The Design Of Frequence Modulation Recciver Based On Software Defined Radio

Followed by the architecture of Software Defined Radio, a digital demodulationsystem have been built by designig the hardware, algorithms, and software,whichaimed to research the FM radio signal. Morever, by software reconfiguration, thesystem could compatible with many other modulation methods, Which reflected allthe advantages in flexiblity, efficience, and opening of SDR.First, an overview to the SDR was taked out on its history, development,application as well as research state in communication system.,Then three schemes ofsoftware radio were compared in terms of performance, cost, flexibility, which wereRF low-pass sampling, RF band-pass sampling and digital IF. Finally a suitable onewas selected, and Some models are choosed for them. According to the mathematicaldefinition on modulation and demodulation, several demodulation methods in thediscrete domain were compared, and the charge pump phase-locked loop was selectedto achive the FM demodulation by its advantage on resources consumption andoperation speed. After selecting the device and the algorithm, the Xilinx logicdevelopment kit was selected as the development environment.Second, the hardware design of the hole system was finished, including thepower, RF down-conversion, analog to digital converter, JTAG and configuration,audio output and so on..Third, the simulation and FPGA implementation were carried out followed bythe mathematica modeling. In accordance with the principle of the PLL, the closed-loop transfer function,the loop bandwidth,and the phase margin was derivated. Underthe guidance of the practical experience and the needs of this paper, the parameters ofeach module was caculated out. With those paramenters， a simulation on XilinxSystem Generator plantform proved that the PLL works successfully,and coulddemodulate the FM signal correcttly. After demodulation, a stereo separationalgorithm was designed based on FM stereo spectrum. In addition, the A/D and D/Ainterface design was also achieved useing the System Generator modules.Finally, by compling he interface modules and the algorithm module to soft-coreCPU peripherals, the software-defined radio with reconfiguration ablity was achived..