De-emphasis

In telecommunication, de-emphasis is the complement of pre-emphasis, in the antinoise system called emphasis. Emphasis is a system process designed to decrease, (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 differences or saturation of recording media in subsequent parts of the system.

Special time constants dictate the frequency response curve, from which one can calculate the cutoff frequency.

Pre-emphasis is commonly used in audio digital recording, record cutting and FM radio transmission.

In serial data transmission, de-emphasis has a different meaning, which is to reduce the level of all bits except the first one after a transition. That causes the high frequency content due to the transition to be emphasized compared to the low frequency content which is de-emphasized. This is a form of transmitter equalization; it compensates for losses over the channel which are larger at higher frequencies. Well known serial data standards such as PCI Express, SATA and SAS require transmitted signals to use de-emphasis.

See also

  • Pre-emphasis

External links


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Look at other dictionaries:

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  • Emphasis — Saltar a navegación, búsqueda Emphasis Información personal Origen Castellón, España …   Wikipedia Español

  • Emphasis — Thomas R. Kobayashi mieux connu sous le nom d Emphasis est un compositeur franco japonais de musique électronique. Né à Tokyo et vécu à Paris, il sera inspiré par ces différentes cultures dans sa musique. Il a passé son adolescence au lycée… …   Wikipédia en Français

  • emphasis — I noun accent, accentuation, affirmation, attention, concentration, consequence, consideration, distinction, distinctness, eminence, emphasis, energy, exclamation, force, force of expression, force of voice, forcibleness, highlight, ictus,… …   Law dictionary

  • emphasis — 1570s, from L. emphasis, from Gk. emphasis significance, indirect meaning, from emphainein to present, show, indicate, from en in (see EN (Cf. en ) (2)) + phainein to show (see PHANTASM (Cf. phantasm)). In Greek and Latin, it developed a sense of …   Etymology dictionary

  • emphasis — [em′fə sis] n. pl. emphases [em′fəsēz΄] [L < Gr emphasis, an appearing in, outward appearance < emphainein, to indicate < en , in + phainein, to show < IE base * bha , to shine > OE bonian, to polish] 1. force of expression,… …   English World dictionary

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  • emphasis — noun 1 special importance/attention ADJECTIVE ▪ big (informal), considerable, great, heavy, huge ▪ schools that put a heavy emphasis on sporting achievement ▪ …   Collocations dictionary


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