Research On TCAS Signal Processing Technology In Interference Environment

With the rapid development of China's air transportation industry,the air traffic has become increasingly busy.During the flight,the aircraft needs to communicate frequently with other aircraft and ground equipment in the neighboring airspace.There are a lot of radar electromagnetic signals in the air,and the mutual interference between the electronic equipment is severe,especially frequency band of 1030/1090 MHZ used by TCAS signals.These interferences severely degrade the performance of TCAS.In order to guarantee aviation safety,the research of TCAS signal processing technology in the interference environment is urgent.In order to solve the co-channel interference problem of TCAS signal,the following work was carried out in this thesis.1?Aiming at the FRUIT interference problem caused by Mode A/C signals,an investigation of enhanced preamble detecting and data decoding technique of TCAS signal with FRUIT interference.Firstly,the method of pulse detection and pulse edge detection was investigated.Based on the investigation,the frame matching problem of preamble and subsequent test and verification process were analyzed.Then,three different data decoding methods are studied and the potential errors in various decoding methods were analyzed.Finally,the performance of the decoding algorithms under different FRUIT interference intensity was explored by three groups of simulation experiments2?Aiming at the Garble interference problem caused by Mode S signal,two different types of separation technology of a mixture of different mode S source signals were investigated.AZCMA and MDA are blind separation algorithms utilizing the modulation properties of mode S.The two algorithms have a better separation performance when the sources are highly overlapping than the overlap is low.The performance of the MDA is better than AZCMA.In addition,the Projection Algorithm was also researched,which could be used for separation when the Time difference of arrival of sources is large enough.Projection Algorithm has a better performance and smaller computational complexity than AZCMA and MDA.Based on projection algorithm,an enhanced projection algorithm applicable to a mixture of more than two sources was designed,and multiple sets of simulation experiments were used on its performance analysis.3?This paper studied the mode S data link format coding method commonly used by TCAS,and used the characteristic to detect the signal decoding result.Two different error correction algorithms were studied in this thesis.Among them,the Sliding Window Algorithm is applicable to the message whose error pattern is within a 24-bit window,while the Brute Force Algorithm is applicable to the message whose total number of error bits is less than five.