PURPOSE: To obtain a demodulation output having extremely good linearity with a simple constitution and a low cost, by providing a comparator which compares an input signal with a demodulating signal and delivers a control signal for improvement of linearity of the modulation output.
CONSTITUTION: A comparator 4 compares the level of an input video signal Sa of an input terminal 2 with that of a demodulated video signal Sb. A control signal is delivered to an FM modulator 1 in accordance with the level difference between both signals Sa and Sb, and the control is performed to obtain the coincidence of level between these signals Sa and Sb. Thus the linearity is improved for the modulation output sent to an output terminal 5. Therefore a modulator does not need good linearity, and a demodulation output of good linearity can be obtained with a simple constitution and a low cost.
HOSOYA NOBUKAZU
ARAI TAKESHI
