m.e.ash   aug 1970    subroutine stmdld
compute delay and doppler for signal
sent from a ground station to a satellite over to another
satellite and then down to another ground station
calculate theoretical value of radar or radio transponder
observation of one satellite by another (both with same
central body)
interpolation through sbtrp,sctrp added 1977 oct - j.f.chandler

nvel =0 positions determined
nvel =1 positions and velocities determined
nvel =2 positions, velocities and accelerations determined
nvel = 3 position,velocity,acceleration and jerk determined
norm =0 normals to sites not determined
norm =1 normals to sites determined