Demodulation of CPFSK and GMSK Signals Using Digital Signal Processing DPLL with Sequence Estimator

摘要

Phase locked loops (PLL's) are well known as a threshold extension demodulator for analogue FM signals. This capa- bility may lead to the low bit error rate demodulation for digital FM signals. APLL has also its native frequency tracking ability and is suited to the demodulation of the signals having large Doppler shifts, for ex- ample signals from Low Earth Orbit (LEO)satellites. In this paper, we study the demodulation scheme of Continuous Phase FSK (CPFSK) and Gaussian filtered MSK (GMSK) signals using a Digital Signal Pro- cessing type Digital PLL (DSL DPLL).