r.w.king  oct 1981  subroutine radgps
calculation of one-way time delay and doppler shift for
observations of earth satellites with speed of light assumed
infinite (no falsi iteration required)

correct for propagation effects
set up ipct as follows:
-2: 1st leg of phase delay doppler
-1: 2nd leg of phase delay doppler
1: time delay

there are three possible doppler observables:
lopler=-1  observable is phase
lopler= 0  observable is averaged integrated frequency (jpl)
(no longer implemented)
lopler= 1  observable is instantaneous frequency