Sensors & Transducers (Dec 2023)
A Study on the Parameters Affecting Clock Comparisons Using Global Navigation Satellite Systems
Abstract
Navigation satellites are reliable and cost-effective means that can serve as an intermediate and efficient facility for comparing remote clocks, eliminating the technical challenges associated with physically moving clocks. Historically, the Global Positioning System (GPS) was the only Global Navigation Satellite System (GNSS) that is used in clock comparisons through observing the same satellites at the same time. However, the evolution of other fully operational GNSS, has opened up alternative avenues for distant clock comparisons through the Common-View (CV) technique. Typically, there are many parameters affecting the stability and accuracy of CV clock comparisons. Some of them are related to the type of GNSS, while others are related to the laboratories and clocks being compared. So, identifying the effect of each parameter on the comparison results is always a hot topic for research. This paper builds upon a previous research work done by the author. The main focus of this paper revolves around a thorough analysis of different factors affecting CV clock comparisons using different GNSSs, including the effect of the number of the satellite vehicles utilized, the effect of the geographical distance between laboratories, and their impact on the number of common observations. Additionally, the study delves into the stability and accuracy of comparison results and the correlation between them. To conduct this study, the timing data from ten pairs of national time and frequency laboratories were analyzed during a period of 30 days. The ten laboratories are from a total of eight countries, including the United States of America, Germany, the United Kingdom, China, the Netherlands, Kazakhstan, the Czech Republic, and Hong Kong
