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[aesmith]

Hi,

Over the past few months our DSL line downstream attenuation has gradually increased, from 54.5dB to now 57 or 57.5dB.   To my mind that's a fairly significant change, given that we're on a long line and need all the signal strength we can get.   The most recent change corresponds to the repair of a fairly major fault, with according to the OR guy something like a mile of cable being replaced.   Why would that have caused a worsening attenuation?   Thinner gauge cable, or just more joints in the line?

I suspect the answer is probably no, but is there anything that we can do over the medium/long term to resist this gradual deterioration of the line?   At the moment it seems like every time a fault is fixed the line gets reinstated to just a little bit lower quality than before the fault.

Cheers, Tony S

[kitzuser87430]

I presume, as you have not mentioned it, your synch rates are approximately the same, or have these decreased as well?

[konrado5]

Could you attach your old and new Hlog?

[aesmith]

Synch speed has dropped from around 4400 - 4500, down to only just over 4000.  In fact to keep it over 4meg to retain the 3.5meg profile, I have set the router target noise margin to 5.0dB.    So like for like, around a 12% drop in synch speed.

Will have a look for HLOG, hopefully snapshots are saved by DSL Stats on the PC.

[aesmith]

HLOGs attached, one from either 29th April as shown on the graphic, or from 8th May judging by the filename (was also saved in the 8th May directory).   At that time (either of those times) downstream attenuation was 54.5dB.

Second is from today, attenuation currently 57.5dB.

Looking back at the history on A&A, of course there tend only to be snapshots taken when there were issues, however it appears the biggest change came about when our pole was replaced.  Before 21st June it was 54.5 or sometimes 54 or 55.   On 21st June our line failed hard down for both DSL and PSTN ("dis in network"), a fault was logged and actioned but the line restored itself prior to the Openreach visit (which was a no fault found).  Just recently a neighbour mentioned that the pole had been replaced and I see that it's dated 21st June.   Attenuation on 23rd June and subsequent snapshots is 57.5 or sometimes 57.

By the way, you'd think if they're carrying out planned works that they'd say so when a fault is raised.

[konrado5]

It looks as longer line.

[William Grimsley]

Yes, it is longer, but how has this happened?

[konrado5]

Perhaphs there are thinner wires.
aesmith: could you attach also your old and new QLN?

[aesmith]

That was my first thought, when I thought the change coincided with the recent replacement of around a mile of the underground cable on the exchange side of our DP pole.  A small change in cable gauge or quality could have a big effect over that length.   However as said the change seems to correspond with when our DP pole, formerly flagged as unsafe, was replaced.   The infrastructor invoice is (I assume) and underground joint on the main cable, a new sheathed cable up the new pole, aerial cables over the road (for some reason two, even though only three houses are served).   I don't know if the aerial cable was replaced.   On our side of the road there's the other pole with I think our 5 pair armoured cable running to the top.   From that pole the armoured cable runs about 1/2 mile until the cable to our house branches off.

QLN attached.   Didn't seem to save yesterday, so one if from today and one from 8th May/29th April ...

[aesmith]

Any ideas?   I have a horrible feeling that there's nothing that can be done, unless possibly it reaches the stage where the line can't achieve the recorded FTR.    It does seem to stink that BT appears to have no obligation to even maintain current line quality in terms of DSL capability.

[konrado5]

The power output also affects on attenuation measurement. I had anomalous synchronization: SNR margin about 15 dB and higher power output. Then I've had other Hlog. I attach two Hlogs.

[aesmith]

Coincidentally around 25 minutes ago the line went down ..
 "BT Test xDSL Copper Test:Fail Line test failed report fault to OR.fail Line test failed report fault to OR. T108:FAULT - Dis In Network"

Now it's back up with 55.5dB attenuation, almost back where it was to start with.

[konrado5]

Is there any difference in power output?

[aesmith]

How would I tell that?   I'll attach HLOG and QLN from before and after today's resynch, but to be honest I don't know what I'm looking at on those plots.

[aesmith]

QLN