Cisco GainMaker Optoelectronic Node 1GHz with 65 86 MHz Split Installation Guide
Reverse Balancing the Node with the Enhanced Digital Return (EDR) Modules
Reverse Balancing the Node with the Enhanced
Digital Return (EDR) Modules
Introduction
This section explains the reverse balancing procedures for the node using digital
reverse modules.
When balancing the reverse path, refer to your system design print for the required
When balancing the reverse path, refer to your system design print for the required
reverse signal level. Use appropriate padding and equalization to provide proper
signal level to the reverse transmitter.
CAUTION:
Never attempt to reconfigure the unit beyond its normal setup.
Never attempt to reconfigure the unit beyond its normal setup.
Changes to the node configuration may cause degradations that affect
its performance. Do not use digital carrier measurement to set up the
forward or reverse paths. Familiarize yourself with your cable system
specifications before performing the setup.
The 2:1 EDR technology is designed to carry reverse path signals from 5 MHz to 42
MHz. This technology digitizes the analog input and then sends a high-speed serial
bitstream over fiber to a digital receiver at the link end. By converting the analog RF
band to a digital format, two full bandwidth digital links can be multiplexed
together over the same fiber and recovered at the receiver.
There are various test equipment combinations that enable proper balancing of the
There are various test equipment combinations that enable proper balancing of the
reverse path. Regardless of the type of equipment used, the balancing process is
fundamentally the same. A reverse RF test signal (or signals) of known amplitude is
injected into the RF path at the RF input of the node. The reverse transmitter
converts the RF test signal(s) to an optical signal and transmits it to the headend (or
hub site) via fiber optic cable. At the headend, the reverse optical receiver converts
the optical signal back to an RF signal that is then routed out through the receiver RF
output. The amplitude of the injected test signal must be monitored at the receiver
output, and compared to the expected (design value) amplitude.
Method of Generating and Monitoring Test Signals
The reverse RF test signals that are injected into the reverse path of the RF launch
amplifier being balanced may be generated by the following method.
Multiple CW signal (tone) generator
Reverse sweep transmitter
The amplitude of the received test signals at the output of the reverse optical
receiver in the headend or hub may be measured and monitored using the
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