Research On Software Radio Platform Based On GNU Radio

The development of the transistor promotes the digital revolution of radio technology. Over the past few decades, Steady progress of radio technology makes the radio device becomes smaller and more powerful. Digital devices gradually replace each analog device of the radio device. Digital technology continue to move forward until RF front end, and achieve full digital communication- software radio (SR). But, the problem of cost is impossible to avoid in the application and promotion. For expensive high-speed digital devices, people have to find a cost acceptable to meet the performance requirements of digital radio technology, and it resulted in a software-defined radio (SDR) technology. That is, converting the analog signal to digital signal in IF, and all baseband and IF processing is completed in digital device. Because the loop bandwidth, gain, data rate and other adjustments is easy to implement in digital device, the reconfigurable radio equipment is more flexible. The SDR device can also be reprogrammed to adapt to any channel coding, modulation and data rate.This design is to build a communication system based on the research of Open Source Radio Organization-GNU Radio. The GNU Radio libraries is a digital signal processing library based on the GNU General Public License (GPL), it collects the wisdom of radio workers all of the world. This design includes tasks: IF software radio research, IF board (USRP2) schematic and PCB design, building baseband processor platform, debugging RF board (RFX900).The first chapter introduces the theory of software radio and implementation of SDR platform, such as multi-band and broadband antennas, RF front end, digital-analog conversion module and digital hardware platforms.The second chapter describes the design process and the module function of Universal Software Radio Peripheral(USRP2). It includes schematic design, PCB design, hardware debug and writing test code. The third chapter describes building process of the GPP platform, including the installation of the libraries and digital signal processing module testing.The fourth chapter analyzes the architecture of the software radio system in this paper. The communication system is divided into three parts: baseband, IF and RF. The architecture is explained by analyzing the function of each part in the send and receive channel independently.Chapter V interprets the process of B/QPSK modulation and demodulation in GNU Radio, as we should make further efforts to study digital signal processing technology.