Color transmission system discrimination circuit and method in television set

提供一种在可接收多种电视播送方式的接收机中能够正确且快速地判别信号接收过程中的彩色传输制式的彩色传输制式判别电路。该彩色传输制式判别电路备有：抑制状态变化检测电路23，用于检测与90度相位上的彩色同步信号分量、1 80度相位上的彩色同步信号分量及SECAM判别信号对应的3种彩色抑制信号变化后的情况；程序装置22，由其输出信号起动并每隔规定时间按顺序执行第1、第2及第3阶段；第1锁存电路29～31，用于锁存在第1阶段取入的彩色抑制信号；第2锁存电路32～33，用于锁存在第2阶段取入的彩色抑制信号；及判别译码器34，根据在第3阶段取入的彩色抑制信号及上述第1和第2锁存电路29～33的输出信号输出彩色方式的判别信号及基准副载波信号频率的判别信号。 In a receiver capable of receiving a plurality of television systems, a color transmission system discrimination circuit is provided, which is capable of exactly and rapidly determining a color transmission system which is being received. The color transmission system discrimination circuit includes: a killer state change detection circuit 23 for detecting a change in three kinds of color killer signals corresponding to a burst signal component in a 90° phase, a burst signal component in a 180° phase, and a SECAM discrimination signal; a sequencer 22 which is driven with an output signal of the killer state change detection circuit 23 and performs the first, second, and third stages in this order respectively for a predetermined period of time; first latch circuits 29 to 31 for latching the color killer signal captured in the first stage; second latch circuits 32 and 33 for latching the color killer signal captured in the second stage; and a discrimination decoder 34 for outputting a discrimination signal of a color system and a discrimination signal of a frequency of a reference sub-carrier signal, based on the color killer signal captured in the third stage and the output signals of the first and second latch circuits 29 to 33.