Kinematic Ambiguity Resolution With a High Precision C/A Code Receiver

Kinematic carrier phase ambiguity resolution, i.e., on the fly, which is the key to cm-level accuracy differential GPS positioning, is investigated using high precision, single frequency, 10channel, C/A code receivers. The major characteristic of this unit is a narrow correlation spacing which improves code measuring accuracy to 10 cm and reduces code multipath interference. The high code accuracy enables the user to reduce the search area which contains the correct integer ambiguity solution. The principles of the least-squares search procedure used herein to obtain the correct ambiguity solution are described. Land kinematic test results are presented for the case of a benign multipath environment and that of a comparatively high multipath environment. For the benign multipath case, the correct ambiguities are found within 1 to 3 minutes 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.