Satellite broadcasting: The feasibility of adding a PSK subcarrier sound signal to a FM television signal

Experimental work is described which was carried out to determine whether a four-phase, phase-shift keyed (p.s.k.) sound subcarrier signal could be added to the baseband of a frequency-modulated (FM) television signal of the type currently proposed in Europe for satellite broadcasting, either instead of, or in addition to, the recommended FM sound subcarrier signal. It was found that while a four-phase p.s.k. sound signal could replace the FM sound subcarrier signal, it could not be used additionally without visible disturbance to the picture. Although p.s.k. would have the advantage of enabling two independent high-quality sound programmes to be radiated, the removal of the FM signal would mean a loss of any compatibility with receiver sound demodulation circuits used for reception in normal television broadcasting.