What compression systems do the DBS services use?
Each of the DBS services transmits a bitstream which contains compressed audio, compressed video, authorization information, program guide information, and other information. The decoders in subscribers homes decode the digital bitstream converting it into video and audio which can be displayed by conventional TV sets. Each service requires a decoder designed to work with its system. Primestar uses a proprietary video compression system developed by General Instruments called DigiCipher-1. The format used by the other services is based on the MPEG-2 compression standard but also uses some proprietary components. The EchoStar/Sky Angel services use a transmission system based on the DVB standard which seems to be becoming a world broadcast standard. DVB uses the standard MPEG-2 and also attempts to standardize more of the systems.
