Abstract: A method for calculating the phase reception pattern of an antenna system utilized in attitude determination is disclosed. The antenna system is disposed on a platform (or rate table) that rotates about a single, fixed axis at a constant rate as incoming signals from one or more satellites are received, thereby revolving the antennas about the axis. Information collected from the satellite signals is utilized to calculate a differential phase map (phase measurement error correction map) for the antenna system. The rate of rotation of the table is approximately known, and small variations in the rotation rate may be compensated. The baseline vector connecting two or more antennas is preferably approximately perpendicular to the axis of rotation of the platform. Phase measurement data is collected and may be processed off-line to compute a phase measurement correction map. Attitude calculations may be compensated with the determined differential phase measurement correction map.