We consider the design of a unified software-hardware system for synchronizing remote time scales by a satellite communications channel with nanosecond accuracy. The main principles are described for the construction of a system for the transmission of time scales and a system for delay calibration of the transceiver equipment of satellite communications station, the comparison errors due to ionospheric effects are analyzed, a procedure is given for calculating the relativistic errors, and the main requirements are formulated for software for comparison of remote time scales.