Amplitude Modulation:

 

Amplitude Modulation

Amplitude Modulation (AM) is a method of encoding information onto a carrier wave by varying the amplitude of the carrier wave in proportion to the message signal. In AM, the amplitude of the carrier wave is changed (modulated) based on the amplitude of the input signal. The frequency and phase of the carrier wave remain constant.

The resulting modulated signal consists of three components: the original carrier wave at its original frequency, and two side bands at frequencies above and below the carrier frequency. The two side bands carry the same information as the message signal, but are mirrored and inverted versions of each other.

AM is widely used in radio broadcasting and communication systems, where it is used to transmit voice, music, and other types of audio signals. However, AM is less commonly used in other applications due to its relatively poor noise immunity and susceptibility to interference.

There are several variations of AM, including:
Double-sideband AM (DSB-AM): This is the simplest form of AM, where both sidebands are transmitted. DSB-AM requires the most bandwidth and power of all AM variations. 

Single-sideband AM (SSB-AM): In SSB-AM, only one of the sidebands is transmitted, along with the carrier wave. This results in a more efficient use of bandwidth and power, but requires more complex modulation and demodulation techniques. 

Vestigial side band AM (VSB-AM): VSB-AM is a compromise between DSB-AM and SSB-AM, where a portion of one side band is transmitted along with the carrier and the other side band is filtered out. This results in a more efficient use of bandwidth than DSB-AM, but with less complexity than SSB-AM.

Overall, AM is a widely used modulation technique for radio broadcasting and communication systems, and can be easily implemented using simple analog circuits.