Apparatus for Doppler correction in a wireless communications system, including
a first frequency synthesizer for generating a carrier signal oscillating at a
rate responsive to a first input, a counter coupled to the first input for generating
a Doppler compensation signal, the counter having a clock input, and a second frequency
synthesizer coupled to the clock input for generating a clock signal oscillating
at a rate responsive to a rate input. The rate input is adjusted over time according
to a predetermined sequence so that the Doppler compensation signal compensates
for the Doppler effect experienced by, for example, ground-to-satellite communications
in a satellite communications system.