Advanced Studies on Ambiguity Function Method and Implementation in the RTKLIB
Status: Abgeschlossen, Januar 2015
Bearbeitung: M.Sc. Sahan Dandenyia Gamage
The key to GNSS positioning is ambiguity resolution (AR). Frequent interruption from Losses of Lock necessitate a new approach particularly in real-time kinematic and rapid static surveying. In order to address the above issues, the research focused on Ambiguity Function Method (AFM) which can absorb the cycle-slip effects. The primary objective of the study is to analyse the behaviour of AFM and thereby understand the applicability of AFM in real-time GNSS surveying. The methodology used is to analyse the behaviour of AFM over length of baseline by introducing three major case studies; zero baseline, short baseline(< 2km) and long baseline(>8 km). Moreover, AFM is evaluated for single and dual frequencies in each case study. The influence of the number of epochs and the number of satellites were investigated.
The Fig 1 shows the maximum ambiguity function value (AFV) over baseline length. The AFM seems to behighly reliable for short baseline lengths (< 2km). To apply the AFM in kinematic applications, fast searching methods and algorithms, initial position from relative positioning and statistical parameter for interpretation of errors in solutions should be introduced. Otherwise it is difficult to fully exploit the advantage of AFM in terms of insensitiveness to cycle-slip effects over LAMBDA method which is much faster in ambiguity fixing and widely being applied.
