Kinematic Ambiguity Resolution with High‐Precision C/A Code Receiver

Abstract

On‐the‐fly resolution of carrier phase ambiguities, which is the key to centimeter‐level accuracy in differential kinematic GPS positioning, is investigated using a high‐precision, single‐frequency, 10‐channel, C/A code receiver. The major characteristic of this C/A code receiver is its narrow correlation spacing, which improves code‐measuring accuracy to 10 cm and reduces code multipath interference. The high accuracy of the code enables the user to reduce the search area containing the correct integer‐ambiguity solution. The principles of the least‐squares search procedure used herein to obtain the correct ambiguity solution are described. Kinematic test results for land are presented for the cases of a benign multipath environment and a comparatively high multipath environment. For the benign multipath case, the correct ambiguities are found within 1–3 min, with a high success rate, under a relatively good six‐satellite geometry (GDOP ≈ 3) and a short monitor‐remote separation (<5 km). In the presence of carrier phase multipath caused by nearby trees, however, the success rate decreases to less than 50% and the correct ambiguity solutions are found only after a significantly longer observation period.