'''Digital Satellite System''' is the initialism expansion of the '''DSS''' digital [[satellite television]] transmission system used by [[DirecTV]]. Only when digital transmission was introduced did [[direct broadcast satellite]] (DBS) television become popular in [[North America]], which has led to both DBS and DSS being used interchangeably to refer to all three commonplace digital transmission formats -; DSS, DVB-S and [[4DTV]]. Analog DBS services, however, existed prior to DirecTV and were still operational in continental Europe until April 2012.<ref>{{cite web |title=AnalogueSat |url=http://www.selkirkshire.demon.co.uk/analoguesat/intro.html |access-date=2013-05-25 |url-status=dead |archive-url=https://web.archive.org/web/20121228075422/http://www.selkirkshire.demon.co.uk/analoguesat/intro.html |archive-date=2012-12-28 }}</ref>
At the time of DirecTV's launch in 1994, the [[DVB-S]] digital satellite system in use in the majority of the world had not yet been standardised, the [[Thomson SA|Thomson]] developed DSS system was used instead.
While functionally similar in DVB-S -– [[MPEG 2]] video, [[MPEG-1 Layer II]] or [[Dolby AC-3|AC3]] audio, [[QPSK]] modulation, and identical error correction ([[Reed-SolomonReed–Solomon error correction|Reed-SolomonReed–Solomon coding]] and [[Viterbi decoder|Viterbi]] [[forward error correction]]), the transport stream and information tables are entirely different from those of DVB. Also unlike DVB, all DSS receivers are proprietary DirecTV reception units.
DirecTV is now using a modified version of [[DVB-S2]], the latest version of the DVB-S protocol, for [[HDTV]] services off the [[SPACEWAY-1]], [[SPACEWAY-2]], [[DirecTV-10]] and [[DirecTV-11]]<ref>{{Cite web |url=http://dtv.client.shareholder.com/releasedetail.cfm?ReleaseID=324646 |title=ArchivedThe copyDIRECTV Group, Inc. - DIRECTV Remains Clear HD Leader with 130 HD Channels on Tap for Mid-August |access-date=2008-08-03 |archive-url=https://web.archive.org/web/20080805052202/http://dtv.client.shareholder.com/releasedetail.cfm?ReleaseID=324646 |archive-date=2008-08-05 |url-status=dead }}</ref> satellites; however, huge numbers of DSS encoded channels still remain. The ACM modulation scheme used by DirecTV prevents regular DVB-S2 demodulators from receiving the signal although the data carried are regular MPEG-4 transport streams.
