Required navigation performance

About: Required navigation performance is a research topic. Over the lifetime, 343 publications have been published within this topic receiving 3477 citations. The topic is also known as: RNP.

Area navigation high-altitude network study

Abstract: A high-altitude area navigation (RNAV) network study was conducted at the National Aviation Facilities Experimental Center (NAFEC) in order to (1) apply and evaluate the FAA/Industry RNAV Task Force concepts for RNAV route structures in the high-altitude airspace, (2) offer alternative approaches, where appropriate, and (3) derive data relative to the potential benefits to the air traffic control (ATC) system and to its users by the implementation of RNAV. For design purposes, the enroute structure was based on the requirements for an all-RNAV high-altitude environment starting in 1977. Route structures were evaluated through fast time simulation of a mixed RNAV/VOR environment, with traffic samples representing projected traffic densities for the pre-1977, 1977-1982, and post-1982 time periods with varying mixes of RNAV-equipped aircraft. Alternative route structure design principles were developed which differed from the RNAV Task Force concepts in (1) the configuration of arrival and departure routing into and out of terminal areas, (2) the use of one-way routes, (3) the use of charted routes versus provision for noncharted offset tracks, (4) the treatment given to traffic from intermediate terminals with respect to nearby flows between more distant terminals, and (5) route width requirements.

Integration of satellite positioning and a track database for safety-critical railway control systems

Abstract: Although Global Navigation Satellite Systems (GNSS) have been widely used in aviation, vehicle and marine navigation, and have also found non-safety railway applications (eg for locating trains in order to provide passengers with arrival and departure information), they still cannot be used in a standalone mode for safety critical railway applications such as automatic train control, automatic door opening or train integrity monitoring This is because GNSS suffers from the line-of-sight problem, namely, GNSS might be unavailable when trains run through the areas with low satellite visibility (eg in urban canyons, deep cutting sides and tunnels) A potential solution is to integrate satellite navigation measurements with other sensors such as a track database, INS or an augmentation system This thesis is concerned with the evaluation of the potential role of a track database for this purpose A rigorous mathematical model for the integration of GNSS with the track database is developed The key feature of this model is its ability to model errors in both GNSS measurements and the track database to achieve realistic performance statistics for the combined system Knowledge of the position of the railway lines turns positioning, in principle, into a one dimensional problem This thesis uses both simulated London area information and real railway satellite availability information from the Birmingham area to assess the improvements in Required Navigation Performance (RNP) parameters that might be obtained if railway authorities invest in a track database The stimulation shows that the integration system improves the accuracy and increases the redundancy so that the system only needs as few as two satellites to calculate the position and accuracy, three satellites to computes the Receiver Autonomous Integrity Monitoring (RAIM) and four satellites to do the Fault Detection and Exclusion (FDE) The cost-efficient accuracy of track database and suitable RNPs are also discussed for safety-critical railway requirements

GPS Risk Assessment for Civil Aviation

Abstract: JHU/APL conducted an independent risk assessment (see Reference [1]) to determine the ability of GPS and its augmentations to provide navigation performance for the future National Airspace System (NAS). The main conclusions were: (a) GPS with appropriate WAAS/LAAS configurations can satisfy the required navigation performance as the only navigation system installed in the aircraft and the only navigation service provided by the FAA; (b) Risks to GPS signal reception can be managed, but steps must be taken to minimize the effects of intentional interference (with assumed available surveillance radars and with onboard anti-jam systems); (c) A definitive national GPS plan and management commitment is needed to establish system improvements with civil aviation users and to provide greater informational access to the civil aviation community. The evaluation relied heavily on statistical simulation analyses to assess performance of GPS, GPS/WAAS, and GPS/LAAS against requirements as expressed by accuracy, integrity, continuity, and availability for Oceanic through Category III Precision Approach operations. The most significant risks and their associated mitigations (if necessary) were also evaluated for acceptability. A significant technical contribution of the effort was the unique simulation methodology used to evaluate the very small probability values given in the navigation requirements. In addition, the assessment was very wide in scope and therefore, provided a consistent and comprehensive evaluation of GPS performance for civil aviation.

Robust Time Synchronization Methods for Future APNT

Abstract: The paper deals with concepts and methods to provide a robust time synchronization algorithm for a network of ground stations, which provide an APNT (Alternative Positioning, Navigation and Timing) service. Besides the concept to synchronize the stations to an external GNSS time scale such as GPS, Galileo or EGNOS or with the use of a geostationary satellite, the concept to generate an internal timescale by a composite clock algorithm is investigated. Using the calculated time offsets relative to the composite clock offset, the ground station signals are synchronized, to mitigate the clock related error of the pseudo range measurements. As discussed within the paper, the application of a composite clock algorithm requires a measurement network, whose network graph is connected. The robustness of a ring network is studied by simulation of clock feared events of time and frequency offset steps and the performances are evaluated in terms of Required Navigation Performance (RNP).