Range-Limited Horizon Correlation for Navigation Checkpointing

A performance study for a system which uses range-limited horizons as navigation checkpoints for an airborne vehicle is presented. This is a continuation of performance studies previously reported for systems using actual horizons and fixed-range terrain profiles. The use of range-limited horizons permits a single system concept to be used at all vehicle altitudes. Digital topographic data and computer simulations used for system performance analyses are described. Analysis results are presented for flights at various altitudes. Different terrain roughnesses and a range of random profile errors and vehicle altitude errors are considered. System error limits are selected to give suitable checkpoint detection performance and position and heading determination errors are analyzed. The results indicate that system operation is feasible if sufficient terrain roughness is available at the checkpoint location. The results of an analysis of the effects of vehicle motion during sensor scan and sensor azimuth beamwidth are presented. (Author)