Amplitude modulation

Amplitude modulation(AM) is the simplest form of modulation .It is an analog-to-analog conversion method. Here the information or AF(Audio Frequency) signal changes the amplitude of the carrier wave without changing its frequency or phase. Amplitude modulation (AM) is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent.

Mathematically,the process can be expressed as

AM      S(t)=[1+n_ax(t)]cos2πf_c t

Where 2πf_c t  is the carrier and x(t) is the input signal(caring data),both normalized to unity amplitude.The parameter n_a, known as the modulation index, is the ratio of the amplitude pf the input signal to the carrier.

The original wave form of AM are given below: