Splining before carrier injection improves the accuracy of the result. The environments were identical range independent isovelocity waveguides. Comparisons closer than 1000 meters range were not valid. In the this environment, these waves attenuate rapidly from the source and are not an issue for ranges greater than 1000 meters or so. Decreasing depth increments increases computation time and output file size, but also accuracy.
Comparisons are valid only for range-independent cases.
Generally, the Parabolic Equation method will give more accurate range dependent results than normal modes. This document, in LaTeX format. This document, in PostScript format.