Forward Path - Cisco GS7000 Installation And Operation Manual

Forward Path

Introduction
Forward path refers to signals received by the node from the headend. These signals
are amplified in the node and routed to subscribers through the cable distribution
network.
4-Way Forward Path Signal Routing
1.2 GHz GS7000 Node 4-way forward path signal routing functions are described
below.
Stage
1
2
3
4
5
6
Description
1310 nm or 1550 nm optical signals from the headend are applied to receiver
module 1 (and/or modules 2, 3, and 4, if used) in the 1.2 GHz GS7000 Node.
The receiver 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 signals travel across the OIB and cables to the Forward Configuration
Module (FCM). The FCM determines how RF signals from the different receiver
modules are routed to the four independent forward amplification paths in the
RF amplifier module. The 1X4 FCM splits the RF signals entering it equally
between the four forward amplification paths in the RF amplifier module.
Each of the forward amplification paths in the RF amplifier module is composed
of one input amplification stage and one interstage amplification stages in series
followed by a power doubler output amplification stage. This topology
provides one driven output port for each of the forward amplification paths in
the RF amplifier module, for a total of four driven node output ports.
Each of the forward amplification paths in the RF amplifier module also
contains padding, trimming, thermal compensation, equalization, and filtering
circuitry.
Node signal directors are present at two of the nodes forward output ports and
allow the signals at those ports to be redirected to the nodes auxiliary output
ports or split equally between the primary and auxiliary node output ports. In
this way, the node can be configured to have up to six output ports.

Forward Path

21