LDACS airborne antenna deployment method considering electromagnetic compatibility with BDS

Abstract

The invention discloses an LDACS airborne antenna deployment method giving consideration to BDS electromagnetic compatibility, and the method comprises the following steps: determining all possible electromagnetic compatibility interference test scenes of an LDACS interference BDS receiver based on a general flight process and analysis of system signal characteristics; establishing an electromagnetic compatibility link budget model for causing in-band and out-of-band interference to the BDS by the LDACS; link budgeting is carried out on all test scenes, and the interference degree of LDACS on BDS signal receiving is evaluated theoretically; designing an experimental platform for testing the electromagnetic compatibility between the LDACS and the BDS, and evaluating the electromagnetic compatibility between the LDACS and the BDS; and calculating the antenna minimum isolation between the LDACS antenna and the BDS antenna. According to the LDACS airborne antenna deployment method giving consideration to the electromagnetic compatibility with the BDS, a deployment scheme of the LDACS antenna on a common civil aviation passenger plane under the condition that only the constraint condition of the electromagnetic compatibility between the LDACS and the BDS is considered is provided, the LDACS international standardization process is promoted, and application and popularization of the system are promoted.

Description

Technical Field

[0001] The present invention relates to the field of aviation communication and navigation technology, and in particular to a method for deploying an LDACS airborne antenna taking into account electromagnetic compatibility with a BDS. Background Art

[0002] With the rapid development of the global economy, the demand for air transportation is growing. Based on the current growth scenario, EUROCONTROL predicts that the number of flights in Europe in 2040 will increase by 43% compared to 2019.

[0003] The increasing number of flights is a huge challenge to the Air Traffic Management (ATM) system. However, existing aviation communication technologies have problems such as low data transmission rate, low spectrum efficiency, and imperfect security. In order to ensure the sustainable growth of global air traffic, the air traffic management system needs to be modernized to improve air traffic efficiency and flight safety.

[0004] The development of the Future Communication Infrastructure (FCI) proposed by the International Civil Aviation Organization (ICAO) can meet the needs of aviation development and further modernize the air traffic management system. The future air / ground communication system L-band Digital Aeronautical Communications System (LDACS) is one of the most important data links within the FCI, as it is expected to cover the main part of air / ground communications.

[0005] LDACS has the advantages of large bandwidth, high speed, low latency and high security. It is the first ICAO-certified system that truly integrates communication, navigation and surveillance. LDACS follows modern and efficient transmission concepts and is applied to the fourth-generation mobile radio system. However, since there is no large continuous free spectrum available in the L band, the transmission bandwidth is limited to approximately 500 kHz. In order to avoid dividing this limited bandwidth between the forward and reverse links, frequency division duplexing is applied. This design method can support net data rates of 561 kbps to 2.6 Mbps for the forward and reverse link channels. Compared with current air / ground communications, LDACS increases data throughput by at least 50 times and up to 200 times.

[0006] As a new system, LDACS must solve the electromagnetic compatibility problem with other existing aviation L-band communication, navigation and surveillance systems. Beidou Navigation Satellite System (BDS), an important new infrastructure in my country, is one of them. The signal operating frequency of BDS is adjacent to that of the LDACS system, especially the B2a signal centered on the frequency of 1176.45MHz. The deployment of LDACS cannot affect the safe operation of BDS. Therefore, solving the electromagnetic compatibility problem between LDACS and BDS is crucial to promoting the development of the LDACS system and the standardization process of the LDACS system. Summary of the invention

[0007] The purpose of the present invention is to provide a method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS. First, all possible scenarios of LDACS interfering with BDS receivers are constructed. Then, based on signal transmission characteristics, link budget models of in-band and out-of-band interference caused by LDACS to BDS are established respectively, and link budgets are performed for all established scenarios. The interference degree of LDACS on BDS signal reception in different scenarios is theoretically evaluated. An electromagnetic compatibility test experimental platform is designed, and the influence of LDACS on BDS signal reception is specifically evaluated based on the platform. Based on the electromagnetic compatibility test results and theoretical analysis results, a research method for a deployment scheme of LDACS antennas on general civil aircraft is provided under the condition that only the electromagnetic compatibility constraints of LDACS and BDS are considered.

[0008] To achieve the above object, the present invention provides a method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS, comprising the following steps: S1. Based on the general flight process and the analysis of the system signal characteristics, determine all possible EMC interference test scenarios of LDACS interfering with the BDS receiver; S2. Based on the signal propagation process and signal characteristics in different electromagnetic compatibility interference test scenarios, the electromagnetic compatibility link budget model of the in-band and out-of-band interference caused by LDACS to BDS is established respectively; S3. Based on the established LDACS and BDS parameter standards and link budget model, link budget is performed for all test scenarios to theoretically evaluate the degree of interference of LDACS on BDS signal reception; S4. Design an electromagnetic compatibility test experimental platform between LDACS and BDS, and conduct electromagnetic compatibility evaluation between LDACS and BDS based on the electromagnetic compatibility test experimental platform; S5. Calculate the minimum antenna isolation between the LDACS antenna and the BDS antenna.

[0009] Preferably, in step S1, the LDACS airborne terminal and the LDACS ground station are used as interference sources to interfere with the signal reception of the BDS airborne receiver and the BDS ground receiver, and different electromagnetic compatibility test scenarios are determined in combination with different flight states of the aircraft.

[0010] Preferably, the determined electromagnetic compatibility test scenarios include: Interference of LDACS airborne terminals of other aircraft in the air to BDS airborne receivers; Interference from LDACS ground stations to BDS airborne receivers in the air; Interference from the LDACS airborne terminal to the BDS airborne receiver on the same aircraft; Interference from the airborne LDACS to the BDS airborne receiver at the airport; Interference of the airport's LDACS airborne terminal to the BDS airborne receiver in the air; Interference from LDACS ground stations to BDS airborne receivers at airports; Interference from the airport's LDACS airborne terminal to the airport's BDS airborne receiver; Interference from the airborne LDACS to the BDS ground receiver; Interference from the airport's LDACS airborne terminal to the BDS ground receiver; Interference from LDACS ground station to BDS ground receiver.

[0011] Preferably, in step S2, the electromagnetic compatibility link budget model quantitatively analyzes the interference degree of the LDACS system to the BDS from a theoretical level by determining the specific parameters of each link in the signal emission, signal transmission and signal reception processes; and constructs two different electromagnetic compatibility link budget models for in-band interference and out-of-band interference, respectively, according to the signal characteristics of the LDACS and BDS systems.

[0012] Preferably, in step S4, the designed electromagnetic compatibility test experimental platform includes a hardware part and a software part, the hardware part includes a vector signal generator, a BDS signal simulation generator, a combiner, a frequency division duplexer and a USRP, and the software part is a BDS software receiver; The vector signal generator is used to simulate the transmission of LDACS signals in real time, and its adjustable parameters include signal frequency, signal power and signal duty cycle; The BDS signal simulation generator is used to simulate the satellite transmitting BDS signals in real time. Its adjustable parameters include antenna gain, signal power and specific satellite parameters of signal transmission; The combiner is used to combine the LDACS analog signal and the BDS analog signal; USRP is used to collect the mixed signal after combining; The BDS software receiver is used to perform signal processing on the mixed signal.

[0013] Preferably, in step S4, the specific interference degree of the LDACS system on the BDS is evaluated by analyzing the characteristics of the BDS signal after combining, specifically: by calculating the effective carrier-to-noise ratio, primary-to-secondary peak ratio CPPR, and peak-to-average ratio CPPM of the BDS signal, the interference degree of the LDACS on the BDS is accurately measured.

[0014] Preferably, in step S5, based on the theoretical calculation results of the electromagnetic compatibility link budget model and the test results of the electromagnetic compatibility test experimental platform, the free space signal propagation model is used to calculate the minimum antenna isolation between the LDACS antenna and the BDS antenna when the LDACS antenna is deployed on the top of the machine; the signal propagation model around a cylinder is used to calculate the minimum antenna isolation between the LDACS antenna and the BDS antenna when the LDACS antenna is deployed on the belly of the machine.

[0015] Therefore, the present invention adopts the above-mentioned LDACS airborne antenna deployment method taking into account the electromagnetic compatibility with BDS, and the beneficial effects are as follows: (1) The present invention provides a specific and complete research method for the electromagnetic compatibility test and evaluation of the LDACS system and the BDS, including theoretical calculation, experimental test platform, and compatibility evaluation indicators.

[0016] (2) Based on the general flight process and the analysis of the system signal characteristics, the present invention identifies 10 test scenarios for the electromagnetic compatibility test and evaluation between the LDACS system and the BDS, and proposes a link budget model for the electromagnetic compatibility test and evaluation when the LDACS causes in-band and out-of-band interference to the BDS.

[0017] (3) The present invention designs an electromagnetic compatibility test and evaluation experimental platform between LDACS and BDS. The deployment scheme of LDACS antenna on general civil aircraft only considering the electromagnetic compatibility constraint conditions between LDACS and BDS will help promote the international standardization process of LDACS and promote the application and promotion of the system.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of a method for studying electromagnetic compatibility between LDACS and BDS and a method for studying a deployment scheme of LDACS airborne antennas in accordance with an embodiment of the present invention that takes electromagnetic compatibility with BDS into consideration; Figure 2It is a schematic diagram of electromagnetic compatibility scenario analysis of LDACS and BDS systems according to an embodiment of an LDACS airborne antenna deployment method taking into account electromagnetic compatibility with BDS of the present invention; Figure 3 It is an electromagnetic compatibility link budget model for out-of-band interference to BDS in an embodiment of an LDACS airborne antenna deployment method taking into account electromagnetic compatibility with BDS of the present invention; Figure 4 The invention discloses an electromagnetic compatibility link budget model for in-band interference caused by LDACS to BDS in an embodiment of an LDACS airborne antenna deployment method taking into account electromagnetic compatibility with BDS. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0021] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0022] like Figure 1 As shown, a method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS includes the following steps: S1. Based on the general flight process and the analysis of the system signal characteristics, determine all possible EMC interference test scenarios of LDACS interfering with the BDS receiver.

[0023] First, according to the application status and signal characteristics of LDACS and BDS, it is clarified that in the scenario analysis, the LDACS airborne terminal and LDACS ground station are used as interference sources to interfere with the signal reception of the BDS airborne receiver and the BDS ground receiver. Based on this, combined with the different flight states of the aircraft, all possible interference situations are fully considered, 10 different electromagnetic compatibility test scenarios are determined, and comprehensive electromagnetic compatibility link budget and testing are carried out to meet the electromagnetic compatibility test requirements of LDACS and BDS.

[0024] The 10 different EMC test scenarios identified include: Interference of LDACS airborne terminals of other aircraft in the air to BDS airborne receivers; Interference from LDACS ground stations to BDS airborne receivers in the air; Interference from the LDACS airborne terminal to the BDS airborne receiver on the same aircraft; Interference of the airborne LDACS terminal to the BDS airborne receiver at the airport; Interference of the airport's LDACS airborne terminal to the BDS airborne receiver in the air; Interference from LDACS ground stations to BDS airborne receivers at airports; Interference from the airport's LDACS airborne terminal to the airport's BDS airborne receiver; Interference from the airborne LDACS to the BDS ground receiver; Interference from the airport's LDACS airborne terminal to the BDS ground receiver; Interference from LDACS ground station to BDS ground receiver.

[0025] S2, such as Figure 2 As shown, based on the signal propagation process and signal characteristics in different electromagnetic compatibility interference test scenarios, the electromagnetic compatibility link budget model of LDACS causing in-band and out-of-band interference to BDS is established respectively; The link budget model is a mathematical model that simulates a series of signal transmission behaviors from the transmission system to the reception system. The model evaluates the performance of the communication link by integrating various influencing factors in the signal transmission process. According to user needs, the communication system can be continuously optimized by adjusting the parameters of different links of the model to improve the communication quality of the communication system.

[0026] The electromagnetic compatibility evaluation link budget model of the LDACS system for BDS in the present invention integrates the three major processes of signal emission, signal transmission, and signal reception. The electromagnetic compatibility link budget model can quantitatively analyze the degree of interference of the LDACS system to BDS from a theoretical level by determining the specific parameters of each small link in the signal emission, signal transmission, and signal reception process. The results of the quantitative analysis can provide a reference for the parameter optimization of system deployment. In addition, according to the signal characteristics of the LDACS and BDS systems, two different electromagnetic compatibility link budget models are constructed for in-band interference and out-of-band interference, respectively.

[0027] S3. Based on the established LDACS and BDS parameter standards and link budget model, link budget is performed for all test scenarios to theoretically evaluate the degree of interference of LDACS on BDS signal reception.

[0028] S4. Design an electromagnetic compatibility test experimental platform between LDACS and BDS, and conduct electromagnetic compatibility evaluation between LDACS and BDS based on the electromagnetic compatibility test experimental platform.

[0029] The present invention designs an electromagnetic compatibility experimental test platform to quantitatively evaluate the electromagnetic interference level of LDACS signal on BDS signal reception, so as to ensure the safe operation of BDS. The designed electromagnetic compatibility test experimental platform includes a hardware part and a software part. The hardware part includes an R&S vector signal generator, a Spirent GSS9000 BDS signal simulation generator, a combiner, a frequency division duplexer and a USRP X310, which simulates the transmission of LDACS and BDS signals, and uses the combiner to combine the two signals, and uses the USRP X310 to collect the mixed signal, so as to simulate the interference of LDACS signal on BDS signal, and at the same time, it can also avoid the wireless interference of other signals and noise in the space on BDS. The software part is a BDS software receiver, which is used to perform signal processing on the mixed signal, calculate the compatibility evaluation indicators such as the equivalent carrier-to-noise ratio of the BDS signal, and determine the interference degree of the LDACS system on the BDS.

[0030] The main equipment functions of the electromagnetic compatibility test platform are as follows: The R&S vector signal generator is used to simulate the transmission of LDACS signals in real time. Its adjustable parameters include key parameters such as signal frequency, signal power and signal duty cycle. Spirent GSS9000BDS signal simulation generator is used to simulate satellite transmission of BDS signals in real time. Its adjustable parameters include antenna gain, signal power and the specific satellite of signal transmission. The combiner is used to combine the LDACS analog signal and the BDS analog signal; USRP is used to collect the mixed signal after combining; After the LDACS analog signal and the BDS analog signal are combined, the signal is collected by USRP X310 and the collected signal data is saved in the computer. The mixed signal is processed based on the software receiver. The specific interference degree of the LDACS system on the BDS is evaluated by analyzing the characteristics of the combined BDS signal. Specifically, the interference degree of the LDACS system on the BDS is accurately measured by calculating the effective carrier-to-noise ratio, correlation peak to the next peak ratio (CPPR), correlation peak to mean peak ratio (CPPM) and other parameters of the BDS signal.

[0031] Comprehensive test and evaluation platform: The R&S vector signal generator, Spirent GSS9000 signal generator, USRPX310, combiner, frequency division duplexer, and BDS software receiver are integrated into a comprehensive test and evaluation platform. The platform can automatically execute the test process according to the set test plan and output the change curve of BDS signal characteristics with LDACS signal power.

[0032] The LDACS and BDS electromagnetic compatibility experimental test platform designed by the present invention provides a reference experimental scheme for electromagnetic compatibility testing between two different systems. Using the test method of the experimental platform, the maximum LDACS interference signal power that can be tolerated to avoid harmful interference to the BDS receiver can be obtained, and based on this result, the minimum propagation loss required for the LDACS signal from transmission to reception by the BDS receiver can be calculated, providing a reference for the promotion of compatibility standards.

[0033] By combining the test results obtained from the experimental test platform with different signal space propagation models, it is possible to implement a deployment plan for LDACS antennas on general civil airliners under the electromagnetic compatibility constraints of the LDACS and BDS systems, providing a reference for the application and deployment of LDACS.

[0034] S5. Calculate the minimum antenna isolation between the LDACS antenna and the BDS antenna.

[0035] Based on the theoretical calculation results of the electromagnetic compatibility link budget model and the test results of the electromagnetic compatibility test experimental platform, the free space signal propagation model is used to calculate the minimum antenna isolation between the LDACS antenna and the BDS antenna when the LDACS antenna is deployed on the top of the aircraft; the signal propagation model around a cylinder is used to calculate the minimum antenna isolation between the LDACS antenna and the BDS antenna when the LDACS antenna is deployed on the belly of the aircraft.

[0036] LDACS antenna deployment scheme design Calculation of minimum isolation between LDACS and BDS antennas based on link budget model Based on the electromagnetic compatibility interference test scenarios between LDACS and BDS systems, the minimum distance between the transmitting system and the receiving system in each scenario is first determined, and then the propagation loss in each scenario is calculated according to the signal free space propagation model. The obtained propagation loss is then brought into the electromagnetic compatibility link budget model. For each scenario, the link budget is performed under both in-band and out-of-band interference conditions, and the LDACS signal power received by the BDS receiving system is obtained to determine the scenario with the greatest interference.

[0037] Based on the scenario with the greatest interference, the maximum interference signal power threshold that the BDS receiver can tolerate to avoid harmful interference is selected according to the ICAO Global Navigation Satellite System RF interference mask. Then, according to the system performance standards, the performance parameters such as signal characteristics and antenna characteristics involved in the link budget model are selected to carry out the electromagnetic compatibility link budget of the LDACS and BDS systems.

[0038] like Figure 3 , Figure 4As shown in the figure, according to the established LDACS to BDS system electromagnetic compatibility link budget model, the calculation formulas of interference signal power in out-band and in-band interference cases are derived respectively: (1); in, is the interference signal power in the case of out-of-band interference, in dBm, is the equivalent isotropic radiated power of the transmitting system signal, in dBm. is the spatial propagation loss in dB, is the antenna gain of the BDS receiving antenna, in dBi, is the feeder loss, in dB.

[0039] (2); in, The interference signal power in the case of in-band interference, in dBm; is the signal attenuation due to frequency offset obtained according to the LDACS transmit spectrum mask, in dB; is the signal bandwidth of the transmitting system, in Hz; is the signal bandwidth of the receiving system, in Hz.

[0040] When the maximum interference signal power threshold of the BDS receiver is set, different values ​​are selected according to the in-band interference situation and the out-of-band interference situation. This power threshold is used as the interference signal power. At the same time, the values ​​of other parameters are substituted into formula (1) and formula (2) to obtain the minimum propagation loss required to avoid harmful interference of the LDACS signal to the BDS receiver.

[0041] According to the minimum propagation loss, combined with different spatial signal propagation models, the minimum antenna isolation between LDACS and BDS that meets the minimum propagation loss can be obtained. According to the different requirements of installing the LDACS antenna on the top or belly of the aircraft, different spatial signal propagation models need to be used to calculate the antenna isolation. Combined with the different interference types, the antenna isolation needs to be calculated in the following four different situations: The LDACS antenna is installed on the belly of the aircraft. Antenna isolation under out-of-band interference. The LDACS antenna is installed on the belly of the aircraft. Antenna isolation under in-band interference. LDACS antenna is installed on the top of the machine, antenna isolation under out-of-band interference; The LDACS antenna is installed on the top of the machine. Antenna isolation under in-band interference. When the LDACS antenna is mounted on the top of the aircraft, the free space propagation loss model is used, which is defined as: (3); in, is the free space propagation loss in dB; is the LDACS system signal transmission frequency, in MHz; It is the distance from the transmitting device to the receiving device, in km.

[0042] Given the transmission frequency of the LDACS signal, the minimum isolation between the LDACS and BDS antennas is obtained by combining the minimum propagation loss under two different interference conditions, in-band and out-of-band. When the LDACS antenna deployed on the top of the machine meets the antenna isolation under two different interference conditions, the LDACS antenna top deployment plan can be met when only the electromagnetic compatibility constraints of the LDACS and BDS systems are considered.

[0043] When the LDACS antenna is installed on the belly of the aircraft, the signal propagation loss model around a smooth cylinder is used. This model is based on the free space propagation loss model and is defined as: (4); in, k for r / 15, r is the radius of the cylindrical fuselage, in m, F is the signal frequency in MHz, D is half of the circumference of a circle, in m. L is the antenna horizontal isolation, in meters.

[0044] For this formula, the known quantities are the given LDACS signal transmission frequency and the minimum propagation loss under two different interference conditions, in-band and out-of-band, and the unknown quantities are the cylindrical body radius and the antenna horizontal isolation. Therefore, the following conclusions can be drawn: 1) Given any fuselage radius r , the corresponding minimum antenna horizontal isolation can be obtained L ; 2) When the antenna horizontal isolation is 0, the minimum aircraft radius that can avoid harmful interference can be obtained; 3) Based on the fuselage radius r As the independent variable, the antenna horizontal isolation can be obtained L With the body radius r The change curve.

[0045] For an aircraft with a specific cylindrical fuselage, when the LDACS antenna deployed on the belly meets the antenna horizontal isolation requirements for both in-band and out-of-band interference conditions, the LDACS antenna belly deployment solution can be met when only the electromagnetic compatibility constraints of the LDACS and BDS systems are considered.

[0046] Calculation of minimum isolation between LDACS and BDS antennas based on electromagnetic compatibility test platform The electromagnetic compatibility experimental test platform designed by the present invention can simulate the transmission loss of the LDACS signal during transmission by actively controlling the input LDACS signal power, that is, the difference between the maximum transmission EIRP of the LDACS and the LDACS power at the front end of the BDS receiver during the experimental test is used as the transmission loss. The specific experimental steps are as follows: Step 1: Use a spectrum analyzer as the receiving system to transmit LDACS signals and BDS signals separately, and measure the line loss from the LDACS signal and BDS signal transmitting system to the receiving system; Step 2: Set a reasonable range of LDACS signal power and BDS signal transmission power according to line loss, and set a reasonable LDACS signal transmission frequency according to demand; Step 3: traverse the power range of LDACS with a step size of 2 dB, and measure and record the performance parameters such as equivalent carrier-to-noise ratio, CPPR, CPPM, etc. of the combined BDS signal at each different LDACS power; Step 4: Draw the curves of different performance parameters of BDS signal changing with LDACS power based on the experimental results.

[0047] In order to ensure the comprehensiveness of the deployment plan, the test results should include both in-band interference and out-of-band interference. Based on the result curve of the electromagnetic compatibility experimental test platform, the degree of interference of different LDACS powers on the BDS receiver can be intuitively seen. Combined with the minimum performance standard for the safe operation of the BDS system, the maximum LDACS interference signal power that the BDS system can tolerate can be determined. Finally, the difference between the maximum EIRP of the LDACS signal and the maximum LDACS interference signal power that the BDS system can tolerate is used as the minimum transmission loss of the LDACS signal required to avoid harmful interference to the BDS.

[0048] According to the minimum propagation loss and the free space propagation model, the minimum antenna isolation between LDACS and BDS can be obtained when the LDACS antenna is deployed on the aircraft roof. According to the minimum propagation loss and the signal propagation model around a cylinder, the curve of the minimum antenna isolation between LDACS and BDS as a function of the aircraft radius can be obtained when the LDACS antenna is deployed on the aircraft belly. The specific calculation process is the same as the method for calculating the minimum antenna isolation between LDACS and BDS based on the link budget model.

[0049] Therefore, the present invention adopts the above-mentioned LDACS airborne antenna deployment method that takes into account the electromagnetic compatibility with BDS, and proposes a research method for the deployment scheme of LDACS antennas on general civil airliners under the electromagnetic compatibility constraints of LDACS and BDS. It mainly uses the different deployment requirements of LDACS on the top or belly of the aircraft, respectively uses the free space propagation model and the signal propagation model around a smooth cylinder, and based on the theoretical calculation results of the link budget and the experimental test evaluation results, determines the minimum isolation between the LDACS antenna and the BDS antenna, and proposes the necessary requirements for the deployment of the LDACS antenna.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS, characterized in that: The following steps are involved: S1. Based on the general flight process and the analysis of the system signal characteristics, determine all possible EMC interference test scenarios of LDACS interfering with the BDS receiver; S2. Based on the signal propagation process and signal characteristics in different electromagnetic compatibility interference test scenarios, the electromagnetic compatibility link budget model of the in-band and out-of-band interference caused by LDACS to BDS is established respectively; S3. Based on the established LDACS and BDS parameter standards and link budget model, link budget is performed for all test scenarios to theoretically evaluate the degree of interference of LDACS on BDS signal reception; S4. Design an electromagnetic compatibility test experimental platform between LDACS and BDS, and conduct electromagnetic compatibility evaluation between LDACS and BDS based on the electromagnetic compatibility test experimental platform; S5. Calculate the minimum antenna isolation between the LDACS antenna and the BDS antenna.

2. According to claim 1, a method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS is characterized in that: In step S1, the LDACS airborne terminal and the LDACS ground station are used as interference sources to interfere with the signal reception of the BDS airborne receiver and the BDS ground receiver. Different electromagnetic compatibility test scenarios are determined in combination with different flight states of the aircraft.

3. According to claim 2, a method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS is characterized in that: The identified EMC test scenarios include: Interference of LDACS airborne terminals of other aircraft in the air to BDS airborne receivers; Interference from LDACS ground stations to BDS airborne receivers in the air; Interference from the LDACS airborne terminal to the BDS airborne receiver on the same aircraft; Interference from the airborne LDACS to the BDS airborne receiver at the airport; Interference of the airport's LDACS airborne terminal to the BDS airborne receiver in the air; Interference from LDACS ground stations to BDS airborne receivers at airports; Interference from the airport's LDACS airborne terminal to the airport's BDS airborne receiver; Interference from the airborne LDACS to the BDS ground receiver; Interference from the airport's LDACS airborne terminal to the BDS ground receiver; Interference from LDACS ground station to BDS ground receiver.

4. The method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS according to claim 3, characterized in that: In step S2, the electromagnetic compatibility link budget model quantitatively analyzes the interference degree of the LDACS system to the BDS from a theoretical level by determining the specific parameters of each link in the signal emission, signal transmission and signal reception process; according to the signal characteristics of the LDACS and BDS systems, two different electromagnetic compatibility link budget models are constructed for in-band interference and out-of-band interference respectively.

5. The method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS according to claim 4, characterized in that: In step S4, the designed electromagnetic compatibility test experimental platform includes a hardware part and a software part. The hardware part includes a vector signal generator, a BDS signal simulation generator, a combiner, a frequency division duplexer and a USRP, and the software part is a BDS software receiver. The vector signal generator is used to simulate the transmission of LDACS signals in real time, and its adjustable parameters include signal frequency, signal power and signal duty cycle; The BDS signal simulation generator is used to simulate the satellite transmitting BDS signals in real time. Its adjustable parameters include antenna gain, signal power and specific satellite parameters of signal transmission; The combiner is used to combine the LDACS analog signal and the BDS analog signal; USRP is used to collect the mixed signal after combining; The BDS software receiver is used to perform signal processing on the mixed signal.

6. The method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS according to claim 5, characterized in that: In step S4, the interference degree of the LDACS system on the BDS is evaluated by analyzing the characteristics of the combined BDS signal. Specifically, the interference degree of the LDACS system on the BDS is accurately measured by calculating the effective carrier-to-noise ratio, primary-to-secondary peak ratio CPPR, and peak-to-average ratio CPPM of the BDS signal.

7. The method for deploying LDACS airborne antennas taking into account electromagnetic compatibility with BDS according to claim 6, characterized in that: In step S5, based on the theoretical calculation results of the electromagnetic compatibility link budget model and the test results of the electromagnetic compatibility test experimental platform, the free space signal propagation model is used to calculate the minimum antenna isolation between the LDACS antenna and the BDS antenna when the LDACS antenna is deployed on the top of the machine; the signal propagation model around a cylinder is used to calculate the minimum antenna isolation between the LDACS antenna and the BDS antenna when the LDACS antenna is deployed on the belly of the machine.

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