Viewing The Rf Output Signal - Cisco 7246 - uBR Router Hardware Installation Manual

Chapter 4 Connecting the Cisco uBR7200 Series Router to the Cable Headend
Narrow your span even further from 6 MHz to 100 kHz to zoom in on the center frequency of the channel
Step 8
carrier and reduce your resolution bandwidth and video bandwidth to absolute minimum values for your
particular spectrum analyzer. Your analyzer should display a signal similar to the one shown in
Figure
Figure 4-10
Save this plot on your spectrum analyzer display for comparison with the RF output signal of the
Step 9
upconverter.

Viewing the RF Output Signal

After you have isolated, displayed, and saved the downstream IF signal on your spectrum analyzer, you
must go through the same sort of procedure for the RF output signal from your upconverter.
Step 1 Disconnect the spectrum analyzer from the downstream IF interface on the cable interface card and
reconnect the downstream IF interface to the IF input on your upconverter.
Note Be sure that you have added the appropriate attenuation to your downstream path, if necessary. For more
information, refer to the
Connect the spectrum analyzer to the RF output of the upconverter.
Step 2
Step 3 Set the center frequency on the spectrum analyzer so that it matches the RF output frequency of your
upconverter. For this example, 555 MHz is the RF output frequency.
Allow the spectrum analyzer to complete at least one complete sweep of the RF output.
Step 4
Note Be sure to adjust the reference level of the current measurement so that its peak value is equal to that of
the saved signal.
OL-5421-03
4-10.
100-kHz "Zoom" View of Carrier Center Frequency
"Setting the North American Upconverter Input Level" section on page
Cisco uBR7200 Series Universal Broadband Router Hardware Installation Guide
Connecting and Configuring the Downstream
4-5.
4-11