Have a look at the notch in the SNR at around tone550 ... and also at 1100. The bit loading at 2bits/tone on low frequencies is very low ...

I see, I noticed that in your reply. That does indeed look odd, I'm not sure how I could report this to BT though given my connection is stable today now interleaving depth has increased and that I'm not meant to even be able to access this sort of data anyway. If anyone has any ideas I'd welcome them.

Would it be worth me doing a line fault check via the BT website to see if it can pick something up?

In reply to a post by Ixel:

I also found a reply on another forum to my problem quite interesting, but I'm still unsure whether I should call BT Business and report a possible fault. With interleaving depth things seem stable now, haven't had a problem all day today but it has also been warm and sunny. For the past few days where I've been experiencing problems it has been raining and cooler. Anyway the reply I'm mentioning is at http://business.forums.bt.com/t5/Broadband-and-inter....

Any other suggestions or what not feel free to add, much appreciated .

If only all this wasn't such a secretive black art...........

I have well documented the FACT that my connection (when it was having fairly recent problems) performed & was far more stable during wet & cold weather, the problems only appearing during warm & dry weather.


Work that one out !!!


EDIT:

Just for curiosity, were you originally supplied with the ECI modem & the HG612 you are using to access the stats is an "addition"?

Edited by deleted (Wed 13-Jun-12 19:21:57)

I see, very strange.

No, I was supplied with the HG612 as the only modem, not an ECI variant.

Edit: I'm wondering if my master socket has a problem, other than anything external it's the only thing I haven't tested internally as I don't have a spare one to replace it, only standard ADSL microfilters or the ADSLNation faceplate, which I imagine will make the line ten times worse if I tried?

Edited by Ixel (Wed 13-Jun-12 19:40:33)

In reply to a post by Ixel:

I see, very strange.

No, I was supplied with the HG612 as the only modem, not an ECI variant.

We have been led to believe that the modem & the DSLAM should be matched for compatibility purposes.

From your band plan details we are able to confirm you are connected to an ECI DSLAM.

Other modems will work with the ECI DSLAM, but we have also seen "notches" at lower frequencies as mentioned by MHC when using "unmatched" modems..
I don't think that is a major issue, but you never know........

Edit: I'm wondering if my master socket has a problem, other than anything external it's the only thing I haven't tested internally as I don't have a spare one to replace it, only standard ADSL microfilters or the ADSLNation faceplate, which I imagine will make the line ten times worse if I tried?

I recently diagnosed a faulty OR supplied VDSL2 faceplate by using a standard ADSL dangly filter plugged directly into the actual test socket (OR VDSL2 faceplate completely removed).
Instantly, my connection's SNRM levels stabilised & I was able to use the phone again without causing a disconnection.

So, yes. by all means try out an ADSL microfilter. I can assure you that they do work O.K. wiith FTTC connections. You MAY even see an immediate improvement.

BT OR are currently trialing microfilters with a view to eventually making FTTC a self-install service, pretty much like a standard ADSL connection.

In reply to a post by Bald_Eagle1:

So, yes. by all means try out an ADSL microfilter. I can assure you that they do work O.K. wiith FTTC connections. You MAY even see an immediate improvement.

BT OR are currently trialing microfilters with a view to eventually making FTTC a self-install service, pretty much like a standard ADSL connection.

They "work" but the ADSL filters are not wonderful at the higher frequencies on 17A and may present strange impedances which can affect the signal with higher attenuation or distortion of phase.

Could be worth seeing if it changes that notch!

Another update.

Call me paranoid but the line is becoming worse again, and this time it's evident.

Look at the latest line graphs and see how erratic the SNR is becoming, up and down like a yoyo! http://i.imgur.com/jvipy.png

I'll change the faceplate shortly and hope to see improvements, otherwise it will have to be flash back to locked firmware and a phone call to BT tonight, assuming business support work at these hours.

Edit: With the current state of the connection I'm barely able to get a speed of 8Mbps through anywhere except the BT speedtester site which claims I have about 50Mbps or so throughput on the DL.

Edited by Ixel (Wed 13-Jun-12 22:49:18)

Still early days! You don't strictly need a filter at all. For maximum line liberation, maybe go commando and plug the Huawei into the test socket behind the faceplate.

cheers, a

Switched faceplate to ADSLNation XTE-2005, but this improvement could mean anything at the moment in my view. The connection always fully restores after reconnecting the RJ11 cable for a while, then degrades to a point where it becomes virtually unusable.

Line State
---
Just before I changed faceplate: http://i.imgur.com/aRkuJ.png
After I changed faceplate: http://i.imgur.com/nfRSi.png

Considerable difference with the return of the lower tones. Wonder if this will last or whether it was indeed a faulty faceplate that Openreach installed.

Input anyone?

You are still getting an impressive 80/20Mbps throughput. The absolute maximum throughput for that particular Openreach VDSL2 service.

In the second of those two sessions that you have graphed, the throughput is achieved by a different bit loading profile. Loading is higher in subcarriers further up the bandplan. Since you're still getting 80Mbps, it's not cause for complaint.

The spectrum management of the ECI DSLAMs, is distinct from the management in the Huawei DSLAM. The ECI seems more dynamic - as we can see here. Not a fault. More of a feature, perhaps.

During the negotiation for the second session, the background noise in downstream band D3 was measured as slightly lower than in the first session. Consequently, the DSLAM controller decided to utilise the extra SNR in those tones by loading them slightly more.

That would provide relief on the lower tones, which could be an advantage: it is likely to reduce crosstalk for ADSL (and other VDSL2) subscribers whose broadband service is provided in the same D-side cable bundles as your own.

Otherwise, the two sessions look very similar. In particular, the line attenuation characteristics - evident from both the Hlog graphs and the raw numeric data - are essentially unchanged between sessions.

The notch (or trough) in the SNR graph (and in the bit loading graph), centred on DMT#500, is a result of that spectrum management. The notch is not caused by line noise since that would manifest in the QLN graph.

On the basis of those graphs, I would be very happy with that service. If you're experiencing connectivity issues, that's perhaps caused by a problem at a higher layer of the communications stack.

cheers, a

Edited by deleted (Wed 13-Jun-12 23:49:00)