Chapter 8: Downstream Cable Access Modules (DCAMs)
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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This feature ensures that on a mixed mode port the 64-QAM channels operate at an RF power level that is 6 dB lower
than that of the 256-QAM channels on the same port.
When a port enters mixed modulation mode, the CMTS issues a notice to the user that 64-QAM channels are operating
at 6 dB less than the stated level.
If a port having only 64-QAM channels becomes a mixed modulation port by the addition of a 256-QAM channel,
whether that channel is added to the existing channels or is a 64-QAM channel reconfigured to be a 256-QAM channel,
then the RF power level of the existing 64-QAM channels is unchanged but the RF power level of the newly added 256-
QAM channels is that of the 64-QAM channels plus 6 dB.
If a port having only 256-QAM channels is converted to mixed modulation mode by adding a new 64-QAM channel or
by converting an existing channel to 64-QAM, then the RF power level of the existing 256-QAM channels on that port
remains unchanged and the RF power level of the 64-QAM channel(s) is 6 dB less than that of the 256-QAM channels.
If a port ceases to be in mixed modulation mode and all the remaining channels are using 64-QAM modulation, then
the power level of these 64-QAM channels does not change.
If a port ceases to be in mixed modulation mode and all remaining channels are using 256-QAM modulation, then the
power level of these channels does not change.
This feature does not violate the power level requirements of the DRFI Spec, which states that the highest channel
power on a port is used as the reference level against which all parameters are specified.
NOTE: power levels measured by the C4 CMTS are specified to be within 2 dB of the stated level.
Also, there are no new or modified CLI configure or show commands for this feature (Annex A Mixed Modulation per F-
connector).