3. Operating Instructions
Figure 3.39.
Smith chart representation of short fault (red arrow).
Figure 3.40.
Smith chart representation of a 50 ohm resistive load (red arrow).
3.11.21. Normalized TDR Traces
This process creates a normalized TDR trace based on a calibrated S
11
return loss trace. A
normalized TDR trace appears as another trace in the region of S
11
calibration. The normalized
trace should be cleaner than the Measured DUT trace, with fewer aberrations. The normalized
trace also has an adjustable rise time to help the operator determine what effect a particular
cable fault will have on signals with differing rise times. The following procedure creates a
normalized TDR trace:
1. Create an S
11
return loss plot using the procedure as described on page 49.
2. From the
SParam & Normalize Tools
menu, select
Apply Normalization
.
3. Select
Normalize Pulse Rise Time
and use the
M-FUNCTION
knob to select a suitable
rise time for the cable system as applicable. Note that selecting a rise significantly shorter
than the native rise time of the TDR instrument will result in a degraded trace.
4. Note that the S
11
Options, such as the
Between Cursors On/Off
setting is used by the
TDR normalization process. If
Between Cursors
mode is turned on, the normalized trace
56
CT100B TDR Cable Analyzers Operator’s Manual
