Virtual Radio Receiver Development And Research Of The Key Techniques

The conception of software radio, which is referred to programmable or configurable radio system, was formed by Joe Mitola in 1991. The term includes two aspects, one is using changeless hardware platform and reconfiguring the system only through software, the other is adapting the newly applications by assembling the hardware in a special way. The key idea of software radio is making A/D/A conversion module as near to antenna as possible, and carrying out the later digital signal processing by software.In this paper, a sort of digital intermediate frequency receiver based on virtual radio, whose illumination comes from a representative software radio system called SpectrumWare, is introduced combining with the key techniques and theories of software radio system. The main content of this part are the framework, function operational principle and driver design of the system.Two main approaches of automatic modulation recognition algorithms are discussed, decision-theoretic method and pattern recognition method. About the decision-theoretic method, two algorithms based on likelihood function are proposed and compared, and the results of the simulations in Matlab are shown. In the aspect of pattern recognition method, high-order cumulants are adopted in the modulation recognition and the algorithms in the condition of multi-path are proposed too.