Chapter 9: Upstream Cable Access Modules (UCAMs)
STANDARD Revision 1.0 C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved. 309
Modulation Profiles: Default and User-defined
Modulation profiles define the following parameters:
Modulation Type (QPSK, 8QAM, 16QAM, 32QAM, 64QAM, 128QAM)
Differential Encoding On/Off
Preamble Length
Reed-Solomon FEC Correctable Bytes (T)
Reed-Solomon FEC Information Bytes per Codeword (k)
Scrambler SEED
Maximum Burst Size
Guard Time Size
Shortened Last Codeword On/Off
Scrambler On/Off
ATDMA Reed-Solomon Interleaver Depth (Ir= 0 for Dynamic Mode, = 1 for off, = 2 through floor (2048/(k+2T)) for Fixed
Mode
ATDMA Reed-Solomon Interleaver Block Size
(Br= 2*(k+2T) through 2048)
Preamble Type
SCDMA Spreader On/Off (default = off for IUCs 3 and 4, on others)
SCDMA Framer Codes Per Subframe (selected so that the Subframe holds 1 FEC codeword)
SCDMA Framer Interleaver Step Size (default =3)
Trellis Coded Modulation (TCM) On/Off (default = Off)
In the CMTS there is a default modulation profile that is automatically created for the user: modulation profile 2.
Modulation profile 1 supported a previous version of the upstream CAM and is no longer available. CMTS users are free to
create user-defined modulation profiles.
User-defined modulation profiles provide a shortcut method for a user to easily create modulation profiles just by
specifying the desired channel type and modulation rate. User-defined modulation profiles can be assigned to any number
from 3–n to create a new profile. (It is recommended that you do not use 2; otherwise you will overwrite the default). If
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