Efficient ambiguity resolution using constraint equation

Precise relative positioning is possible by using the carrier phase observables of Global Positioning System (GPS). To use carrier phase for positioning, however, initial integer ambiguity included in the carrier phase measurement must be resolved. Many integer ambiguity search techniques while on the move, the so called on-the-fly (OTF) ambiguity search, have been proposed in recent years. But there still remains a strong requirement for fast and real-time OTF integer ambiguity search technique. A fast method to fix integer ambiguity is proposed in this paper. With the proposed method, one can find the relationship between integer ambiguities which is independent of the user position, and it uses the relationship as a constraint equation. It is known that only three elements of ambiguities are independent, and the remaining dependent elements can be determined after the position is obtained by independent elements. By using the constraint equation, the dependent elements can be directly determined without knowing the user position. And these ambiguities with covariance information are used as a new rejection criteria. The proposed technique is applied to real data to demonstrate its effectiveness