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Explained: How Does Satellite Internet Work?

July 28, 2009

satellite_dishSatellite Internet service appears to be becoming more and more popular. Once the exclusive domain of exploration companies and war journalists, there are now thousands of people with an extra dish on the home or RV. Part of the reason for this is that certain technologies have increased the bandwidth and decreased the cost.

Now, there are geostationary satellites. That’s a fancy word for saying the satellite stays still in relation to your position on Earth.  You have to set the dish up just once and, barring windstorms or worse, the dish stays in constant communication with the satellite.

The latest way to communicate with satellites for Internet service is over something called the Ka band (pronounced kay-eh). The Ka band is a set of frequencies that are between 18.3 GHz and 31 GHz. More specifically, the uplink (that part of the call that is going from your home to the satellite) is in the range of 27.5 GHz and 31 GHz. The downlink (that part of the call that is coming from the satellite to your home) is in the range of 18.3 Ghz and 20.2 Ghz.
What the heck is a GHz? Giga Hertz. Giga for a 1,000,000,000, and Hertz for a cycle per second. Picture a wave on the ocean. It has two parts, the crest of the wave that comes high out of the water. Then there is the trough of the wave, which goes below the normal waterline. Now picture a cot and some Bud Light Lime….mmmmm. Okay back to school.

When the crest AND the trough are done passing over the same point in the water, that can be thought of as one cycle. Now imagine that happening in just one second. That’s a Hertz.  Now imagine that happening a thousand times in one second! That’s a megahertz. Now imagine that happening 1,000,000,000 times in a second! That’s a gigahertz. My brain hertz.

sine_waves real_wave
See the similarities?

Why do you need to know this? Well, those numbers relate to transmitting power and what the signal can carry for information. The lower frequencies transmit longer distances with less power, but aren’t capable of carrying a lot of information. That’s why the old 900Mhz phones don’t have the voice quality of the 2.6Ghz phones. Yet you could take those old phones down the block with you.

So, using the higher frequency ranges for satellite Internet allows for more data to be sent, giving us something close to high-speed Internet even if we’re an Alaskan recluse.

Because of the high frequency rates, that signal has to be stepped down and lose a bit of power before it hits the delicate electronics of the modem. This is done using a device that is on the dish itself as well as having a minimum of 150 feet of high-quality RG6 coax cable connecting the dish to the modem. So if you wonder why the installer used such a long cable just to wrap it up and drop half of it on the floor, well, this is why.

Something else you should know about is that Ka band satellite uses spot beams. A spot beam covers a specific area that really isn’t that big – about a third the size of Alberta. Each spot beam can support only so many users. If you hear that your buddy in Montana can get service, but you can’t because your spot beam is full, there isn’t much you can do about it. Also, you can’t move your service from spot beam to spot beam unless you are a certified installer. You will also need a clear line of sight to the satellite.

Here’s what the spot beams look like. As you can see, service is NOT available anywhere, like they sometimes advertise.

anik-f2-spots

What’s the downside? Latency. What’s latency?  Gamers call it lag. It’s that time when your signal is going between your house and the satellite. Typically, it’s about 230 milliseconds or more. That doesn’t seem like much considering the signal is covering about 45,000 miles in that time. However, when it comes to things like VoIP or online gaming, it makes it nearly impossible to do.

Another downside is something called the Fair Access Policy or FAP. What this means is that your Satellite Internet Service Provider will put limits on how much you can download over a period of time – usually 24 hours. If you exceed that, they will automatically slow your speed down to something close to dial-up, to give other users fair access to the satellite. When this happens, you have been FAP’ed. So, if you are a chronic downloader, (or just leave your computer on connected to the internet for long periods of time) you’ll have to change your ways for satellite Internet.

Is it picture time yet? Of course it is.

satellite_diagram

All this for about $800 for the hardware and $50 a month for ongoing service. Not bad, when you consider bringing in a phone line down a logging road will cost about $10,000 a pole. However, if you want to put a self-pointing dish on your RV, you’re going to need to dig a little deeper as the hardware will run you about $10,000. You could try to take a stationary dish with you, but pointing the new dishes can take up to eight-hours to aim, and you must be a certified installer.

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