The probability distribution of the GPS baseline for a class of integer ambiguity estimators

In current global positioning system (GPS) ambiguity resolution practice there is not yet a rigorous procedure in place to diagnose its expected performance and to evaluate the probabilistic properties of the computed baseline. The necessary theory to bridge this gap is presented. Probabilistic statements about the `®xed' GPS baseline can be made once its probability distribution is known. This distribution is derived for a class of integer ambiguity estimators. Members from this class are the ambiguity estimators that follow from `integer rounding', `integer bootstrapping' and `integer least squares' respectively. It is also shown how this distribution di€ers from the one which is usually used in practice. The approximations involved are identi®ed and ways of evaluating them are given. In this comparison the precise role of GPS ambiguity resolution is clari®ed.