information (via voice or data), or ethnic foreign-language radio programming. For the transmission of Muzak's background music service to its subscribers (i.e., supermarkets, restaurants, etc.), this transmission method (along with another method using leased phone lines) have been phased out with Muzak now transmitting its programming via satellite. Venture Technologies, which owns a large number of analog low-power television stations with audio subcarriers that operate as FM radio stations, proposed using SCA rules to continue transmitting those analog audio services along an ATSC 3.0 signal. Receiving the SCA Signal Most programming transmitted by SCA/SCMO is usually pay/subscription-based, making unauthorized reception of such programming illegal, but programming which is not commercial in nature, such as reading services, can be received legally. Companies in the past such as Norver, ComPol, Mani National Corporation, McMartin, & Dayton Industrial; and current companies such as Metrosonix make radios and adapters for receiving SCA/SCMO channels. It can be difficult to keep the main channel's FM stereo difference subcarrier from interfering with such SCA decoders, as the stereo signal is a much stronger signal, and distortions due to multipath can also cause problems. See also Bruce Elving, author and advocate of SCA broadcasting Radio Data System — widespread program information standard; sometimes considered a type of SCA Second audio program (SAP) — a similar service on television signals FMeXtra — a digital audio implementation of SCA References External links The FCC's page for SCA A page on SCA and Radio Reading Service history Radio in the United States Radio in Australia Mass media regulation in Canada