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. 222
Note: Each MAC domain must consist of channels from exactly one 16D CAM or one XD CAM and exactly one 12U or 24U
CAM. In other words, the MAC domain cannot include ports from more than one downstream CAM or from more than one
upstream CAM.
The 16D CAM hardware supports:
Sixteen 40 or 55 Mbps downstream channels (numbered 0-15 within the card)
For supported frequency ranges see Downstream Frequency Range (page 248).
Note: The 16D hardware supports downstream center frequencies up to 999 MHz, but for the best performance it is
advisable to go no higher than 960 MHz. The downstream maximum frequency must be set appropriately using the
following command:
configure cable freq-dsmax
Four RF block upconverters (numbered 0-3). The process of combining multiple carriers digitally and then upconverting
with a single block upconverter is referred to as RF block upconversion, and the group of carriers that is block
upconverted is referred to as an RF block upconverter group. Each RF block upconverter can support up to four
channels simultaneously.
Four downstream physical connectors (numbered 0-3) which are hard-wired to correspond to one RF block
upconverter each.
Primary Software Function
The primary software functions of the 16D CAM include:
Packetization, queueing, and scheduling of all downstream packets
Downstream channel bonding of flows
Creation of DOCSIS downstream SYNC messages
Combining of the digital representation of four single channels into a single wideband channel suitable for
upconversion
Conversion of the wideband digital signal into an analog signal and placement of this at a selected point in the CATV RF
spectrum
Support of a configurable modulation depth (64QAM and 256QAM) per RF block upconverter
Support for interleaver depth selection on a per port, block upconverter, F-connector or channel basis. (This applies to
Annex B only; Annex A has a fixed interleaver.)
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