Patent ID: 8199052
Filing Date: 2012-06-12
Classification: G01S

Abstract:
1. A method of estimating a rotational position of an object, the method comprising: prior to flight of the object during which the object spins, preloading the object from external to the object with a preloaded intended trajectory, a preloaded space vehicle ephemeris data, and a preloaded system time of a satellite positioning system; initializing a timer based on the preloaded system time; during flight, maintaining a timer-based time via the timer without input from satellite positioning system signals; calculating line-of-sight (LOS) vectors based at least on the preloaded intended trajectory and the timer-based time; acquiring satellite positioning signals from a plurality of space vehicles and generating at least one of a correlated in-phase measurement or a correlated quadrature-phase measurement from each of the acquired plurality of satellite positioning signals; and determining a roll phase relative to each of the space vehicles corresponding to at least some of the acquired plurality of satellite positioning signals by phase locking to an amplitude modulation of at least one of the correlated in-phase output signal or the correlated quadrature-phase output signal for each of the at least some of the acquired plurality of satellite positioning signals, wherein the amplitude modulation is caused by rolling of the object.