Observed features of GPS Block IIF satellite yaw maneuvers and corresponding modeling

After comparing the modeled and the estimated yaw angles during yaw maneuvers for eight Block IIF Global Positioning System satellites over 1 year, we have observed discrepancies between the yaw directions in the vicinity of zero beta angle. Two features of the turn maneuvers are extracted after analysis of the observed differences: (1) The noon-turns reverse yaw direction when the beta angle falls between [-0.7A degrees, 0A degrees]; (2) midnight-turns always take the direction that completes < 180A degrees of total yaw. We present the approach implemented to account for the discrepancies between the observed and modeled yaw attitudes. In particular, an empirical beta angle bias is applied in the noon-turn model to correct the yaw direction error, and a short-route constraint is applied in the midnight-turn model for more robust performance.