Design aspects of FM stereo tuners and adaptors

The stereophonic composite signal may be decoded in adaptor circuitry by time multiplex or sum-and-difference approaches. To obtain suppression of SCA (background music) signals while maintaining adequate separation of the two stereophonic audio signals double, single, or residual sideband demodulation of the stereo subcarrier can be employed. Satisfactory reception of FM stereo signals requires tuner circuitry of higher performance than for equal monophonic performance. Calculated and measured stereophonic separation, distortion, and signal-to-noise ratio are shown with major causes of these performance aspects.