Research On Receiver Nonlinear Behavioral Modeling Method Based On Polynomial

The era of rapid development of information technology,the types of electronic information equipment are gradually diversified,and intensive and continuous work in the same time and space has made the electromagnetic environment of electronic information equipment increasingly deteriorating.The electromagnetic environment effect of the electronic information system has become a factor that can't be ignored if the communication link can work normally.The receiver is the core equipment of the electronic information system.Due to the nonlinear devices inside,when the power of the undesired strong electromagnetic interference signal exceeds the sensitivity threshold of the receiver,its energy will enter the receiving RF front end from the antenna port Nonlinear phenomena such as intermodulation and gain compression directly affect the communication quality of the entire communication system.Therefore,in order to ensure that the communication system can operate effectively in a complex electromagnetic environment,it is necessary to study and evaluate the nonlinear effects of the receiver.One of its key technologies is to establish the receiver's behavior model.Based on the external input and output data of the single frequency conversion super heterodyne receiver,this thesis proposes a polynomial-based receiver behavior modeling method for its nonlinear effects.The established behavior model can predict the receiver's nonlinear response.The evaluation of receiver nonlinear effects under complex electromagnetic environment has reference value.The main research work of the thesis is as follows:1.The basic structure and nonlinear effects of super heterodyne receivers are analyzed in depth.In order to establish the receiver's behavior-level model more accurately,analyze the root cause of the receiver's nonlinear characteristics,and explain the effect mechanism of the main nonlinear devices.2.A behavior model structure and modeling method for super heterodyne receivers are proposed.The memoryless nonlinear module and the linear module of Hammerstein model are used to characterize the nonlinear characteristics and memory effect of the receiver,and expand and improve on the basis of this structure.The nonlinear unit is represented by an orthogonal structure composed of instantaneous transfer functions in the time domain,and the linear unit is described by a linear filter.A two-step identification method is used to identify the instantaneous transfer function in the nonlinear module and the unknown parameter in the linear module,respectively.The output nonlinear data obtained by the single-tone excitation drive receiving system are respectively fitted with three nonlinear basis functions: power series,Bessel function,Chebyshev polynomials,and the coefficients of the Fourier series are used to solve The formula derives the relationship between the three fitted polynomials and the instantaneous transfer function respectively;the least square method is used to obtain the parameters of the linear module through the definition of the memory effect.3.Through the combination of MATLAB and ADS simulation,the proposed nonlinear behavior modeling method of receiver is verified.ADS simulation results in time domain and frequency domain and AM-AM characteristics agree well with the calculation results of the behavior model programming.The calculation results of the behavior model show that the receiver behavior model based on power series,Bessel function and Chebyshev polynomial can effectively characterize the dynamic behavior of the receiver.In terms of time efficiency,the Bessel function-based behavior model occupies a certain advantage.