| 摘要 |
PURPOSE:To obtain a frequency converting carrier wave signal rejecting the frequency component of fsc+ or -3fL, by applying a chrominance sub-carrier singal having fsc, fL(<fsc) in frequencies to a frequency converting circuit. CONSTITUTION:A chrominance sub-carrier wave signal having fL(=688kHz) in the chrominance sub-carrier wave frequency is obtained from a frequency division circuit 9 having 1/8 of frequency dividing ratio. This signal is applied to a phase shift circuit 17 having 60 deg. of phase shift, and the obtained chrominance sub-carrier wave signal and the chrominance sub-carrier signal from the circuit 9 are applied to a synthesis circuit 18 for synthesis, and the synthesized output is applied to a frequency converting circuit 10. Further, a reference oscillation circuit 11 having the oscillating frequency of fsc (=3.58MHz) in chrominance sub-carrier wave frequency is provided, and the chrominance sub-carrier wave signal is applied to the circuit 10. Thus, the frequency converting carrier wave signal in which the frequency component of fsc+ or -3fL is especially suppressed among the excessive frequency components of the circuit 10 is obtained. |
