| 摘要 |
PURPOSE:To obtain sufficient discrimination sensitivity and color killer sensitivity, by advantageously considering that a SECAM color signal has different-frequency discrimination signals which alternate at intervals of one line. CONSTITUTION:To an input terminal 2, a color signal input containing discrimination signals is applied as an FM detection input. To a gate termial 3, a gate pulse for extracting the discrimination signals is applied. Then, an FM detecting circuit 1 extracts detection output currents IO1 and IO2 only during a gate pulse period. Transistors 5-8, on the other hand, alternate the detection output currents of the circuit at intervals of one horizontal period and are driven by an FF circuit driving a SECAM switch. Therefore, a discrimination output current flowing from an output terminal 12 is extracted by being inverted in polarity at intervals of one line as the detection output currents of the discrimination signals obtained by the FM detecting circuit 1. |
