Specifications

57
Glossary
AC
Alternating current. It refers to a voltage or current that is periodically changing
over time. It can also refer to the type of electrical coupling to a scope's
vertical amplifier or trigger circuitry. AC coupling means that the DC
component of a waveform is blocked.
accelerating
voltage
The potential used to accelerate the electrons in a scope's CRT. This gives the
electrons enough kinetic energy to excite the atoms in the tube's phosphor,
causing light to be emitted from the phosphor, resulting in an oscilloscope
trace.
ADC
Analog to digital converter. It is an electronic circuit used to digitize analog
signals for further digital processing.
aliasing
The false appearance of non-existent signal frequencies in signals that aren't
sampled correctly. Related phenomena are Moire patterns and wagon wheel
spokes in movies that don't appear to move at the right speed or direction.
alternate sweep
In analog oscilloscopes, this is a method of generating a dual-trace display at
higher sweep speeds. One entire trace is drawn, then the other, in an
alternating fashion. Contrast to chopped sweep.
alternate trigger
A dual-trace triggering scheme in which the channel 1 signal triggers the
channel 1 trace, and the channel 2 signal triggers the channel 2 trace in an
alternating pattern. Each signal becomes its own trigger source and a
synchronized display can be obtained even if the two signals have no time
relationship.
analog
When describing an oscilloscope, it means an oscilloscope that uses
predominantly analog circuitry to process and display waveforms. When
describing electronics, it means circuitry that uses a wide variety of voltage or
current values. Contrast this with digital electronics, which deals with two
voltage values. In some cases, digital signals must be regarded as analog
(which, in fact, they are physically) in order to obtain correct operation or
explain certain behaviors.
ARB
Abbreviation for arbitrary waveform generator.
arbitrary waveform
generator
A signal generator that can generate waveforms with an arbitrarily defined
shape other than the standard Sine, Square, or Ramp waveforms found on
function generators.
armed
In referring to an oscilloscope's trigger section, the trigger is armed when the
scope is waiting for a trigger signal and, when one is found, causes a single
sweep of the timebase.
Thus, with a digital scope, a common scenario is to set
the scope up for a single sweep to capture a transient event. This is done on
the B&K 254X/253X scopes by pressing the SINGLE button. This arms the
trigger. After a trigger event occurs, the trigger goes into the unarmed state.
attenuation
The process of decreasing the amplitude of a signal.
averaging
A smoothing process achieved by summing more than one measured value
and divided by the number of values summed. Because noise on electrical
signals often has a zero average (i.e., oscillates randomly about zero volts),
averaging waveform data is a valuable way of removing the noise from a
signal. For good signal fidelity, the signal must not change its underlying
behavior over the averaging period.
AWG
Initialism for arbitrary waveform generator.
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