Satellite Internet - What is it ?A Primer / Editorial by Thomas (Bouncer) Blakely, CCNA, CCDA
2001-06-11 09:18 by Tom Blakely
WARNING! Stunningly long piece to follow. Please use next restroom exit !... and bring me a cookie while you're up. Here we go:
So you're waaaaaaay out in the country, and neither DSL nor Cable is an option. Like say ..in Kosova. Or Bosnia. Or, God forbid, North Dakota. Perhaps on a ship. You'd like to get the internet, but carrier pigeon seems to be your only option. Wherever you are, if you're north of the equator and have a view of the visible sky to the south of you, you may have another option. You can probably get internet ...via Satellite. Yes, just like Wolf Bliitzer and James Bond you too can have nearly instant communications with the vast internet.
"Where do I sign up!" you cry out... Well... I wouldn't pop the champagne just yet. There's some issues we need to discuss, which I'm going to try to do in this editorial. Okay...You have to understand and remember one very simple premise:
Satellite communications are line of sight.
That one sentence is the core of what drives everything else. I won't go too much into the history as it's not relevant, except to mention Syncom2, the first Geostationary Satellite.
What the heck is a Geostationary Satellite anyways?
Ever noticed that if you drop something it falls to the ground? So did the folks at NASA, and they got concerned because they didn't want satellites dropping out of the sky. It's embarrassing and expensive. So they had to try and find the point where the satellite would maintain enough speed to keep it from falling to earth while staying in a fixed spot over the equator.
Why do it this way?
22,300 miles over the equator there is a whole belt of satellites zooming along. This area is named after Sir Dr. Arthur C. Clarke the science-fiction novelist. It is frequently referred to as "Clarke's Constellation" Because it was he, back in 1947, who postulated the idea of using satellites for point-to-point-to-point radio communication. Science Fiction indeed.
Why a fixed position? Why Line of sight?
Geostationary Satellites are at fixed positions at an altitude of 22,300 miles from Earth. They can "see" (and be seen from) a huge area of land and ocean, and this area they can "see" is called the "footprint". They are also frequently located over the equator. You can imagine what the foot print looks like by holding a flashlight at a fixed distance from a basketball and turning the light on. The closer you get, the smaller the footprint. Make sense?
Now if you hold the flash light at a fixed distance from the centerline or "equator" of the basketball AND aim it at the upper half you will see that the "footprint" elongates and gets much larger on one side, extending itself by half again. And turning from a simple circle, into an oval. That's why a lot of birds are "parked" in orbit over the equator. There is a consequence to this large footprint though. Radio waves travel at the speed of light, or about 186,000 miles per second. So any traffic from you to the satellite has to go 22,300 miles up, go through the satellite, and be retransmitted 22,300 miles back down.
The net effect is that it adds about a minimum of 240ms to the round trip. This is from an ideal position as close to the satellite as possible, which is probably in the ocean at the equator. And remember, that if you send for a web page both the request and the response have to travel these distances in addition to any ground distance. A more realistic expectation is a response of about 500-1000ms.
What is this "200ms" stuff?
Imagine you are driving a racecar. Now imagine it's about three-quarters of a second delay (750ms) between the time you try to steer left, and the time the racecar starts to respond (750ms). You see the problem. It's like driving on ice and is simply not useable for many internet games that require fast reflexes. Some flight games may be useable, because they don't need as fast a response. However, popular first person shooters like Quake III and Tribes 2 and Counter-Strike are almost unplayable.
I'm sure you're tired of the history lesson and would like me to get on with how you can get it if you want it.
You have two primary options right now.
THE NEW SYSTEMS CONDUCT YOUR REQUESTS AND THE RESPONSES FROM HUGHES ENTIRELY VIA SATELLITE. THERE IS NO LANDLINE/MODEM.
The Other system is by Gilat, and is being sponsored by Microsoft and Radio Shack. It also uses the newer two way satellite system. It is part of the DiSH Network for TV access and is called StarBand.
The nice thing about these systems is that service is available just about everywhere in North America and Europe, and many places in South America as well.
I would like to mention this:
I hope this primer leaves you with a clearer understanding of the theory and operational issues with Satellite Internet access. As an aside there are some Low Earth Orbit/Observable satellites called "LEO's" which promise to offer all the current systems do, and more. Including MUCH lower delay times in the 10 to 20ms range. These systems, however, aren't slated to come online until about 2005 if they ever do. So for the time being, you'll just have to accept the delay inherent in the system.
Average pricing is between $40 - $60 USD a month. Some require you to buy more equipment than others and both run specials and deals so prices will tend to vary.
Finally, I want to mention this. Satellite internet represents the best opportunity for schools, communities, and individuals in remote areas to gain access to world wide communications. It is unique because it is simply not subject to local control over access or content. It has the ability to reach people no other communications medium can at a practical cost.
Thomas Blakely, CCNA, CCDA