4-5
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
These two sections describe the procedures necessary to use a spectrum analyzer. You may also use a
signal level meter that has the ability to measure the average power level of digitally modulated carriers,
as well as a QAM analyzer. Some instruments to perform these measurements include:
•Acterna SDA-5000 w/Option 4 (http://www.acterna.com)
•Agilent 8591C, N1776A, 2010 or 3010 (http://www.tm.agilent.com)
•Sunrise Telecom AT-2000RQ, CM1000 or CR1200R (http://www.sunrisetelecom.com)
•Telsey DMA-120, DMA-121 or DMA122 (http://www.telsey.it)
•Trilithic 860DSP w/Option QA1 (http://www.trilithic.com)
If you complete these measurements using one of the previously mentioned options, your downstream
signal can be verified as correctly configured and it can assist you with troubleshooting your network
later on.
If you want to measure the downstream RF signal using the spectrum analyzer channel power option,
proceed to the following section, “Measuring the Downstream RF Signal Using the Channel Power
Option on a Spectrum Analyzer.” If you want to measure the downstream RF signal using CATV mode,
proceed to the “Measuring the Downstream RF Signal Using CATV Mode on a SpectrumAnalyzer”
section on page 4-11.
Measuring the Downstream RF Signal Using the Channel Power Option on a Spectrum Analyzer
The following sections describe how to measure the downstream RF signal using the channel power
option on a spectrum analyzer:
•Measuring the Downstream IF Signal at the CiscouBR7225VXR Router, page 4-5
•Measuring the Downstream RF Signal at the Upconverter Output, page4-7

Measuring the Downstream IF Signal at the Cisco uBR7225VXR Router

Note Refer to the user guide that accompanied your spectrum analyzer to determine the exact steps required
to use your analyzer to perform these measurements.
Step1 Connect a spectrum analyzer to the downstream connector on a Cisco cableinterface line card installed
in a CiscouBR7225VXR router.
Step2 Turn the power switch on the spectrum analyzer to the ON position.
Step3 Set the spectrum analyzer to view the downstream intermediate frequency (IF) signal with a center
frequency of 44MHz for a North American headend or 36.125 MHz for a European headend.
Step4 Set the span to 10 MHz. Your analyzer should display a signal similar to the one shown in Figure4-3.