16
Oscilloscope Terms
© 2014 Velleman NV
CLIPPING
When the ‘top’ or ‘bottom’ or both extremes of a signal are cut-off (‘clipped’), e.g. because the signal
cannot swing any further due to power supply limitations. An undesired property of amplifiers that are
driven beyond their specifications.
COMPENSATION
A probe adjustment for X10 attenuator probes that balances the electrical properties of the probe
with the electrical properties of the oscilloscope.
COUPLING
The method of connecting two circuits together.
6.4
- D -
DC COUPLING
The oscilloscope displays both the AC and the DC component of a signal.
DC REFERENCE
DC measurement is always performed with respect to a ground level, so we need to define this
ground level. If you do not set the DC reference, the readout might not be correct. In most cases,
this ground level will be the center of the screen, however this is not mandatory.
DC VOLTAGE DC
With DC, the current flows in a single direction, it does not reverse. A DC source has a polarity: (+)
and (-).
DECIBEL (DB)
The decibel (dB) is a logarithmic unit used to express the ratio between two values of a physical
quantity (usually measured in units of power or intensity). One of these quantities is often a
reference value, and in this case the dB can be used to express the absolute level of the physical
quantity. The decibel is also commonly used as a measure of gain or attenuation, the ratio of input
and output powers of a system, or of individual factors that contribute to such ratios. The number of
decibels is ten times the logarithm to base 10 of the ratio of the two power quantities.
DIGITAL
Digital scopes perform an analog to digital conversion on the incoming signal and handle all the
calculations and displaying in the digital domain. Digital signals feature only two fixed levels, usually
0V and +5V.
DIGITAL STORAGE OSCILLOSCOPE
A digital storage oscilloscope is an oscilloscope which stores and analyses the signal digitally
rather than using analogue techniques. Digital oscilloscopes usually analyze waveforms and provide
numerical values as well as visual displays.
DIGITIZE
Converting an analog signal to digital. When digitizing the samples, the voltage at each sample time
is converted to a number. This is done by comparing the voltage with a number of levels. The
resulting number is the number of the highest level that’s still lower than the voltage. The number of
levels is determined by the resolution. The higher the resolution, the more levels are available and
the more accurate the input signal can be reconstructed.
DISTORTION
Undesired alteration of a signal due to external causes such as overloaded circuits, badly designed
circuits, etc…
