Cisco GS7000 Installation And Operation Manual page 148

Appendix B
Enhanced Digital Return Multiplexing Applications
Balancing and Alignment
Follow these steps to reverse balance and align the node with EDR.
1 Refer to the reverse system design print on the RF amplifier assembly cover and
inject the proper level into the forward output test point of a port of the RF
launch amplifier with a reverse sweep transmitter or a CW signal generator. The
insertion loss of all forward output test points is 20 dB (relative to corresponding
port).
Note: For the location of the forward output test point of each port, see RF
Assembly (on page 59).
Important: To calculate the correct signal level to inject, add the reverse input
level (from the design print) to the insertion loss of the forward output test point.
Formula:
Reverse input + Insertion loss = Signal generator setting
Example:
Reverse input = 15 dBmV
Insertion loss = 20 dB
Result: Signal generator setting=15 dBmV + 20 dB = 35 dBmV
Note: The ADC full-scale (100%) level for a single CW carrier is +33 dBmV. This
is the level at which the ADC begins clipping.
Note: The reverse attenuator (pad) and reverse equalizer in the GS7000 Node is
selected during the reverse system design, and it is based on the drive level into
the digital module which is determined by system performance requirements,
type and quantity of return carriers, etc. Consult data sheet to determine proper
operational level.
2 Verify the level of the reverse output test point. This output level leaves the RF
launch amplifier via the coaxial cable to the multiplexing digital module input.
(Use an SMB connector to F-connector test cable.)
3 Have the person in the headend refer to the headend system design and set the
output of the receiver to the specified output level. See the instruction guide that
was shipped with receiver for setup procedures.
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