Missed Detection Probability Requirements for LAAS Integrity Monitoring of Ranging Sources

摘要

As with the conventional air navigation aids, ground-basedrnaugmentation systems for satellite navigationrnprovide integrity monitoring to detect ranging sourcernsignal failures. For satellite-based ranging sources thernmonitored failure classes are uncorrectable ephemerisrnerror, excessive satellite clock acceleration, signalrndeformation, excessive code-carrier divergence, and lowrnsignal level. This paper describes an analytical techniquernused to derive the probability of missed-detectionrnrequirements of these fault classes for the PerformancernType 1 (PT1) Local Area Augmentation System (LAAS)rnGround Facility (LGF) specification. This technique isrnbased on a state probability model where the transitionrnprobability matrix accounts for failure generation andrndetection. The model provides a structured approach tornderive integrity risk from the probability of being in anrnundetected failure state. Although the results are appliedrnto LAAS, the model has general application to otherrnaugmentation systems. The results are dependent on thernprior probabilities of classes of failures, which arernuncertain at this time. To circumvent this problem, anrnupper-bound failure rate is assumed.