Research And Design Of Digital Down Conversion In Software Radio Systems

Because of the coexistence of multi-system for radio communications, there are some problem.For example, different systems of communications equipment are not mutually compatible, and it isdifficult to formulate a uniform standard. Software radio and its platform have been proposed forthe first time in 1992. The basic idea is to construct a standardized, modular, open hardwareplatform. Emphasizing on common platform for open hardware, software defined radio as much aspossible uses reconfigurable application software, in order to achieve functions of common radiocommunications. The software on this platform is required to achieve communication protocols,modulation and demodulation type, encryption and decryption mode, the operating band, channelequalization and other main functions.IF(Intermediate Frequency) processing technology is a core part of the Software DefinedRadio. The RF(Radio Frequency) signal that the antenna receives, is transformed into IF signal aftermixing. Then this signal is processed by the A/D converter, extracted and filtered, and ultimatelyachieve the purpose of digital down conversion which makes software-defined radio have theobvious advantage of the broadband, open and programmable.This paper is mainly based on the existing theoretical basis to analyze and studies thecomposition and function of the software radio system requirements. It uses FPGA technology anddevices to build a hardware platform for software radio digital downconversion, and designes itsassociated circuit. The platform builds a wireless communication system flexibly and from the RFfront-end by the A/D conversion, realize down-conversion software control using FPGA.Thesystem gives full play to the FPGA algorithm structure is efficient and reconfigurable and achievesthe design requirements of the entire digital down-conversion.