3. Getting Started
3.10.4. Temperature Correction
The CT100B automatically adjusts for changes in temperature. This eliminates the need for a
warm-up period. However, a stable temperature is required for some functions, such as
performance checks. To view the internal temperature, go to MENU → Settings → Display and
toggle on Temperature. In the Display submenu you can also toggle on Temp Comp. When
temperature is displayed on the screen with Temp Comp toggled on, a message is shown giving the
status of temperature correction. When the CT100B is fully adjusted, the message reads “TC:
OK” in green text.
3.11. Cable Length Settings
When scanning a cable, the correct cable length needs to be chosen for the most accurate results.
If using the Special Main menu, press the blue MENU button then Measurement → Meas. Settings
and press the Cable Len button to toggle through the different lengths. If using the Standard Main
menu, press the blue MENU button and choose a cable length.
• Short: For cables of up to approximately 300 ft. (90 m) long.
• Medium: For cables up to 1500 ft. (450 m) long.
• Long: For cables up to 6000 ft. (1800 m) long.
The exact limit to the cable length setting depends on the Vp setting. All limits given above are
based on a Vp of 0.66. Higher Vp cables will have longer length limits and lower Vp cables will
have shorter length limits.
To measure cables over a mile (2 km) in length, use Extra Long Mode. Go to MENU →
Measurement to toggle on Extra Long Mode. Extra Long Mode allows the CT100B to obtain
traces out to 48,000 ft. (14,600 m), assuming a Vp of 0.66. Extra Long Mode is slower than other
cable lengths and some instrument features are not available. When in Extra Long Mode, the
Cable Length menu option will indicate Extra Long Mode On. Selecting the Cable Length menu
option will switch off Extra Long Mode.
3.12. Sample Resolution
The sample resolution setting establishes the number of sample points per unit of time or distance
in the live TDR trace. In general, higher sample resolution sharpens traces at larger horizontal
scales by increasing the effective sampling efficiency of the TDR trace (the ratio of sampled vs.
actual change in voltage from sample to sample). For larger horizontal scales it also helps ensure
that all cable faults are sampled adequately enough to be detected and displayed on the instrument
screen. Note that the sample resolution of cable scans can be set separately (see Section 4.8). The
following TDR trace sample resolution settings are available in MENU → Measurement → Meas.
Settings → Resolution (Special Main menu) or MENU → Resolution (Standard Main menu):
1. Screen: Screen resolution (1 sample/pixel). Fastest trace, adequate for many routine
cable-testing tasks. At large horizontal scales, the resolution is low and small faults may be
undetectable, or at least underestimated. This is because there may be too few samples in
the region of the fault for the fault to be reliably identified on the trace. For example, if a
34 CT100B TDR Cable Analyzers Operator’s Manual
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