A New Evaluation of Maximum Allowable Errors and Missed Detection Probabilities for LAAS Ranging Source Monitors
Thomas J. Zaugg · 2002
Category I LAAS ranging source monitors protect against ranging source faults that could result in differential errors between airborne and ground systems by evaluating test metrics and excluding a ranging source when one of its corresponding metrics exceeds some threshold. The difference between the detection threshold and the test metric bias that corresponds to the maximum allowable error (MERR) results in a certain missed detection probability. However, the missed detection probability does not necessarily bound the probability of misleading information for error levels less than the MERR. In this paper, an integrity approach that takes into account the complete relationship between the maximum allowable error, the probability of missed detection and the probability of misleading information for all levels of differential error is presented. This integrity approach eliminates the need for a time to alert requirement for many of the ranging source monitors and simplifies the analysis of transient errors resulting from signal deformation faults. The extension of this approach to Cat II/III systems will also be presented.