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Chapter 4
Connecting the Cisco uBR7225VXR Router to the Cable Headend
Display a signal complete with preamble and upstream data transmission information similar to the
Step 1
resulting signal from
Spectrum Analyzer" section on page
one in
Figure 4-34
Note
Figure 4-34
Figure
or want to skip the following section describing its use when viewing your upstream signal, proceed to
Step
3.
(Optional) View your upstream signal using a vector signal analyzer such as the Agilent 89441A.
Step 2
The advantage of displaying these signals with the vector signal analyzer is that you can view them over
the time domain for a specified time interval. In addition, the vector signal analyzer enables you to
measure the digital channel power of a very short duration data transmission, like the preamble of a
digital signal.
a.
Set up your vector signal analyzer to view both the "frequency" domain and "time" domain of your
upstream signal. Your vector signal analyzer should display a pair of signals similar to those in
Figure
OL-17309-01
Step 3
through
Figure
4-34.
Preamble Amplitude Before Resolution and Video Bandwidth Reduction
is a display from a standard spectrum analyzer. The following figures,
4-38, are taken from a vector signal analyzer. If you do not have access to a vector signal analyzer,
4-35.
Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide
Step 10
under the
"Measuring the Upstream RF Signal Using a
4-22. Your spectrum analyzer should display a signal similar to the
Measuring the Upstream RF Signal
Figure 4-35
through
4-29
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