Integer cycle ambiguity resolution under conditions of low satellite visibility

GPS attitude determination systems use carrier phase measurements at three or more antennas to determine platform orientation. Since the antenna separation is usually more than half of the GPS carrier wavelength, the measurements contain an integer cycle ambiguity that must be resolved before attitude can be calculated. This paper will present a new algorithm to instantaneously and reliably resolve the integer cycle ambiguities under conditions of low satellite visibility using at least four antennas in a non-planar array. The new algorithm makes it possible to establish and maintain an attitude solution with as few as two satellites if clock differences are calibrated or three satellites if they are not. Analysis of antenna array geometry and algorithm performance using simulated data will also be presented.