The geometrical factors of a navigational systems

Vessels engaged in coastal navigation must have their position determined with high accuracy. This can be ensured only by satellite systems such as GPS and GLONASS. The paper presents generalized concepts of geometrical factors of a navigational system. Such factors are used in the analysis of the accuracy of various radionavigational systems aimed at selecting the best system for a given area. The modern process of navigation is described in a four-dimensional space - three geometric dimensions and time. For this reason both the description and analysis of navigational systems should be performed in the same space. The traditional geometric factor of the land-based radionavigational system was generalised to include the factors GDOP, PDOP, HDOP, VDOP and TDOP for the needs of the accuracy analysis of a GPS system. These terms are related to the so-called geometry of navigational system - through mutually related positions of gradients of navigational functions determining position Iines (hyperplanes). They are connected with non-Iinear regression through a probabilistic relation between the measured navigational parameters. Consequently, the concept of geometric factors in the process of navigational parameters estimation can be also extended to include a larger number of dimensions appropriate for the state vector.