ADS-B Antenna Array Active Calibration Algorithm Without Extra Pilot Sources

Automatic dependent surveillance-broadcast(ADS-B)is playing an increasingly important role in civil aviation industry.The positions,velocities and some other information of the aircrafts can be obtained from the signals of the navigation satellites,and these information can be transmitted from ADS-B equipment of the aircrafts by the data link and received by the base stations on the ground.However,the ADS-B signals can be interfered by several interferences,including overlapped,spoofing jamming and so forth.To suppress interferences,the use of an array antenna is a best choice,and the accurate array manifold should be known.In fact,the real array manifold and the ideal array manifold are not the same,and the performance of the anti-jamming algorithms can be sharply affected by array errors and even failure to anti-jamming.To calibrate the gain and phase errors,position errors and mutual coupling of the array,a series of work conducted as following:Firstly,the basic knowledge of array antenna and array errors is introduced,and that laid the theories foundation of the follow-up work.Secondly,based on the characteristic of ADS-B signals transmitted by the aircrafts,an active calibration algorithm without pilot sources is proposed to calibrate ADS-B antenna array errors.ADS-B signals that the aircrafts broadcast are used as the pilot sources,and the pilot sources do not need to be set manually.According to the positions of the aircrafts and the position of the array antenna,the DOAs of the ADS-B signals can be obtained.Then the estimation of array errors is converted to solving an optimization problem.By iterating until it converges,the array errors are estimated.By repeating the simulation,the obtained array errors are averaged to improve the correction effect.Finally,on the basis of simulation,the ADS-B antenna array is used to receive ADS-B signals,and some ADS-B signals are selected by the established criteria to correct the ADS-B antenna array.Experiments show that the proposed method is feasible and effective.The reasons why the calibration effect is not perfect is analyzed,and several possible factors are listed.