National Instruments NI 447 Series User Manual page 70

N
NC
NI-DAQ
noise
nonreferenced signal
sources
Nyquist frequency
Nyquist Sampling
Theorem
O
offset-binary format
operating system
oversampling
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normally closed, or not connected
NI driver software for DAQ hardware
an undesirable electrical signal—noise comes from external sources such
as the AC power line, motors, generators, transformers, fluorescent lights,
soldering irons, CRT displays, computers, electrical storms, welders, radio
transmitters, and internal sources such as semiconductors, resistors, and
capacitors. Noise corrupts signals you are trying to send or receive.
signal sources with voltage signals that are not connected to an absolute
reference or system ground. Also called floating signal sources. Some
common example of nonreferenced signal sources are batteries,
transformers, or thermocouples.
a frequency that is one-half the sampling rate. See also Nyquist Sampling
Theorem.
the theorem states that if a continuous bandwidth-limited analog signal
contains no frequency components higher than half the frequency at which
it is sampled, then the original signal can be recovered without distortion
a method of digitally encoding sound that represents the range of amplitude
values as an unsigned number, with the midpoint of the range representing
silence. For example, an 8-bit sound stored in offset-binary format would
contain sample values ranging from 0 to 255, with a value of 128 specifying
silence (no amplitude). See also
base-level software that controls a computer, runs programs, interacts with
users, and communicates with installed hardware or peripheral devices
sampling at a rate greater than the Nyquist frequency
two's complement
G-9
Glossary
format.
NI 447X User Manual