Abstract: In a video signal processing system, a single adaptive passband equalizer is used to process a composite Quadrature Amplitude Modulated (QAM) signal encoded with high priority (HP) and standard priority (SP) components. The equalizer output is phase corrected by a de-rotator, and filtered to separate the HP and SP components. Error signals respectively representing HP and SP phase errors are developed. One of the error signals controls the operation of the de-rotator. Both error signals are used to generate updated coefficients for the adaptive equalizer. Afterwards the HP and SP components are decoded and combined.

Abstract: In a high definition television signal encoder, high priority and standard priority digital data are each separated into quadrature I and Q components, spectrally shaped by digital filtering, and time division multiplexed to produce respective quadrature amplitude modulated signals of the 32-QAM type. The high priority QAM signal and the standard priority QAM signal exhibit different bandwidths and carrier frequencies. The high priority and standard priority QAM signals are combined in digital form to produce a prioritized dual 32-QAM digital signal before being conveyed to a single analog-to-digital converter and analog RF transmission networks.