Spacecraft velocity determination in nongeostationary mobile satellite communications

Measuring the motion characteristics of a spacecraft is the most important task in the operation of any satellite system. Based on the obtained coordinates and components of the velocity vector, the orbit of the spacecraft is determined and its motion predicted, which is necessary for organizing control and communications. However, due to the incomplete determinism of the orbit due to the influence of gravitational anomalies, the resistance of the medium and other disturbing forces, this prediction needs constant refinement. Trajectory parameters of spacecraft are traditionally determined using measuring channels of radio engineering systems with an active response, combined with telemetry and command information transmission channels, using ground-based control complex with the involvement of specialized command and measurement systems, command-measuring complexes and a ballistic center. Also known are methods for trajectory measurements of a spacecraft using global navigation satellite systems, which presupposes the presence on board of the equipment for receiving navigation signals. At the same time, for existing and prospective space systems for various purposes, it is becoming increasingly important to expand the areas of autonomous operation. The article describes a method for determining the velocity of a non-geostationary spacecraft with a multibeam antenna system without using ground-based measuring instruments. The estimation of errors of the velocity vector for the method of direct measurement of the radial velocities of the object. Proposed measures to improve the accuracy of determining the velocity of the spacecraft using information about the location of the subscriber.