THE LEAST-SQUARES AMBIGUITY DECORRELATION ADJUSTMENT - A METHOD FOR FAST GPS INTEGER AMBIGUITY ESTIMATION

The GPS double difference carrier phase measurements are ambiguous by an unknown integer number of cycles. High precision relative GPS posit ioning based on short observational timespan data, is possible, when r eliable estimates of the integer double difference ambiguities can be determined in an efficient manner. In this contribution a new method i s introduced that enables very fast integer least-squares estimation o f the ambiguities. The method makes use of an ambiguity transformation that allows one to reformulate the original ambiguity estimation prob lem as a new problem that is much easier to solve. The transformation aims at decorrelating the least-squares ambiguities and is based on an integer approximation of the conditional least-squares transformation . This least-squares ambiguity decorrelation approach, flattens the ty pical discontinuity in the GPS-spectrum of ambiguity conditional varia nces and returns new ambiguities that show a dramatic improvement in c orrelation and precision. As a result, the search for the transformed integer least-squares ambiguities can be performed in a highly efficie nt manner.