Code-and-carrier-phase based Two-Way Satellite Time and Frequency Transfer (TWSTFT) Experiment Between INRiM, LNE-SYRTE and PTB

International audienceTWSTFT has been one of the most popular techniques used for comparison of remote atomic clocks. It typically employs the code-phase of a signal modulated by a pseudorandom noise (PN) code sent and received by microwave link via a geostationary telecommunications satellite. The National Institute of Information and Communications Technology (NICT) has developed a Two-Way Carrier-Phase (TWCP) satellite frequency transfer technique and successfully integrated it with PN code-phase for time transfer in a new modem called Software Ranging System (SRS). Three SRS modems have been deployed to Istituto Nazionale di Ricerca Metrologica (INRiM / IT), LNE-SYRTE (OP) and Physikalisch-Technische Bundesanstalt (PTB) for experimentation in comparison of local realization of Coordinated Universal Time (UTC(k), where k is the laboratory responsible for the generation of the time scale). We will present preliminary code-phase-based and carrier-phase-based results for the links between UTC(IT), UTC(OP) and UTC(PTB). A comparison with other satellite time and frequency transfer techniques currently available at all sides is carried out, i.e. TWSTFT link using SATRE modems and using Software-Defined Radio (SDR) receivers. We find that TWSTFT with SRS modems achieve promising results of about 3e-15 at 1-day averaging time using code-phase measurements