Velleman projects EDU09 Assembly instructions - Manual (Page 15)

- 15 -
Oscilloscope terminology
DC coupling: The oscilloscope displays both the AC and the DC component of a signal.
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. See also ‘Analog’.
Distortion: Undesired alteration of a signal due to external causes such as overloaded circuits, badly designed circuits, etc…
Noise: Undesired random addition to a signal.
Ripple: Unwanted periodic variation of a DC voltage.
Signal: Voltage applied to the input of the oscilloscope. The subject of your measurement.
Sine wave: Mathematical function that represents a smooth repetitive oscillation. The waveform shown at the start of this glossary is a
sine wave.
Spikes: Fast, short duration transients in a signal.
AC voltage:
(AC: Alternating Current) With AC, the flow of the current periodically reverses, as opposed to DC, where the current flows in
one direction. An AC source does not have a polarity.
Bandwidth: Usually expressed in MHz. It is the frequency at which an applied sine wave will be displayed at an amplitude of around 70%
of its original amplitude. More expensive scopes feature a higher bandwidth. Rule of thumb: the bandwidth of an oscilloscope needs to be
at least 5 times higher than the frequency of the signal applied to the input of the scope. The EDU09 bandwidth goes up to 200KHz.
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:Direct Current) With DC, the current flows in a single direction, it does not reverse. A DC source has a polarity, (+) and (-).