One-Way Satellite vs. Two-Way Satellite

Atl-Connect's SkySpeed satellite service is a "one-way" service, which means that we use your phone line and modem to connect for "upstream" data, and we send data to your computer by way of the satellite and a dish on your roof. Other systems are "two-way", meaning that the satellite dish is used to receive as well as send data to the satellite.

A common misconception about two-way is that it's better than one-way because it's faster (the upstream connection is advertised as a 400Kbps link, just like the downstream). However, when you actually use the service, you'll find that the surfing speed of a two-way satellite connection actually moves more slowly than one-way!

Satellites were not originally designed for two-way communication. The original intent for a satellite is one-way broadcasting, not uploading or accepting a transmitted signal. Two-way communications force the satellite to do something counter to its fundamental design. Because of this, there are delays in accepting and forwarding information (such as web page requests), resulting in a slower two-way surfing experience.

Using satellite to transmit both ways (the process of sending and receiving signal) can take from 700 to 1300 milliseconds (as reported by Hughes). After 700 milliseconds, the standard networking stack will generally consider the information packets "lost," and will automatically resubmit the request, sometimes several times. Although this process is invisible to you, you'll experience it as waiting time...not unline the waiting you experience on a dialup-only connection.

By way of comparison, the transmission time for one-way satellite (telephone line plus satellite) is approximately 400 milliseconds; well below the 700 milliseconds required by the two-way system, and below the threshold where most networking systems will give up and try again. As a result, page requests make it to their destination immediately, and the satellite broadcasts the results immediately to you. The result is a FASTER surfing experience with one-way satellite connections.

Starband says on their website that "when sending e-mails with large attachments or uploading large files to the Internet, you may experience speeds closer to that of dial-up service." (Starband website 10/29/2002 http://www.starband.com/faq/benefits.htm)

Earthlink says (and this also applies to DirecWay) that their data uploads via satellite are "similar to a dial-up modem" (Earthlink website 10/29/2002 http://register.earthlink.net/cgi-bin/wsisa.dll/broadband/satellite/faq.html - select FAQ link)

As if better performance weren't reason enough, our one-way system is actually less expensive (by a fair margin) than any of the two-way alternatives!

More information about our SkySpeed Satellite service is available here.

Posted by WebWiz at January 14, 2003 12:09 PM