The Design And Implementation On The Techniques Of Digital Up Conversion And Digital Down Conversion In The Software Radio

The conception of Software Radio is raised by Joe Mitola of MILTRE on a conference. It's clou is to construct a exoteric, normative, and blocking hardware platform, and use softwares to achieve different functions such as working frequency, the types of modulation and demodulation, data formating, encrypting mode, and communication protocols and so on, and make the board band A/D and D/A converter close to antenna, so as to develop a new kind of flexible and exoteric wireless communication system. Software Radio gains abroad attention as soon as this conception is put forward. Software Radio is not only used in military and civil wireless communication but also used in other fields, such as electronic war, radar, etc. Therefore, it is significant to make deep research and development on Software Radio.This paper deals with the design and implementation of Digital Up Conversion and Digital Down Conversion based on the field-programmable gate array (FPGA). Firstly, the related theory of Digital Up Conversion, Digital Down Conversion and the foreground of FPGA are introduced. Then the development and implementation foreground are presented. Finally, the design and implementation of several important function modules are discussed in details. These modules are the numerically controlled oscillator(NCO), the decimating digital filter ,the pulse-shaping filter and the multiplierless interpolating digital filter. In these modules, the NCO module is introduced first combined with the algorithm look-up table (LUT) and Coordinate Rotation Digital Computer (CORDIC). Follow that the decimating digital filter including the cascade of cascade dintegrator-comb (CIC) filters and Half-Band filters (HBF) is introduced. Besides, second-order polynomials (ISOP) filter is used in order to compensate the CIC'spassband attenuation. In the end, the pulse-shaping filter with polyphase decomposition structure and the multiplierless interpolating digital filter consists of a sharpened CIC filter are discussed.