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[les-70]

    In case it is of some interest I thought I would post on progress with a new FTTC connection and related testing.  The connection is the first on the cabinet so I expect it to start good and then suffer increasing cross-talk.

    The install  (I have mentioned most of this in a related post but put it here as the starting point.)

 An  Openreach engineer came last Friday pm and seemed very capable.  He installed the filter and ECI modem, did work at the cabinet called the exchange a few times, and tested the sync etc but was not interested in the strange actual download speeds resulting.   In spite of a 80/20 sync throughput varied between 1 and 74mb/s    this continued over  the weekend and 1mb/s occurred quite often.

On the following Monday an email re another engineer visit came.  I phoned TalkTalk Business and I discovered that Openreach denied that I had had an install and denied that I am or can be connected to FTTC.  After a couple more calls to TTB technical support they finally agreed that Openreach must be wrong and TTB think the engineer may have omitted to sign the job off!  Just before the engineer finished at 16:30 the poor engineer had a phone call sending him some 50 miles and was not pleased - I guess this relates to his possible omission. The lack of that sign off seems to mean that TTB can't control my connection, they can detect it but most info is just missing apart from the PPOE login and identifying the connection as FTTC. Late on Monday the connection suddenly started to work as it should with a 72 -75 mb/s download each time tested    - I guess something was done somewhere. 

However the saga continued through the week with Openreach finally admitting that I am connected on the Wednesday when an install was done next door.   Openreach now on the Thursday say they will "complete" the order today!   I will update as this happens or does not............  I am told it has completed a week later to the hour however technical support are still unable to control setting related to my account - I suspect a continuing saga!!

  Interestingly I am told that the DLM initialization does not start till it is signed off. You never know what is really true when your told these things but it suggests that in principle it could be turned off.

  I hope nothing else goes wrong!!

[les-70]

    QLN noise as the only FTTC connection and then with just next door as well

   The impact of just one other connection was a shock to me    and dropped my attainable from 107 to 93 Mb/s  and the snrm dropped from 14 to 10.  Makes BT wholesale estimate of 80/20 for my line most unlikely as it would not take much more of this to take the snrm below 6.   I have long believed that I have a section of split pair but then again maybe this the reality of an just an average connection.  I attach the qln before and after my neighbor was connected. It is interesting to flash between them to see the exact change that a single other connection causes.  For info the HG612 latest blob 038 and the HG622 on Blob 033 both show qln and hlog for the upstream tones as well.

[burakkucat]

Looking at the tones between 1200 - 1950, I prefer the second graph rather than the first!

Regarding the acronym "blob". As used within the context of the Huawei HG612 firmware image, the term should be Binary BLOB. I will go even further and state that most persons making reference to a "blob" really should have used the phrase "firmware image".

[les-70]

  Have a look at the matching snr and see if you like that!  Most of the loss of spikes is to be expected if the cross talk signature is fairly smooth but I am also puzzled why some spikes don't still show.   The change in qln is an overall ratio of about 2.5 in power level. Assuming the cross-talk on different lines is incoherent with  each other I reckon about another similar 6 connections will get me to 6db at 80Mb/s.  I take comfort in it needing (I think!!!) about 40 similar lines to reduce the sync to 60mb/s.  That  would be more than enough do me fine as to be honest I never found much wrong with my old asdl2 speeds - just could not resist a new thing to play with!

( I hope the cross-talk is incoherent between lines or the effect is much worse - no square root if remember correctly - if coherent its 2-3 more connection to 6db at 80 and only 6 more to 60)

[burakkucat]

Thank you for posting those corresponding SNR graphs.

As you say, the effect is clear to see. 

[Chrysalis]

to les-70, my line had similiar affects from 2 seperate single installs, I also suspected a split pair.  In private conversations with asbo he suggested to me tho that a split pair is very unlikely.  I have never managed to get a *'permanent' pair swap so I am still on the same pair.  But in my area there is supposedbly a fault on the tie pairs on my cabinet.

Also like yourself my crosstalk is most brutal on the lower tones, some other guys on here have commented that seems odd to them as they expect more crosstalk on weaker tones but your line mirrors mine with the effect (except yours is currently much less severe than mine).

* - reference permanent, I had a visit where my drop wire was replaced, I dont know if they also did a new pair on D side but I think they did and my sync went from around 71mbit to an attainable of around 120.  However it was temporary as the head openreach guy for my area overuled the engineer telling him to put my original wires back in place.

To barakkucat you seem knowledgable but never reply to my problem threads

[burakkucat]

To barakkucat you seem knowledgable but never reply to my problem threads

   b*cat hides.

[les-70]

  Chrysalis   Yes I also expected more cross talk at the higher frequencies. However I assume that the cross talk is attenuated much like the main vdsl signal and after attenuation the higher frequency cross talk is currently smaller than the noise floor with no cross talk. At least on my and from the sound of it your connection,

[Chrysalis]

that was how I always seen it also, but others see it a different way.

another theory was that my line was getting crosstalk from a longer line which only used the lower tones but I doubt that would be the situation with your neighbour.

[les-70]

 I believe a third line has now been enabled. The second one (taking mine as first) gave a 4db snrm drop and the third a 1.5 db drop.  As mentioned above I hope each subsequent drop gets smaller but they will vary in impact according to where they are.   Latest snr and qln attached.  I will wait until a few more seem to have connected before I post an update on this. 

[les-70]

   I happened to have TBB quality meter running when for while I put in the supplied ECI modem and noticed a difference in the TBB QM with it.

   I also have a unlocked ECI , that showed a snrm reduction of 3db compared with the HG612 - it does not encourage to me use it.

  The connection was being used quiet heavily at times.  The trace has the HG622 up till 10.00 ish, then the ECI until about 14:30. After that it is the HG612 with gaps later on when the router, and not the HG612 had reboots.

   I notice no dropped packets with the HG612, just few with the HG622 and a lot more drops with the ECI.   I am sure that it maters but it puts me more off the ECI.

[burakkucat]

. . . no dropped packets with the HG612, just few with the HG622 and a lot more drops with the ECI.

Perhaps I am interpreting the TTB "wotsit" incorrectly but I would have said no dropped packets with the HG622, a few with the HG612 but many dropped packets when the ECI B-FOCuS modem was deployed. 

[Chrysalis]

are you on a huawei cabinet?

[les-70]

It is an ECI cabinet hence my puzzling over the poor ECI modem performance.   Second I apologize for the small tbb qm picture, here is link to the bigger version.

     http://www.thinkbroadband.com/ping/share-large/73b85c4f3f4211b86082544dae641047-08-01-2014.png

  On the graph I think the red down is dropped packets  and the up spikes are just slow pings due to the connection being busy.  ISP congestion tend to raise the whole green and blue floor.

   As mentioned above after 14:30 there are two red block due to router reboots.  Note that the HG622 loss up to 10:00 is so small it is hard to see and it has some excuse for loosing a few as it is acting as both modem and router.

[les-70]

 For todays extra I turned off last night and applied my 301c to get a TDR. 

At the install I asked the engineer if he could do a TDR and his JDSU tester. He reported in his words "two potential issues are raised by tester" which he said "given the sync speed - did
not matter" and confirming Walters comment else where added "we can't open up all the junction boxes with potential issues unless there is major problem".  I suspect I may have got a
more sympathetic response had all the eventual cross talk also been present.

  I attach the TDR results before and after FTTC.  The one before has distances indicated on it both in the trace and my estimate of the actual distances to features.  The tester is
not calibrated and my distances may be off a bit.  There is no significant change in the traces apart from the loss of what I thought was the exchange, as it should with FTTC.

  It looks like the cab is a bit nearer than I thought if that is the final feature with FTTC. The other features between me and the cabinet can't be good and may be splits or bridged taps or just bad joints and gauge changes.