Hughes Model 230 Projector Service Manual

							Glossary
Model 230 Service Manual B-3
Luminance
Abbreviated as Y.  The portion of the signal that
contains the black and white information, which
affects brightness.
Noise
An undesirable electrical interference of a signal.
Overscanning
Displaying less than the complete area of an
image to a viewer (i.e., scanning beyond the
visible area).  All TV sets are overscanned at
least slightly, so that viewers do not see blanking.
Raster
The area illuminated by the scan lines on a CRT.
Resolution
The degree of sharpness of a displayed or
printed character or image;  the amount of detail
in a picture.  On a display screen, resolution is
expressed as the number of horizontal dots
(columns) by the number of vertical lines (rows).
For example, a 680 x 400 resolution means 680
dots across each of 400 lines.
Retrace
The blanked-out line traced by the scanning
beam of a picture tube as it travels from the end
of any horizontal line to the beginning of either
the next horizontal line or field.  The beam is
turned off during retrace.
RGB (Red, Green, Blue)
Refers to the method of recording and generating
colors in a video system.  On a television or color
monitor, colors are displayed as varying
intensities of red, green and blue dots.  When
red, green and blue are all turned on high, white
is produced.  When all dots are turned off, the
base color of the screen appears.
Rollbar Assembly
Assembly where the front and rear cover are
hinged to. Used to hold covers in place.
S-VHS
A high band video recording process for VHS that
increases picture quality and resolution capability.
S-VHS tape machines use a special output
terminal which allows separate output of
luminance (Y) and chrominance (C) picture
information to monitors equipped with S-Video
inputs.
S-Video
A video signal that has the luminance (Y)
information separated from chrominance (C)
information. 
						

							Glossary
B-4 Model 230 Service Manual
Saturated Color
1)  A color as far from white, black or gray as it
can be (i.e., vermilion rather than pink).  2)  A
display misadjustment that results in unnaturally
bright colors.
Scan
To scan is to move across a picture frame a line
at a time, either to detect the image, as in an
analog or digital camera, or to refresh a CRT-
based video screen.
Scan Line
One of many horizontal lines in a graphics frame.
Scan Rate
The frequency of line scanning for a monitor or
projector.
Synchronization
Also called sync for short.  Working together.
At the same time, horizontal and vertical sync
signals from the signal source control the
monitors scan circuits to properly time the lines
and frames of a picture.
Technician Remote
Remote control used during Model 230 setup and
adjustment. Alternative to Standard Remote.
Provides access to many of the setup functions
by direct keys instead of by menu maneuvering.
Throw
Distance to the screen from the projector.
Underscan
Decrease raster size H and V so that all four
edges of the picture are visible on the display.
Vertical Height Pots
Potentiometers located on the Horizontal/Vertical
Deflection Board. Used to adjust Vertical height.
Vertical Resolution
The amount of detail that can be perceived in the
vertical direction;  the maximum number of
alternating white and black horizontal lines that
can be counted from the top of the picture to the
bottom.
Vertical Scan Frequency
The vertical scan frequency of the input signal.
(V-Freq)
Vertical Scan
Reverses the image vertically for use with ceiling
Reversal Jumper
displays or mirror-bounced displays. Located on
the Scan Reversal Board.
Vertical Synchronization
The number of times per second a frame is
Frequency
transmitted to a video display screen.
Xenon Arc Lamp
See Arc Lamp. 
						

							Glossary
Model 230 Service Manual B-5