Research On The Key Technology And Engineering Implementation Of Digital Channelized Receiver

Passive detection system has a sequence of advantages as follows: low cost ofconstruction and operation, high battlefield survivability and silence in obtainingintelligence, etc. Due to these features, it has been widely used in the field of targetdetection. The background of this thesis is the development of a space target passivedetection system based on digital array. The center problem of this thesis is the designand implementation of the direct-path reference signal and target return signal receivingsub-system. With respect to the problem, this paper conducts in-depth research in RFsignals direct sampling based on high speed sampling, quadrature digital downconverter theory, the architecture of digital channelized receiver and the implementationof receiving sub-system. Mainly, five parts of content are included in this dissertation:In introduction, the study background and significance of this paper is introducedand the research status of digital channelized receiver is summaried. It also presents themajor content of this thesis in the end.At the beginning of the second part, the general design and key technique of thesystem is proposed. This part is mainly about direct-path reference signal receivingsub-system. RF signals direct sampling technique and quadrature digital down convertertheory are applied to the direct-path reference signal receiving sub-system. Two sets ofreceiving process are designed based on the techniques. One is for outfield experimentin the early stage of the program, the other is for the principle prototype. Both solve theproblem of receiving direct-path reference signal.The advantages and disadvantages of different structures of digital channelizedreceiver are discussed in the third part. According to the specific applicationbackground, a multi-channel digital channelized receiver on the foundation of RFsignals direct sampling and polyphase DFT structure is designed.Then, using the structure of channelized receiver proposed in part3, the methodsof instantaneous frequency measurement(IFM) and signal splicing in frequency domainare introduced in order to increase frequency resolution and solve cross-channel signalproblem. In the end of this part, an intact structure of a channelized receiver whichsynthesize the techniques of channelization, instantaneous frequency measurement andcross-channel signal processing is put forward.At last, the implementation of the direct-path reference signal and target returnsignal receiving sub-system is introduced. The experimental receiver has been used inpractice. The FPGA program for the signal receiving sub-system of the principleprototype has been developed and validated by simulation results of Modelsim.