A time synchronization method, communication ground station and user terminal

Abstract

The invention discloses a time synchronization method and a time synchronization device based on small inclination synchronous orbit satellite communication system. The time synchronization device provided by the invention comprises a communication ground station and a user terminal, used for performing Doppler frequency compensation on received and transmitted signals, time synchronization on the whole network and pre-deviation on frequency of the transmitted signal. According to the method and device, the variation of a path and the Doppler frequency deviation of signals between the user terminal and the SIGSO satellite can be compensated based on the terminal; the communication ground station measures and compensates the path delay, Doppler frequency deviation and satellite transponder clock drifting between the communication ground station and the satellite; via time synchronization and pre-deviation on transmitting frequency, the communication ground station and the transmitter of the user terminal ensure that the time when the signal arrives the communication ground station or the terminal is just the begin of a communication time slot distributed by the system, which can greatly improve the capture speed of the communication signal, and thus the system capacity of the communication system is improved, and the unit communication cost is reduced.

Description

technical field [0001] The invention relates to satellite communication technology, in particular to a time synchronization method based on a small-inclination synchronous orbit satellite communication system, a communication ground station and a user terminal. Background technique [0002] With the development of satellite communication technology, geostationary orbit satellite resources and orbital resources are becoming more and more scarce. At the same time, the cost of launching a geosynchronous orbit satellite is very high. Therefore, the utilization rate of space satellites is maximized and the satellite's in-orbit Lifespan has become a research hotspot in satellite communication applications. [0003] In 2002, Academician Ai Guoxiang of the Chinese Academy of Sciences led the invention of a navigation system based on communication satellites (patent application number: CN200410046064.1, name of invention: transponder satellite communication navigation and positioning...

AI Technical Summary

Problems solved by technology

However, satellites in low-inclination geosynchronous orbits must consider the impact of satellite motion on signals when performing satellite communication application services. First, satellite motion will introduce Doppler frequency shifts in communication signals, prolonging the capture time; secondly, satellite motion The distance between the satellite and the user changes periodically, which affects the accuracy of the TDMA time slot. When a large number of users communicate, it is easy to collide with communication data and reduce the efficiency of communication.

In view of this, there is currently no large-scale application of satellite communication systems in geosynchronous orbits with small inclination angles

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