A study on PPP clock augmentation using a CSAC
| Main Authors: | Fernández, Enric, Calero, David, Parés, M.Eulàlia |
|---|---|
| Format: | Proceeding |
| Bahasa: | eng |
| Terbitan: |
, 2017
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/1248750 |
Daftar Isi:
- Precise Point Processing (PPP) is a navigation technique able to provide high precision, at least on the order of few centimetres, based on precise clock and satellite orbit data models. However, the main drawback of PPP is its convergence time, which depends mainly in satellite visibility and geometry, among other factors. This convergence time could last for some hours for a centimetre level precision. As an alternative for real-time computation, recent developments lead to Fast-PPP technique (a suitable alternative to real time kinematics technique or RTK). But the PPP improvements has been mainly based on a better knowledge about satellites on-view, through their monitoring with a growing up network of reference stations, and the use of multi-constellation signals but not on the receiver conditions, such as its clock stability. Hence, this research aims to study the effect of clock augmentation using a small chip-scale Cesium atomic clock (CSAC) as an input oscillator for a GNSS geodetic-grade receiver. Thus, a static dual-frequency antenna and an RF splitter provide GNSS signal to the aforementioned GNSS receiver and to a second unit of the same model using its internal oscillator, so both solutions can be compared and studied. Furthermore, low satellite visibility condition (< 6 satellites) are simulated by subtracting some of the satellites in view because in these scenarios is where a more stable clock may help. The data acquired is also limited to processing periods of 13 minutes or 90 minutes. Evaluating the solutions obtained for different processing periods will allow the determination of its impact on this study. To process the GNSS acquired data, an open source tool is selected (RTKLIB). In addition, IGS Ultra-Rapid (less than one-day delay) and Final (around 13 days of delay) clock and orbits correction files are needed plus the data logs from the receivers that are converted to RINEX format files. Next, solutions are evaluated in terms of precision and accuracy for different convergence times. According to the tests results, at least small improvements at a centrimetic-level in the precision and accuracy are obtained with a CSAC, mainly in low visibility conditions and sort acquisition periods, as forecasted.