| 摘要 |
A duplex narrowband start-up link between first and second stations A,B provides control and addressing information regarding data blocks which are sent via a unidirectional broadband link from the first to the second station. The data blocks may be encrypted and the encryption key may be transmitted via the narrowband link, the control and addressing information not being encrypted. The broadband link may be via a satellite and may employ an MPEG-2 signal but for transmission of non-video data. There may be a further unidirectional broadband satellite link for transmission of data blocks from the second to the first station, the narrowband link providing control and addressing information for both directions of data block transmission. |
