| 摘要 |
<p>PURPOSE:To facilitate the digital processing of the color TV signal, by obtaining an oscillation signal having the relation of an integral multiple of the horizontal scanning frequency synchronously with the chrominance subcarrier signal of the color TV signal. CONSTITUTION:The color TV signal is given to Y/C separating circuit 2, and luminance signal Y and color signal C are supplied to synchronizing separating circuit 3 and inverting circuit 4 respectively. The horizontal synchronizing signal extracted by circuit 3 is given to counter 5 and burst flag generating circuit 7. Counter 5 generates signal f/2 inverting for every H and signal f/4 inverting for every 2H and supplies them to circuits 4 and 7, and circuit 7 generates burst flag pulse BF for every other 1H and supplied it to gate circuit 6. Circuit 4 inverts the phase of color signal C according to the inversion signal and applied it to gate 6. Gate 6 thins out the output of circuit 4 for every other 1H and gates only the chrominance carrier part of it by signal BF and applies the result to the PLL. The PLL oscillates always frequency f1 matched to the chrominance subcarrier of the input video signal, and f1 becomes an integral multiple of the horizontal frequency.</p> |
