TELEVISION SIGNAL SYNTHESIZER

摘要

PURPOSE:To reproduce a multiplex signal excellently by providing a means for applying carrier wave elimination to a signal being brought into a residual side band by a Nyquist filter having amplitude characteristics symmetrical in odd number with respect to a video carrier frequency during a blanking period and superimposing the result on a television signal. CONSTITUTION:High-frequency components 4.2-5.2MHz of a luminance signal are subjected to frequency conversion by subcarriers of 4.2MHz so as to have a frequency of 0-1.0MHz. In this case, the phase of the subcarrier is controlled so as to be inverted by a phase controller 15 for each horizontal scanning period, for one field or for one frame. The signal subjected to frequency conversion by the subcarrier of the phase as above is given to a modulator 11. The carrier P1 obtained from an oscillator 9 is modulated in terms of amplitude by an amplitude modulator 7 by using an output signal of an adder 6. The obtained amplitude modulation wave is subjected to band limit by a 1st filter 8 to form a residual-side band and the result is fed to an adder 13. The carrier P1 shifted in terms of phase by 90 deg. by the phase shifter 10 is used as the carrier P2. The carrier P2 is subjected to double-side band amplitude modulation by using the output signal of the frequency converter 5 at the modulator 11 and the result is subjected to carrier wave elimination double-side band amplitude modulation during the blanking period.