The Washington NOC is also a primary entry point station in the Emergency Alert System.
Many of these problems were resolved when the PRSS moved to the digital-based SOSS system, mentioned later in this article.
It acted as a 1-way wire that provided NPR stations with text messages regarding programming and other information.
Because NPR, at the time, had the only operational satellite network that could transmit in high quality, full fidelity, stereo sound, several music based commercial programs were distributed via NPR's satellite system such as Rockline, Hollywood Live, several live concerts, and some Westwood One content.
The DSC demod was interfaced to the SOSS PC, which ran custom control software running under OS/2 Warp.
Using SCPC frequency & satellite transponder data for program feeds received from the DSC demod (which was tuned to a fixed transponder and SCPC frequency), the software would automatically tune any one of the six audio demods to whatever program feeds the station would want to receive (the 1st generation analog PRSS receivers had to be tuned manually for each feed).
DACS messaging functions were also integrated into the SOSS PC using its software and the DSC demod.
The six audio demods were controlled by the SOSS PC via several RS-485 serial connections from a board installed in the PC called the ARTIC board ("A Real-Time Interface Co-Processor"), with each demod respectively equipped with a RS-485 serial control interface.
The ContentDepot no longer uses linear feeds of SCPC-based digital audio bitstreams like the SOSS.