Characterization of OP TWSTFT stations in colocation based on combined use of code and carrier phase data

The TWSTFT carrier phase technique permits to improve the short term stability of the two-way links. The basic idea of this method is to calculate the offset between the frequencies of the two remote clocks in comparison. The frequency of the local oscillator on-board and Doppler coefficients are also determined. By applying the carrier phase method using the two OP ground stations in a common clock mode, a frequency stability of 1×10^-12 is reached at 1 s while with the OP satellite simulator, a value of 4×10^-13 is achieved.