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[Weaver]

I have noticed that my line #2 is also showing cyclic upstream SNRM variation, but a different waveform and a much smaller amplitude, only ~1dB high. Times are UTC, day is 2019-04-22



Line #2, despite the number, is the most recently installed one, installed last summer.

* What on earth is the short duration high state period - ~5:05pm - 7:25pm UTC - all about ?

[j0hn]

To my eyes the time period you mention is when the line is operating normally, at the 6dB target.
It's the 1dB drops between 11am - midnight that are when some form of interference is present.

What causes the 1dB drops in upstream is anyone's guess.

[Weaver]

John - you make a very good point. I was thinking about the shape, it’s not just a simple high/low waveform as for line 3. So maybe some device got turned off for that period. Will see what happens on other days.

Right now line 2 is ‘low’ @ upstream SNRM of 5 dB, and attenuation is 41.2 dB, power is 12.4 dBm. So the question is: is this a variation of noise or attenuation or output power? I’ll check when the graph goes high and compare.

With line 3 I think the conclusion was that it has to be a line fault [?] (was that agreed?) because it is attenuation that goes up and down, not noise, so the question is whether or not this is similar.

[burakkucat]

With line 3 I think the conclusion was that it has to be a line fault [?] (was that agreed?) because it is attenuation that goes up and down, not noise, so the question is whether or not this is similar.

Without looking back through the earlier posts, I believe that was my conclusion . . . the attenuation of the physical metallic pathway should not change in such a fashion.

[Weaver]

Even weirder waveform. This is not about a 24 hour period at all.

[DiggerOfHoles]

This is my cordless phone charging it's battery left. Right not. DS SNR.

[DiggerOfHoles]

What on earth is the short duration high state period - ~5:05pm - 7:25pm UTC - all about

Both patterns look like two shifts going to work and turning something on.

At 7km your line could pass a lot of noisy things on way to exchange.

[burakkucat]

At 7km your line could pass a lot of noisy things on way to exchange.

Except for the majority of that length it is just moorland, overlying granite bedrock. 

[DiggerOfHoles]

Do the Belgians care?

[Weaver]

This has possibly returned - it is a bit soon to tell. But there is a step 1.6 dB high showing in the most recent graph:



See https://forum.kitz.co.uk/index.php/topic,23742.msg401882.html#msg401882

[Weaver]

Line 2 - Tue 2019-09-10 to Wed 11. It seems that line 2 has now become the new line 3. Compared with how it was a month ago, now the waveform is regular, with a 24 hour period and 1.5dB height

[johnson]

I don't think I can offer any insight into the step changes in SNRM you have, other than saying I have experienced similar in my downstream and have no explanation. Lights switching on? Some sort of construction tools being used?

But I do enjoy seeing graphs from my firmware! 

V2 is coming, but I need everyone to be able to build it.

[Weaver]

Your firmware has been absolutely invaluable during the month of hell recently. It has shown exactly how bad and how widespread the problems have been.

As for cutting out some candidate explanations: it only applies to one line and not to others; it’s upstream-only.

I need to look at the numerator and denominator of a ratio here, I think, and I have been lazy in not doing this earlier in this case. I need to look at the attenuation, power output and the noise level in the high and low parts of the square wave once more. If we assume for the moment that it is not the case that the output power of a transmitter is going up/down, then either the attenuation could be going up/down or the absolute noise level could be going up down. For the former, I would assume a change in resistance due to a ‘semi-contact’ make/break - I don’t have the words I need here. For the latter, interference would seem more likely, but then we are stuck with explaining how it can only be one line.

Since line 2 seems to have taken on the upstream-waveform of line 3, while line 3’s upstream has been cured, I do wonder if someone possibly swapped E-sides when they fixed the recent month of hell. Would that be a possible candidate explanation?

[burakkucat]

Since line 2 seems to have taken on the upstream-waveform of line 3, while line 3’s upstream has been cured, I do wonder if someone possibly swapped E-sides when they fixed the recent month of hell. Would that be a possible candidate explanation?

We don't know if you now have four lines, divided into D-sides & E-sides, or just one line with a D-side & an E-side plus three EO lines. However we do have a strong hint that the fourth, latest, line you had installed has "taken" an E-side from one of the two cabinets (on the A87, at Harrapul (I hope I have spelt the name correctly)) for its deployment.

However pair swapping does seem to be indicated by your latest observations. 

[Weaver]

That’s a good point. Line 2 is the latest, and has an E-side and indeed we don’t know about the others, I shouldn’t have made that mistake.

Yes, it could be taken as evidence for pair-swapping; line 2 became like the new line 3, but also more significantly, line 3 changed; its troublesome behaviour went away. So that suggests line 3 also has an E-side now, no?