A flight test method for integrating L-band digital air communication system and CNS

Abstract

The application discloses a kind of L-band digital aviation communication system CNS integration's test flight method, belong to aviation communication navigation monitoring technical field.The present application aims at solving the problems of single verification function and lack of CNS integrated comprehensive verification of existing LDACS test flight method.The method of the present application comprises: deploying at least four known positions and clock synchronization LDACS ground station, form cellular network;Design integrated test flight method, including flight path design, test flight subject design, test flight parameter design, test flight method design, wherein test flight subject covers LDACS communication performance test flight, LDACS navigation accuracy test flight, mixed navigation source test flight with DME, and multi-point positioning monitoring function test flight;Then perform flight test and synchronously collect multi-source data, carry out CNS integrated performance evaluation, including communication, navigation, monitoring performance evaluation.The present application can systematically verify the communication, navigation, monitoring integrated function of LDACS, and provide technical support for the standardization and actual deployment of LDACS.

Description

Technical Field

[0001] This invention relates to the field of aviation communication, navigation, and surveillance technology, specifically to a comprehensive flight test method for the integrated communication, navigation, and surveillance (CNS) functions of an L-band digital aviation communication system (LDACS). Background Technology

[0002] The L-band Digital Aeronautical Communications System (LDACS) is a key component of the International Civil Aviation Organization's (ICAO) future communications system, designed to address spectrum congestion and low data link rates in the existing VHF band. Employing technologies such as Orthogonal Frequency Division Multiplexing (OFDM), LDACS not only provides high-capacity data communication capabilities but is also designed as an integrated CNS system with navigation and surveillance functions, serving as a backup for the Global Navigation Satellite System (GNSS).

[0003] Currently, the performance verification of LDACS systems mainly includes two types of methods:

[0004] 1. Laboratory simulation testing: Evaluation is conducted by constructing a virtual flight environment using a channel simulator. While this method is low-cost and repeatable, it cannot fully simulate the dynamic multipath effects, atmospheric propagation loss, and complex electromagnetic interactions with existing aviation systems (such as distance measuring instruments, DMEs) in a real flight environment, thus limiting the reliability of its verification results.

[0005] 2. Real-world Flight Testing: The German Aerospace Center (DLR) conducted flight measurement activities for the LDACS navigation function in 2012-2013. This measurement activity employed a four-ground-station and one-airborne-receiver architecture, evaluating the multilateral positioning accuracy of LDACS through a butterfly-shaped flight path and verifying its feasibility as a GNSS backup. However, the above methods still have the following shortcomings: 1. Limited verification function: Publicly available flight test methods from institutions such as the DLR mainly focus on evaluating the navigation accuracy of LDACS, without systematically covering the integrated verification of its communication and surveillance capabilities; 2. Lack of a standardized CNS integrated flight test process: Existing flight tests are mostly designed for specific research purposes, lacking a standardized flight test method capable of jointly evaluating the three core performance aspects of LDACS: communication, navigation, and surveillance; 3. Insufficient integration with actual operational scenarios: Existing flight test methods rarely consider the dynamic spectrum coexistence verification of LDACS and the existing DME system, and do not fully utilize traditional navigation facilities such as DME for hybrid positioning flight test verification.

[0006] Therefore, there is an urgent need for a systematic and comprehensive method to conduct integrated flight test verification of the CNS integration function of the LDACS system in a real environment, so as to support the standardization and practical application deployment of LDACS technology. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the lack of real-world comprehensive flight test verification of the integrated CNS function of the LDACS system in the existing technology, especially to overcome the technical defects of the existing flight test function being single, not covering the joint evaluation of CNS, and lacking coexistence verification with the DME system, and to provide a flight test method for the integrated CNS of the L-band digital aviation communication system.

[0008] To solve the above-mentioned technical problems, the technical solution provided by this invention is a test flight method for an L-band digital aviation communication system (CNS) integrating communication systems, comprising the following steps:

[0009] Step S1: Deploy the ground verification system

[0010] In the ground area of ​​the selected test flight airspace, at least four LDACS ground stations with known locations and high-precision clock synchronization are deployed to form a cellular coverage network. The LDACS ground stations include communication transceivers and navigation surveillance signal processing units. At the same time, at least one of the LDACS ground station locations is equipped with a DME or there is a DME in the airspace as a spectrum coexistence verification source and a hybrid navigation source.

[0011] Step S2: Design an integrated flight test method

[0012] Based on the CNS integration verification requirements of LDACS, a comprehensive flight test method covering communication, navigation, and surveillance functions is designed. The comprehensive flight test method includes the following design elements: flight path design, flight test subject design, flight test parameter design, and flight test method design. Among them, the flight test subject design includes LDACS communication performance flight test, LDACS navigation accuracy flight test, hybrid navigation source flight test with DME, and multi-point positioning and surveillance function flight test.

[0013] Step S3: Conduct flight tests and simultaneously collect multi-source data.

[0014] According to the integrated flight test method designed in step S2, the test aircraft equipped with LDACS airborne equipment performs flight tests, simultaneously collecting communication data, navigation data, and monitoring data;

[0015] Step S4: Integrated CNS Performance Evaluation

[0016] The data collected in step S3 is used to evaluate communication performance, navigation performance, and surveillance performance.

[0017] Furthermore, the flight path design in step S2 includes a cruise level flight segment, a climb / descent segment, a turning maneuver segment, and a cell edge crossing segment. The flight path includes at least one "petal-shaped" path for navigation accuracy assessment / airborne LDACS antenna pattern assessment, in order to evaluate the impact of the LDACS ground station geometry on positioning accuracy and airborne LDACS communication functionality.

[0018] Furthermore, the flight test parameter design in step S2 includes the following key parameters: the aircraft altitude level, flight speed, flight distance, and maneuvering overload of the test aircraft. The aircraft altitude level of the test aircraft includes at least three altitude levels: low (FL100), medium (FL280), and high (FL380). The flight distance must meet the requirements for line-of-sight communication.

[0019] Furthermore, the flight test method design in step S2 specifically includes:

[0020] For the LDACS communication performance test flight: the test aircraft flew along a predetermined route and, under the condition of meeting the line-of-sight communication requirements with the LDACS ground station, evaluated the peak rate, average rate, end-to-end transmission delay, and voice communication quality of the uplink and downlink.

[0021] For the LDACS navigation accuracy test flight: when the test aircraft performs level flight, turning maneuvers, climb / descent, and "petal" trajectory flight, simulate GPS signal failure scenarios and evaluate the LDACS horizontal / vertical positioning error.

[0022] For the test flight with the DME hybrid navigation source: the test aircraft flew along a predetermined route to simulate a GPS signal failure scenario, and simultaneously received LDACS and DME ranging signals to evaluate the horizontal / vertical positioning error under the hybrid navigation source; the number of LDACS ground stations participating in the positioning was gradually reduced to evaluate the positioning availability and positioning accuracy attenuation under the hybrid navigation source.

[0023] For the test flight of the multipoint positioning surveillance function: the test aircraft flew along the edge of the cellular network area to evaluate the track update rate, positioning continuity and coverage boundary of the wide area multipoint positioning (WAM) system.

[0024] Further, in step S3, the communication data includes: recording the throughput, end-to-end delay, packet loss rate, and signal-to-noise ratio of uplink and downlink data packets; the navigation data includes: recording the position, speed, and time information calculated in real time by the airborne receiver based on the LDACS ground station signal, while simultaneously collecting the output of the BD / GPS receiver installed on the aircraft as a reference true value; and the monitoring data includes: recording the real-time trajectory data of the test aircraft calculated by the ground station network through a multi-point positioning algorithm.

[0025] Further, in step S4, the communication performance evaluation involves calculating the peak / average throughput, two-way transmission delay, and data integrity of LDACS communication at different flight phases, and evaluating the voice communication quality; the navigation performance evaluation involves evaluating the positioning accuracy by comparing the LDACS-solved position with the reference true value, calculating the horizontal / vertical positioning error, integrity, and availability, and comparing it with the required navigation performance (RNP) index; and the surveillance performance evaluation involves evaluating the track update rate, positioning continuity, and maximum coverage distance of the WAM system.

[0026] The advantages of this invention compared to the prior art are:

[0027] 1. Integrated verification: In a real flight environment, the flight test verification of the three core functions of LDACS' CNI is systematically integrated, overcoming the shortcomings of the single verification dimension of existing technologies and more closely meeting its operational requirements as a CNI system.

[0028] 2. Authenticity: The results are verified under real dynamic flight conditions, complex electromagnetic environments, and actual atmospheric propagation effects, and have higher credibility and engineering reference value compared to laboratory simulations.

[0029] 3. Hybrid Positioning Verification: A hybrid navigation verification process with the DME system was specifically designed, providing key technical support for the gradual deployment of LDACS in the current aviation environment.

[0030] 4. Standardized Methods: It provides a complete and reproducible flight test process, including ground deployment, flight test method design, data acquisition, and performance evaluation, which is conducive to the formation of industry standard flight test specifications. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the deployment of a ground verification system for a flight test method of an L-band digital aviation communication system (CNS) integrating the present invention.

[0032] Figure 2 This is a schematic diagram of the long-distance level flight track of a test flight method for an L-band digital aviation communication system (CNS) integrated with the present invention.

[0033] Figure 3 This is a schematic diagram of the "plum blossom-shaped" flight path of a test flight method for an L-band digital aviation communication system CNS integrated system according to the present invention.

[0034] Figure 4 This is a schematic diagram of a cellular network crossing flight path for a test flight method of an L-band digital aviation communication system (CNS) integrating the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0036] Example 1, in conjunction with Appendix Figure 1-4 A test flight method for an L-band digital aviation communication system integrating CNS (computer, communication, and electronic) communication systems includes the following steps:

[0037] Step S1: Deploy the ground verification system

[0038] Four LDACS ground stations will be deployed in the selected test flight airspace, such as... Figure 2 As shown, each cellular network represents the coverage area of ​​the corresponding LDACS ground station, where LDACS ground station C also deploys DME stations;

[0039] Step S2: Design an integrated flight test method

[0040] Based on the CNS integration verification requirements of LDACS, a comprehensive flight test method covering communication, navigation, and surveillance functions is designed. The comprehensive flight test method includes the following design elements: flight path design, flight test subject design, flight test parameter design, and flight test method design.

[0041] Flight path design includes:

[0042] Long-distance level flight path, such as Figure 2 As shown, the test aircraft flew back and forth between the F1 and F2 waypoints 2 to 3 times for line-of-sight communication performance evaluation.

[0043] "Plum blossom petal-shaped" flight path, such as Figure 3 As shown, the test aircraft entered from F3, and the waypoints were F3→F4→F5→F6→F7→F8→F9→F10→F11→F12→F13→F14→F15 in sequence. The flight path included level flight and turning maneuvers in multiple directions, which were used for dynamic navigation accuracy evaluation.

[0044] Cellular networks traverse flight paths, such as Figure 4 As shown, the aircraft flew back and forth between the F15 and F16 waypoints 2 to 3 times for multi-point positioning surveillance and hybrid navigation source flight test evaluation.

[0045] Flight test course design:

[0046] This includes flight tests of LDACS communication performance, LDACS navigation accuracy, hybrid navigation source with DME, and multi-point positioning and monitoring functions.

[0047] Flight test parameter design:

[0048] The flight altitude of the test aircraft (e.g., low (FL100), medium (FL250), high (FL350)) is determined according to the test requirements and test conditions. The flight speed and turning bank angle are determined according to the aircraft type (speed is typically Mach 0.6 to 0.8, and turning bank angle is typically 20° to 30°).

[0049] Flight test method design:

[0050] LDACS communication performance test flight: The test aircraft flew along a long-distance level flight path, and under the condition of meeting the line-of-sight communication requirements with the LDACS ground station, the peak rate, average rate, end-to-end transmission delay and voice communication quality of the uplink and downlink were evaluated.

[0051] LDACS navigation accuracy test flight: When the test aircraft flew along a "plum blossom petal" flight path, a GPS signal failure scenario was simulated to evaluate the LDACS horizontal / vertical positioning error;

[0052] Hybrid navigation source test with DME: The test aircraft flew along the cellular network flight path to simulate a GPS signal failure scenario, while simultaneously receiving LDACS and DME ranging signals to evaluate the horizontal / vertical positioning error under the hybrid navigation source; when flying along the cellular network flight path, the number of LDACS ground stations involved in positioning was reduced from 4 to 1 to evaluate the positioning availability and positioning accuracy attenuation under the hybrid navigation source.

[0053] Multipoint positioning surveillance function flight test: Combined with the DME hybrid navigation source flight test, evaluate the track update rate, positioning continuity and coverage boundary of the wide area multipoint positioning (WAM) system.

[0054] Step 3: Conduct flight tests and simultaneously collect multi-source data.

[0055] Following the integrated flight test method designed in step S2, flight tests were conducted using a test aircraft equipped with LDACS airborne equipment. The airborne LDACS equipment calculated the test aircraft's position in real time and recorded the positioning results at a preset frequency. Simultaneously, the high-precision integrated navigation system recorded the reference trajectory at a higher frequency. During voice communication, the quality of voice communication between the two parties was recorded, including continuity and noise levels. The ground center station recorded WAM monitoring trajectory data, timestamps and throughput information of uplink and downlink communication data packets, and simultaneously recorded ranging data from the DME ground station.

[0056] Step 4: Integrated CNS Performance Evaluation

[0057] The data collected in step S3 is used to evaluate communication performance, navigation performance, and surveillance performance, including:

[0058] Communication performance evaluation: Within line-of-sight range, the average uplink and downlink throughput can reach more than 2Mbps (this value is based on system design specifications, and actual test results vary with environmental conditions), and the end-to-end latency can be controlled within 10 milliseconds;

[0059] Navigation performance evaluation: The positioning accuracy was evaluated by comparing the LDACS-calculated position with the reference true value. Under typical test conditions, the horizontal positioning error was better than 10 meters and the vertical positioning error was better than 20 meters, which met the navigation index requirements of RNP1 (the above values ​​are exemplary results under specific test conditions, and the actual positioning error is related to factors such as ground station geometry, flight altitude, and environmental multipath).

[0060] Surveillance performance evaluation: The WAM system can provide continuous track updates with an update rate of 0.5 to 2 Hz. There are no lost or only a few lost track points within the coverage area, and the positioning results are consistent with the airborne terminal calculation results.

[0061] It should be noted that the specific values ​​listed in the above examples (such as throughput, latency, positioning error, etc.) are exemplary data, intended to illustrate the technical effects of the present invention, and do not constitute a limitation on the scope of protection of the present invention. Actual test results may vary depending on the specific test environment, equipment configuration, and flight conditions.

[0062] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one preferred embodiment of the present invention, and the actual implementation is not limited thereto. In conclusion, if those skilled in the art are inspired by this description, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention, without creative design of similar embodiments, should fall within the protection scope of the present invention.

Claims

1. A test flight method for an L-band digital aviation communication system integrating CNS (computer, communication, and electronic) communication, characterized in that... This includes the following steps: Step S1: Deploy the ground verification system In the ground area of ​​the selected test flight airspace, at least four LDACS ground stations with known locations and high-precision clock synchronization are deployed to form a cellular coverage network. The LDACS ground stations include communication transceivers and navigation surveillance signal processing units. At the same time, at least one of the LDACS ground station locations is equipped with a DME or there is a DME in the airspace as a spectrum coexistence verification source and a hybrid navigation source. Step S2: Design an integrated flight test method Based on the CNS integration verification requirements of LDACS, a comprehensive flight test method covering communication, navigation, and surveillance functions is designed. The comprehensive flight test method includes the following design elements: flight path design, flight test subject design, flight test parameter design, and flight test method design. Among them, the flight test subject design includes LDACS communication performance flight test, LDACS navigation accuracy flight test, hybrid navigation source flight test with DME, and multi-point positioning and surveillance function flight test. Step S3: Conduct flight tests and simultaneously collect multi-source data. According to the integrated flight test method designed in step S2, the test aircraft equipped with LDACS airborne equipment performs flight tests, simultaneously collecting communication data, navigation data, and monitoring data; Step S4: Integrated CNS Performance Evaluation The data collected in step S3 is used to evaluate communication performance, navigation performance, and surveillance performance.

2. The flight test method for an L-band digital aviation communication system integrating CNS as described in claim 1, characterized in that... The flight path design in step S2 includes a cruise level flight segment, a climb / descent segment, a turning maneuver segment, and a cell edge crossing segment. The flight path includes at least one "petal-shaped" path for navigation accuracy assessment / airborne LDACS antenna pattern assessment, in order to evaluate the impact of the LDACS ground station geometry on positioning accuracy and airborne LDACS communication functionality.

3. The flight test method for an L-band digital aviation communication system integrating CNS as described in claim 1, characterized in that... The test flight parameter design in step S2 includes the following key parameters: the test aircraft's altitude level, flight speed, flight distance, and maneuvering overload. The test aircraft's altitude level includes at least three altitude levels: low (FL100), medium (FL280), and high (FL380). The flight distance must meet the requirements for line-of-sight communication.

4. The flight test method for an L-band digital aviation communication system integrating CNS as described in claim 1, characterized in that... The flight test method design in step S2 specifically includes: For the LDACS communication performance test flight: the test aircraft flew along a predetermined route and, under the condition of meeting the line-of-sight communication requirements with the LDACS ground station, evaluated the peak rate, average rate, end-to-end transmission delay, and voice communication quality of the uplink and downlink. For the LDACS navigation accuracy test flight: when the test aircraft performs level flight, turning maneuvers, climb / descent, and "petal" trajectory flight, simulate GPS signal failure scenarios and evaluate the LDACS horizontal / vertical positioning error; For the test flight with the DME hybrid navigation source: the test aircraft flew along a predetermined route to simulate a GPS signal failure scenario, and simultaneously received LDACS and DME ranging signals to evaluate the horizontal / vertical positioning error under the hybrid navigation source; the number of LDACS ground stations participating in the positioning was gradually reduced to evaluate the positioning availability and positioning accuracy attenuation under the hybrid navigation source. For the test flight of the multipoint positioning surveillance function: the test aircraft flew along the edge of the cellular network area to evaluate the track update rate, positioning continuity and coverage boundary of the wide area multipoint positioning (WAM) system.

5. The flight test method for an L-band digital aviation communication system CNS integration according to claim 1, characterized in that... In step S3, the communication data includes: recording the throughput, end-to-end delay, packet loss rate, and signal-to-noise ratio of uplink and downlink data packets; the navigation data includes: recording the position, speed, and time information calculated in real time by the airborne receiver based on the LDACS ground station signal, while collecting the output of the BD / GPS receiver installed on the aircraft as a reference true value; and the monitoring data includes: recording the real-time trajectory data of the test aircraft calculated by the ground station network through a multi-point positioning algorithm.

6. The flight test method for an L-band digital aviation communication system integrating CNS as described in claim 1, characterized in that... In step S4, the communication performance evaluation includes: calculating the peak / average throughput, two-way transmission delay, and data integrity of LDACS communication at different flight phases, and evaluating voice communication quality; the navigation performance evaluation includes: evaluating the positioning accuracy of the LDACS-solved position and the reference true value, calculating the horizontal / vertical positioning error, integrity, and availability, and comparing it with the required navigation performance (RNP) index; and the surveillance performance evaluation includes: evaluating the track update rate, positioning continuity, and maximum coverage distance of the WAM system.

Images