Timing options and frequency control concepts for meeting user requirements with the second-generation global navigation satellite system (GNSS2)

This paper has described the first phase of an on-going study of work investigating the feasibility of a wholly-civil European second-generation Global Navigation Satellite System. The issues of time and frequency underpin the whole system, and this has been highlighted through the options available for frequency-band allocation, clock development, and time-transfer techniques for global navigation and global time- and frequency-dissemination. The NPL propose that further studies on issues such as local real-time ionospheric and tropospheric delay evaluation, two-way time-transfer to geostationary satellites for real-time satellite ephemeris determination, and multipath effects and methods to ameliorate them through multi-frequency receivers and directional antennae, would be beneficial towards developing the next-generation of global navigation satellite systems.