Specifications

59
CRT
Cathode ray tube. It is the vacuum tube with a thermionic emitter and
electrostatic deflection plates (some may also contain deflection coils) that
accelerates electrons that impact on the phosphor screen, producing light. A
CRT is used with virtually all analog oscilloscopes.
cursor
A marker (usually a horizontal or vertical dotted line) on a scope that can be
used to make measurements by lining up the marker with a waveform feature.
DC
Direct current. The general use means a voltage or current whose value is
constant.
DDS
Stands for direct digital synthesis, a digital architecture used in many modern
function generators.
dead time
The time that the scope is not capturing the signal. This applies to both analog
and digital scopes and is not usually specified.
decibel
A dimensionless number used to represent a ratio between two quantities of
the same type. If the two quantities are a and b, then their ratio in decibels is
defined to be 10log



. It is often used to represent the ratio of two powers.
When used to represent the ratio of two voltages or currents, the expression
20log



is usually used because the power is proportional to the squares of
these quantities.
delayed time base
A secondary time base in an oscilloscope that is used to display a smaller
section of the trace shown with the main time base. Its trigger position and
time width are adjustable to allow inspection of different portions of the main
trace at various horizontal magnifications.
digitize
The process of converting an analog signal to a sequence of digital values by
an analog to digital converter.
division
A major mark in the graticule (grid) of a scope's display screen. Common
numbers of divisions are 10 or 12 horizontal by 8 vertical.
DSO
Digital storage oscilloscope. An oscilloscope that acquires signals with digital
sampling.
dual trace
A scope with two vertical channels that is capable of displaying the voltage
versus time of two waveforms at the same time.
duty cycle
In a pulse train waveform, the fraction of the pulse train's period that is the
width of the pulse.
envelope
A curve joining the peaks of an oscillating signal. This term is often used in the
context of amplitude modulation, where the envelope is usually easy to see
with an oscilloscope.
equivalent time
sampling
A sampling method of a digital oscilloscope that can only be used on periodic
signals. It allows the scope to digitize waveforms with frequencies higher than
the sampling frequency by sampling one or a few points in many periods of the
waveform and combining the sampled data.
extrinsic noise
Noise in an electrical circuit that is caused by physical processes outside of (or
extrinsic to) the circuit. An example is an AC voltage induced in the circuit's
wiring by an external changing magnetic field.
fall time
The time it takes for a signal to fall from a higher level to a lower level in value.
Opposite of rise time.
focus
An adjustment on an analog oscilloscope that allows the trace to be adjusted
from a fine line to a wide line.
frequency
The number of periods per unit time of a waveform. Usually expressed in
hertz, Hz, often with an SI multiplier. It is equal to the reciprocal of period.
gain
The amount of gain in the vertical amplifier of an oscilloscope.
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