Abstract:
A fast Doppler (carrier frequency drift) tracking
earth station modem is presented in this paper. The modem is
designed to track high carrier frequency offsets for low-earth
orbital (LEO) satellite applications. LEO satellites have very
high Doppler offsets with considerable Doppler rates (rate of
change of frequency). The earth station modem tracks Doppler
offsets at a data rate of 128ksym/s for QPSK modulation. The
synchronisation circuit of the modem consists of, frequency
synchronisation, symbol timing synchronisation and phase
synchronisation. We look into the design and performance
analysis of the modem, in particularly the synchronisation
system of the modem.
