Research And Implementation Of ATC/DME Signal Simulation Module

Due to the rapid progress of the aviation industry and the increasingly urgent need for high quality aviation services,it has become increasingly important to ensure flight safety.Therefore,effective preventive measures,such as regular inspections and patrols,are required to maintain good aviation management by using radar technology in order to precisely control aircraft routes,as well as to ensure continuous safe operations.Equipment such as Air Traffic Control Transponders(ATC TRANSPONDER,XPDR)and Distance Measuring Equipment(DME)based on secondary radar technology have been commonly adopted and are widely used in the aerospace safety systems of many countries.With the continuous progress of avionics technology and the improvement of test standards,the traditional general-purpose test instruments have been difficult to meet the requirements of ATC transponder and rangefinder testing,especially in terms of poor performance in response to real-time and functional diversity.In order to meet the higher requirements,more advanced test equipment is needed.By developing ATC/DME signal simulation modules,various complex operating scenarios can be simulated to better evaluate and assess the performance of the equipment under test.Based on the principle of secondary radar system and the principle of rangefinder system,this paper studies the ATC/DME signal simulation method and proposes a hardware system scheme.The main research contents of the paper are as follows:1.The working principle of ATC transponder and rangefinder and their related signal characteristics are discussed in depth,and combined with the analysis of functional indexes,the transceiver with zero IF architecture is adopted,the transceiver channel configuration is carried out by supporting software,and finally the received signal preprocessing and DDWS(Direct Digital Waveform Synthesis)functions are realized.2.The ATC/DME signal modulation and demodulation method is studied,and the related logic modules are designed for the simulation of ATC interrogation signal,decoding of ATC answer signal,simulation and decoding of DME interrogation and answer signal,etc.After the principle analysis and simulation,a Morse code digital coding method is studied and proposed for the simulation and decoding of DME identification code;a linear shift register is used to generate pseudo-random numbers to simulate the random pulses of DME,and the related details are explained in detail.3.The direct frequency measurement method is used to design and implement the probability of answer test function with ATC transponder as the test object.Using DME ground equipment as the research object,a method of answering probability control is proposed and the related details are analyzed.The test platform was constructed and the overall solution’s performance index was assessed.The results of the test indicated that the ATC/DME signal simulation module fulfilled the specifications’ criteria.