Editing Limiter

{{Short description|Electronic amplitude-limiting device}}
{{About|signal processing|engine speed limiters|Centrifugal governor|limiting related to the Law of the Minimum|Limiting factor}}
{{More citations needed|date=February 2024}}

[[File:Clipping waveform.svg|thumb|alt=Comparison of soft and hard clipping.|Comparison of soft and hard clipping.]]

In [[electronics]], a '''limiter''' is a circuit that allows signals below a specified input power or level to pass unaffected while [[Attenuator (electronics)|attenuating]] (lowering) the peaks of stronger signals that exceed this threshold. Limiting is a type of [[dynamic range compression]]. [[Clipping (audio)|Clipping]] is an extreme version of limiting.

'''Limiting''' is any process by which the amplitude of a signal is prevented from exceeding a predetermined value.

Limiters are common as a safety device in live sound and broadcast applications to prevent sudden volume peaks from occurring. Limiters are also used as protective features in some components of [[sound reinforcement system]]s (e.g., powered [[mixing board]]s and [[power amplifier]]s) and in some [[bass amplifier]]s, to prevent unwanted [[Distortion (music)|distortion]] or [[loudspeaker]] damage.

==Types==
Limiting can refer to a range of treatments designed to limit the maximum level of a signal. Treatments in order of decreasing severity range from [[clipping (signal processing)|clipping]], in which a signal is passed through normally but sheared off when it would normally exceed a certain threshold; soft clipping which squashes peaks instead of shearing them; a hard limiter, a type of variable-gain [[audio level compression]], in which the gain of an amplifier is changed very quickly to prevent the signal from going over a certain amplitude or a soft limiter which reduces maximum output through [[gain compression]].<ref>{{cite web |url=https://manual.audacityteam.org/man/limiter.html |title=Limiter |access-date=2018-05-22 |publisher=Audacity Team}}</ref>

== Usage ==

=== In aerospace and military ===
{{unreferenced|section|date=April 2018}}
For military two-way radio sets and aircraft VHF voice telecommunications, the voice limiter is known as a [[vogad]]. It is designed to work with high levels of background noise near the microphone. One form operates by up-converting the audio signal to an ultrasonic frequency, hard limiting that signal, and
then down converting the result. The frequency conversion uses image-cancelling heterodyning. The advantage of clipping the supersonic signal is that the odd harmonics
produced will still be out-of-band when down converted. This is in contrast to standard hard limiting, as in an electric guitar fuzz box, where the harmonics are highly audible. This device ultimately gives a distinctive character to the voice communication, which despite being highly distorted, ensures spoken words remain clear.

=== In audio production ===
[[Bass instrument amplifier]]s and power amplifiers are more commonly equipped with limiter circuitry to prevent overloading the power amplifier and to protect speakers. [[Electric guitar amp]]s do not usually have limiters.

[[PIN diode]]s can be used in limiter circuits to reflect the energy back to the source or clip the signal.<ref>{{cite web |title=PIN Limiter Diodes in Receiver Protectors |url=http://www.skyworksinc.com/uploads/documents/200480C.pdf |accessdate=2015-07-28 |publisher=Skyworks}}</ref>

[[Mastering engineer]]s often use limiting combined with make-up gain to increase the perceived [[loudness]] of an audio recording during the [[audio mastering]] process.<ref>{{cite book |title=Mastering Audio: the art and science |edition=3rd |author=Bob Katz |publisher=Focal Press |date=2015 |isbn=978-0-240-81896-2 |page=81}}</ref>

==== FM radio ====
An [[FM radio]] receiver usually has at least one stage of amplification that performs a limiting function. This stage provides a constant level of signal to the FM [[demodulator]] stage, reducing the effect of input signal level changes to the output. If two or more signals are received at the same time, a high-performance limiter stage can greatly reduce the effect of the weaker signals on the output. This is commonly referred to as the FM [[capture effect]].

Generally, FM demodulators are not affected by amplitude variations, since the baseband is contained in the [[frequency deviation]]s. Some detectors, including the [[Detector (radio)#Ratio detector|ratio detector]], inherently limit gain by the nature of the circuit design. In [[AM radio]], the information is located in the amplitude variations, and distortion can occur due to spurious signals that could cause the baseband to be misrepresented.

=== In utilities ===
In [[Canada]], while the [[cold weather rule]] is in effect, limiters are used to lower the capacity of houses of non-paying customers. The limiters allow enough power to run a furnace and a few lights. Tampering with the limiter is illegal.<ref>{{Cite web |last=Alberta |first=Government of |title=Utilities Disconnection |url=https://ucahelps.alberta.ca/ |access-date=2024-02-16 |website=ucahelps.alberta.ca |language=en}}</ref>

==See also==
* [[Clipper (electronics)]]
* [[Flow limiter]]
* [[Negative feedback]]
* [[Variable-gain amplifier]]

==References==
{{reflist}}
{{FS1037C MS188}}

[[Category:Electronic circuits]]
[[Category:Dynamics processing]]