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Oscilloscope Terms
6.13
- S -
SAMPLING
Sampling is the reduction of a continuous signal to a discrete signal. Every time the scope
“samples” an input waveform, it memorizes the voltage value at that instant and converts it to a
binary number which can be stored in memory.
SAMPLING RATE
Usually expressed in samples or mega samples/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.
SENSITIVITY
Indicates the smallest change of the input signal that makes the trace move up or down on the
screen. Usually expressed in mV.
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.
SLOPE
It determines where the scope will trigger. This can be on the rising or on the falling slope of the
signal.
SPIKES
Fast, short duration transients in a signal.
6.14
- T -
TIME BASE (TIME/DIVISION)
Determines the time the trace needs to scan from the the left hand side to the right hand side of a
division. The time base is calibrated in time/div and usually measured in seconds/division.
TRACE
A line that is drawn on the screen, which represents the signal at the input.
TRIGGER
It defines when a signal is acquired and stored in memory. Digital storage oscilloscopes can provide
pretrigger viewing, they constantly process the input signal whether a trigger has been received or
not.
6.15
- V -
VERTICAL SENSITIVITY
An indication of how much the vertical amplifier can amplify a weak signal. Vertical sensitivity is
usually measured in millivolts (mV) per division.
VOLT
The unit of electric potential difference.
