Propagation model for signal fluctuations on transionospheric radio links

The complex phase method has been further extended to the problem of electr omagnetic (EM) field scintillations on Earth-satellite GPS paths of propaga tion. The numerical and analytic technique based on the method has been dev eloped to characterize the transionospheric channel of propagation. The eff ects of additional range errors due to the ionospheric electron density flu ctuations in space and time have been studied taking into account the ray b ending due to the inhomogeneous background ionosphere and the diffraction o n local random ionospheric inhomogeneities. In the method developed, the im pact of the Earth's magnetic field is accounted for by the anisotropic spat ial spectrum of the ionospheric turbulence with different outer scales alon g and across the magnetic field lines. The variances of the EM field phase (yielding range errors) and level (log amplitude) fluctuations have been ca lculated for different models of the background ionospheres characterized b y different height electron density profiles and total electron content. Th e conditions of the saturated regime of propagation, which will likely resu lt in the degradation of a GPS navigation system, have been discussed. In a ddition, the scattering function of the GPS transionospheric channel of pro pagation has been constructed and simulated for a wideband signal.