A Frequency Demodulation Technique Based on Sliding DFT Phase Locking Scheme for Large Variation FM Signals

A new frequency demodulation scheme based on sliding discrete Fourier transform (SDFT) and a phase locking scheme (PLL) is proposed for extracting message signal from sinusoidal frequency modulated signals. A wide operating range of the PLL, especially the pull-in range is utilized in extracting modulation signal from the large deviation FM signals. As fundamental frequency SDFT bin is involved in the design, the SDFT PLL scheme is suitable for demodulating linear FM signals of frequency range between d.c. and second harmonic of the carrier. Simulation and experimental results prove the fast acquisition behavior and competence of the SDFT PLL in modulation signal retrieval.