Terrain Analysis Package (TAP) Radio Propagation Software

Air-to-Ground Coverage Predictions

SoftWright's Terrain Analysis Package Software (TAP)^tm is used by system designers to establish a high confidence level in the adequacy of radio communication and navigation between land based facilities and aircraft in flight. Land facilities can include voice communications to and from the tower for both air-traffic and ground control, flight service stations, VORs (VHF omni-range navigation facilities. It can also include data links between aircraft in flight and land-based facilities both government and corporate needs.

The majority of such facilities employ conventional AM modulation, The predictions are quite easily done with the TAP software, since the primary factors are terrain obstruction and free-space loss between the antennas used for the facilities. The preferred predictive model for rf propagation between air and ground is Bullington. It has no antenna height restrictions. Most of the other models are valid only for mobile units very close to the surface of the land. Some, such as Longley-Rice actually have warnings that they are not reliable when an antenna height exceeds 1000' above ground level. Coverage for land facilities communicating with aircraft is often calculated to 40,000 feet AMSL and even higher at times.