GNSS Integrity Concepts for Maritime Users

Integrity Concept for Maritime Autonomous Surface Ships’ Position Sensors

“…The rationale for the k coverage factor (or elliptical scale factor) in (10) comes from the assumption of uncertainty normal distributions in both the North and the East directions of position parameters and assumption of integrity risk value defined as the probability that the user will experience a true position outside the HPL and possibly AL without being informed within the TTA. In the simulation study described in the following sections of this paper the k for GNSS maritime equipment has been calculated according to (17) to achieve integrity risk value specific for the operation or area set in [3]. A method developed in [29] has been taken into account as well.…”

“…The "elliptical" presentation of a protection area provides navigator with the extra benefit coming from knowledge of N-E variances and their covariance resulting in changes of the ellipse's orientation and shape. That is why the concept of MVPA has been further developed for Electronic Chart Data Information System (ECDIS) where a vessel is shown as a 2-dimensional spatial object (a model of ship's hull contour) [17]. The detailed mathematical model is as follows.…”

“…Its definition of reliability of position fix was a precursor to the definition of circular protection level (PL) that was concurrently developed by ICAO and RTCA for aviation domain [4] as an upper confidence bound on the error in the position. In order to determine PL value, the 1σ circular bound on the error in the position is derived from augmentation data (assuming multivariate normal distribution) and multiplier of this bound (further called k-factor) is derived from the probability of fault-free missed detection [1, 3,17].…”

“…However, the resolution A.915 (22) has not addressed the issue of the PL algorithm for IR monitoring. (assuming multivariate normal distribution) and multiplier of this bound (further called k-factor) is derived from the probability of fault-free missed detection [1, 3,17]. The relations among PL, AL, and PE could be interpreted in the Stanford diagram [4] (see the Figure 2).…”

Hybridized-GNSS Approaches to Train Positioning: Challenges and Open Issues on Uncertainty

“…Among them, the Global Navigation Satellite System (GNSS), a constellation of satellites transmitting positioning and timing data from space to GNSS receivers, that use these data to determine their location [3], still is the only LDS able to provide position, velocity, and time (PVT) necessary for localization purposes, on a global scale and on a continuous time basis. By definition, GNSS provides a global coverage, ensured by the harmonization of the technical specifications (such as frequencies and bandwidth allocation) among the European Galileo, the NAVSTAR Global Positioning System (GPS) from USA, the Russian GLONASS, and the BeiDou requirements, performance standards, and future concepts of maritime GNSS integrity are discussed in [6].…”