How It Works: Satellite Internet Access

Satellite Internet Access: a high-speed Internet service that uses a satellite dish to provide downloads at up to 400 kilobits per second.

Feeling left out of the broadband buzz because you can't get cable or digital subscriber line Internet access? Satellite Internet access may be the solution. If you can get a clear view of the southern sky, you can use satellite access to get streaming media, download big files, or just surf the Web faster. While it's not as cheap or simple to install as cable modems or DSL, for some it's the best (and only) answer.

Here's what you should know:

• You can download files at up to 400 kbps, but uploading currently requires an analog modem, which limits performance.
  
  
• By the end of this year, two-way satellite service should be available, obviating the need for an analog modem and allowing for faster uploads of up to 200 kbps.
  
  
• Only one company provides service now, although more will offer access in the near future.
  
  

Satellite Internet access is a lot like satellite television: A "bird" orbiting the earth beams data to a dish attached to your house. The dish relays the data at speeds of 400 kbps or more to a special satellite modem connected to your PC.

Notice we didn't say anything about upload speeds. Currently, satellite services require an analog, ISDN, or wireless modem for uploading files. Each Web page request you make can only travel as fast as your current modem. The system was set up that way to keep costs down.

When you put all those pieces together, here's how it works: You dial into your ISP with your modem. While surfing a Web site, you click a link to view a different Web page. Software on your PC attaches a piece of code (called tunneling code) to your request. Instead of requesting the file directly from the Web server, the request goes to the satellite service's Network Operations Center (NOC), located on terra firma. The NOC then requests the Web page. The Web server sends the requested Web page back to the NOC.

The NOC beams the Web page to a satellite, which forwards the data to your dish. The dish passes the Web page to your PC through the satellite modem. The whole process should take less than half a second.

Potential Drawbacks

All these steps can result in latency (a noticeable delay between the time you click and the time you receive data). The delay can occur as your request is routed from your PC via modem to the NOC, to a Web server, back to the NOC, and then 22,200 miles to the satellite and back down to your dish. Latency is less of an issue with a steady stream of data, such as a shareware download or streaming music files.

Your performance may suffer when other users sign on to the service, since the bandwidth provided by the satellite is shared between users, as it is with cable Internet access. The satellite only has a certain amount of bandwidth it can dole out. However, upcoming two-way satellite systems, which will eliminate the need for an analog modem connection for uploads, will have greater bandwidth available--as much as 1.5 megabits per second down, 200 kbps up.