The study of SCA interference in stereo FM receivers

The FM Stereo Broadcast System as adopted by the FCC two years ago included the accommodation for the transmission of an SCA background channel service on the RF carrier along with the two stereo channels. This simultaneous transmission of a third channel with the stereo program can result in an inter-modulation interference in improperly designed or aligned stereo FM receivers. In evaluating SCA interference, this paper shall consider: 1. The nature of SCA interference; 2. Possible sources of the interference in a stereo FM receiver; 3. Results of the testing of a cross-section of the stereo FM receiver market; and 4. Methods of minimizing the interference.