The Key Technologies Research On ADS-B Performance Evaluation And Promotion Under Complicated Electromagnetic Environment

In recent years, with the rapid increase in civilian aircraft, airborne and ground monitoring information transmission requirements, aviation spectrum environment has become more and more complicated. Complex electromagnetic environment is the key factor to the decline in surveillance performance of automatic dependent surveillancebroadcast(ADS-B). In order to ensure that ADS-B can provide safe and efficient surveillance service for long-term, it is necessary to evaluate and predict ADS-B surveillance performance in the future environment, and develop new technology to promote ADS-B surveillance performance under complicated electromagnetic environment.Aiming at the problem of ADS-B performance evaluation and promotion, on the basis of brief introduction of ADS-B principle, complicated electromagnetic environment and the definition of ADS-B surveillance performance, the main works of this thesis are summarized as follows.1、Aiming at the problem of ADS-B performance evaluation under the complicated electromagnetic environment, a new evaluation method based on the analytical model is proposed. The method consist of two parts, 1090 MHz signal environment model and ADS-B performance evaluation model, first of all, according to the measured data a model for evaluating the 1090 MHz signal environment is established, including the regional traffic flow distribution model, the received signal power distribution model and the co-channel interference model. Secondly, combined with signal environment model ADS-B performance evaluation model is established, including receiver decoding performance model under interference environment, receiver sensitivity model and performance evaluation and prediction model. Compared with the measured evaluation or simulation method, the analytical model has great advantage, which is based on the historical data to predict performance in different scenarios.2 、 Aiming at the problem of ADS-B receiver decoding performance under complicated electromagnetic environment, a blind source separation technology based on the analytical constant modulus algorithm is investigated. Combined with the special PPM modulation properties of Mode S and analytical constant modulus algorithm, three blind source separation algorithms applicable to ADS-B in Garble have been designed, including ACMA, MDA and MS-ZCMA algorithm. Simulation results are analyzed in detail the influence of SNR, source angular deviation, the number of samples, and overlapping time delay to performance of the three algorithms, the experimental results show the MDA and MS-ZCMA algorithm to achieve the ideal performance requirements. Compared with general blind separation algorithm, this method does not have to repeat the convergence problem, and can separate more than two overlapping signals.3、Aiming at the problem of ADS-B data transmission performance under the complicated electromagnetic environment, a technique to increase ADS-B data link capacity based on phase encoding is proposed. First of all, several key techniques are indicated, including hybrid modulation, signal synchronization, encoding and checking, and feasibility and safety assessment. Secondly, aiming at the problem of burst synchronization for the new data link, a high precision synchronization algorithm based on frequency offset capture and phase error tracking is proposed, and the effectiveness of the algorithm is verified by simulation experiments. Encoding phase information on 1090 MHz extended squitter(1090ES) signal is a promising method to increase capacity without extra transmissions, and enhance the ADS-B data transmission performance.