Reference
80E00 ElectricalSampling Modules User Manual 35
Overview Controlelem ents& resources
Totake a common mode or differential TDR
measurement(cont.)
Common mode
TDR
13. Notice that both channels assert a positive TDR step for
common-mode TDR.
14. When the TDR steps on the two channels are the same
polarity (both positive or negative), you can define a
math waveform that represents the average common-
mode signal by pressing the VERTICAL MENU button,
selecting the Vert tab, selecting Waveform M1,On, and
then selecting Define,C1,+,C2,Math Waveform On,
andOK.
Takea
measurement
15. Takeyour measurement. For more informati on, see
Takeautomatic measurements on page 25, orTa ke
cursormeasurements on page 26.
Enable
differentialTDR
measurements
16. Pressthe SETUP DI ALOGS button and select the TDR
tab.
17. Clickthe TDR STEP Polarity box for one channel to
invert the polarity of one of the step generators.
Note: Although you have inverted a TDR step, the step
is only displayed inverted when the acquisition units are
Volts.
18. Pressthe SETUP DI ALOGS button.
Step
polarity
TDRtab
DifferentialTDR 19. Onechannel isasserti ng a positive step and the other
channel is asserting a negative TDR step. These
conditions set up differential TDR.