Research On The Performance Of Tap Three-channel Radiation Interference Adaptive Cancellation System

On a common platform,there are usually multiple receiving antennas and transmitting antennas,which are wide band omnidirectional antennas.Because of near-field coupling,the receiving antenna will be coupled to the transmitting signal from the transmitting antenna.This signal is an interference signal to the receiving antenna.Due to limited platform space and too close range of the transmitting and receiving antenna,the power of the interference signal entering the receiving antenna is large,which will cause the problem of receiver blocking and receiver SNR greatly reduced.In order to solve these problems,the adaptive interference cancellation technology is adopted,but the two-channel adaptive interference cancellation system currently used has the problem of insufficient wide band interference cancellation ability,so this paper presents a tapped three-channel adaptive interference cancellation system.Firstly,the principle,structure and application of adaptive filter on the theoretical basis of adaptive interference cancellation technology are introduced,two common adaptive filtering algorithms,their advantages and disadvantages are analyzed,and the adaptive interference cancellation technology based on orthogonal vector synthesis is introduced.The time-domain analysis of the two-channel system is carried out,and the expression of the convergence rate and the offset ratio of the two-channel system under the broadband is deduced.Secondly this article from the point of view of time domain to complete the tap three-channel adaptive radiation interference offset system theoretical derivation,solving the weights of three-channel system expression and offset than expression,established the system gain,low pass filtering gain,reference signal parameters such as amplitude,tap delay and the weights of index and interference offset than quantitative relationship.By analyzing the weighted differential equation of the system,the convergence condition of the three-channel system and the method to improve the cancellation performance of the system are givenThen the influence of null shift on system performance is analyzed in time domain.The analysis shows that null shift has no effect on the average convergence rate of the system,but can affect the interference cancellation ratio of the system.Finally,through Matlab/Simulink platform simulation,the results prove the feasibility of the three-channel system,and verify the correctness of the theoretical analysis on the influence of system convergence speed,system interference cancellation ratio and zero drift.The simulation results show that the three-channel system has a good cancellation performance under broadband interference.By summarizing the problems and shortcomings in the research process,the author puts forward some ideas and Suggestions for further research and implementation.