Glossary
©
National Instruments Corporation
G-5
SC-2311 User Manual
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 and/or DIO devices plugged into a computer,
and possibly generating control signals with D/A and/or DIO devices in the
same computer
dB
decibel—the unit for expressing a logarithmic measure of the ratio of two
signal levels: dB=20log10 V1/V2, for signals in volts
DC
direct current
DC coupled
allowing the transmission of both AC and DC signals
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) that means
use the current
default setting
.
device
a plug-in data acquisition product, card, or pad that can contain multiple
channels and conversion devices. Plug-in products, PCMCIA cards, and
devices such as the DAQPad-1200, which connects to your computer
parallel port, are all examples of DAQ devices. SCXI modules are distinct
from devices, with the exception of the SCXI-1200, which is a hybrid.
DIFF
differential mode
differential input
an analog input consisting of two terminals, both of which are isolated from
computer ground, whose difference is measured
differential
measurement system
a way you can configure your device to read signals, in which you do not
need to connect either input to a fixed reference, such as the earth ground
or a building ground
digital port
See
port
.
digital trigger
a TTL level signal having two discrete levels—a high and a low level
DIN
Deutsche Industrie Norme
DIO
digital input/output
dithering
the addition of Gaussian noise to an analog input signal for the purpose of
increasing the resolution of a measurement when using averaging
down counter
performing frequency division on an internal signal
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