Functional model modification of precise point positioning considering the time-varying code biases of a receiver

Abstract Precise Point Positioning (PPP), initially developed for the analysis of Global Positing System (GPS) data from a large geodetic network, gradually becomes an effective tool positioning, timing, remote sensing atmospheric water vapor, and monitoring Earth’s ionospheric Total Electron Content (TEC). The previous studies implicitly assumed that receiver code biases stay constant over time in formulating functional model PPP. In this contribution, it is shown assumption not always valid can lead to degradation PPP performance, especially Slant TEC (STEC) retrieval timing. For reason, modified by taking into account time-varying two frequencies. It different Modified Carrier-to-Code Leveling (MCCL) method which only obtain variations Receiver Differential Code Biases (RDCBs), i.e., difference between frequencies’ biases. (MPPP) model, temporal become estimable their adverse impacts on parameters, such as ambiguity clock offsets, delays, are mitigated. This confirmed undertaking numerical tests based real dual-frequency GPS set global continuously operating reference stations. results imply exhibit correlation with ambient temperature. With improvement 42% 96% achieved Differences STEC (DSTEC) compared original regard values those derived Geometry-Free (GF) carrier phase observations. medium long term (1 × 10 4 1.5 s) frequency stability clocks also significantly improved.