A method for determination of clock onboard satellite combining L-band phase smoothed code and C-band TWTRS measurements

Yang Xuhai (2011) presented a new method for determining the offset of navigation satellite onboard clock that processes ion-free code and phase combinations together with simultaneous TWSTFT measurements in the mode of transmitting and receiving with the same station (TWTRS for short) (signal flow: ground station-satellite-own ground station), which was called combination solution. The estimation error of the radial component of the orbit is not correlated with the clock estimation error. But there are still some details to analyze further. A successful determination of clock offset with respect to the master clock depends to a large extent on the correct determination of the inter-system bias. Two aspects of this paper are as follow: on the one hand, code measurement accuracy is limited as some minor errors are submerged in the overall trend and not easy to find. So the carrier phase smoothed code measurement can be used to improve the code measurement accuracy. On the other hand, clock offset onboard can be calculated independently from individual ground station by the combination solution. Taking difference for the same clock offset onboard during the same period can assess the combination solution. The RMS of residual value is less than 2 ns.