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.
E Z SSTV (pronounced Easy SSTV)
Very popular, easy to use, feature packed, free SSTV program.
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 Committe.
PAL
Television standard used in most of Europe. Stands for Phase Alternation Line.
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

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