No, you THINK a fault is developing because you have a slightly fluctuating noise margin and a few errors.

No loss of sync or noticable affect on throughput = no fault.

I know a fault is developing from past experience. Just curious, did you read what I said that noise is audible on the QLN test? Proves it.

Edited by deleted (Thu 09-Feb-17 10:59:29)

I'm not familiar with that particular graph system. I assume one line is downstream noise margin and one upstream. The red looks like normal overnight behaviour until approximately 10am when a noise source started. I don't understand why the green is often behaving differently but notice an earlier start to the decline followed by a small sudden dip at the same time as the red 10am one.

Does that time suggest anything to you?

The call your phone provider and raise a noisy line fault and request a visit from a telephony engineer

Not at all, nothing is causing this internally as everything's been checked.

It's not bad enough to start thinking about calling our friend out. Though, what I can't understand is that when the downstream SNR margin was lower there was less noise than there is now!

Edited by deleted (Thu 09-Feb-17 12:08:03)

What are the two colours please?

Oh, sorry. The downstream SNR margin is red and the upstream SNR margin is green.

Completely agree.

In reply to a post by WilliamGrimsley:

that noise is audible on the QLN test?

Be aware that a telephony "quiet line" test isn't normally abbreviated to QLN. The abbreviation usually goes with the modem's measurements prior to sync, and the graph that we can create from it.

The difference is that one applies to the audible spectrum, and the other applies to every bit of spectrum apart from the audible bit. On the first, you expect no noise. On the other, you expect noise.