Limiting
Encyclopedia
Limiting: Any process by which a specified characteristic (usually amplitude) of the output
Output
Output is the term denoting either an exit or changes which exit a system and which activate/modify a process. It is an abstract concept, used in the modeling, system design and system exploitation.-In control theory:...

 of a device is prevented from exceeding a predetermined value.

Limiting can refer to non-linear clipping
Clipping
-Words:* Clipping , the cutting-out of articles from a paper publication* Clipping , shortening the articulation of a speech sound, usually a vowel* Clipping , the formation of a new word by shortening it, e.g...

, in which a signal is passed through normally but "sheared off" when it would normally exceed a certain threshold. It can also refer to a type of variable-gain audio level compression
Audio level compression
Dynamic range compression, also called DRC or simply compression reduces the volume of loud sounds or amplifies quiet sounds by narrowing or "compressing" an audio signal's dynamic range...

, in which the gain of an amplifier is changed very quickly to prevent the signal from going over a certain amplitude.
  • Hard limiting ("clipping
    Clipping (signal processing)
    Clipping is a form of distortion that limits a signal once it exceeds a threshold. Clipping may occur when a signal is recorded by a sensor that has constraints on the range of data it can measure, it can occur when a signal is digitized, or it can occur any other time an analog or digital signal...

    ") is a limiting action in which there is
    • (a) over the permitted dynamic range
      Dynamic range
      Dynamic range, abbreviated DR or DNR, is the ratio between the largest and smallest possible values of a changeable quantity, such as in sound and light. It is measured as a ratio, or as a base-10 or base-2 logarithmic value.-Dynamic range and human perception:The human senses of sight and...

      , negligible variation in the expected characteristic of the output signal, and
    • (b) a steady-state signal, at the maximum permitted level, for the duration of each period when the output would otherwise be required to exceed the permitted dynamic range in order to correspond to the transfer function
      Transfer function
      A transfer function is a mathematical representation, in terms of spatial or temporal frequency, of the relation between the input and output of a linear time-invariant system. With optical imaging devices, for example, it is the Fourier transform of the point spread function i.e...

       of the device.
  • Soft limiting is limiting in which the transfer function of a device is a function of its instantaneous or integrated output level. The output waveform
    Waveform
    Waveform means the shape and form of a signal such as a wave moving in a physical medium or an abstract representation.In many cases the medium in which the wave is being propagated does not permit a direct visual image of the form. In these cases, the term 'waveform' refers to the shape of a graph...

    is therefore distorted, but not clipped.
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