The CVC pertains to secure downloads of firmware to cable modems. To understand this, you will want to read the BPI specification, starting on section 9.1, page 77.

Sorry that I don’t have primers on these yet. I’ve guess you’ve given me a number of topics to write on, however I’m deep into a downstream and upstream bonding impairment research that I hope to get a few articles out on soon.

-Brady

DOCSIS 2.0 and 3.0 did add additional modulations to the upstream. You will now find 8-PSK, 32-QAM, 64-QAM and 128-QAM with Trellis Code Modulation (TCM). 8-PSK, 32-QAM and 128-QAM w/TCM are rarely used because they do not offer substantial data increases over the standard modulation of 16- and 64-QAM.

A lot of plants have migrated to 16-QAM successfully and are in the process of determining if the RF plant can support 64-QAM. There are a number of factors to look at including noise, group delay, micro-reflections, laser clipping, etc.

Keep in mind that 16-QAM only need 18 dB MER while 64-QAM needs 24 dB MER. So the plant must be in a lot better shape.

-Brady

Wanted to understand the reason behind having QPSK or 16QAM only for Upstream while we have 64 or 256 QAM for Downstream channels.

Also it would be great iof you could point me to an article which explains all the fields of a CM configuration file.
I need to understand significance of fileds like MIC, QoS, CVC data etc..

One more query,

Why do we have only QPSK or 16 QAM for upstream when we are using 64 or 256 QAM for downstream.

Can you also point me to an article/link which explains each field in CM configuration file….