It’s become a familiar part of the landscape. Chances are if you don’t have a dish on your roof, someone in your neighborhood does. Between DIRECTV and DISH, there are close to twenty million satellite TV subscribers, meaning close to one in ten homes is getting television service from the sky. That’s a pretty impressive success rate for an industry that barely existed twenty years ago.
Satellite television means any live video service supplied via earth-orbiting satellite, and can be separated out into three categories: Free-to-Air (FTA), FreeView and Direct Broadcast Satellite (DBS.) While the basic technologies for both are the same, one has become almost extinct while the other thrives. Let’s look a little closer at what makes satellite TV work.
There’s a formula that tells us how quickly an object is going to go around the earth, and it has to do with how close it is. As something is closer to the earth, gravity pulls it faster and faster, while further objects travel around the earth slowly. The International Space Station goes around the earth every 92 minutes, while the moon, which is much further away, makes the trip in about 29.5 days. The sweet spot for communications satellites is roughly 22,000 miles above mean sea level. At that distance an orbit of the earth takes exactly one day, meaning the satellite seems to hang in space above a particular point on earth.
When a satellite is fixed in space relative to the earth, a dish can point to it and it s a fairly simple matter to broadcast signals up to it and have them bounce down much like making a bank shot in pool. That’s the basis of all satellite TV: signals go up, signals come down.
Free to air
The term “Free to air” means satellite transmissions that are completely unencrypted. This form of satellite TV was very popular in the 1980s but has almost completely disappeared today. Free to air transmissions require a motorized dish that points at many different satellites, one at a time, and requires you (or your computer) to know what is on each satellite. It’s not a very efficient way to watch TV, but back when premium channels sent their programs up to satellites without any encryption, it was pretty popular.
Direct Broadcast Satellite
The term “Direct Broadcast Satellite” describes a service where a master system operator (like DIRECTV or DISH) collects a lot of different programs, beams them all up to the same satellite, and collects a fee for letting you watch them. DBS has become popular since it acts like traditional pay TV.
DBS was designed from the start to be customer-friendly. The goal was a digital service that used a dish no larger than 20″ high and did not need to be reaimed for every program, because it was felt that the large size and technical complexity of FTA dishes made them unpopular. In exchange for developing the technology to make dishes smaller and easier to use, governments around the world granted satellite TV companies the right to encrypt their signals, making it possible to charge customers for decryption.
Encryption is the key to modern satellite TV, because the process of building all the land-based and sky-based parts of a satellite TV system is incredibly expensive. If anyone could put up a satellite dish and get free TV, there would be no reason for companies to invest so heavily. Both DIRECTV and DISH have put millions of dollars into encryption schemes that have managed to stay one step away from hackers for decades, no small feat.
FreeView satellite, seen almost exclusively in Europe and the Middle East, is a version of FTA that uses the same dishes as DBS and is free to residents (or is part of the same tax structure that brings over-the-air TV.) The technology is the same as DBS but without encryption. There are practically no FreeView satellite systems in the Western Hemisphere; they’re used to broadcast state-sponsored TV to areas that don’t have good over-the-air reception.