on antenna group gating according to claim 1 or 2, characterized in that, The digital processing unit is a radio frequency on-chip system or an FPGA digital receiver, providing no less than 6 synchronous receiving channels; The channel selection unit is a switch and interface network, and the mapping rules are stored in the form of a static mapping table, which predefines the antenna access combinations and corresponding control words for different working modes.

4. The dual-band broadband direction finding system based on antenna group gating according to claim 1, characterized in that, The feature extraction of the digital processing unit includes amplitude extraction and phase difference extraction, and outputs unified format feature data containing amplitude, phase difference, frequency point identifier and time information; The orientation estimation of the digital processing unit is achieved in a combined manner: coarse measurement determines the azimuth range based on amplitude response differences, and fine measurement combines amplitude and phase difference characteristics to complete the accurate angle calculation.

5. The dual-band broadband direction finding system based on antenna group gating according to claim 2, characterized in that, The calibration data managed by the control and interaction unit is an amplitude and phase feature library. The amplitude and phase feature library is established by the system through anechoic chamber calibration or turntable calibration. It is organized by frequency band, frequency point index, antenna group, channel combination and angle to form a feature table containing amplitude ratio and phase difference information.

6. The dual-band broadband direction finding system based on antenna group gating according to claim 5, characterized in that, The digital processing unit is implemented using FPGA modular design, which is divided into data path and control path. The data path processing flow is as follows: AD sampling, digital channelization, FFT operation, amplitude and phase extraction, feature data generation, amplitude-power mapping and attenuation compensation, antenna repositioning mapping, coarse amplitude comparison, fine phase comparison, angle mapping and output; The processing flow of the control path is as follows: configuration management of local oscillator, frequency point and attenuation, loading and selection of calibration table and lookup table data, array amplitude determination, channel gating control, area decision and direction finding mapping, and external interface interaction.

7. The dual-band broadband direction finding system based on antenna group gating according to claim 3, characterized in that, The six low-frequency array elements of the second antenna group can be directly connected to the six synchronous receiving channels of the digital processing unit without additional selection or switching. The first antenna group connects the target area antenna and the receiving channel through the channel selection unit, and only one selection switch is needed to complete the acquisition of precision measurement data.

8. A dual-band broadband direction finding method based on antenna group gating, applied to the dual-band broadband direction finding system based on antenna group gating as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: The control and interaction unit sends out the monitoring frequency band and working mode, and the channel selection unit completes the configurable connection between the first antenna group or the second antenna group and the receiving channel of the digital processing unit according to the static mapping table. S2: The signal conversion unit converts the radio frequency signal received by the antenna array into a signal that can be processed by the digital processing unit. The digital processing unit completes signal sampling and amplitude and phase difference feature extraction, and outputs feature data in a unified format. S3: If the signal belongs to the first frequency band of 6-18GHz, the azimuth is limited to a certain apex region by comparing the amplitude of the 6 arrays. The channel selection unit switches only once to connect the high-frequency array elements in the apex region to the receiving channel. After extracting the amplitude and phase characteristics, the phase ambiguity of the interferometer is removed by using the amplitude coarse measurement result, and then the accurate angle estimation is achieved by the interferometer method. S4: If the signal belongs to the second frequency band of 2-6GHz, the target's apex sector is determined by comparing the six amplitudes. The two low-frequency array elements corresponding to the apex sector are selected, and amplitude or phase comparison is performed directly based on the direct channel data for direction finding. S5: The digital processing unit completes amplitude matching based on the amplitude and phase feature library and outputs the direction finding results under the unified coordinate definition to the control and interaction unit.

9. The dual-band broadband direction finding method based on antenna group gating according to claim 8, characterized in that, In step S3, the determination of the apex region of the first frequency band is achieved by six-sided parallel amplitude search. The amplitude data of the six array surfaces are compared to determine the array surface with the largest amplitude. The corresponding azimuth region is the range of the apex of the hexagon where the largest array surface is located.

10. The dual-band broadband direction finding method based on antenna group gating according to claim 8 or 9, characterized in that, In step S5, before the direction finding result is output, the control and interaction unit verifies the calculation result of the digital processing unit and, in conjunction with the validity judgment of the calibration data, if the error exceeds the preset threshold, returns to step S2 to re-extract features and calculate direction finding.

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