Fluke Oscilloscope Calibration Manual page 27

100%
90%
10%
0%
Scope risetime depends on V/div setting.
t
r, Display
Oscilloscope Calibration Techniques
Signal = fast pulse 100kHz to 10MHz
Risetime measurement readout
Risetime displayed consists of two
components
– risetime of signal (calibration source)
– risetime of oscilloscope
t =
r , UUT
t
= real risetime of oscilloscope
r,UUT
t = risetime shown on screen
r,Display
t = risetime of calibration source
r,Calibrator
t
= t
r,Display
r,UUT
Scopes with selectable internal 50Ω Ω Ω Ω termination
calibrated for bandwidth using 50Ω Ω Ω Ω setting and a
50Ω Ω Ω Ω signal source. Good matching is important.
( ) (
)
2
t − t
r , Display r , Calibrator
t
if t > 4
r,UUT
r,Calibrator
2