| 摘要 |
PURPOSE:To make it unnecessary to provide a cipher device on every terminal equipment by providing one set of cipher device for concealing satellite communication on an earth station without providing it on every terminal equipment, compressing continuous data of plural terminal equipments and converting them to one burst data, and thereafter, ciphering it. CONSTITUTION:One set of cipher device 8 is provided in an earth station 7 to which plural terminal equipment 6 have been connected by a circuit. Continuous data transmitted from plural terminal equipments 6 are compressed by a speed converting part 9, become one burst data, and it is ciphered by a cipher part 11 burst-operated by a burst control part 10, error-corrected and encoded by an error correcting and encoding part 12, and thereafter, modulated by a modulating part 13 and transmitted from an antenna 14. Received data is demodulated by a demodulating part 15, error-corrected by an error correcting part 16, and thereafter, cipher data is decoded by a decoding part 17. This decoding part 17 also executes decoding of a burst unit by control of the burst control part 10. The decoded burst data is expanded by the speed converting part 9 and sent as continuous data to the terminal equipment 6. |
