Study And Design Of A Software Radio Receiver

The software radio (SWR) is a new developing technology with the progress of micro-electronics technique in recent years. It was first presented in the field of military communication, and later introduced to personal communications and permeated through the technological field of other electronics. As a new communication system, the software radio is made up of "A/D-DSP-D/A" hardware platform and various kinds of function module, and the different communication functions can be realized by the way of updating the software. Because it has overcome the limitation of the traditional design on radio, which regarded the hardware with single function and narrow expansibility as its core, and it has enormous potential market value, the software radio has been concerned extensively in the whole world after it was proposed for the first time. In the paper, the current status of the domestic and international research on software radio is introduced, and the principle of sampling, multi-rate signal processing, digital modulation and demodulation is discussed. A software radio experimental platform on FPGA+DSP is set up in the paper, which focuses on the digital down converter (DDC) and the digital orthogonal demodulation. The receiver adopts the digital structure of wide-IF to sample and quantize the IF signal. And the signal processing units such as DDC, digital demodulation and so on, are defined by the software, which can be downloaded into FPGA for their realization. The structure reduces the rate of sampling and the speed of digital processing, and requires low-performance hardware, which can be realized easily. Finally, the simulation of system grades about the receiver is carried on with SystemView, and different function units are described with HDL to emulate, synthesize, layout, route, download and debug. The paper shows that the software radio system has the flexibility, openness and compatibility in processing the multi-band and multimode signal, and indicates that FPGA is especially suitable for the standardized designing of SWR with its advantage of reconfiguration and parallel processing.