4-17
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
•
Agilent 8591C, N1776A, 2010 or 3010
(
http://www.home.agilent.com/agilent/home.jspx?cc=US&lc=eng
)
•
Sunrise Telecom AT-2000RQ, CM1000 or CR1200R
(
http://www.sunrisetelecom.com/products/cable.php
)
•
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 Spectrum Analyzer”
section on page 4-23
.
Note
An analog TV channel modulator with external IF loops is not suitable for use as a QAM digitally
modulated carrier upconverter. These units typically do not have the phase noise and linearity
performance levels required for 64- and 256-QAM digital signals, and they might cause degraded
performance and possible system failure.
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 Cisco uBR7200 Series Router” section on page 4-17
•
“Measuring the Downstream RF Signal at the Upconverter Output” section on page 4-19
Measuring the Downstream IF Signal at the Cisco uBR7200 Series 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.
Step 1
Connect a spectrum analyzer to the downstream connector on a Cisco cable interface card installed in a
Cisco uBR7200 series router.
Step 2
Turn the power switch on the spectrum analyzer to the ON position.
Step 3
Set the spectrum analyzer to view the downstream intermediate frequency (IF) signal with a center
frequency of 44 MHz for a North American headend or 36.125 MHz for a European headend.
Step 4
Set the span to 10 MHz. Your analyzer should display a signal similar to the one shown in
Figure 4-15
.
