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Glossary
© National Instruments Corporation G-3 NI PXI/PCI-1409 User Manual
CPU Central processing unit.
CSYNC Composite synchronization signal. Signals in a color video system that
multiplex all picture information into a single signal, such as NTSC, PAL,
or SECAM.
D
D/A Digital-to-analog.
DAC Digital-to-analog converter. An electronic device, often an integrated
circuit, that converts a digital number into a corresponding analog voltage
or current.
DAQ Data acquisition. (1) Collecting and measuring electrical signals from
sensors, transducers, and test probes or fixtures and inputting them to a
computer for processing. (2) Collecting and measuring the same kinds of
electrical signals with A/D or DIO boards plugged into a computer, and
possibly generating control signals with D/A and/or DIO boards in the
same computer.
dB Decibel. The unit for expressing a logarithmic measure of the ratio of
two signal levels: dB = 20log
10
V1/V2, for signals in volts.
DC Direct current.
default setting A default parameter value recorded in the driver. In many cases, the default
input of a control is a certain value (often 0).
DMA Direct memory access. A method by which data can be transferred between
computer memory and a device or memory on the bus while the processor
does something else. DMA is the fastest method of transferring data
to/from computer memory.
DRAM Dynamic RAM.
driver Software that controls a specific hardware device, such as an image or data
acquisition device.
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.