The Large Capacity Of Spread Spectrum Communication Equipment And Key Technology Of Fpga Technology Research

Because of having many merits such as small transmit power, simple equipment, agility of communication mode, and strong anti-destroied ability, wireless communication becomes an important tool of wireless department and other telecommunication and command. As for communicational hardness, flexibility and agility, wireless communication also holds its unsurpassed advantages. Communication rate and anti-jamming ability are two keys to weight the level of a communication system. The system Large Capacity Spectrum Spreading Communication System developed by us has been achieved domestic high level at those two aspects.AS a key part of Large Capacity Spectrum Spreading Communication System project, this thesis investigates the design and realization of aynchronization technique in time and frequence domain, Digital Down Converter and Digital Up Converter technique, and interface technique between FPGA and terminal,DSP,A/D,D/A, and some other correlation problems using FPGA.The main contents of this dissertation are summarized as following:Aiming at time and frequency synchronization technique, after introducing the algorithm of time and frequency synchronization which adapt to our system, this thesis devides the synchronization process into three parts to discuss in detail, including time synchronization based on short serial, detecting the end of time synchronization based on long serial, and frequence synchronization based on long serial.This thesis introduces the basis theory of digital intermediate frequency, partitions the whole intermediate frequency system into CIC Filter, CIC Compensation Filter and mixing circuit, and discusses their realization respectively. According to theory analyse and simulation, we've confirmed parameters of CIC Filter, investigated the affection to the performance of compensation caused by filter steps in CIC Filter, and analysed both mixing part and its performance.Interface between FPGA and exterior device is a main problem of realizing this system. Based on the embody request, this thesis presents the purpose which the interface between FPGA and terminal, DSP want to achieve. Finnally, a solution scheme is given.