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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
Connecting and Configuring the Downstream
Figure 4-8
Phase Noise Measurement
Note
Notice that the total channel power (across 6 MHz) does not change between the modulated carrier and
the unmodulated continuous wave (CW) carrier.
Step 6
Zoom in on the CW signal (the center 6 MHz in
Figure 4-8
) by reducing the span on your spectrum
analyzer from 12 MHz to 6 MHz.
Step 7
Change the resolution bandwidth from 100 kHz to 1 kHz so that the sweep time slows to around
18 seconds. Be sure, however, that you retain the 1-kHz video bandwidth and the same center frequency.
Your analyzer should display a signal similar to the one shown in
Figure 4-9
.
Figure 4-9
6-MHz Channel Band
Note
Your signal might show additional signals or “spurs” similar to the ones displayed in
Figure 4-9
. These
are characteristics of the modulator in this mode and do not affect downstream data transmission.
Содержание 7246 - uBR Router
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