GNSS Integer Ambiguity Validation: Overview of Theory and Methods

Abstract

Integer carrier-phase ambiguity resolution is the key to fast and high-precision Global Navigation Satellite System (GNSS) positioning and navigation. It is the process of resolving the unknown cycle ambiguities of the carrier-phase data as integers. Once this has been done successfully, the very precise carrier-phase data will act as pseudorange data, thus making very precise positioning and navigation possible. Procedures for carrier-phase ambiguity resolution not only consist of integer ambiguity estimation, but also include ambiguity acceptance testing. Such testing is important, in particular in light of the ever increasing integrity demands on GNSS solutions. Although the statistical theory of integer ambiguity estimation is reasonably well established, this cannot yet be said of ambiguity acceptance testing. The aim of this contribution is to provide an overview of current theory and methods of ambiguity validation, and to present it in a unifying framework. It will also provide the tools for comparing a devaluating current procedures for acceptance testing and therefore create the possibility to devise new tests that are better than existing ones.