Research On Digital Down Conversion Of Software Radio Based On FPGA

With the widely use of Software Radio in military, Wireless Communications and Digital Television, the Digital Down Conversion (DDC) technology, as one of the core technologies of Software Radio, draws more and more attentions.In this dissertation, we mainly study the design and implementation of DDC technology based on FPGA, and introduce the basic theory of DDC technology and the common algorithm. As introduced, DDC is divided into two modules according to their functions, which are digital mixer and digital filter banks. We design the DDC based on the method of top-down modularization design. The simulation results of each functional module, as well as the frequency spectrum show the correctness of the design.In aspect of Numerically Controlled Oscillator (NCO) design, a scheme based on the Look-up Table (LUT) method and the Scaling-Free Coordinate Rotate Digital Computer (CORDIC) algorithm is designed. The occupied on-chip resources of the proposed scheme is 1/3 less than the traditional method in order to reduce the power consumption and the wait time for system tuning is reduced, so that the system optimization is achieved.In aspect of the digital filter module, the decimation filter with adjustable parameters is achieved based on the combination of Cascaded Integration Comb (CIC) filter and Half-band (HB) filter. Meanwhile, the realization of FIR shaping filter is achieved with the Distributed Algorithm (DA).