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GPRS stands for General Packet Radio System. We use GPRS to access the internet through a cellular telephone when we are on the ship in South African waters or when we're away from the office. This allows us to check our e-mail, and update the website; both are vital means of keeping in contact with other parts of the Programme as well as the general public.
Ship to shore communications GPRS is a protocol (way of "talking", electronically) which uses packet switching technology. Unlike a normal telephone call (or the older GSM data transfer protocols of CSD and HSCSD), you don't have a line open all the time; instead, the system sends small chunks of data - packets - over the system utilising bandwidth very effectively. Any information that you send or receive over the network is chopped up into these small packets and sent one at a time whenever there is spare capacity in the network - it's quite similar in principle to the TCP/IP protocol used on the Internet and many LANs.
Conventional calls vs. GPRS. Conventional calls and data channels (see left) open one or more channels permanently for the duration of the call. CSD and voice calls take one data channel full time; HSCSD opens as many spare channels as possible (up to about 8) to improve throughput - a single channel is 9,600 bps. GPRS (right) instead transmits packets intermittently over one or more channels. Billing on a GPRS system is done by charging for data throughput; units are 20kb in size; both uploaded and downloaded data are charged for. GPRS is ideal for applications like web browsing and web-based e-mail, which only intermittently send or receive data; HSCSD is more appropriate when uploading or downloading large files. |
