National Instruments PCI-1411 User Manual
Page 39
Glossary
G-4
www.ni.com
drivers
Software that controls a specific hardware device, such as an image
acquisition board.
dynamic range
The ratio of the largest signal level a circuit can handle to the smallest
signal level it can handle (usually taken to be the noise level), normally
expressed in decibels.
E
EEPROM
Electrically erasable programmable read-only memory. ROM that can be
erased with an electrical signal and reprogrammed.
external trigger
A voltage pulse from an external source that triggers an event such as
A/D conversion.
F
field
For an interlaced video signal, a field is half the number of horizontal
lines needed to represent a frame of video. The first field of a frame
contains all the odd-numbered lines, the second field contains all of the
even-numbered lines.
FIFO
First-in first-out memory buffer. The first data stored is the first data sent
to the acceptor; FIFOs are used on IMAQ devices to temporarily store
incoming data until that data can be retrieved.
frame
A complete image. In interlaced formats, a frame is composed of two fields.
ft
Feet.
G
gamma
The nonlinear change in the difference between the video signal’s
brightness level and the voltage level needed to produce that brightness.
genlock
Circuitry that aligns the video timing signals by locking together the
horizontal, vertical, and color subcarrier frequencies and phases and
generates a pixel clock to clock pixel data into memory for display or into
another circuit for processing.