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Glossary
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National Instruments Corporation G-15 PCI-6023E/6024E/6025E User Manual
T
TC terminal count—the highest value of a counter
T/H track-and-hold—a circuit that tracks an analog voltage and holds the value
on command
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
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
PCI.book Page 15 Wednesday, September 16, 1998 9:09 AM