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Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide
OL-17309-02
Chapter4 Connecting the Cisco uBR7225VXR Router to the Cable Headend
Measuring the Downstream RF Signal
Figure4-8 Measuring the RF Signal at the Upconverter Output—Overload Condition Corrected
with Attenuation
Step7 Change the spectrum analyzer settings to view the digital channel power. This setting enables you to see
if there is too much power on the upconverter output. In Figure4-9, the upconverter output is reading
+64.31 dBmV, which is beyond the DOCSIS-specified range of +50 to +61dBmV.
Tip A spectrum analyzer might become overloaded and produce false readings (such as internally generated
spurs) when measuring a signal at this amplitude.
Figure4-9 Measuring the RF Signal at the Upconverter Output—Upconverter Output Level Too
High
Step8 Adjust the power on the upconverter output to ensure that it is between +50 and +61dBmV. In
Figure 4-10, the upconverter output is reading +57.06dBmV, which is within the correct range.