Glossary
G-4
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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 IMAQ or
DAQ 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.
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.
