3. Operating Instructions
6. Use the
M-FUNCTION
knob to highlight the mask to be imported.
7. Press the
Import
→
Internal
option.
8. The mask will be copied to internal storage of the CT100B.
3.11.10.4. Deleting a Mask
Once masks are backed up to a computer, they can be deleted from the CT100B as follows:
1. Press the
FILE
button to open the
File
menu.
2. Press the
Masks
option to enter into the
Masks
menu.
3. Select
Masks
option again. A scroll dialog appears, showing all saved masks.
4. Mark specific masks for deletion using the
Toggle Selected
option or select them all with
the
Mark All
option.
5. Select the
Delete
option. You will have to confirm the deletion.
3.11.11. Envelope Plot (Transient/Intermittent Fault Detection)
Cable system troubleshooting frequently involves detecting and localizing transient or
intermittent faults, such as a twisted pair cable with frayed insulation that briefly shorts its
conductors when mechanically disturbed, or a coaxial connector that reflects an open when
shaken. The CT100B’s
Envelope Plot
mode simplifies characterization of these types of
intermittent faults. To create an Envelope Plot, use the following procedure:
1. Position the TDR trace such that the area of interest is located on the screen at a
satisfactory horizontal and vertical scale. Resolution from previous measurement will be
preserved.
2. Select
MENU
→
Measurement
menu.
3. Select
Envelope Plot
submenu.
4. Select
Envelope Plot Off
to turn Envelope Plot mode on.
5. Use the
Fill Mode On/Off
option to toggle between
Fill Mode
and
Probability Density
display mode.
6. The CT100B can monitor a trace for extended periods of time with appropriate power
management settings are enabled.
7. Sometimes manipulation of the cable and/or connectors of interest during Envelope Plot
monitoring will provoke an intermittent TDR fault.
Fill Mode
fills in an area plot between the maximum and minimum impedance values. This is
useful to highlight the location of the fault because the fault typically creates an “arrow” that
points to the location of the fault as shown in Figure 3.26.
Probability Density
mode shows the underlying TDR traces which can be useful to determine
the fault mechanism and likelihood of occurrence as shown in Figure 3.27. Both modes provide
the range of impedance values at cursor, as shown in Figure 3.28.
44
CT100B TDR Cable Analyzers Operator’s Manual
