Digital satellite TV is broadcast from a satellite located on orbit around the Earth. A homeowner who subscribes to the service must put a satellite dish outside that picks up the signal and delivers it into the home. Subscribers can receive all major national channels and premium channels, although local channels are sometimes difficult to receive.
The satellites that send the digital signals are located about 22,200 miles (35,730 km) above the Earth. They move with the Earth, in order to constantly remain in the same position relative to the ground. This orbit is referred to as geosynchronous. The satellites receive the initial signal from a broadcast center on the Earth, and then send it back down to the subscribers' dishes. The digital satellite signal is then processed through the subscribers' in-home receivers, and sent into the television for viewing.
The receiver is a key piece of equipment, because the code sent from the satellite is encrypted. Without encryption, anyone could buy a black market satellite dish, and hook it up to their television to receive free service. Video is first compressed and then is encrypted, a process that takes place at the initial broadcast point on the ground. When the signal is sent from the dish to the receiver, the receiver decompresses and interprets the signal. The receiver can only interpret the signal correctly if it has been programmed with the correct security codes by the service provider.
Some manufacturers of computer equipment offer digital satellite TV cards that can be installed in computers. They claim that these cards can pick up and decrypt the signals from a satellite TV provider for no charge except the initial purchase price. These cards essentially pirate the signal, and are not recommended because of their legal implications.
The major competitor for digital satellite TV is cable service. There are some advantages and disadvantages to digital satellite service that should be considered for someone seeking to subscribe. The major advantage is availability. Many rural areas do not have access to digital cable service, but have no problem with receiving the wide variety of stations available through digital satellite TV. The major disadvantage is weather related outages. Since the signal relies on a transmission coming from the sky, the service is vulnerable to outages and interruptions during bad weather.
Much like digital cable, digital satellite TV receivers can have the ability to record programs. Many can also pause or rewind live television just like a digital video recorder (DVR) system does with digital cable. To receive the high definition (HD) channels through the receiver, the subscriber must have an HD television, just as with cable.