ATC Channel Model And Simulation Of Test Environment On Ground

Air Traffic Control Transponder is an important device,which transmits regulatory of traffic management information and avoids aircraft collisions.It is also an important guarantee for the safe flight.During the flight,the transponder and the tower may fail to communicate with each other,which is caused by the multipath effect and the Doppler shift.The multipath effect result from the reflection of the fixture and the Doppler shift result from the high-speed motion of aircraft.The traditional test only tests the basic function of transponder,such as frequency and pulse width and so on.Anti-multipath performance can't be tested.If the test were carried out under flight,high cost and long test period will be inevitable.Therefore,simulating fading test environment on the ground is of great significance for testing multi-path performance of transponder.Firstly,based on the working principle of transponder,simulation scheme was designed and the reconstruction of the data link was completed.Secondly,transmission characteristics in flight,the causes of multipath effects and the impact on the signal was studied,Doppler power spectral density was analyzed,such as cruise,takeoff and landing,taxing,parking scenarios.Static channel modeling of the transponder was completed.Then based on the static scenarios,the simulation scheme of dynamic fading test environment is designed.The flight data of FlightGear is used to calculate the Doppler shift,extra power loss and propagation delay.Finally,the simulation of dynamic fading test environment was completed and the BER performance of up and down data link was analyzed.Through the analysis of the transmission characteristics of the transponder signal,the channel model is established and the transmission performance is analyzed.Finally,based on the flight data and the channel model,the simulation of the fading test environment in the ascending and descending stages is completed.The research results is of the great significance for the construction of the fading test environment on the ground.