| 摘要 |
A SECAM-encoded chrominance signal is converted to a chrominance signal of a quasi-PAL form for further processing in PAL decoder apparatus. Converter includes an FM detector serving to demodulate respective SECAM subcarriers sequentially, and a modulator wherein the color-difference signals recovered by the FM detector amplitude modulate in appropriate sequence quadrature-related phases of PAL subcarrier frequency oscillations derived from the PAL decoder. The color-difference signals supplied to the modulator are augmented by line rate pedestals effecting the insertion of bursts in the quasi-PAL signal developed by the modulator. The phasing of the inserted bursts alternates between a first phase corresponding to the oscillation phase subject to modulation by R-Y color-difference signals, and a second phase differing from the first phase by 180 DEG . Insertion of bursts of the first phase immediately precedes the development of R-Y modulated subcarrier waves by the modulator, while insertion of bursts of the second phase immediately precedes the development of B-Y modulated subcarrier waves by the modulator.
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