64 InFocus Corporation — Introduction Guide - DLP Multimedia Projector
Term Description
Screen Gain As it applies to projectors, gain is the measurement of a projection screen’s light reflectance with
unity gain being one. A high gain screen will reflect more light along a narrower path than lower gain
screen. Screen gains under one use a gray screen to absorb ambient light to help maintain contrast
ratios.
Screen Trigger A 12V connection from a projector to an electric screen which tells the screen to deploy when the
projector is turned on and roll up when the projector is turned off.
SDI Serial Digital Interface (SDI) is a standard for digital video transmission over coaxial cable. The most
common data speed is 270 megabits per second (Mbps). However, speeds of up to 540 Mbps are
theoretically possible. A related standard, known as high-definition serial digital interface (HD-SDI)
provides a nominal data rate of 1.485 Gbit/s Standard 75-ohm cable is used.
SDTV Standard Definition TeleVision. A class of digital television (DTV) that refers to the 480i format. 480i
is an interlaced video format that produces a full frame of 480 lines of video in two successive fields.
The first field includes the odd lines and the second field includes the even lines. Sometimes used to
refer to regular television.
SECAM Sequential Couleur avec Mémoire. A television standard closely related to PAL but with a different
method of sending colour information. Runs at 625 horizontal lines of resolution updating 25 frames
a second. Used in France and Russia as well as other countries. Many eastern European countries
are starting to phase out SECAM in favor of PAL.
Shielded A feature of speakers and cables where a metal layer is added to contain and protect a signal from
creating or receiving electromagnetic interference.
Short Throw
Lens
A lens designed to project a large image from a short distance.
Short Throw
Projector
A projector with a short throw lens.
Short Throw
Wall Mount
Projector
A projector that mounts on a wall adjacent to the projection screen. The throw distance is generally
just a few inches and allows people to move freely through the room without concern of intercepting
the light path.
SHP Super High Pressure. A type of projector lamp.
Signal-to-Noise
Ratio
The ratio of noise to signal measured in dB. The higher the number, the better.
SPL Sound Pressure Level. Commonly used to describe a speaker’s efficiency at one watt at 1 meter
distance. The actual amount of sound output using dB. There are various weightings used such as
A, B or C which reflect the human ear’s sensitivity at different sound levels. A-weighting is used for
levels up to 55dB SPL, B-weighting from 55dB SPL to 85dB SPL and C-weighting for 85dB SPL up.
A quiet office is 40dB SPL and a rock concert is 110dB SPL.
sRGB sRGB stands for standard Red, Green, and Blue, and is a standard for rendering colour evenly across
a variety of platforms.
Streaking A visual artifact of trailing colours behind an on-screen object or across a screen.
Subpixel On a flat-panel display, one of the primary colour picture elements of which 3 make up a full colour
capable pixel.
SVGA SVGA is a display resolution measuring 800 pixels horizontally by 600 pixels verically giving a total
display resolution of 480,000 individual pixels. SVGA has a 4:3 aspect ratio.
SXGA SXGA is a display resolution measuring 1280 pixels horizontally by 1024 pixels vertically giving a total
display resolution of 1,310,720 individual pixels. SXGA has a 5:4 aspect ratio.
Glossary
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