Preemphasis

Preemphasis

In processing electronic audio signals preemphasis refers to a system process designed to increase, within a band of frequencies, the magnitude of some (usually higher) frequencies with respect to the magnitude of other (usually lower) frequencies in order to improve the overall signal-to-noise ratio by minimizing the adverse effects of such phenomena as attenuation distortion or saturation of recording media in subsequent parts of the system. That is the mirror of the deemphasis. The whole system is called emphasis.The frequency curve is decided by special time constants. The cutoff frequency can be calculated from that value.

Preemphasis is commonly used in telecommunications, digital audio recording, record cutting, in FM broadcasting transmissions, and in displaying the spectrograms of speech signals.

An example of this is the RIAA equalization curve on 33 rpm and 45 rpm vinyl records.

In high speed digital transmission, pre-emphasis is used to improve signal quality at the output of a data transmission. In transmitting signals at high data rates, the transmission medium may introduce distortions, so pre-emphasis is used to distort the transmitted signal to correct for this distortion. When done properly this produces a received signal which more closely resembles the original or desired signal, allowing the use of higher frequencies or producing fewer bit errors.

See also

*Federal Standard 1037C and MIL-STD-188
*Preemphasis network

External links

* [http://www.sengpielaudio.com/calculator-timeconstant.htm Preemphasis - Frequency response and equalization EQ - Conversion: time constant to cut-off frequency and vice versa]


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  • Preemphasis — išankstinė pataisa statusas T sritis automatika atitikmenys: angl. accentuation; preemphasis vok. Preemphasis, f; Vorverzerrung, f rus. предварительная коррекция, f pranc. préaccentuation, f; prédistorsion, f …   Automatikos terminų žodynas

  • preemphasis — išankstinė pataisa statusas T sritis automatika atitikmenys: angl. accentuation; preemphasis vok. Preemphasis, f; Vorverzerrung, f rus. предварительная коррекция, f pranc. préaccentuation, f; prédistorsion, f …   Automatikos terminų žodynas

  • Preemphasis — Die Präemphase (Aktzentuierung) und Deemphase (Deakzentuierung), engl. preemphasis and deemphasis, ist die zum Prinzip gehörende Verbiegung (lineare Vorentzerrung) des Audio Frequenzgangs, mit der unter Berücksichtigung des… …   Deutsch Wikipedia

  • Preemphasis — Preẹmphasis   [zu Emphase] die, , Akzentuierung, Nachrichtentechnik: die senderseitige Amplitudenanhebung bei den hohen Frequenzen eines Modulationssignals vor der Frequenzmodulation zur Gewährleistung eines etwa gleichen Phasenhubs und damit… …   Universal-Lexikon

  • Preemphasis — Pre|em|pha|sis die; <aus gleichbed. engl. preemphasis zu pre (vgl. ↑prä...) u. emphasis (vgl. ↑Emphase)> im Funkwesen Vorverzerrung (Verstärkung) der hohen Töne, um sie von Störungen zu unterscheiden (im Empfänger erfolgt die… …   Das große Fremdwörterbuch

  • Preemphasis improvement — In FM broadcasting, preemphasis improvement is the improvement in the signal to noise ratio of the high frequency portion of the baseband, i.e., modulating, signal, which improvement results from passing the modulating signal through a… …   Wikipedia

  • Preemphasis network — In telecommunication, a preemphasis network is a network inserted in a system in order to increase the magnitude of one range of frequencies with respect to another. Note: Preemphasis is usually employed in FM or phase modulation transmitters to… …   Wikipedia

  • preemphasis — /pree em feuh sis/, n. Electronics. a process of increasing the amplitude of certain frequencies relative to others in a signal in order to help them override noise, complemented by deemphasis before final reproduction of the signal being… …   Universalium

  • preemphasis — noun Amplification applied to certain frequencies of a signal to improve its signal to noise ratio …   Wiktionary

  • Preemphasis — Pre|ẹm|pha|sis 〈f.; Gen.: ; Pl.: unz.; Funkw.〉 Übertragung der höheren Frequenzanteile eines Funksignals mit vergrößerter Amplitude zur Verbesserung des Störabstandes bei Frequenzmodulation; Ggs.: Deemphasis [Etym.: <Prä… + Emphase] …   Lexikalische Deutsches Wörterbuch

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