Measurement Computing WavePort rev.3.0 - Manual (Page 138)

xii Glossary 04-28-00 WavePort User’s Manual
Differential mode
The differential mode measures a voltage between 2 signal lines for a single channel. (Also see single-ended mode).
Differential mode voltage
Differential mode voltage refers to a voltage difference between two signals that are referenced to a common point.
Example: Signal 1 is +5 VDC referenced to common. Signal 2 is: +6 VDC referenced to common.
If the +5 VDC signal is used as the reference, the differential mode voltage is:
+1 VDC (+ 6 VDC - +5 VDC = +1VDC).
If the +6 VDC signal is used as the reference, the differential mode voltage is:
-1 VDC (+ 5 VDC - +6 VDC = -1 VDC).
ESD
Electrostatic discharge (ESD) is the transfer of an electrostatic charge between bodies having different electrostatic
potentials. This transfer occurs during direct contact of the bodies, or when induced by an electrostatic field. ESD
energy can damage an integrated circuit (IC).
Excitation
Some transducers [e.g. strain gages, thermistors, and resistance temperature detectors (RTDs)] require a known
voltage or current input in order for the sensor to operate. This known input is called the Excitation.
Gain
The degree to which a signal is amplified (or attenuated) to allow greater accuracy and resolution; can be expressed
as ×n or ±dB.
Isolation
The arrangement or operation of a circuit so that signals from another circuit or device do not affect the isolated
circuit. In reference to WavePort, isolation usually refers to a separation of the direct link between the signal
source and the analog-to-digital converter (ADC). Isolation is necessary when measuring high common-mode
voltage.
Linearization
Some transducers produce a voltage in linear proportion to the condition measured. Other transducers (e.g.,
thermocouples) have a nonlinear response. To convert nonlinear signals into accurate readings requires software to
calibrate several points in the range used and then interpolate values between these points.
Multiplexer (MUX)
A device that selects a signal from among several signals and outputs it on a single channel.
Sample (reading)
The value of a signal observed on a channel at an instant in time. When triggered, the ADC reads the channel and
converts the sampled value into a digital representation.
Scan
A series of measurements across a pre-selected sequence of channels.
Sequencer
Defines and controls the state of the measurement system for each step of a scan.
Simultaneous Sample-and-Hold
An operation that captures samples from multiple channels at the same instant in time. The result is elimination of
time skew between measurement of individual channels.