Characteristics of Onefold Clocks of GPS, Galileo, BeiDou and GLONASS Systems

Qingsong Ai; Kamil Maciuk; Paulina Lewinska; Lukasz Borowski

doi:10.3390/s21072396

Characteristics of Onefold Clocks of GPS, Galileo, BeiDou and GLONASS Systems

Sensors (Basel). 2021 Mar 30;21(7):2396. doi: 10.3390/s21072396.

Authors

Qingsong Ai^{1

2}, Kamil Maciuk³, Paulina Lewinska^{4

5}, Lukasz Borowski⁶

Affiliations

¹ State Key Laboratory of Geodesy and Earth's Dynamics, Innovation Academy for Precision Measurement Science and Technology, Wuhan 430071, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ Department of Integrated Geodesy and Cartography, AGH University of Science and Technology, 30-059 Krakow, Poland.
⁴ Department of Engineering Surveying and Civil Engineering, AGH University of Science and Technology, 30-059 Krakow, Poland.
⁵ Department of Computer Science, University of York, York YO10 5DD, UK.
⁶ Department of Geotechnical Engineering, Faculty of Civil Engineering and Architecture, Lublin University of Technology, 20-618 Lublin, Poland.

Abstract

This research is focused on searching for frequency and noise characteristics for available GNSS (Global Navigation Satellite Systems). The authors illustrated frequency stability and noise characteristics for a selected set of data from four different GNSS systems. For this purpose, 30-s-interval clock corrections were used for the GPS weeks 1982-2034 (the entirety of 2018). Firstly, phase data (raw clock corrections) were preprocessed for shifts and removal of outliers; GLONASS and GPS satellites characterize a smaller number of outliers than BeiDou and Galileo clock products. Secondly, frequency and Hadamard deviation were calculated. This study concludes that the stability of GPS and Galileo is better than that of BDS (BeiDou Navigation Satellite System) and GLONASS. Regarding noise, the GPS, Galileo, and BDS clocks are affected by the random walk modulation noise (RWFM), flashing frequency modulation noise (FFM), and white frequency modulation noise (WFM), whereas the GLONASS clocks are mainly affected only by WFM.

Keywords: BeiDou; GLONASS; GNSS; GPS; Galileo; clock; clock analysis.