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glossary.txt
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1996-06-09
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Glossary of SSTV Terms
----------------------
AVT
Amiga Video Transceiver. (1) Interface and software for
use with Amiga computer, developed by Ben Blish-Williams,
AA7AS, and manufactured by Advanced Electronics Applications
(AEA). (2) A family of SSTV transmission modes first
introduced with the AVT product.
Back Porch
The blank part of a scan line immediately following the
horizontal sync pulse.
Chrominance
Color component of a video signal. Robot color modes transmit
pixel values as luminance (brightness, symbol "Y") and
chrominance (color differences R-Y and B-Y) rather than RGB
(red, green, blue).
Demodulator
A device (for SSTV) that extracts the image and sync information
from the received audio signal.
Frame
One complete image (top to bottom). As an example, the
Scottie S1 mode has 240 scan lines in a frame.
Frame Sequential
An early color SSTV transmission scheme that sent three separate
images with the red, green, and blue components. Now obsolete.
Front Porch
The blank part of a scan line just prior to the horizontal sync.
FSTV
Fast Scan TV, often called ATV (Amateur TeleVision). Provides
full motion video at the expense of large bandwidth
requirements. Can not be used on any HF or lower VHF bands.
Interlace
A scan line ordering different than simple top to bottom.
For example, the NTSC and PAL standards use a field of even
scan lines and a field of odd scan lines to make a complete frame.
Line Sequential
A method of of color SSTV transmission that sends Red,
Green & Blue sequentially for each scan line. This method
permits viewing the image in color as it is received, line
by line.
Luminance
Brightness component of a video signal. Usually this is
computed as Y (luminance) = 0.59 * G (Green) + 0.30 * R (Red) +
0.11 * B (Blue).
Martin
A family of SSTV transmission modes developed by Martin
Emmerson, G3OQD, in England.
NTSC
Television standard for North America and Japan. National
Television System Committee.
PAL
Television standard used in most of Europe. Stands for
Phase Alternation Line.
Pasokon TV
The most respected name in SSTV.
Pixel
A single picture element on a display. The dots (or blocks)
which make up a computer display or printer output.
P7 Monitor
A very long persistence Cathode Ray Tube (CRT) used in
the very early SSTV displays.
RGB
Red, Green, Blue. A popular model for representing colors.
Most colors can be simulated, to the human eye, by mixing
different blends of red, green, and blue light.
Robot
Abbreviation for the slow scan equipment from Robot Research.
A family of SSTV transmission modes introduced with this
equipment.
Scan Converter
Device which converts one video standard to another. For
instance, the Robot 1200C converted between NTSC and SSTV.
Scottie
A family of SSTV transmission modes developed by Ed Murphy,
GM3BSC, in Scotland.
SECAM
Color TV standard used in France and the CIS. Sequential Color
And Memory.
SSTV
Slow Scan Television. A method of sending still images
with audio signals.
VIS
Vertical Interval Signalling. The vertical sync signal,
the the beginning of an image, contains digitally encoded
information about the format of the following image. Most
SSTV receiving systems use this to automatically select
the proper receive mode. First used in the Robot 1200C modes.
Wraase
A family of SSTV transmission modes used by the Wraase
SC-1 and SC-2 scan converters developed by Volker Wraase, DL2RZ,
of Wraase Electronik, Germany.