PERFORMANCE ANALYSIS OF INTEGRATED GPS/GLONASS CARRIER PHASE-BASED POSITIONING
摘要
Due to the different signal frequencies for the GLONASS satellites,the commonly- used double-differencing procedure for carrier phase data processing can not be implemented in its straightforward form,as in the case of GPS.In this paper a novel data processing strategy,involving a three-step procedure,for integrated GPS/GLONASS positioning is proposed.The first is pseudo-range-based positioning, that uses double-differenced (DD) GPS pseudo-range and single-differenced (SD) G LONASS pseudo-range measurements to derive the initial position and receiver clock bias.The second is forming DD measurements (expressed in cycles) in order to estimate the ambiguities,by using the receiver clock bias estimated in the above step.The third is to form DD measurements (expressed in met ric units) with the unknown SD integer ambiguity for the GLONASS reference satel lite as the only parameter (which is constant before a cycle slip occurs for thi s satellite).A real-time stochastic model estimated by residual series over prev ious epochs is proposed for integrated GPS/GLONASS carrier phase and pseudo-rang e data processing.Other associated issues,such as cycle slip detection,valida tion criteria and adaptive procedure(s) for ambiguity resolution,is also d iscussed.The performance of this data processing strategy will be demonstrated through case study examples of rapid static positioning and kinematic positionin g.From four experiments carried out to date,the results indicate that ra pi d static positioning requires 1 minute of single frequency GPS/GLONASS data for 100% positioning success rate.The single epoch positioning solution for kinemat ic positioning can achieve 94.6% success rate over short baselines (＜6 km).