An Analysis of Time-varying Property of Widelane Carrier Phase Ambiguity Fractional Bias

The approach of estimating undifferenced wide-lane FCB by sequential least squares is discussed.Then,it is pointed out that the daily wide-lane FCBs in satellites and receivers are assumed unchanged in advance,while lack of discussion and analysis of its time-varying property.Global GPS observations of ten days on 350stations are processed and the time-varying property of wide-lane FCB in satellites and receivers is analyzed and discussed in detail from two aspects,undifferenced FCB between receiver and satellite and single-difference FCB between receivers.Results show that,① After smoothing,undifferenced wide-lane FCB is stable in a continuous arc without cycle slip,and can converge to 0.1cycles by using more than 90epochs(45minutes)data,so it is suggested the shortest arc to estimate wide-lane FCB should be longer than 45minutes;② The rate of change disagrees over time in different days for wide-lane FCB in receivers,the maximum change in one day can reach up to 0.3cycles.Besides,receiver reboot will make FCB reinitialize and destroy its continuity.Thus,the analysis of wide-lane FCB time-varying property in receivers indicates that the assumption of sequential least squares proposed by reference[4—5]is not reliable.In order to obtain more precise undifferenced wide-lane FCB in satellites,the instability of daily wide-lane FCB in receivers needs to be considered.A new receiver FCB parameter should be added in the case of receiver reboot and the receiver FCB parameter can be estimated as a random walk process.