Accurate frequency transfer: progress in the implementation of the GPS carrier phase method at the BNM-LPTE

This paper describes the equipment and the software used at the Laboratoire Primaire du Temps et des Frequences du Bureau National de Metrologie (BNM-LPTF), Paris, France. The comparison of two H-masers in short baseline, located at the BNM-LPTF and at the Laboratoire de l´Horloge Atomique du Centre National de la Recherche Scientifique (CNRS-LHA), Orsay, France, computed with the BNM-LPTF software and with the BERNESE V4.0 software shows an agreement of 100 ps (1σ). In addition, comparisons have been made over ten days with the H-masers of the Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany, and of the National Physical Laboratory (NPL), Teddington, United Kingdom. The data collected show that a modulation with an amplitude of 50 ps and a period of 700-800 ps affects the H-maser of the NPL. In addition these comparisons show that the noise of the H-maser of the PTB was higher than those of the NPL and the BNM-LPTF during the observation period. Finally the best relative frequency stability obtained, in the case of the BNM-LPTF/NPL comparison, is about 3×10^-15 for averaging periods between 6×10⁴ s and 3×10 ⁵ s. This result is in good agreement with the expected stability of H-masers