Single-baseline GNSS attitude determination: The problem of degenerate solutions

Global Navigation Satellite System (GNSS)-based attitude determination uses pseudorange and carrier phase measurements collected at multiple antennas to achieve highly accurate baseline orientation estimations. Due to the inherent nature of the attitude estimation problem, a degenerate solutions can occur, yielding multiple attitude estimations that cannot be resolved. It is analyzed in this contribution the nature of the problem and the conditions under which such ambiguous estimations occur from a pure theoretical standpoint.