Abstract
The H2020 DEMETRA project provides short latency clock monitoring services to the time users using the Atomium precise point positioning (PPP) software developed by the Royal Observatory of Belgium. In this paper, three recent updates of the current Atomium software are introduced: adding Galileo signals in the PPP computation; the option to constrain the receiver clock; PPP with integer ambiguity resolution. The advantages of these updates are demonstrated: Combining the Galileo and global positioning system (GPS) signals for PPP time transfer will further improve the frequency stability inside the computation batch; PPP with receiver clock constraint is not only used to reduce the short-term noise of the clock measurements but can also be used for some specific applications to a keep continuous clock solution in the computation batch or retrieve correct clock measurements from extremely noisy environments; the integer PPP allows a continuous clock solution, and improves the mid-term and long-term stability of the frequency transfer compared to the current PPP frequency transfer techniques.
Highlights
The global navigation satellite systems (GNSS) include the United States of America’s global positioning system (GPS), Russian’s global navigation satellite system (GLONASS), Europe’s Galileo and China’s BeiDou navigation satellite system
Treats the carrier phase ambiguities as float values, ignoring the fact that these ambiguities should be integers. It was reported in [24] that using the carrier phase measurements with integer ambiguity resolution will improve the stability of GNSS time transfer and eliminate the clock jumps or random walk introduced by float ambiguity solutions
To focus on the performance of the software themselves without the effect of the quality of the compared clocks, two kinds of experiments were built: 1. Common clock difference (CCD), where the two GNSS stations are driven by the same external clock; 2
Summary
The global navigation satellite systems (GNSS) include the United States of America’s global positioning system (GPS), Russian’s global navigation satellite system (GLONASS), Europe’s Galileo and China’s BeiDou navigation satellite system. Atomium is a GPS+GLONASS PPP software dedicated to GNSS time transfer and geodetic positioning It uses the least-square method to estimate the following parameters: receiver clock error at each epoch; user antenna position for the whole daily data batch; tropospheric zenith wet delay at defined interval, and float phase ambiguities. The old version of Atomium PPP in DEMETRA treats the carrier phase ambiguities as float values, ignoring the fact that these ambiguities should be integers It was reported in [24] that using the carrier phase measurements with integer ambiguity resolution will improve the stability of GNSS time transfer and eliminate the clock jumps or random walk introduced by float ambiguity solutions.
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