Matrox Corona Installation And Hardware Reference page 95

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PLL
Phase-locked loop. Typically used in genlocked systems, a
PLL provides a very stable pixel clock that is based or
referenced to some other signal, usually a horizontal sync. A
PLL adjusts the pixel clock frequency according to changes
or variations of its reference signal. Adjusting the pixel clock
frequency ensures that the same number of pixels appears
on every line.
Progressive scanning
Describes a transfer of data in which the lines of the source
input device are written sequentially into the destination
buffer.
Also known as non-interlaced. See also interlaced scanning.
PSG
Programmable synchronization generator. It has various
functions related to video synchronization and control. For
example, it supplies feedback signals to the PLL, and is fully
responsible for the sampling clock value.
RAMDAC
Random access memory digital-to-analog converter. A digital
to analog converter that includes static RAM for use as a
look-up table.
Real-time processing
The processing of an image as quickly as the next image is
grabbed.
Also known as live processing.
Reference levels
The zero and full-scale levels of an analog-to-digital
converter. Voltages below a black reference level are converted
to a zero pixel value; voltages above a white reference level
are converted to the maximum pixel value. Together with the
analog gain factor, the reference levels affect the brightness
and contrast of the resulting image.