Method and apparatus for noise reduction of cyclic signal by selecting majority logic state of corresponding portions of plural cycles

摘要

An EDTV application utilizing a Synchronous Vector Processor (SVP) includes the operation whereby noise is reduced in the operation to demodulate the chroma signal. Initially, the NTSC composite video is separated into the luminance (Y) and the chroma (C) signals by a Y/C separator algorithm (272). The chroma signal is then processed through a colorburst calculation algorithm (290). During the colorburst calculation, the phase of the colorburst signal is determined by processing the chroma signal through a phase detector (416) to provide the phase components Si and Mi. Both signals are cyclic signals and are processed in accordance with a majority noise reduction algorithm. The majority noise reduction algorithm is operable to sample a given portion of one of the cycles in the cyclic signal and also sample corresponding portions in adjacent cycles both prior to the present portion and preceding the present portion. A decision as to a logic state of the present portion is made by comparing all of the logic states of the sampled portions and forcing a select portion to the logic state of the majority of the sampled portions. This is then input to a phase shift circuit (414) and then to a demodulator (412) to adjust the phase thereof and output demodulated chroma.