Subtend, Between The Stars

Inter-satellite ranging is crucial in Gravisat and autonomous navigation. The technology of inter-satellite high accuracy ranging is developed here. In this paper, two ranging technology, Microwave Carrier Phase measurement and Code Smoothed Carrier are mainly discussed here.Microwave carrier observable has the highest accuracy in ranging system. The oscillator drift effect can be minimized by dual one-way phase measurement, and the ionosphere delay can be eliminated by the linear combination of dual-frequency. The lower accuracy of Pseudorange and the need for ambiguity is overwhelmed in code smoothed carrier observables. The smoothing accuracy is mainly depended on the choice of weight factor after modified by dual-frequency. Two choices for weight factor is given and compared in this paper.The demodulation for satellite signal is given in the last, including the capture, tracking of pseudorange and carrier-loop tracking.