PURPOSE: To make color signal processing circuits of NTSC-system and PAL- system VTRs common, by converting the NTSC color signal and the PAL color signal to a low band by carrier signals where the phase is shifted at 90° and 45° in evey one horizontal period of time.
CONSTITUTION: A chrominance signal fSC applied to an input terminal 1 has the amplitude made constant in an ACC circuit 11 and is supplied to the first frequency converting circuit 12. An output signal SH of the first VCO 18 is divided into a carrier frequency fLSC of the low-band color signal by a frequency dividing circuit 19 and is applied to a phase selecting circuit 20. The phase selecting circuit 20 sets the phase of an output signal SC so that the phase of the color signal is shifted in every one horizontal time by a prescribed value (90° for the NTSC system and 45° for the PAL system). The output signal SC is multiplied by the output signal of the second VCO having a center frequency fSC in the second frequency (fSC+fLSC) of the sum between them, and this carrier signal is multiplied by the chrominance signal fSC in the first converter 12 to obtain a low-band color signal having the carrier frequency fLSC as a difference signal.
NAKAGAWA HIMIO
KOJIMA NOBORU
SHIBATA AKIRA
KOMATSU KEIICHI
