National Instruments PCI-6023E - Manual (Page 121)

Glossary
PCI-6023E/6024E/6025E User Manual G-14 © National Instruments Corporation
Shannon Sampling
Theorem a law of sampling theory stating that if a continuous bandwidth-limited
signal contains no frequency components higher than half the frequency
at which it is sampled, then the original signal can be recovered without
distortion
S/H sample-and-hold—a circuit that acquires and stores an analog voltage on a
capacitor for a short period of time
signal conditioning the manipulation of signals to prepare them for digitizing
SISOURCE SI counter clock signal
SNR signal-to-noise ratio—the ratio of the overall rms signal level to the rms
noise level, expressed in decibels
software trigger a programmed event that triggers an event such as data acquisition
software triggering a method of triggering in which you simulate an analog trigger using
software. Also called conditional retrieval.
SOURCE source signal
SS simultaneous sampling—a property of a system in which each input or
output channel is digitized or updated at the same instant
S/s samples per second—used to express the rate at which a DAQ board
samples an analog signal
STARTSCAN start scan signal
STC system timing controller
switchless device devices that do not require dip switches or jumpers to configure resources
on the devices—also called Plug and Play devices
synchronous (1) hardware—a property of an event that is synchronized to a reference
clock (2) software—a property of a function that begins an operation and
returns only when the operation is complete
system noise a measure of the amount of noise seen by an analog circuit or an ADC when
the analog inputs are grounded
PCI.book Page 14 Wednesday, September 16, 1998 9:09 AM