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for VGA. The scan rate relates to the speed at which the computer updates the
images or lines on the display. SVGA updates the lines nearly twice as fast a TV
can display them.
SCAN RATES
NTSC TV
PAL TV
SVGA
The differences in horizontal and vertical scan rates, the number of lines and
the fact the TV is always interlaced and VGA usually is not creates many chal-
lenges for the conversion of VGA to TV.
Many Scan Converters on the Market attempt to convert VGA to TV by cutting
the VGA horizontal scan rate by half since the standard VGA scan rate is 31.5,
half of this is 15.7, roughly equal to the horizontal scan rate of TV. These scan
converters generally require software drivers to interact with the computers VGA
card clock. Often times these software solutions result in incompatibilities.
TV Super Scan 2 Enhanced is a true frame buffer Scan Converter. No Soft-
ware is needed, all conversion is done in hardware. Video memory is embedded
in the circuitry which allows a full frame of video to be stored.
The incoming scan rate is measured and evaluated against the scan rate re-
quired for broadcast quality video. The adjusted scan rate is sent out to your TV
display. This conversion happens in real time with no delay.
Horizontal
:
15.6 kHz
:
15.7 kHz
:
24-48 kHz
Chapter 3 - Video Concepts
Vertical
Lines
60 Hz
480
50 Hz
576
45-72kHz
200-800
27
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