Digital Satellite System - (DSS, Digital Satellite, DSAT) - Service and supporting infrastructure that broadcasts numerous video channels in digital form to customers using direct broadcast satellite methods. DSSs use digital rather than analog signals.

DirecTV’s primary data distribution standard is DSS but at least some, particularly their HDTV signals are transmitted using DVB-S2. At the time of DirecTV's launch in 1994, DVB-S had not yet been fully standardized so they used a standard largely developed by Thomson.

Also see
http://en.wikipedia.org/wiki/Digital_Satellite_System.

See the Interactive Television Institute.