Zipa ovo i prije su firme razne lansirale cluster satelita.
Citiraj:
While you may never have considered buying a sat-phone, you may change your mind after learning a few key facts, especially when you consider the drastic reduction in the cost of equipment and airtime that has occurred in the past few years.
The primary satellite network infrastructure was built by Intelsat in 1965 and changed the way the world communicated. It spawned incredible capabilities, especially in the maritime world where one company now supplies communications to virtually every cruise ship in the world so its passengers and crew can talk, text, and email from sea.
In about 1997 the first low earth orbit satellite network was launched by Motorola to provide handheld service anywhere in the world. The system was called Iridium and consisted of 66 satellites that crisscrossed the globe on a continual basis. The constellation of satellites communicated directly with each other in space, and then to ground stations in thirteen different locations around the world. Handsets could communicate with any phone, anywhere through this infrastructure. Ultimately, Iridium went bankrupt due to inept marketing and unrealistic expectations of user demand, but the network survived and is now thriving.
At about the same time, GlobalStar launched a similar network, but with entirely different architecture, called bent-pipe. This system relied upon 48 satellites that were placed in orbit about 900 miles above the earth. Globalstar provided cellular-equivalent audio quality, unlike Iridium which has an extremely narrow bandwidth. This means that audio intelligibility on Iridium (and Inmarsat) is a bit more difficult to understand.
Globalstar went bankrupt in 2002. It has lost about half of its first generation satellites and is just trying to rebuild itself. Presently, its service is very limited and not entirely reliable on a 24/7 basis.
A regional network, Thuraya launched in 1997 and began operations in about 2001. Based in the UAE, it was designed to serve Europe, Africa, and the Middle East. Its handsets are dual-mode, which means that subscribers can roam on both GSM networks as well as talk via satellite. They now have sold more than 600,000 handsets.
The fourth and latest entrant into the satellite phone arena is Inmarsat.This company began operations to supply communications to the maritime industry in 1979. In 2010 they introduced their IsatPhone-Pro handset that talks through their global constellation that covers the planet except for the North and South poles.
The four satellite networks provide essentially the same services, but in very different ways, with different kinds of technology, coverage and quality. Which system is right for you depends on how and where you will make and receive phone calls, and what other services you may require.
GPS je zaista olakšao život, ali ovo sve poslije je pretjerivanje. Poslije Muska pojaviće se neki novi konzorcijum koji će za koji kilometra iznad postaviti svoje satelite.
Ove Iridiumove satelite nekad pratim i čekam kad zasvjetle na nebu.
Da li su sateliti ovih kompanija služili za satelitski internet radi kojega je ova tema pokrenuta?