Study of observability of motion of an orbital group of navigation space system using intersatellite range measurements. I

The problem of specification of reference ephemeris (reference motion) using intersatellite range measurements on a given interval between spacecrafts of the space navigation system is formulated; observability for this problem is analyzed. Observability is the possibility of unambiguous determination of motion parameters of the orbital group of the space navigation system using known inter-satellite measurements on a given measurement interval. Linear approximate model describing the dependence between measurements and specified parameters are obtained for investigation of observability properties. In the framework of linear model problems of observability of motion of two any spacecrafts of the navigation system are studied using intersatellite range measurements.