Summary: IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 46, NO. 3, MARCH 1998 309
Doppler Characterization for LEO Satellites
Irfan Ali, Member, IEEE, Naofal Al­Dhahir, Member, IEEE, and John E. Hershey, Senior Member, IEEE
Abstract--- Mobile ground­based terminals observe significant
Doppler on the forward channel when communicating through
low earth orbit (LEO) satellites. This paper deals with the
analytic derivation of the Doppler shift measured by a user
on the surface of earth on a signal transmitted by a circular
orbit LEO satellite. Two simplifications are performed to obtain
the analytical expression of the Doppler shift as a function
of time. First, during the visibility duration of the satellite at
a terminal, the trajectory of the satellite with respect to the
earth is approximated by a great circle arc. Second, the angular
velocity of the satellite with respect to the user is assumed to be
constant. Numerical results validate the approximations. Another
result of our analysis is an expression for the visibility window
duration of a satellite at a terminal as a function of the maximum
elevation angle. An algorithm for estimating the parameters of the
Doppler curve based on a couple of Doppler and Doppler­rate
measurements is also presented.

Source: Al-Dhahir, Naofal - Department of Electrical Engineering, University of Texas at Dallas

Collections: Engineering