Single-frequency time and frequency transfer with Galileo E5

The GNSS main technique currently used for accurate time and frequency transfer is the so-called “geodetic time transfer”, based on a consistent modeling of dual-frequency code and carrier-phase measurements. This technique enables frequency transfer with an uncertainty of 0.1 nanoseconds thanks to the very low noise level of the carrier phase measurements, but the accuracy of time transfer can only reach the level of a couple of nanoseconds in the best cases, due to the noise and multipath of the GPS and GLONASS codes. However, in the near future Galileo will offer one promising signal, namely the broadband signal E5, with an ultimate low range noise in the cm range and with the lowest multipath error impact observed before. This paper investigates the use of this precise code for accurate time transfer.