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→In FM radio: I added this new section regarding the modules I encountered when working at Plessey as a student. Sadly I do not know the name of process or the supplier of the modules that implemented this process. |
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Generally, FM demodulators are not affected by amplitude variations, since the baseband is contained in the frequency deviations. Some detectors, including the [[Detector (radio)#Ratio detector|ratio detector]], inherently limit gain by a 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 Aerospace and Military VHF Voice Communications==
For military two-way radio sets and aircraft VHF voice telecommunications, a special form of limiter is commonly used. It is designed to work with
high levels of background noise near the microphone. It usually operates by up-converting the audio signal to a supersonic 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 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==
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