Muse-NTSC converter having two oscillators

摘要

A MUSE-NTSC converter of a relatively simple and small scale circuit design. An oscillation signal from a 28.63636 MHz oscillator (20) is eight times as large as a subcarrier frequency fsc. A Y image processing circuit (17) and a chroma encoder (18) can perform various kinds of processing, such as dividing a frequency of the oscillation signal from the 28.63636 MHz oscillator (20) and the like, to produce a subcarrier frequency. A signal separating circuit (3') receives the oscillation signal from the 28.63636 MHz oscillator (20) as a single system clock and performs some kinds of signal processing which vary from a full wide mode to a zoom mode. Thus, in performing PLL on system clocks in the MUSE mode and the NTSC mode, there may be only one PLL circuit (21) for synchronizing an oscillation signal from a 32.4 MHz oscillator (19) and the oscillation signal from the 28.63636 MHz oscillator (20) in phase.