The PBS Satellite Service (also known as the PBS National Program Service, with the primary C-band feed being formerly known as PBS Schedule X in Eastern Time, with the West Coast delay signal designated PBS-XP) consists of feeds relayed from PBS by satellite to public television stations throughout the United States. The service was launched in September 1978. The service provides a mixed variety of programming selected from PBS's regular network services. In the X/XP years a satellite feed was multicast by some PBS member stations on an over-the-air DTV sub-channel along with their regular programming, or during overnight hours on their main channel to provide a second opportunity for viewers to watch or record primetime programming. PBS currently utilizes two transponders on the AMC-21 satellite. Transponder 24 is a MCPC (multiple channel per carrier) which currently has seven channels uplinked from the PBS NOC (Network Operations Center) in Alexandria, VA. Transponder 23 utilizes four SCPC (Single channel per carrier) feeds which are shared amongst different affiliates across the country at various times. Currently, select stations broadcast the feed, usually overnight, like KGTF (PBS Guam, broadcasts most of the channel as a localised feed). The channel is also available over satellite providers like DirecTV (Channel 389). PBS stations provide all of their channels free to TV providers who do not receive local channels. As of 2020, PBS's satellite feeds, as well as a few other PBS stations, can be received unscrambled using a free-to-air satellite receiver set to these coordinates: PBS at 125°W (on the AMC-21 satellite), Ku-band, unencrypted. Montana PBS at 125°W (on the AMC-21 satellite), Ku-band, unencrypted. LPB at 87°W (on the SES-2 satellite), Ku-band, unencrypted. PBS affiliate KETA, part of the Oklahoma Educational Television Authority (OETA), was also available on AMC 21 until June 2016. Their removal from satellite coincided with the completion of their transition to fiber distribution. PBS transitioned to a fiber-based interconnection system known as sIX, otherwise known as the sixth generation of PBS's interconnection system, in July 2021. The original end date for the PBS Satellite Service was slated for 2016, but was later pushed to 2018, and was then pushed again to the beginning of 2021; none of these deadlines were met. PBS's feeds are still active as of January 2022, however, concerning PBS's three primary NPS distribution feeds (HD03, HD04, and HD05), the only programs airing on these feeds are news