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Cisco uBR7200 Series Universal Broadband Router Hardware Installation Guide
OL-5421-03
Chapter 4 Connecting the Cisco uBR7200 Series Router to the Cable Headend
Measuring the Downstream RF Signal
Figure 4-33
Measuring the RF Signal at the Upconverter Output in CATV Mode—Digital Channel
Power Screen Using Video Averaging
Note
The approximate in-channel peak-to-valley flatness can be verified using the spectrum analyzer’s video
averaging feature. Be aware, however, that values registered while in the video averaging mode are
typically around 2.5 dB below the actual channel power.
Note
Any in-channel frequency response problems at the headend can impair network performance or prevent
a cable interface on the HFC network from operating. The specified maximum peak-to-valley
measurement from a Cisco cable interface card is +/–1.5 dB across 5.6 MHz. At the output of the
upconverter, the maximum tilt should not /–1.5 dB across 5.6 MHz. If the tilt is greater than
+/–1.5 dB across 5.6 MHz when measured, the upconverter might not be compatible with digital QAM
signals, or the upconverter might be defective.
Step 11
Verify that your headend RF measurements meet the recommended DOCSIS parameters listed in the
tables in
Appendix B, “RF Specifications.”
Step 12
Record your headend settings and measurements in
Appendix G, “Site Log,”
as you verify them. This
will assist in troubleshooting the Cisco uBR7200 series router installation later in the process.
Step 13
After you have analyzed and adjusted the RF signal according to the steps outlined on the preceding
pages, proceed to
“Connecting and Configuring the Upstream” section on page 4-30
.
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