Hi
I've had FTTC for a couple of months now with an unlocked HG612 modem and I keep an eye on the line. I was the 2nd person on the cab and started off with a margin of 10.8, this settled to around 9.5 over the weeks presumably as others have joined, but it didn't fluctuate in the short term and would chart as almost a flat line.
I get max 80/20 sync speeds.
So SNR margin didn't vary much except by a 0.1 or 0.2 when monitored. My line is all underground from the cab and ADSL was pretty much the same, a stable SNR margin.
Recently I noticed that SNR was going back up to 10.8 then a few seconds later dropping back down again so I set dslstats running and get the constant repeatable fluctuation as attached. Errors follow the same pattern, with an increase of errors on the lows. Line is not interleaved at the moment.
While this isn't causing me a problem yet as I still have margin, I'm thinking at some point as more crosstalk takes hold this flapping of SNR could start having a negative effect, it might also cause the DLM to switch to interleaved as errors creep up because bit-swapping can't cope with the swinging SNR and lowering margin due to crosstalk.
No noise on the telephone line.
Just wondered if anyone recognised the pattern? My first thought was perhaps it was another VDSL connection that was having sync problems, so I was seeing cross-talk as this other line attempted to sync, then it failed, cross-talk goes and SNR pops back up, it then tries to re-sync, cross-talk knocks it down again, however this has been going on for 3 days now constantly all the time.
Probably nothing I can do about it, just a frustration of the technology. Oh to have a fibre connection and not have to worry about degrading line conditions or noise.
Regards
Phil