When feeding FM stereo encoder + RDS on ST with an audio which its bandwidth (lowpass) is higher than 16kHz, the stereo subcarrier will interfere with RDS (especially at around 54kHz)
The Omnia9 encoder does not do this. When I feed my audio through (it is lowpassed at 17kHz), the lower sideband of the stereo subcarrier extends normally down to 21kHz but the upper sideband stops at 54kHz. (ST encodes all the way to 55kHz, which interferes with RDS)
Maybe this is a modified version of single sideband? It would be really great to have an option to limit the upper stereo sideband to 54kHz in ST.