Electronics Chapter 3

Chapter 3

Modulation

It is the process of impressing or imparting a low frequency source information (voice, audio, video, or data) onto a high-frequency bandpass signal with a carrier frequency fc by the introduction of amplitude, frequency or phase perturbation.

Demodulation

It is the reverse process where the received signals are transformed back to their original form.

Amplitude Modulation

It is an analog modulation scheme in which the amplitude of a relatively high- frequency carrier signal is varied in accordance with the instantaneous amplitude of an information signal.

Coefficient of Modulation

A term used to describe the amount of amplitude changed (modulation) present in an AM waveform.

OVERMODULATION

It creates side frequencies (harmonics) further from the carrier known as SPLATTER, BUCKSHOT, or SPURIOUS EMISSIONS which create interference to other radio services and since spectrum space is tightly controlled by law, overmodulation is illegal.