| 摘要 |
PURPOSE:To obtaifn an SECAM color discriminating circuit with high resistivity to noise and assured operation, by discriminating the color with the burst signals of both the R-Y and B-Y signals of two color subcarrier waves. CONSTITUTION:The color signal supplied from an input terminal 3 is supplied to a band pass filter 16 from an amplifying circuit 17 via an amplitude limiting circuit 17, and the signal component containing the B-Y signal of reference subcarrier wave is extracted to suply to an input of a multiplication/wave detection circuit 18. The color signal supplied to an SECAM switch 10 from the circuit 8 is separated into the R-Y and B-Y signals in terms of an output to extract. Then the signal is supplied to the other input of the circuit 18 from the output in which the R-Y signal emerges when the working phase of an FF7 is correct. The difference signal of these two color subcarrier waves is extracted through a band pass filter 19, and a correct color discriminating state is decided when the output level of the difference signal exceeds a certain value. Thus the killer signal is released. |
