Noise margin on FTTC

I'd like some feedback from any telephony engineers on here as to what might be happening to my line. When the telephone line is active the downstream noise margin and max data rate nose dive. This doesn't happen all of the time so can be a bit of a pain when booking engineers. I have however captured it on video, you 'll need to increase the settings on youtube to make it readable.

https://www.youtube.com/watch?v=O-OMNvw_iew

Maybe a duff filter, or more likely a minor HR on the pair. Could even be something as simple as duff crimps in the cabinet. DLM knows you have a problem, looks like your target SNR is at 9db.

This isn't a self installed service is it ? Or maybe a poor installation by a contractor ?

No filtered face plate has been swapped out by Openreach unfortunately at the time the line wasn't misbehaving itself. I think I'll just have to ring BT and get another engineer booked.

I just thought I would test mine, I have a VDSL faceplate but when press the dial button the noise margin also goes down not a great deal, just from 6db to 5.3-5.4db ish. Is this a normal range or do I have the same issue as Metallifux?

checking mine as mine is 15.1db noise margin. Pick up the phone up and dialing it, the noise margin stay at 15.1db.

Lucky you, that must mean I have some sort of issue I guess.

Think I made it better, As per your recommendation of the MK2 faceplate, I replaced it back for the original and the noise went from 6.3db to 6 - 5.9db when I pressed dial so much better but still not like yours.

My three values stay the same, at 7.0dB.

Not necessarily. A small change can be expected - by initiating a call you are changing the impedance that load the filter, that will effect the apparent impedance of the filter as seen from the line which in turn will have an effect on the VDSL signal and noise. On some phone/filter/line combinations the net effect might be zero whereas on others it could be 1 dB or so. Changing the faceplate/filter has demonstrated this. Using the very old GPO style phones also causes a significant change in some cases.

The OP however, does appear to have a problem that needs sorting.

OK thank you MHC so nothing to worry about. In comparison to mine yes I think he has a problem.