Tytuł pozycji:
Relative accuracy of DGPS
It is important to know the accuracy of navigational parameters while analyzing them. This refers not only to position coordinates, although position determination or the assessment of a GPS system often involves navigational parameter accuracy. Generally, accuracy is the degree of consistency between the measured or estimated value of a given quantity and its real value. Accuracy is usually interpreted as a statistical measure (or statisticaldeterministic measure) of measurement errors. Relative accuracy is used in reference to radionavigational systems. According to the USCG Navigation Center Federal Radionavigation Plan, relative accuracy is the accuracy at which the user can determine a position relative to another user by means of the same system at the same time. Another approach is presented in geodesic and hydrographic publications, where both local accuracy and the relative ellipsis of errors are given. This article will attempt at combining and generalizing the two concepts in the form of relative position vector accuracy. The generalized definition of that accuracy is based on a theorem on the difference of random vectors and the concept of crosscovariance matrix of two random vectors. The concept of relative (differential) accuracy can be extended to cover any kind of measurements. When there is a significant positive correlation, differential measurements should be used, as is the case in hyperbolic systems. On the other hand, summing systems are more accurate in cases where negative correlation is significant. Elliptical systems would be the right ones for positioning systems. Theoretical considerations are illustrated with practical examples of relative accuracy assessment in which AIS (DGPS) is used in ship-to-ship or ship-VTS communication. In the case of an AIS system, both positions are independently determined, but can be correlated through a common (D)GPS or another system. It is a classical example of relative accuracy application. It can also be used in a repeated assessment of hydrographic survey accuracy on condition that we possess recorded raw measurements of position coordinates or other measurements of position parameters.
Opracowanie rekordu ze środków MEiN, umowa nr SONP/SP/546092/2022 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2022-2023).
