This is the older original Advertising agency system, which usually began operation in 1982. Although A is actually classed since rather older technology, new stations continue to be joining the program, and there are now some 22, 000 mobile stations of various sorts working Inmarsat A.
Inmarsat-A can support two-way cell phone, telex, send, E-mail and with the High Speed Data option, it can support data transmission up to 64 kilobits per second. In addition to supporting simultaneous two-way data transmission, the HSD option can be used intended for the tranny of nonetheless pictures and compressed video pictures or for online video conference cell phone calls. Inmarsat-A support Enhanced Group Calling - the reception of Maritime Safety Information which can be provided for 'All Stations', or to a team of vessels, as well as to vessels within a specific region. The ability to receive EGC is a pre-requisite to get GMDSS qualification. Some Inmarsat-A terminals requires the appropriate of an external EGC recipient for reception of these MSIs.
The cellular station communicates with the satellite on eq in the L-band - 1 ) 5 to 1. 6 Gigahertz (remember, that may be 1, six-hundred MHz, or perhaps 1, 600, 000 kHz). The satellite tv in turn convey with the L'ENSEMBLE DES on eq in the C- band -- 4 to 6 Gigahertz.
There are two principle downsides to the Inmarsat-A system - it is the most expensive of all of these in terms of call up charges, also because it uses large bandwidth and relatively low power, it requires a large parabolic antenna. On board a vessel in sea, this antenna has to be kept frequently pointed on the satellite regardless of how the yacht moves. This involves gyroscopes, motor and substantial power. An average marine Inmarsat-A antenna is housed in a dome up to one and a half metres in diameter, and weighs around a hundred kilos. Inmarsat-B
Inmarsat-B is the modern digital variation of the advertising agency Inmarsat-A. (A for Egal and M for Binary! ) The digital technology makes better use of the band width and the satellite television power resulting in lower...