Glossary
PCI/PXI-1408 and NI-IMAQ for Win95/NT
G-10
©
National Instruments Corporation
O
operating system
base-level software that controls a computer, runs programs,
interacts with users, and communicates with installed hardware or
peripheral devices
P
PAL
Phase Alternation Line—one of the European video color
standards; uses 625 lines per frame. See also NTSC.
PCI
Peripheral Component Interconnect—a high-performance
expansion bus architecture originally developed by Intel to
replace ISA and EISA; it is achieving widespread acceptance as a
standard for PCs and workstations and offers a theoretical
maximum transfer rate of 132 Mbytes/s
PCLK
pixel clock signal—times the sampling of pixels on a video line
PCLKIN
pixel clock in signal
PFI
programmable function input
PGIA
programmable gain instrumentation amplifier
picture aspect ratio
the ratio of the active pixel region to the active line region; for
standard video signals like RS-170 or CCIR, the full-size picture
aspect ratio normally is 4/3 (1.33)
pixel
picture element—the smallest division that makes up the video
scan line; for display on a computer monitor, a pixel’s optimum
dimension is square (aspect ratio of 1:1, or the width equal to the
height)
pixel aspect ratio
the ratio between the physical horizontal size and the vertical size
of the region covered by the pixel; an acquired pixel should
optimally be square, thus the optimal value is 1.0, but typically it
falls between 0.95 and 1.05, depending on camera quality
pixel clock
divides the incoming horizontal video line into pixels
pixel count
the total number of pixels between two HYSNCs; the pixel count
determines the frequency of the pixel clock