Carrier Phase Wrap-Up Induced by Rotating GPS Antennas

With the advent of GPS receivers mounted on spinning vehicles such as artillery shells, an interesting additional error must now be accounted for: carrier phase wrap-up. Phase wrap-up is an apparent change in the GPS carrier frequency caused by rotation of the receiving antenna. It is distinguished from Doppler shift in that phase wrap- up is carrier frequency independent and does not affect group delay. In this paper we present a formal procedure for calculating the effect of phase wrap-up on antenna output as a function of antenna type and satellite geometry. This procedure quantifies additional phase tracking errors for GPS receivers from which the effect on the navigation solution is determined. We apply the procedure to a common antenna type-the crossed dipole-and compare the results to laboratory data.