Overmodulation is the condition that prevails in

telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...

when the instantaneous level of the modulating

signal In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...

exceeds the value necessary to produce 100%

modulation In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the ''carrier signal'', with a separate signal called the ''modulation signal'' that typically contains informatio ...

of the

carrier Carrier may refer to: Entertainment * ''Carrier'' (album), a 2013 album by The Dodos * ''Carrier'' (board game), a South Pacific World War II board game * ''Carrier'' (TV series), a ten-part documentary miniseries that aired on PBS in April 20 ...

. In the sense of this definition, it is almost always considered a fault condition. In layman's terms, the signal is going "off the scale". Overmodulation results in spurious emissions by the modulated carrier, and

distortion In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signal ...

of the recovered modulating signal. This means that the envelope of the output waveform is distorted. Although overmodulation is sometimes considered permissible, it should not occur in practice; a distorted waveform envelope will result in a distorted output signal of the receiving medium.

References

See also