Cisco Cisco 1 GHz GainMaker Amplifier インストールガイド
Balancing the Reverse Path
The amplitude and tilt 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 following.
Spectrum analyzer (when using a CW generator for test signals)
Signal level meter (when using a CW generator for test signals)
Reverse sweep receiver (when using a reverse sweep transmitter for test signal)
Communicating Test Results
The variance in relative amplitude and tilt of the received signal from desired
The variance in relative amplitude and tilt of the received signal from desired
(reference) may be relayed to the field technician via the following.
Radio, by a second technician in the headend or hub who is monitoring a
spectrum analyzer or signal level meter
A dedicated forward TV channel whose associated modulator has its video input
being generated by a video camera focused on the spectrum analyzer display
An associated forward data carrier (if using a particular type of reverse sweep
system)
If a portable reverse sweep generator with built-in forward data receiver is used to
generate the reverse test signals, only one technician is required to perform the
balancing. This type of system is becoming increasingly popular due to its ease of
use.
In this case, the sweep system includes a combination reverse sweep receiver and
In this case, the sweep system includes a combination reverse sweep receiver and
forward data transmitter, which is located in the headend or hub. The frequency
response characteristics of the received sweep signal, including relative amplitude
and tilt, are converted by the headend sweep receiver to a data format and
transmitted in the forward RF path as a data carrier by combining it into the forward
headend combiner.
The portable sweep generator or data receiver that is injecting the test signals into the
The portable sweep generator or data receiver that is injecting the test signals into the
reverse path in the field is simultaneously receiving the incoming data carrier via the
forward RF path, and converting it back to a sweep display which represents what is
being received by the headend unit.
While one technician in the field can monitor the received amplitude and determine
While one technician in the field can monitor the received amplitude and determine
whether it deviates from reference or not, any variation in amplitude required at the
output of the receiver in the headend would typically be accomplished by a second
technician in the headend, who is in communication with the technician in the field.
Note: When using a reverse sweep system such as this, be sure to consult the
Note: When using a reverse sweep system such as this, be sure to consult the
manufacturer's guide to determine proper headend combining and to ensure proper
telemetry levels.
To Prepare the Amplifier for Reverse Path Balancing
Complete the following steps for initial reverse path balancing.
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