A term used to describe the short-time instability of a signal. The instability may be in amplitude, phase, or both. The term is applied especially to signals reproduced on the screen of a cathode-ray tube.

Related Terms


A series of screens, wires, or plates through which steam is passed to remove entrained moisture.


A cage or screen in which a thermometer and sometimes other instrument are placed to shield them from the direct rays of the sun and from other conditions that would interfere with registration of true conditions. It is usually a small wooden structure with louvered sides.


1. The slowly decaying luminescence of the screen of the cathode-ray tube after excitation by an electron beam has ceased. 2. A broad, high arch of radiance or glow seen occasionally in the western sky above the highest clouds in deepening twilight, caused by the scattering effect of very fine particles of dust suspended in the upper atmosphere.


A cathode-ray tube having a specially coated screen which changes color but does not necessarily luminesce when struck by the electron beam. It shows a dark trace on a bright back- ground.


The echo generated e.g. by a vessel on a radar screen


A fictive line displayed on the radar screen separating the fairway for inbound and outbound vessels so that they can safely pass each other


To brighten the phosphorescent plan position indicator screen through the effects of the echoes on the sweep.


The bright area on the phosphorescent plan position indicator screen resulting from the brightening of the sweep by the echoes.


A magnetic compass in which the lubber’s line and compass card, or a portion thereof, are viewed as an image projected through a system of lenses upon a screen adjacent to the helmsman’s position.


A radar display in which a high persistence screen is excited only when the radar beam is within a narrow sector which can be selected at will.

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