
7. Frequency Domain Smoothing
Figure 14:
Result Visualization Window
shows
S
11
with smoothing turned
OFF (left) and ON (right), the video bandwidth is 50 MHz.
To achieve smoothing of frequency domain traces, a moving average filter
can be activated. The degree of averaging is set in the configuration file,
specified by means of the video bandwidth. The term video bandwidth ac-
tually comes from RF spectrum analysis, but is used accordingly in this con-
text.
Since frequency domain smoothing is a more sophisticated functionality, the
video bandwidth can only be changed in the configuration file
Seunis.con-
fig
(see section
), the entry to be modified is
Video bandwidth
. Make
sure that the software is NOT running while changing the bandwidth. The
default value is 20 MHz for STDR/DTDR-65 devices and 2 MHz for the DTDR-
800 devices. To display the current bandwidth please use the menu entry
Extras
→
Show Video Frequency
of the
Result Visualization Window
.
An example of a smoothed trace is shown in Fig.
. The left plot shows
the original curve, while the smoothed trace is shown on the right. The
67