Digital elevation data and their use for improved broadcast coverage and frequency utilization

Thousands of path profiles incorporated into the ITU-R Study Group 3 (DBSG5) database and those estimated from the shuttle radar topography mission (SRTM) digital elevation model for the same terminal coordinates will be compared. Models that estimate diffraction effects on the propagation of radio waves over irregular terrain in the VHF and UHF bands available for digital TV applications will be used to predict field strengths that will be compared with those from the corresponding measurements. The mean value and the standard deviation of the difference between measurements and predictions will be presented for each model and for both the DBSG5 and the SRTM terrain profiles, as functions of their number of main obstacles. A better basis for comparison between predictions and experimental data was obtained from a special measurement series performed by HTI to determine the height function of the received field strength. These measurements will be described, also compared with model predictions and statistically analyzed.