| 摘要 |
PURPOSE:To carry on transmission from a slave station to a master station by performing switching to a clock from a clock source when the slave station detects the disconnection of a line by a disconnection detecting circuit in case the line from the master station to the slave station is disconnected. CONSTITUTION:When the disconnection detecting circuit 22 detects the disconnection of the line from the master station 30 to the slave station 31, a selector 21 is switched and controlled with a disconnection detection signal and the clock from an internal clock source 23 is selected and outputted. Further, information showing that the line from the master station 30 to the slave station 31 is disconnected is multiplexed with sent data modulated by a modulator 42. The modulator 42 modulates the sent data and line disconnection information according to the slave station internal clock from a terminal 24 and sends the modulated signal through an antenna 19. This signal is received through a satellite 13 and an antenna 14 and demodulated by a demodulator 43. Then the line disconnection information is detected by a line disconnection information detector 33 and the selector is switched to select and output the received clock from the demodulator 43. Consequently, the slave station 31 serves as a main station for the clock temporarily and makes a communication to the master station. |
