Analysis of Certain System Characteristics of Stereo and SCA Operation

This paper analyzes, mostly on a qualitative basis, cross modulation into an SCA channel resulting from a stereophonic signal complying with FCC rules, both signals being applied to a common RF carrier. This type of crosstalk is caused mainly by second order harmonic distortion products of the left minus right double sideband information [L-R(DSB)]. These components fall into the frequency area occupied by the SCA channel. In order to minimize this type of cross modulation, so as to provide a 50 dB signal-to-noise ratio on the SCA subcarrier, distortion products of the L-R (DSB) signal should be kept below 0.2 percent.