If it’s crosstalk would one expect downstream and upstream both to be affected ? - even though the amounts may not be the same.
Valid point ..... which is why I mentioned DSM. It does some weird and wonderful things when it comes to the upstream effects on the SNRM.
I promise you I have seen that stepping on my line several times which only affects the upstream.
Trying to look for the relevant graphs now is like trying to look for a needle in a haystack and this is where I miss MDWS.
Easier for me to find is the effect on my upstream SNRM is when one of my disturbers does a reboot of their modem because I see a distinct spike when scanning through thumbnails.... so I'll post those.
As expected both up and down are affected when they go off line. But look what will happen when they come back online - they have a slightly different mask which affects just my upstream SNRM. Sometimes it goes up and sometimes it goes down. Currently I'm sitting at 9.3dB. I'm quite used to seeing different upstream SNRM values now due to DSM changing power profiles.
I must admit though from my own past experiences, I am more likely to see the stepping effect if it is me who has performed the reboot.... but it is at its most obvious if we have both been knocked out of sync at the same time and my modem comes baak up before theirs. I see DSM trying to take some of my 'surplus / unused' SNRM in those steps. I'd need to do a lot more research into DSM to understand properly how it works... but even then I wouldn't have a clue what power profile openreach use... so for now I am just aware that its there and that Openreach are using it.. but since I have no control over it I see no point fretting.
Although saying that it has crossed my mind on more than one occasion if it would be possible to get into "power battles" with your neighbour
I'm not sure if BTw use DSM with their adsl MSANs - They are likely capable but I can't specifically recall anything being said about them using it for adsl.