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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

Connecting and Configuring the Upstream

This “X-level” test point measurement will be different for every fiber node in the HFC network until you adjust the attenuation on the upstream. You must adjust the attenuation so that this measurement is the same on every fiber node. If you change a receiver or a transmitter at the fiber node, or if you unplug a connector and plug it back in, you must recheck this amplitude measurement. Figure4-24 shows how three distribution network “X-level” test points connected to the same upstream port are all calibrated to +10 dBmV using different attenuators.

Figure4-24 Calibrating Multiple “X-level” Test Points Connected to One Upstream Port

Figure 4-25 shows how three distribution network “X-level” test points connected to the three different upstream ports are all calibrated to +10dBmV using different attenuators.
Cisco
uBR7225VXR
Downstream
271677
Upstream
0 dBmV
3 dB
attenuator
3 dB
attenuator
3 dB
attenuator
40 dB
attenuator
3 dB
attenuator
8 dB
attenuator
21 dB
attenuator
Cable
modems
+48 dBmV
+31 dBmV
+42 dBmV
+50 dBmV
+46 dBmV
+49 dBmV
+58 dBmV
4-way
splitter
X
X
X
+10 dBmV
+10 dBmV
+10 dBmV
To downstream
forward test point
on laser transmitter
+13 dBmV
+18 dBmV
+31 dBmV
Reverse optical
transmitter
Optical
receiver Fiber-optic
cable Distribution
network
+17 dBmV
Reverse optical
transmitter
Optical
receiver Fiber-optic
cable Distribution
network
+17 dBmV
Reverse optical
transmitter
Optical
receiver Fiber-optic
cable Distribution
network
+17 dBmV
Modem transmit levels
Modem transmit levels
Modem transmit levels
Cable
modem
LH
C
Diplex filter