Simulation Of Digital Frequency Conversion

Software Radio is a revolution in wireless communications, its hardware platform is constructed by using general-purpose programmable devices or digital signal processors, and its functions are defined by software. Digital radio frequency technology has been the research focus and a key part of software radio system all the time. In the software radio system design, we usually take a lot of resources and energy for the design of digital up conversion and digital down conversion. In this paper, we focus on the digital frequency conversion part of software radio, and make simulations of digital up conversion and digital down conversion in LabVIEW. Finally, Combined with NI high-speed digitizer and high-speed data streaming technology, we build a test system that the digital frequency conversion operation is processed by computer. The following are the major work done in this paper:1) Firstly, we summarize the basic structure, the technical features and the current research situation of digital frequency conversion, and discuss the theories related to digital frequency conversion technology, including signal sampling theory, multi-rate signal processing and efficient multi-rate digital filter.2) Secondly, based on the basic principles of digital up conversion and digital down conversion, we take more attentions on the multi-rate digital filter and the digital quadrature mixing. After make a detailed analysis of these digital filters, including the cascade integrator comb(CIC) filter, half band filter and finite impulse response(FIR) filter, we implement the simulation of digital up conversion and digital down conversion in LabVIEW, which is a perfect graphical programming tool.3) Then, we discuss the high-speed data streaming technology which based on NI data acquisition. Through the summary and analysis of the efficient data streaming architecture and the efficient program structure of data streaming, we conclude that to realize the high-speed data stream, we not only need high-speed storage devices, but also need a reasonable data stream structure and efficient program structure of data streaming.4) Finally, Combined with digital frequency conversion technology and high-speed data streaming technology, we will analyze and solve the problems that encountered during the experiment. Then we build a test system that the digital frequency conversion operation is processed by computer and take television signals and voice signals to test the system performance.