The signals that are transmitted for satellite TV have a long distance to travel before they finally show up on your TV screen as images and sound. Satellite signals contain a vast amount of high-quality digital data that would be impossible to transmit without modification. To make it feasible to transit this type of wide data stream, the satellite signals are compressed. Compression simply indicates that redundant or unnecessary information is removed from the signal before it is transmitted to the geosynchronous satellite that sends the data to your satellite dish.  The technology allows for the signal to be reconstructed after it has been sent.

MPEG File Compression

The Moving Picture Experts Group (MPEG) provides the standards for the file compression methods used by satellite TV. A specialized type of video file compression is used for this purpose. Using MPEG compression, your satellite TV service provider has the capability to offer significantly more channels and programs for your viewing pleasure. There are currently five MPEG standards available that support various requirements for transmission of data.

To give an example of what can be accomplished with this technology, DirecTV at one time used MPEG-2, which is the form of compression currently used for storing movies on DVDs and for digital cable TV. Depending on the type of programming involved, the TV service provider can use MPEG-2 to greatly reduce a 270-Mbps stream to the range of 5 or 10 Mbps.

MPEG-4 for Increased Efficiency

DirecTV is one of the major satellite TV service providers that now uses MPEG-4 compression for transmission of TV programming data. This was engineered originally for the purpose of steaming video in media with small screens (such as computers and laptops). It features higher efficiency for encoding and can support a much greater bandwidth than MPEG-2. MPEG-2 continues to be the standard for digital TV compression.

The reason is the fact that it has an inherent functionality for analyzing static images as seen in for example, newscasts or talk shows. It works better for this type of data than it does with signals resulting in moving, dynamic pictures. On the flip side, MPEG-4 produces a superior quality picture on your screen for dynamic images because it employs temporal (time) and spatial (space) compression. You can see this method of compression at work when you experience high definition images on your TV screen when watching objects that move quickly while changing direction. Sports programming is one good example of technology in motion for your benefit while watching satellite TV.