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[burakkucat]

Is it possible to get such a massive impact only because of changing the dielectric constant? I can't believe this.

The change in "dielectric constant" would be minuscule^* and certainly not sufficient to account for what is being considered.

* Minuscule but measurable in a laboratory environment.

[Weaver]

I defer to Burakkucat, I hadn't looked it up. And thirty four years since I did electromagnetism II was a long time ago. :-)

[lloyd]

Is it only those with an overhead feed who are seeing this?

[NewtronStar]

There should be small junction box attached to your pemises from here the drop wire enters your premises, if there is water getting into JBox this will cause problems it depends where its situated.

If it's under the eves then it's unlikely. if the junction box is mounted say to lower exterior wall and exposed to elements (not sealed) then it's possible water is the cause and being a small box the dry out period would be short.

This is my hypothesis.

[burakkucat]

Until such time as the cause can be positively identified, I would prefer to file this effect under the "Unknown" heading. 

[NewtronStar]

Until such time as the cause can be positively identified, I would prefer to file this effect under the "Unknown" heading. 

That works for me it's been filed away as morphium 2015 under section Broadband-files it can only be opened by agents mulder and scully 

[lloyd]

NS, I  don't have a jb outside my house.

[JGO]

Is it possible to get such a massive impact only because of changing the dielectric constant? I can't believe this.

The change in "dielectric constant" would be minuscule^* and certainly not sufficient to account for what is being considered.

* Minuscule but measurable in a laboratory environment.

Until the shape was changed to a tube, flat 300 ohm ribbon feeder used to absorb  sufficient water in the polythene dielectric to cause serious mismatch and loss problems.

IF the configuration was largely air spaced such that a drop of water sensibly fills the concentrated electric field region between the wires  I would expect a worse effect. Certainly it looks as if something was overlooked in the design/installation !

[marjohn56]

Is it only those with an overhead feed who are seeing this?

We'll have to do a survey, hands up everyone who sees this effect

[krypton]

There should be small junction box attached to your pemises from here the drop wire enters your premises...

Any water ingress at my end of the wires is impossible because they are terminated inside the building. Every engineer checked the wiring in the junction box at the other end and confirmed it as waterproof. The overhead wires were replaced only a few years ago so the insulation should still be intact.

Even with only one third of the max attainable in upstream direction the SNRM sometimes drops to zero.
More ideas where or how to find the fault location?

[burakkucat]

Any water ingress at my end of the wires is impossible because they are terminated inside the building. Every engineer checked the wiring in the junction box at the other end and confirmed it as waterproof. The overhead wires were replaced only a few years ago so the insulation should still be intact.

I am finding it difficult to think of any sort of scenario which would account for your observations. 

Most puzzling. 

[lloyd]

I have to agree. Very strange. Is there a clue in that us is affected more than ds? Presumably this is just because us uses the higher frequencies?

[burakkucat]

Is there a clue in that us is affected more than ds? Presumably this is just because us uses the higher frequencies?

Huh? US higher frequency than DS? 

From left to right (low to high frequencies) it is US then DS for G.Dmt, ADSL2 & ADSL2+ and US then DS then US then DS, etc, for VDSL2. Or am I looking from the wrong side of the graphs? 

[Edited to correct the subject line.]

[NewtronStar]

The way i would start to investigate this is by looking at the Tones/Bitloading during the time of each event and see if some of the DS/US tones numbers are being effected by a source.

Morphium DS/US SNRM has an ongoing square wave effect over a 3 day period the timing of each dip & rise looks interesting.

[marjohn56]

Well I'm going to throw a spanner into the works. Yesterday the heavens opened and it p****** it down. If you look at my SNR there was an effect, about 2db!

Now, either the line has magically fixed itself, or the effect is not caused by the rain, or if it is, it must be to do with the type of rain or which way the the wind is blowing at the time, a bit like the wrong type of snow!

I'm now completely baffled.

Would the mod like to change the subject of this thread, as was pointed out earlier, I had an issue with my D & U keys and typed them the wrong way around, it's the US that's affected most, not the DS.