PURPOSE: To take synchronization between plural transmission stations by providing a 1st transmission timing control means on a reference station and providing a means detecting the deviation of a signal arrival timing and a means controlling the transmission timing from the deviation to a slave station.

CONSTITUTION: A 1st transmission timing control means sending a signal for a preset prescribed period each is provided on a reference station 10 among plural transmission stations. Moreover, each of transmission stations 11-13 except the reference station 10 is provided with deviation detection means 11a-13a detecting a deviation between the arrival timing of a signal sent from the reference station 10 via a communication satellite 14 and the arrival timing of a signal sent from a station and returned via the communication satellite 14 and 2nd transmission timing communication 11b-13b controlling the transmission timing so that the deviation of both the signal arrival timings is a prescribed value. Thus, the synchronization among the plural transmission stations 11-13 is taken without using a reference burst signal.