The Research And Realization Of HSD Transmission Of INMARSAT System Based On TCP/IP

Based on the Tele-Communication System which is being constructed for the new ships of State Oceanic Administration People's Republic of China, and Combined with the status of Inmarsat-B data communication system, this paper researches and realizes that mobile terminal, here is one of the ships, accesses terrestrial ISDN network through HSD interface of Inmarsat-B, then creates the 64 kbps high speed date (HSD) connection with control center based on TCP/IP.Inmarsat is an internationally owned co-operative that provides worldwide mobile satellite communications. Inmarsat has become the only provider of global mobile satellite communications for commercial and distress and safety applications at sea, in the air and on land. Inmarsat-B is one of the mobile communication systems criterions of Inmarsat; it provides the services of Voice, Telex, Fax and Data. The HSD service can conveniently access terrestrial ISDN network and realize the 64 kbps HSD communication.TCP/IP is a protocol used on Internet. With the high-speed development of Internet, at present TCP/IP has already become the most extensive communication protocol and various kinds of communication media are used for transmitting IP data. TCP/IP protocol guarantees dependability of data transmission, and has nearly offered all services on the network that include email and file transfer, etc.In this paper, I discuss the characteristic of the channel of satellites and analyze the TCP/IP protocol, from such perspectives as system function, system structure, network topological and software structure design and realize Inmarsat Mobile ISDN communication system. According to the systematic function characteristic I have developed communication service software that is installed on the communication server in the control center, and client communication software that is installed on the communication server in the mobile terminal. The communication service is started inthe control center, and files can be transmitted between the mobile terminals and the control center and the user in the mobile terminals can have email communiceition with Internet email addresses. Simulating the mobile terminal on ISDN circuit, Inmarsat Mobile ISDN communication system achieves the anticipated result. After the test through the real satellite channel on the Inmarsat-B station of the 1000 tons II ship, the communication system have passed the confirmation, and now it has successfully been applied to the new ships of State Oceanic Administration People's Republic of China.