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Satellite technologies

Very Small Aperture Terminals (VSATs) 
Small satellite earth stations operating with geosynchronous (GEO) satellites can be used for interactive voice and data, as well as for broadcast reception. For example, the National Stock Exchange in India links brokers with rooftop VSATs. VSATs for television reception (known as TVROs for television receive only) deliver broadcasting signals to viewers in many developing regions, particularly in Asia and Latin America.

A VSAT is made up of 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 user is interconnected with the hub station via the satellite. 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 data speeds typically range from 128 Kbps to 4 Mbps.

Internet via Satellite 
Internet gateways can be accessed via geostationary satellites. For example, MagicNet, an Internet Service Provider (ISP) in Mongolia accesses the Internet in the U.S. via PanAmSat. However, these systems are not optimised for Internet use, so can be quite expensive. Also, there is a half-second delay, though this is more of a problem for voice than data. 

  • DirecPC 
    This system, designed by Hughes, uses a VSAT as a high speed downlink from the ISP, but provides upstream connectivity over existing telephone lines. This approach is designed for rural areas with a telephone service, but where bandwidth is very limited.

  • Interactive Access via VSAT 
    Several companies have developed protocols for fully interactive Internet access via satellite, to make more efficient use of bandwidth and thus lower transmission costs for users. Examples include VITACom, Tachyon, and Aloha Networks.

Bandwidth on demand
Low Earth Orbiting (LEO) systems providing bandwidth on demand, such as McCaw's Teledesic and Alcatel's Skybridge, and new generations of GEOs such as Loral's Cyberstar and Hughes' Spaceway are designed to offer bandwidth on demand for Internet access, video conferencing, and distance education.

Global Mobile Personal Communications Systems 
Using LEO satellites, these systems provide voice and low-speed (typically 2400 to 9600 bps) data virtually anywhere, using handheld transceivers. However, the price per minute for these services is typically much higher than national terrestrial services, and the first generation of LEOs has very limited bandwidth.

Data Broadcasting by Satellite 
GEO satellites designed for interactive voice and data communications can also be used for data broadcasting. For example, China's Xinhua News Agency transmits broadcasting news feeds to subscribers equipped with VSATs. Digital audio can also be broadcast by satellite. Satellite radio , which is now popular in many developed nations,  can be used to transmit educational programmes in a variety of languages for individual reception or community redistribution. It can also be used for delivery of Internet content. Participants identify which websites they want to view on a regular basis, and the satellite can broadcast the data for reception via an addressable modem attached to the radio.

Store-and-Forward Messaging 
Volunteers in Technical Assistance (VITA) has developed a satellite-based system called VITAsat, capable of delivering sustainable, low-cost communications and information services to remote communities. The system uses simple, reliable, store-and-forward e-mail messages relayed to the Internet via LEO satellites. Using compression technology and software that allows access to web pages using e-mail, VITAsat can make the Internet accessible virtually anywhere.

VITA's current two satellite systems have the capacity to serve about 2500 remote rural terminals that could be installed in schools, clinics, community centres and NGOs. VITA plans to include local skill and organisational capacity building and development of targeted information content and services designed specifically to meet the needs of small businesses, local NGOs, educators, health workers, and other relief and development workers.

Case studies
The University of the South Pacific: USPNet
USPNet operated by Information Technology Services (ITS) is a satellite-communications network connecting all 12 member countries of the University of the South Pacific. USPNet can assist in scheduling video conference sessions, coordinating these with regional counterparts, designing and installing video-conference equipment, and digitizing video-based educational materials for the delivery via streaming or download options. All video conference sessions within USP region are free to USP students, staff, management and affiliated researchers.

School on Internet Asia Project

SOI ASIA Project utilizes satellite based Internet to provide Internet environments in a less expensive, easy to deploy, and more feasible way for the universities located in the regions where Internet environments are insufficiently developed; conducts research and development of the necessary technology for IT human resource development in Asia while using the environments; and proposes, through field experiments, a new educational methodology for universities in Japan as well as educational institutions abroad.