Reverse Path; Reverse Path Signal Routing - Cisco GS7000 Installation And Operation Manual

Theory of Operation
Stage
1
2
3
4
5

Reverse Path

Reverse path refers to signals received by the node from the cable distribution network. These signals are
amplified in the node and returned to the headend optically through the fiber portion of the network.

Reverse Path Signal Routing

Node reverse path signal routing functions are described below.
Stage
1
2
3
4
5
Description
Optical signals from the hub or headend are transported to the Remote PHY device in the node.
The Remote PHY module detects the signal on the optical carrier applied to it and outputs an
electrical RF signal to the node Optical Interface Board (OIB).
The RF signal travel across the OIB and cables to the launch amplifier.
The forward amplification path in the RF amplifier module is composed of one common input
amplification stage, HPFT and interstage amplification stage in series followed by a 4-way power
divider. Each output of the power divider feeds a power doubler output amplification stage. This
topology provides four node output ports with one common input signal source.
The forward amplification path in the RF amplifier module also contains trimming, thermal
compensation, attenuation, equalization, and filtering circuitry.
Description
Reverse path RF signals are applied to node output ports.
The RF signals from ports 1 and 2 are combined as well as the signals from ports 4 and 5. Each
set of combined ports are amplified independently in the RF amplifier module. Segmentation or
combination of these reverse signals is set by the switch located on the launch amplifier module.
Each of the reverse amplification paths in the RF amplifier module also contains attenuation,
trimming, filtering, and RF On/Off switch circuitry.
The pairs (ports 1 and 2, ports 4 and 5) of reverse path signals can be combined or keep separate,
depending on the setting of the reverse segmentation switch. They are then routed to the OIB.
The RF signals travel across the OIB to the Remote PHY Device. The Remote PHY Device
converts the RF signals to optical signals which are transmitted through the fiber portion of the
network back to the hub or headend.
Cisco GS7000 Super High Output Intelligent Node Installation and Operation Guide

Reverse Path

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