The Public Radio Satellite System (PRSS) is the interconnected satellite-distributed network managed by NPR (National Public Radio), and used by NPR, Public Radio Exchange (PRX), and American Public Media (APM), as well as independent public radio program producers, to distribute programming via satellite to public radio stations across the United States. The PRSS is maintained by NPR's Distribution division at their Network Operations Center (NOC), located at NPR's headquarters in Washington, DC. A backup NOC is located at Minnesota Public Radio's facilities in St. Paul, Minnesota, in the event of a catastrophe or other situation that would occur at the main NOC's location in Washington. The NOC oversees and monitors all elements and operations of the PRSS system, from outgoing feeds from NPR, APM and PRX, and incoming feeds from member stations. The Washington NOC is also a primary entry point station in the Emergency Alert System. History The PRSS first made its debut in 1979, using the then-new technology (for broadcasting) of satellite distribution. Prior to the PRSS and starting from NPR's founding in 1971, NPR and its member stations used a network of broadcast-quality leased telephone lines furnished by AT&T, which were configured in a "round-robin" loop interconnecting the major NPR member stations at the time. Member stations invested in earth station receiving equipment to be a part of the new PRSS in the form of a grant from the Corporation for Public Broadcasting to cover all costs with the stipulation that the radio station must be on the air for a minimum of 18 hours per day and have at least 3 full-time employees. After a period of years the stipulations would cease and the earth station would become the property of the radio station. The equipment included a receiving dish and an analog audio receiver manufactured by network hardware manufacturer Coastcom under the master contract held by Rockwell. The dish was aimed to Westar 1, the satellite used by PRSS at its debut, and later to Westar IV after the former satellite was retired in 1983. The receiver was able to tune into the several audio channels uplinked by NPR on two transponders on the satellite. The audio channels, transmitted in analog using frequency modulation, were multiplexed on each transponder using SCPC (Single Channel Per Carrier) transmission. The receivers were pre-programmed for 12 channels. There were additional channels that were available and accessible by special Coastcom