Glossary
BNC-2140 User Manual G-4
©
National Instruments Corporation
DD/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
DAC0OUT analog channel 0 output signal
DAC1OUT analog channel 1output signal
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. For example, the default input for a parameter may be do
not change current setting, and the default setting may be no AMUX-64T
boards. If you do change the value of such a parameter, the new value
becomes the new setting. You can set default settings for some parameters
in the configuration utility or manually using switches located on the
device.
delta-sigma modulating
ADC a high-accuracy circuit that samples at a higher rate and lower resolution
than is needed and (by means of feedback loops) pushes the quantization
noise above the frequency range of interest. This out-of-band noise is
typically removed by digital filters.
DGND digital ground signal
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 or a
building ground
DIO digital input/output
UM.book Page 4 Tuesday, July 14, 1998 10:37 AM