ABSTRACT
Radio broadcasting employs both amplitude as well as frequency modulation. The broadcasting in medium wave and short wave frequency bands is accomplished by means of A.M. transmitters. Generally, negative feedback is provided in A.M. transmitters in relation to the modulating signal. The radiated signal is picked up from the antenna, demodulated and combined with the modulated signal and used as negative feedback at the appropriate point. The negative feedback be used with low level modulators, as well as with high level modulators. Whenever a carrier and a modulating signal both are simultaneously applied to a non linear circuit, the amplitude modulation results, as the carrier modules the signal.
