| 摘要 |
<p>The identification circuit for secam system in receivers corrects colour permutation circuit malfunctions by modifying the permutation circuit switch state. It recognises a colour identification signal inserted in the horizontal sweep return, which is faster and more economical than the conventional use of the vertical sweep return. A combined colour carrier signal is amplified and sent with a delayed signal to a permutator which routes the colour signals to red and blue demodulators. Each demodulator receives the delayed signal when the other demodulator receives the non-delayed signal. The permutator is switched by a bistable which is inverted every horizontal line sweep period input. It is controlled by an identification circuit receiving inputs from a colour reference detector and a differentiator at the bistable output.</p> |
