Contents

1 Description

• A satellite dish provides two-way (upload and download) data communications. The upload speed is about one-tenth of the 500 kb/s download speed.
• To access satellite Internet services, subscribers need a satellite dish, two modems (uplink and downlink), and coaxial cables between the dish and the modem.
• Satellite Internet services are used in locations where land-based Internet access is not available, or for temporary installations that are continually on the move. Internet access using satellites is available worldwide, including for vessels at sea, airplanes in flight, and vehicles moving on land.

2 Hardware

There are three ways to connect to the Internet using satellites:

1. One-way multicast satellite Internet systems are used for IP multicast-based data, audio, and video distribution. Even though most IP protocols require two-way communication, for Internet content, including web pages, one-way satellite-based Internet services can be "pushed" pages to local storage at end-user sites by satellite Internet. Full interactivity is not possible.
2. One-way terrestrial return satellite Internet systems use traditional dialup access to send outbound data through a modem and receive downloads from the satellite.
3. Two-way satellite Internet sends data from remote sites via satellite to a hub, which then sends the data to the Internet. The satellite dish at each location needs precise positioning to avoid interference with other satellites. Two-way satellite Internet uses IP multicasting technology, which allows one satellite to serve up to 5,000 communication channels simultaneously. IP multicast sends data from one point to many points at the same time by sending data in a compressed format. Compression reduces the size of the data and the bandwidth.

The key installation requirement is for the antenna to have a clear view toward the equator, where most orbiting satellites are stationed. Trees and heavy rains can affect reception of the signals.

3 Capacity

Upload speeds are about one-tenth of the download speed, which is in the range of 500 kbps.