Improved Knight Method Based on Narrowed Search Space for Instantaneous GPS Attitude Determination

The Knight algorithm can instantaneously resolve integer ambiguities and improve significantly the search speed by skipping over most less-likely integer ambiguity candidates. However, its reliability relies on the volume of the integer ambiguity search space. Utilizing coarse attitude knowledge can reduce the size of the search space. This paper proposes a new method to narrow the search space by taking into account a geometric constraint of visible satellites. The constraint is formulated as a recursive procedure and is thus very suitable to be incorporated into the search loop of the Knight method. Experimental results demonstrate that the proposed method can improve the search efficiency and reliability of the Knight method.