The Ionosphere-weighted GPS baseline precision in canonical form

In this contribution we consider the precision of the ̄oated and the ®xed GPS baseline for the case of weighted ionosphere. Canonical forms of the baseline variance matrices are developed for di€erent measurement scenarios. These forms make the relation between the various variance matrices transparent and thus present a simple way of studying their relative merits. It is also shown how these canonical forms give an intrinsic description of the gain in baseline precision which is experienced when the carrier-phase doubledi€erenced ambiguities are treated as integers instead of as reals. The dependence of this gain on the various contributing factors, such as the decorrelation of the ionosphere, is also included.