This info is very useful, many thanks.
There's some information on the Broadcom CLI here: http://wiki.kitz.co.uk/index.php/Broadcom_CLI
If you look at the graph, you'll see that Ian's choice of an snr value of 85 corresponds with a change in target SNRM of -1 dB, which is what he wanted.
Does anybody know if it's possible to offset the upstream target SNR margin in a similar way?
I'm tempted to have a play with the CLI and see, but not wishing to incur the wrath of the great god of DLM, I thought I would be a coward and ask first!
Cheers,
Bill