Digital Division And Reconstruction Processing Technology Research On Broadband Channelization

In modern electronic warfare,electromagnetic environment is complicated and changeable and signal features in varied forms,which puts forward higher requirements on radar receiver: wide coverage,large dynamic range,high intercept probability,high frequency measuring accuracy,high stability and high sensitivity etc.Besides,it can adapt to the intense complex radiation source.What's more,it can process various arrival signals at the same time and can make the received huge amounts of information in real-time processing.The broadband digital channelized receiver satisfying this kind of requirement,has been paid more and more attention.Therefore,it has become one of the most important direction in digital reconnaissance receiver research.At first,based on the related knowledge including signal sampling theory,multi-rate signal processing,poly-phase filter banks,non-blind-zone channel partition and so on,this paper analyzes the basic principle of digital channelized receiver and the cross-channel problems after channelized processing.Secondly,it introduces the method of channel comprehensive decision,including the non-empty channel decision method(such as amplitude testm,frequency-detection with Cordic method and dynamic double threshold detection method),fitting straight line slope method of singular point spectrum which aims to determine whether the cross-channel signal comes from the same signal,odd-even channel decision method for the narrowband signal.On top of that,it puts forward the corresponding channel decision flow chart and implementation steps.Thirdly,this paper provides the analysis concerning the problem how to recover the cross-channel signals from two aspects.For one thing,sub-channel reconstruction from the perspective of distortion reconstructing,it gives the research of sub-channel reconstruction structure based on the integrated filter banks.For another,from the perspective of adjustable grading bandwidth among sub-channels in digital channelized reconfiguration,it proposes the solution including both odd-even reconfiguration decision rules and tree structure reconfiguration aspects.What's more,it uses MATLAB as the simulation platform to realize approximately perfect reconstruction of the wideband cross-channel signal.In the end,this paper presents the FPGA implementation scheme of digital channelized receiver system in view of the single frequency signal and linear frequency modulation signal.Apart from this,it completes the functional module design and implementation,including direct RF sampling,poly-phase signals generated by DDS as well as BLOCKROM,the data flow fragmentation,poly-phase filtering,parallel IDFT part etc.On the one hand,it carries on the design implementation and waveform simulation combining ISE and MODELSIM software with VHDL language.On the other hand,it gathers the simulation output results from MODELSIM to MATLAB,Finally,it gets waveform both in time domain and frequency domain,thus proving and analyzing the effectiveness of the proposed design scheme.