Short for Very Small Aperture Terminal, an earthbound station used in satellite communications of data, voice and video signals, excluding broadcast television. A VSAT consists of two parts, a transceiver that is placed outdoors in direct line of sight to the satellite and a device that is placed indoors to interface the transceiver with the end user's communications device, such as a PC. The transceiver receives or sends a signal to a satellite transponder in the sky. The satellite sends and receives signals from a ground station computer that acts as a hub for the system. Each end user is interconnected with the hub station via the satellite, forming a star topology. The hub controls the entire operation of the network. For one end user to communicate with another, each transmission has to first go to the hub station that then retransmits it via the satellite to the other end user's VSAT. VSAT can handle up to 56 Kbps.
[pic]
The indoor unit usually fits on a desktop (much like a modem) and contains the circuitry that activates the communications link between the user’s equipment and the satellite. The outdoor unit includes a small antenna, usually 2 to 6 feet, that can be mounted on an end-user’s roof, ground or wall and electronic equipment that transmits and receives signals to and from the satellite transponder
Vsat networks are primarily used for:
1. On-line data delivery and transaction-oriented applications including point-of-sale (for example, credit And debit card authorization), inventory control and real time stock exchange trading
2. Telephone service in areas that are underserved by the existing telecommunications services or in remote Locations without service
3. Internet Protocol (‘‘IP’’) based networking applications such as corporate intranets, corporate training and other broadband multicasting applications, as well as consumer broadband Internet applications.
Satellite-based communications networks offer several