Establishment of Observation Equation for Satellite-to-Satellite Tracking

The satellite-to-satellite tracking observations include light-of-sight-distance,light-of-sight-velocity and light-of-sight-acceleration,which reflect the various-band information of the Earth gravity field.To extract these information,the relationship between the SST observations and the Earth gravity field coefficients should be establishend.Three types of observation equations are created.And these equation could be realized with numerical method conveniently.