and public affairs programming; all other linear prefeeds have moved to sIX. History Starting in the early 1970s, PBS had been distributing programs via telephone lines from AT&T. According to PBS, the use of telephone lines to deliver programming was "incapable of producing high-fidelity sound," so they started to look for an alternate method of distributing via satellite. At the time, which was during the mid-1970s, PBS utilized what was knows as DATE (Digital Audio for TElevision) to transmit stereo audio; however, according to PBS, it was never widely adopted due to "high cost". In September 1978, PBS made programming available via satellite for the first time. PBS utilized four transponders on the Westar 1 satellite to deliver programing. In April 1988, PBS began encoding programs with VideoCipher II, which not only allowed for stereo audio (something PBS had been trying to accomplish since the 1970s), but also enabled multi-channel audio for services such as Descriptive Video Service or for a Secondary Audio Program. The feeds for PBS were usually broadcast in a "fixed key" mode (usually 0000), which allowed anyone with a VideoCipher II receiver to be able to receive these feeds. PBS would encrypt the feeds anytime they aired what they referred to as "private communications," which include teleconferences and previews of programs that they haven't yet received broadcast rights for. In 1994, with the launch of the Ku-Band feeds, PBS began encoding their feeds with DigiCipher I; PBS later switched to DigiCipher II in 1996. PBS made the switch to DVB-S MPEG-2 starting in 2006. In 2012, PBS began encoding their feeds in the DVB-S2 MPEG-4 codec. This is the current codec PBS uses for their feeds. From 1978 until 1994, PBS distributed its content via C-Band (first on Westar 1 from September 1978-February 1982; Westar 4 from February 1982-January 3, 1991; Spacenet 1 from January 3, 1991 – July 18, 1992; and Spacenet 4 from July 18, 1992 – February 5, 1994). On February 5, 1994, which the launch of Telstar 401, PBS transitioned its primary feeds to Ku band. However, one C-band feed remained, which was the PBS-X feed. With the failure of Telstar 401 on January 11, 1997, PBS temporarily moved their feeds to Telstar 402R (later Telstar 4). In October 1997, PBS moved their feeds to AMC-3 (GE-3) at 87°W, where they resided until 2008, when the feeds moved to AMC-21 at 125°W,