Abstract :
FM is widely used in communication systems. FM is widely used in high-fidelity music broadcasting, television audio signal transmission, satellite communications and cellular telephone systems. The design is mainly use MATLAB integrated environment M files to prepare the formula in order to achieve FM modulation and demodulation process. Then, it will draw out of the baseband signal, carrier signal and modulated time domain waveform signal. After that, it will draw out the superimposed signal with noise signal separately, the coherent demodulated signal and the time domain waveform of the demodulated baseband signal. Finally, the relationship between the bit error rate and the signal-to-noise ratio after the FM baseband signal is passed through the channel and the modulation and demodulation system will be drawn out. Then, waveform will be compared through theoretical results to analyze the correctness of the simulation modulation and
demodulation system and the impact of noise on signal demodulation. In this design, the system development platform is Windows Vista while the tools used is MATLAB 7.0. The program was running on the platform to complete the observation of FM modulation and demodulation as well as the demodulation of the superimposed noise. The FM signal through the noise channel, modulation and demodulation system simulation purposes was achieved through this design.
Keyword :
FM; modulation; demodulation; MATLAB 7.0; noise