Research And Simulation On Wideband Digital Channelization

Perfectly reconstructed channelization technology is widely used in software radio,satellite communications and electronic countermeasures.With the development of satellite communication and front-end reception technologies,the receivable bandwidth of the fully reconfigured system is getting wider and wider.Realizing the channelization process efficiently has gradually achieved more attention in this field.For digital channelization,perfect reconstruction filter banks are widely used methods to achieve channelization.In practical engineering applications,a series of problems,such as excessively wide signal bandwidth,filters with high orders and large interference factors,have brought great challenges to the perfect reconstruction of filter banks.This thesis has carried out a series of research and simulation works on wideband digital channelization.First,the common structures of perfectly reconstructed filter banks are compared and analyzed,and the polyphase FFT structure is selected as the final implementation structure of filter banks in our work.Secondly,under floating-point conditions,different reconstruction algorithms are simulated,and filter banks of different lengths are designed.Finally,some fixed-point simulations are carried out on an FPGA implementation structure of filter banks,and the influences of different cutoffs on the system performance are analyzed.The main works in this thesis are as follows:(1)We present several implementation structures for the perfect reconstruction of filter banks.Corresponding channelization schemes are designed under different structures.After comparing the advantages and disadvantages of the halfband structure,polyphase structure,and tree structure,the computational analysis for each structure is provided.(2)We study the principles of several prototype filter methods in wideband digital channelization,and compare their advantages and disadvantages for applicable scenarios.Under the conditions of floating-point operations,we design different prototype filters by using the method based on quadratic constraint quadratic programming and least square,and the method based on frequency sampling.Next,different types of signals are used for channelization to verify the rationality of filter banks.Finally,by analyzing the system's reconstruction error,signal-to-noise ratio,noise power ratio,spurious in band under different parameters,some conclusions are concluded for engineering realization.(3)Aiming at the wideband digital channelization method based on polyphase FFT,an FPGA implementation structure for perfect reconstruction filter banks is given,and the feasibility of the FPGA structure is verified through fixed-point simulation.Different types of signals are used to verify the rationality of the FPGA implementation structures.In addition,under fixed-point operation conditions,the thesis briefly introduces the pinceples of the prototype filter coefficients,FFT modules,input and output signals modules.Finally,a simulation platform for broadband digital channelization technology is built,which will greatly facilitate the follow-up research.