Reference Map Generation Method

摘要

The present invention provides a reference map generation method which is a multi-level procedure structured to minimize cost and provide the required reliability in the selected maps. Given a geographic area within which a terrain correlation fix is desired and a desired flight heading, the first phase is to evaluate the area by inspection of small scale topographic maps. The terrain altitude profiles within a candidate geographic area are digitized and iterative Auto-MADs are calculated in potential reference map areas to determine if there are significant terrain ambiguities, the Auto-MAD array being calculated by computing the mean absolute difference (MAD) between each profile in the candidate reference map and each synthetic radar terrain profile. The synthetic radar terrain profile is obtained directly from the digitized terrain data with no noise introduced. The final phase involves the evaluation of reference map performance using a Monte Carlo simulation procedure, noise models used as inputs being based on analytical models of the process and on analysis of flight test data. The process is iterated until a reference map which is free of terrain ambiguity problems is identified which meets probability of correlation ( p sub c) and circle of equal probability (CEP) requirements. Therefore, it is an object of the present invention to provide a reference map generation method which ensures fix reliability by identifying reference maps with no significant terrain profile ambiguities.