Abstract:Based on the fundamental principle of magnetic compass, and factors that causes interference and instrument errors which affected magnetic azimuth measurement accuracy, a precision azimuth measurement model in term of matrix equation for magnetic compass output data was deduced first; Proofs were given showing that the nowadays widely used analysis models for magnetic azimuth compass were simply simplified models of the precision measurement model under respective special conditions; Ellipse fitting algorithm was exploited under different instrument gestures to get the parameters of the proposed measurement model; Comprehensive methods and conditions for calibrating the azimuth of magnetic compass were presented later in detail; A comparison with experiment data of the ellipse fitting model and the precision measurement model was taken to show and verify all the conclusions drawn at the end.