Satellite Television

Satellite television is a service that delivers television programming to customers (usually paying subscribers) by relaying it from a communications satellite orbiting the Earth directly to the customer's location. The signals are received via an outdoor parabolic antenna usually referred to as a satellite dish and a low-noise block downconverter (LNB). A satellite receiver then decodes the desired television programme for viewing on a television set. Receivers can be external set-top boxes, or a built-in television tuner. Satellite television provides a wide range of channels and services. It is the only television available in many remote geographic areas without terrestrial television or cable television service.

Modern systems are all direct-broadcast satellite television (DBSTV), also known as "direct to home" (DTH). In DBSTV systems, signals are relayed from a direct broadcast satellite on the K_u band frequencies (12-18 GHz) requiring only a small dish less than a meter in diameter. The first satellite TV systems were an obsolete type now known as television receive-only. These systems received weaker analog signals transmitted in the C-band (4-8 GHz) from FSS type satellites, requiring the use of large 2-3 meter dishes. Consequently, these systems were nicknamed "big dish" systems, and were more expensive and less popular.

Early direct-broadcast satellite television systems used analog signals, but modern ones use digital signals which allow transmission of the modern television standard, high-definition television (HDTV). Different receivers are required for the two types. Some transmissions and channels are unencrypted and therefore free-to-air or free-to-view, while many other channels are transmitted with encryption (pay television), requiring the customer to subscribe and pay a monthly fee to receive the programming.

...
Wikipedia