NUM FICHE 005

12

REDACTEUR 030

LAURANT Anne

ORGANISME 035

ISTI

DATE RED 040

9308

ILL 050

DOM GEN 060

transmission par fibres optiques (télécommunications)

DOM SPEC 065

electronics

ENT AN 105

clamp pulse (CATV-A/E, p. 98)

IN ENT AN 110

syntagme nominal, sing.

DEF AN 115

Pulse emitted by a clamp circuit or clamping circuit that reestablishes the direct-current level of a waveform. (GRAW-C/E)

CONT AN 120

Scrambling systems that use baseband scrambling have to provide a clamp pulse that can be transmitted on a subcarrier to restore dc of the scrambled video signal at the receiver. (CATV-A/E, p. 98)

NOTE AN 125

A clamping circuit is used in the dc restorer stage of a television receiver to restore the direct-current (dc) component to the video signal after its loss in capacitance-coupled alternating-current amplifiers, to reestablish the average light value of the reproduced image. There are different clamps: voltage-amplitude-controlled clamp, triode clamp, keyed or synchronous clamp and dc restorer. The latter is a clamp circuit used to establish a dc reference level in a signal without modifying to any important degree the waveform of the signal itself. A typical example of such a waveform is that comprising the video signal of the television system. Scrambling devices were developed for pay television to prevent reception by anyone but a subscriber. If the synchronizing signals are caused to vary at random but predetermined rates, the signal is unusable in conventional receivers. Special receivers may contain unscrambling devices which, by a specially transmitted signal or a built-in keyer (clamp pulse), cause the receiver to synchronize and produce normal picture. (See figure : , GRAW-C/E) (A : GRAW-C/E, GRAW-B/E, pp. 137-139, p. 922)

SYN AN 130

clamping pulse (KING-C/E/F)

ENT FR 205

impulsion de verrouillage (KING-C/E/F; JOLY-C/F/E)

IN ENT FR 210

syntagme nominal, f. sing.

DEF FR 215

Impulsion émise par un caleur, dispositif en général électronique, destiné à maintenir un point déterminé du signal à une valeur de référence donnée; le point du signal est déterminé soit par une référence donnée, soit par un instant donné. (TERM-L)

NOTE FR 225

Le terme "caleur" ainsi que sa définition sont normalisés par la CEI. (TERM-L)

SYN FR 230

impulsion de clamping (EURO-L)

 Retourner à l'index.

 Consulter la bibliographie.

 Retourner à la liste des microglossaires.

© Laurant, Anne 1993.