SCA was deregulated in 1983; since then, both AM and FM licensed broadcast stations have been allowed to use subcarriers in the United States in general without requiring separate authority; authorization is only required for some uses which are still otherwise regulated, such as common carrier or Land Mobile Radio Service transmissions.
[1] The fidelity (bandwidth) of SCA channels on FM is generally quite limited compared to that of the main program material, resulting in audio quality similar to AM radio broadcasting.
The Canadian Radio-television and Telecommunications Commission (CRTC) calls this service Subsidiary Communications Multiplex Operation (SCMO).
Non-broadcasting uses are allowed when the type of use is authorized[clarification needed] under other radio and telecommunications acts, and may require a fee.
Major uses of SCA include: 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.