Progress on absolute calibrations of GNSS reception chains at CNES

GNSS time transfer is widely used for remote clock comparisons, in particular by the BIPM for UTC/TAI. Comparing clocks with this technique requires a calibration of the GNSS reception chain (between the antenna phase center and the reference clock). CNES has been working extensively on the absolute calibration of GNSS reception chains for many years. This paper presents the recent improvements and results obtained at CNES.