Improved diffraction loss prediction for land mobile radio communication

This paper examines and improves the diffraction loss obtained by the Communications Research Centre (CRC) in two main aspects. One is to create a higher resolution and more accurate digital terrain data based on the CRC database. For a given area of interest first the complete quadratic two-dimensional interpolation for elevations is applied to augment the CRC database from 500 meters spacing to 100 meters spacing. If the contour from the augmented database is not checked with the topographic map, then the data of missed critical terrain features are taken directly from the topographic map and are used to correct the augmented database. In this step, the triangular interpolation scheme is introduced to modify the elevations and the weighted vote method is used to modify the surface codes. Thus the modification of the database makes the evaluation of diffraction loss more accurate