Showing papers on "Required navigation performance published in 1994"

Required navigation performance (rnp) for precision approach and landing with gnss application

Abstract: A methodology to determine the required navigation performance (RNP) for aircraft precision approach and landing under instrument meteorological conditions (IMC) is described. The RNP in turn defines an aircraft containment surface about the nominal flight path, called a tunnel, which specifies the allowed approach and landing flight path limits. If the aircraft and its navigation system satisfy the RNP, then the aircraft will successfully traverse the tunnel, terminating in a safe landing. The tunnel is defined by four RNP parameters: accuracy, integrity, continuity, and availability.

Integrity monitoring for precision approach using kinematic gps and a ground-based pseudolite

Abstract: Although DGPS is inherently robust to space-vehicle-related ranging errors, failures in the differential station or airborne receiver can be a threat to continuous precise positioning. The stringent required navigation performance (RNP) for Category III precision landing, therefore, establishes the need for an active integrity verification system. Carrier tracking of ground-based pseudolites can provide comprehensive integrity. The large geometry change that occurs during overflight of a ground-based pseudolite and the great precision of carrier-phase measurements can provide the leverage for effective autonomous integrity monitoring. The measurement residual statistic can be used to detect a wide range of conceivable fault scenarios occurring during the pseudolite overflight, including cycle slips, intentional tampering, and airborne database errors. The potential for autonomous integrity verification for Category III approach is demonstrated through analysis, simulation, and flight tests performed in a single-engine aircraft.

Performance of category IIIB automatic landings using C/A-code tracking differential GPS

Abstract: An experimental DGPS precision approach and landing system was installed and flight tested on the NASA Langley Transport Systems Research Vehicle (TSRV). The GPS ground reference station and avionics units used 10-channel, narrow-correlator, C/A-code tracking receiver engines. The avionics drove the aircraft flight control system with ILS “look-alike” vertical and horizontal angular deviations derived solely from DGPS C/A-code tracking position and velocity. The avionics did not make use of kinematic carrier-phase tracking with on-the-fly cycle ambiguity resolution techniques. A total of 40 DGPS-guided approaches and landings were performed at the NASA Wallops Flight Facility, 31 of them hands-off, automatic landings. Total system error, measured by laser tracker, met the proposed Category III required navigation performance (RNP) or “tunnel concept” accuracy requirements by substantial margins. Touchdown dispersion for the 31 automatic landings also met Category III RNP requirements with significant margin.

Autonomous Integrity Monitoring for GPS-Based Precision Landing Using Ground-Based Integrity Beacon Pseudolites

Abstract: The Integrity Beacon Landing System (IBLS), developed and tested at Stanford University, is a high integrity solution to GPS-based Category III precision landing. IBLS is a kinematic GPS system which incorporates ground-based Integrity Beacon pseudolites placed under the approach path. The large geometry change that occurs during pseudolite overtlight ensures observability for direct cycle ambiguity estimation. Once cycle ambiguities have been initialized, position fixes accurate to the centimeter level are possible. The real-time accuracy performance of IBLS has already been demonstrated through flight tests in a Piper Dakota. The large number of redundant measurements resulting from Integrity Beacon overtlight and the great precision of carrier phase measurements provide the leverage for receiver autonomous integrity monitoring @AIM). Extremely tight detection thresholds may be set without incurring high false alarm rates (preserving high continuity). The measurement residual statistic can be used to detect a wide specuum of fault scenarios, including cycle slips, intentional tampering or spoofing, and spacecraft ephemeris errors. The overall level of IBLS system integrity as well as accuracy, continuity, and availability is quantitatively assessed through analysis, simulation, and flight test. Preliminary results show that the Required Navigation Performance (RNP) specification for Category III integrity of one undetected failure in one billion approaches is achievable using RAIM with Integrity Beacons. Flight tests were performed in a Piper Dakota with purposely induced navigation system failures to demonstrate the effectiveness of real-time autonomous integrity monitoring with Integrity Beacons. The results of these experiments are discussed.