Glossary
©
National Instruments Corporation
G-15
THD
total harmonic distortion—the ratio of the total rms signal due to harmonic
distortion to the overall rms signal, in decibel or a percentage
THD+N
signal-to-THD plus noise—the ratio in decibels of the overall rms signal to
the rms signal of harmonic distortion plus noise introduced
throughput rate
the data, measured in bytes/s, for a given continuous operation, calculated
to include software overhead
transducer
See sensor
transfer rate
the rate, measured in bytes/s, at which data is moved from source to
destination after software initialization and set up operations; the maximum
rate at which the hardware can operate
TRIG
trigger signal
trigger
any event that causes or starts some form of data capture
TTL
transistor-transistor logic—a digital circuit composed of bipolar transistors
wired in a certain manner.
U
UI
update interval
unipolar
a signal range that is always positive (for example, 0 to +10 V)
UISOURCE
update interval counter clock signal
update
the output equivalent of a scan. One or more analog or digital output
samples. Typically, the number of output samples in an update is equal to
the number of channels in the output group. For example, one pulse from
the update clock produces one update which sends one new sample to every
analog output channel in the group.
update rate
the number of output updates per second
V
V
volts
Vcc
positive supply voltage