Satellite TV: VSAT Technology

VSAT is a remote terminal that is part of a satellite communications network. The abbreviation VSAT stands for Very Small Aperture Terminal and refers to small diameter dish antennas, usually of a diameter of 2.4 meters or less. This size is small when compared to the large antennas of earth stations that reach up to 11 meters in diameter or more.

The satellite is essentially a repeater or a mirror that reflects the transmissions that a terminal makes towards the earth. This allows one terminal on the network to communicate with another that is hundreds of kilometers away. Additionally, it also makes possible the broadcasting of information from one terminal to many others, as well as the retransmission of signals from the satellite to the earth. This signal normally covers a wide geographical area.

VSAT stations can be used for communications between two or more earth stations. Employing VSAT stations makes it possible to cover widely in areas of very difficult access while at the same time easily increasing the number of access points.

VSAT stations are also applied for Internet connectivity, both in remote locations and in countries where local regulations require the use of telecommunications structures independent of each of them' own networks.

The architecture for VSAT networks can be star, full-mesh or hybrid. "Star" means a central that communicates with all remote stations. This is an architecture for satellite television broadcasting in which a large central antenna transmits to many other small remote antennas. However, VSAT can offer two-way communication with remote bases as well as reception from the central transmission unit. If there are two remote communications, one of them transmits to the central station. The central station relays the message to the respective station. This means that there are two satellite paths or paths.

"Full Mesh" refers to any terminal on the network that can communicate with any other in a single direction with the satellite. That is, by a single means of communication. There is no intermediate stop with the central satellite. "Hibryd", on the other hand, refers to the network architecture that employs the two designs "Full Mesh" and "Hibryd". An example of this is a network that uses "Star" for data transmissions to the central and also provides voice communications service between all remote "Full Mesh" terminals.

Currently, there are more than 400 million PCs in the world. This figure increases by about 50 million each year. Experts estimate that a figure close to 25% of these personal computers are connected to the Internet. A growing number of users in both the residential and business markets are dissatisfied with the data rats offered by a common telephone modem. Different technologies are competing to provide broad broadband access. The main competitors are part of the Digital Subscriber Line (DSL) technologies that use the local infrastructure of copper networks; cable modems over the cable TV network; recent technologies such as LMDS or MMDS and satellite access.

Each of these technologies has its strengths and weaknesses. For example, Cable Modem networks require intensive installation work and have a limited output when the last coaxial section has a high number of subscribers.

Satellite systems can reach places where other technologies cannot. A satellite provides global coverage in a simple network. The quality of service and reliability are high. In addition, the satellite system is unmatched for broadcasting applications, as well as for delivering the same information to a large number of users. It is necessary to consider that a large majority of Internet users in the future will be transmitting services that require the reproduction of audio and video information.

Satellites, in addition to providing fast Internet access, can provide two-way connectivity by leveraging local infrastructure. For regions of the world that have difficulty bearing the costs of broadband ground stations, satellite Internet may be the fastest and most economical way for an Internet Service Provider (ISP) to gain bandwidth in Internet access.

Along with these applications, VSAT technology has applications in rural telephony and corporate information networks.