LDACS and TACAN electromagnetic compatibility simulation test method

Abstract

The invention discloses an LDACS and TACAN electromagnetic compatibility simulation test method, and belongs to the technical field of aviation navigation, and the method comprises the steps: selecting a test scene through a graphical user interface; signal parameters are configured through a graphical user interface, and a TACAN signal and an LDACS signal are generated; channel parameters are configured through the graphical user interface, and a test channel is generated; configuring demodulation parameters through a graphical user interface, and constructing a receiving end; transmitting the TACAN signal and the LDACS signal through a test channel, and demodulating the TACAN signal and the LDACS signal at a receiving end; evaluating the electromagnetic compatibility of the LDACS to the TACAN, and generating and displaying a test result; according to the LDACS and TACAN electromagnetic compatibility simulation testing method, software simulation of interference testing of an aviation communication system is achieved, and the method has the advantages of being configurable in parameter, extensible in scene, low in cost and the like.

Description

Technical Field

[0001] This invention relates to the field of aviation navigation technology, and in particular to a simulation test method for electromagnetic compatibility of LDACS and TACAN. Background Technology

[0002] TACAN is an aviation navigation system developed in the United States, primarily used for aircraft ranging and direction finding. It achieves navigation through interaction between ground beacons and airborne equipment. Like traditional distance measuring instruments (DMEs), TACAN employs a secondary radar ranging principle. Building upon this, TACAN ground beacons insert a azimuth reference signal into the signal and use a specially structured antenna to amplitude-modulate the signal to achieve direction finding. In my country, TACAN is widely used in the aviation field, and its anti-jamming capabilities are directly related to flight safety.

[0003] LDACS is a next-generation aviation communication system jointly proposed by the U.S. Federal Aviation Administration (FAA) and the European Organization for Air Navigation Safety (EUROCONTROL). It employs Orthogonal Frequency Division Multiplexing (OFDM) modulation technology. Compared to traditional communication systems (such as VDL M2), LDACS offers significantly improved communication bandwidth and data transmission rates, while simultaneously providing navigation and integrated surveillance capabilities, effectively alleviating the strain on aviation spectrum resources. However, LDACS operates in a frequency band that partially overlaps with TACAN, potentially interfering with the TACAN system, affecting its navigation accuracy, and even causing ranging and direction-finding errors. As a new aviation communication system to be deployed, one of the prerequisites for LDACS's deployment is that it must not affect the normal operation of the existing TACAN system.

[0004] Currently, there are limited electromagnetic compatibility (EMC) testing methods for LDACS and TACAN. While it's possible to build realistic physical scenarios for field testing, this method is costly, time-consuming, and struggles to cover all possible interference scenarios. Traditional simulation platforms (such as MATLAB / Simulink or dedicated RF simulation tools) have significant advantages in system modeling and simulation; however, for scenarios requiring rapid iteration and interactive parameter exploration, their workflows are often cumbersome. Modifying model structure or parameters frequently necessitates interrupting simulations and recompiling, slowing down exploratory research. In contrast, GNU Radio provides an open-source Software-Defined Radio (SDR) framework. Its flow graph concept offers greater flexibility and real-time adjustment capabilities, supporting a more dynamic and interactive simulation experience, facilitating efficient exploration of complex design spaces. However, how to build a systematic and repeatable test process for quantitatively evaluating the EMC of LDACS and TACAN based on such a flexible platform remains a technical problem that needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide an electromagnetic compatibility simulation and testing method for LDACS and TACAN to solve the problems in the background art and realize the functions of dynamic simulation, parametric testing and visualization analysis.

[0006] To achieve the above objectives, this invention provides an electromagnetic compatibility simulation test method for LDACS and TACAN, based on the GNU Radio platform and implemented through a graphical user interface, comprising the following steps: S1. Select the test scenario through the graphical user interface. The test scenarios include simulation tests of airborne TACAN receivers and simulation tests of ground TACAN receivers. S2. Configure signal parameters through the graphical user interface, and generate the TACAN and LDACS signals required for the test based on the selected test scenario and the configured signal parameters; S3. Configure channel parameters through the graphical user interface, and generate the test channel required for the test based on the channel parameters; S4. Configure demodulation parameters through the graphical user interface and build the receiver based on the demodulation parameters; S5. Transmit the TACAN signal and LDACS signal through the test channel, and demodulate the received mixed signal at the receiving end to obtain the demodulation information of the TACAN signal. S6. Based on the demodulation information, evaluate the electromagnetic compatibility of LDACS with TACAN under the conditions of test scenario, test channel and receiver, and generate and display the test results.

[0007] Preferably, the graphical user interface includes a test scenario selection interface, a signal parameter configuration interface, a channel parameter configuration interface, a demodulation configuration interface, and a test process information interface.

[0008] Preferably, the test scenario selection interface provides test options for airborne TACAN receivers and test options for ground TACAN receivers; The signal parameter configuration interface dynamically associates and displays the corresponding signal parameter configuration list based on the options selected in the test scenario selection interface; The channel parameter configuration interface provides fading type options and a list of channel parameter configurations; The demodulation configuration interface provides a list of demodulation configurations; The test process information interface displays the demodulated signal waveform, demodulated signal spectrum, signal-to-noise ratio, and changes in the TACAN signal bit error rate, ranging error, and direction finding error.

[0009] Preferably, the signal parameter configuration list specifically includes: When the test options for the airborne TACAN receiver are selected, the list includes signal sampling rate, simulation time, TACAN signal mode, TACAN signal channel, TACAN beacon identifier, number of random fill pulses per second for the TACAN signal, azimuth angle from the aircraft to the TACAN beacon, modulation index at 15Hz and 135Hz, TACAN carrier frequency offset, LDACS signal link, LDACS signal frequency, LDACS duty cycle, LDACS carrier frequency offset, and power ratio of the TACAN signal to the LDACS signal. When the test options for the terrestrial TACAN receiver are selected, the list includes signal sampling rate, simulation time, TACAN signal mode, TACAN signal channel, number of TACAN signal interrogation pulses per second, TACAN carrier frequency offset, LDACS signal link, LDACS signal frequency, LDACS duty cycle, LDACS carrier frequency offset, and the power ratio of the TACAN signal to the LDACS signal.

[0010] Preferably, the fading type options include Ricean fading and Rayleigh fading, and the channel parameter configuration list includes the line length, additive white Gaussian noise power, Ricean factor, and maximum Doppler frequency of the TACAN channel and LDACS channel, respectively.

[0011] Preferably, the demodulation configuration list includes filter gain, filter cutoff frequency, filter transition bandwidth, and filter window function.

[0012] Preferably, in step S6, the electromagnetic compatibility level of LDACS and TACAN is quantified by comparing the changes in bit error rate, ranging error, and direction finding error of the TACAN signal under the presence or absence of LDACS signal interference.

[0013] Therefore, the above-mentioned LDACS and TACAN electromagnetic compatibility simulation test method of the present invention has the following beneficial effects: (1) By providing a fully software-based simulation solution based on GNU Radio, the problems of high cost, long cycle and poor flexibility of LDACS and TACAN electromagnetic compatibility hardware testing are solved; (2) Based on the GNU Radio platform, the flow graph architecture and graphical parameter configuration interface overcome the limitations of traditional simulation tools that often require interruption and recompilation when modifying parameters or models. It supports real-time parameter adjustment and interactive exploration of dynamic scenarios such as aircraft motion and channel time-varying, improving the efficiency and depth of simulation analysis. (3) By using a parameterized configuration interface and a standardized test process, the complex signal generation, channel simulation and performance evaluation steps are solidified, ensuring the consistency and comparability of results under different test conditions, and providing a repeatable and verifiable standardized method for the electromagnetic compatibility evaluation of LDACS and TACAN.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 This is a flowchart of an electromagnetic compatibility simulation test method for LDACS and TACAN according to the present invention; Figure 2 This is a simulation flowchart of the TACAN signal and LDACS signal for an electromagnetic compatibility simulation test method of LDACS and TACAN according to the present invention. Figure 3 This is a channel correspondence diagram of the TACAN signal in the electromagnetic compatibility simulation test method of LDACS and TACAN according to the present invention. Detailed Implementation

[0016] The following detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0017] Example like Figure 1 As shown, this invention provides a simulation test method for the electromagnetic compatibility of LDACS and TACAN. Through software simulation, it simulates the TACAN air-to-ground navigation process of an aircraft under LDACS signal interference. The entire process is controlled through a graphical user interface (GUI), based on the GNU Radio platform and implemented via a GUI. The overall layout of the GUI is shown below. Figure 2 As shown, the interface mainly includes a test scenario selection interface, a signal parameter configuration interface, a channel parameter configuration interface, a demodulation configuration interface, and a test process information interface. The test scenario selection interface provides test options for airborne TACAN receivers and ground-based TACAN receivers. The signal parameter configuration interface dynamically associates and displays the corresponding signal parameter configuration list based on the options selected in the test scenario selection interface. The channel parameter configuration interface provides fading type options and a channel parameter configuration list. The demodulation configuration interface provides a demodulation configuration list. The test process information interface displays the demodulated signal waveform, demodulated signal spectrum, signal-to-noise ratio, and changes in TACAN signal bit error rate, ranging error, and direction finding error.

[0018] The simulation testing method provided in this embodiment specifically includes the following steps: S1. Select the test scenario through the graphical user interface. The test scenarios include simulation tests of airborne TACAN receivers and simulation tests of ground TACAN receivers.

[0019] S2. Configure signal parameters through the graphical user interface, and generate the TACAN and LDACS signals required for the test based on the selected test scenario and the configured signal parameters.

[0020] When the test option for the airborne TACAN receiver is selected, the signal parameter configuration list specifically includes the following parameters: signal sampling rate, simulation time, TACAN signal mode, TACAN signal channel, TACAN beacon identifier, number of random fill pulses per second for the TACAN signal, azimuth angle from the aircraft to the TACAN beacon, modulation index for 15Hz and 135Hz, TACAN carrier frequency offset, LDACS signal link, LDACS signal frequency, LDACS duty cycle, LDACS carrier frequency offset, and power ratio of the TACAN signal to the LDACS signal. When the test options for the terrestrial TACAN receiver are selected, the list includes signal sampling rate, simulation time, TACAN signal mode, TACAN signal channel, number of TACAN signal interrogation pulses per second, TACAN carrier frequency offset, LDACS signal link, LDACS signal frequency, LDACS duty cycle, LDACS carrier frequency offset, and the power ratio of the TACAN signal to the LDACS signal.

[0021] The TACAN signal mode value is "X" or "Y", meaning that the basic Gaussian pulse pairs that make up the TACAN signal are... (in Pulse interval The values ​​are 12 μs or 30 μs.

[0022] The TACAN signal channel values ​​are 1-126. Referring to the TACAN signal mode... Figure 3This means that when testing the airborne TACAN receiver, the carrier frequency is 962-1024 MHz for "1-63X", 1151-1213 MHz for "64-126X", 1088-1150 MHz for "1-63Y", and 1025-1087 MHz for "64-126Y"; when testing the ground-based TACAN receiver, the carrier frequency is 1025-1087 MHz for "1-63X", 1088-1150 MHz for "64-126X", 1025-1087 MHz for "1-63Y", and 1088-1150 MHz for "64-126Y".

[0023] The TACAN beacon identifier consists of three uppercase letters, such as "ABC", which are used to generate Morse code and further encode the identification signal.

[0024] The azimuth angle of the aircraft to the TACAN beacon ranges from 0° to 360°, and is used to set the phase difference between the 15 Hz and 135 Hz components of the TACAN signal modulation envelope and the azimuth reference pulse group.

[0025] The TACAN carrier frequency offset is 0-2 kHz, used to simulate the crystal oscillator error at the transmitter and receiver.

[0026] The random fill pulse logs per second of the TACAN signal range from 1800 to 3600, which is used to simulate the fill density of the ground transmitter when it does not receive identification and ranging response signals.

[0027] The TACAN signal has a polling pulse count of 10-150 per second, which is used to simulate the working state of the airborne transmitter, including search and tracking states.

[0028] S3. Configure channel parameters through the graphical user interface, and generate the test channel required for the test based on the channel parameters.

[0029] The transmission channels of TACAN and LDACS signals are affected by noise, which is reflected in AWGN power during testing.

[0030] For the TACAN air-to-ground navigation process tested in this embodiment, the TACAN signal is approximated as LOS transmission, using Ricean fading to approximate the LOS transmission channel, and controlled by the Ricean factor during testing. In the interference scenario of this navigation process, the LDACS signal includes two links, FL and RL. The FL link, between the TACAN receiver and the ground, is NLOS transmission, using Rayleigh fading to approximate the NLOS transmission channel. In other cases, the LDACS signal is approximated as LOS transmission.

[0031] The maximum Doppler frequency is used to simulate the frequency shift characteristics of an aircraft during high-speed motion.

[0032] In this embodiment, the fading type options for the TACAN channel include Ricean fading, and the fading type options for the LDACS channel include Ricean fading and Rayleigh fading, specifically corresponding to the LDACS signal FL and RL links. The channel parameter configuration list includes the line length and additive white Gaussian noise power for both the TACAN and LDACS channels. For the Ricean channel, it also includes the Ricean factor, and for the ground TACAN receiver test scenario and the LDACS RL signal, it also includes the maximum Doppler frequency.

[0033] S4. Configure demodulation parameters through the graphical user interface and build the receiver based on the demodulation parameters; the demodulation configuration list includes filter gain, filter cutoff frequency, filter transition bandwidth and filter window function, which are used to configure the performance of the low-pass FIR filter.

[0034] S5. Transmit the TACAN signal and LDACS signal through the test channel, and demodulate the received mixed signal at the receiving end to obtain the demodulation information of the TACAN signal. S6. Based on the demodulation information, evaluate the electromagnetic compatibility of LDACS with TACAN under the conditions of test scenario, test channel and receiver, and generate and display the test results.

[0035] The specific evaluation method is as follows: by comparing the changes in three key indicators of the TACAN signal—bit error rate (BER), ranging error, and direction finding error—under two conditions with and without LDACS signal interference, the degree of interference of LDACS on TACAN is quantified, thereby determining the electromagnetic compatibility level.

[0036] Ultimately, all test results, including the real-time waveform of the demodulated signal, signal spectrum, signal-to-noise ratio (SNR), and the change curves of the three key indicators mentioned above, are displayed centrally and visually in the test process information interface, enabling users to intuitively and comprehensively analyze the electromagnetic compatibility effect.

[0037] Therefore, this invention employs the aforementioned LDACS and TACAN electromagnetic compatibility simulation testing method to achieve software-based simulation of interference testing for aviation communication systems. It has advantages such as configurable parameters, scalable scenarios, and low cost, providing an effective testing means for the research and development of avionics equipment and spectrum management. This enables early assessment of interference risks before the deployment of LDACS systems, provides quantitative basis for spectrum planning decisions, effectively reduces the interference risk between new aviation communication systems and existing navigation systems, and ensures flight safety.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A simulation test method for electromagnetic compatibility of LDACS and TACAN, characterized in that, Based on the GNU Radio platform and implemented through a graphical user interface, the following steps are included: S1. Select the test scenario through the graphical user interface. The test scenarios include simulation tests of airborne TACAN receivers and simulation tests of ground TACAN receivers. S2. Configure signal parameters through the graphical user interface, and generate the TACAN and LDACS signals required for the test based on the selected test scenario and the configured signal parameters; S3. Configure channel parameters through the graphical user interface, and generate the test channel required for the test based on the channel parameters; S4. Configure demodulation parameters through the graphical user interface and build the receiver based on the demodulation parameters; S5. Transmit the TACAN signal and LDACS signal through the test channel, and demodulate the received mixed signal at the receiving end to obtain the demodulation information of the TACAN signal. S6. Based on the demodulation information, evaluate the electromagnetic compatibility of LDACS with TACAN under the conditions of test scenario, test channel and receiver, and generate and display the test results.

2. The LDACS and TACAN electromagnetic compatibility simulation test method according to claim 1, characterized in that: The graphical user interface includes a test scenario selection interface, a signal parameter configuration interface, a channel parameter configuration interface, a demodulation configuration interface, and a test process information interface.

3. The LDACS and TACAN electromagnetic compatibility simulation test method according to claim 2, characterized in that: The test scenario selection interface provides test options for airborne TACAN receivers and test options for ground TACAN receivers. The signal parameter configuration interface dynamically associates and displays the corresponding signal parameter configuration list based on the options selected in the test scenario selection interface; The channel parameter configuration interface provides fading type options and a list of channel parameter configurations; The demodulation configuration interface provides a list of demodulation configurations; The test process information interface displays the demodulated signal waveform, demodulated signal spectrum, signal-to-noise ratio, and changes in the TACAN signal bit error rate, ranging error, and direction finding error.

4. The LDACS and TACAN electromagnetic compatibility simulation test method according to claim 3, characterized in that, The signal parameter configuration list specifically includes: When the test options for the airborne TACAN receiver are selected, the list includes signal sampling rate, simulation time, TACAN signal mode, TACAN signal channel, TACAN beacon identifier, number of random fill pulses per second for the TACAN signal, azimuth angle from the aircraft to the TACAN beacon, modulation index at 15Hz and 135Hz, TACAN carrier frequency offset, LDACS signal link, LDACS signal frequency, LDACS duty cycle, LDACS carrier frequency offset, and power ratio of the TACAN signal to the LDACS signal. When the test options for the terrestrial TACAN receiver are selected, the list includes signal sampling rate, simulation time, TACAN signal mode, TACAN signal channel, number of TACAN signal interrogation pulses per second, TACAN carrier frequency offset, LDACS signal link, LDACS signal frequency, LDACS duty cycle, LDACS carrier frequency offset, and the power ratio of the TACAN signal to the LDACS signal.

5. The LDACS and TACAN electromagnetic compatibility simulation test method according to claim 3, characterized in that: The fading type options include Ricean fading and Rayleigh fading, and the channel parameter configuration list includes the line length, additive white Gaussian noise power, Ricean factor, and maximum Doppler frequency for the TACAN and LDACS channels, respectively.

6. The LDACS and TACAN electromagnetic compatibility simulation test method according to claim 3, characterized in that: The demodulation configuration list includes filter gain, filter cutoff frequency, filter transition bandwidth, and filter window function.

7. The LDACS and TACAN electromagnetic compatibility simulation test method according to claim 3, characterized in that: In step S6, the electromagnetic compatibility level of LDACS and TACAN is quantified by comparing the changes in bit error rate, ranging error, and direction finding error of the TACAN signal under the presence or absence of LDACS signal interference.

Images