SuroscillationLe terme suroscillation (ou ringing) désigne un dépassement de la valeur du signal, par rapport à celle qu'il doit prendre en régime établi, à la suite d'une transition rapide. Une oscillation amortie suit souvent ce dépassement. On accepte parfois une suroscillation limitée dans le but d'améliorer le temps de réponse, comme dans le cas du VU-mètre, mais en général, elle n'est pas souhaitée. En audio, elle affecte la qualité sonore. Dans un circuit électrique, la suroscillation est une oscillation indésirable du courant ou de la tension.
Pilot signalIn telecommunications, a pilot signal is a signal, usually a single frequency, transmitted over a communications system for supervisory, control, equalization, continuity, synchronization, or reference purposes. In FM stereo broadcasting, a pilot tone of 19 kHz indicates that there is stereophonic information at 38 kHz (the second harmonic of the pilot tone). The receiver doubles the frequency of the pilot tone and uses it as a frequency and phase reference to demodulate the stereo information.
Edge enhancementEdge enhancement is an filter that enhances the edge contrast of an or video in an attempt to improve its acutance (apparent sharpness). The filter works by identifying sharp edge boundaries in the image, such as the edge between a subject and a background of a contrasting color, and increasing the image contrast in the area immediately around the edge. This has the effect of creating subtle bright and dark highlights on either side of any edges in the image, called overshoot and undershoot, leading the edge to look more defined when viewed from a typical viewing distance.
