Velleman projects EDU09 Assembly instructions - Manual (Page 16)

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Oscilloscope terminology
Input coupling: The drawing shows typical oscilloscope input circuit. There are 3 possible settings: AC-coupling, DC coupling and GND.
With AC-coupling, a capacitor is put in series with the input signal. This capacitor blocks any DC component of the signal and passes only AC.
With DC coupling, the capacitor is bypassed and both the AC and DC component of the signal are passed. Low frequency signals (<20Hz)
should always be displayed using DC coupling. Should AC coupling be used, the internal coupling capacitor will interfere with the signal and
the displayed signal will not be correct.
Sample rate: Usually expressed in samples or megasamples/second, sometimes in MHz. It is the number of times per second the
digital oscilloscope ‘looks’ at the signal at the input. The more it ‘looks’, the better it is able to recreate a faithful image of the waveform
on the screen. Theoretically the sample rate needs to be twice the max. frequency of the applied signal, however, for best results a
sample rate of 5 times the max. frequency is recommended. The EDU09 samplerate is 1,5Ms/s or 1,5MHz.
Sensitivity: Indicates the smallest change of the input signal that makes the trace move up or down on the screen.
Usually expressed in mV.
Slope: It determines where the scope will trigger. This can be on the rising or on the falling slope of the signal.
Vrms: The rms voltage of an AC source represents the required DC voltage to generate the same amount of heat in a resistor as
the AC source would do. For sinusoidal signals, Vrms = Vpeak / sqrt(2)
DC coupling AC coupling GND coupling
rising slope falling slope