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Close to exchange - very low sync speed

lexhamilton
Grafter
Posts: 47
Registered: ‎26-09-2010

Close to exchange - very low sync speed

I seem to have a very strange problem - I'm close to the exchange with a newly installed line, but sync speeds are way down on what I was expecting.
My expected line speed should be in the region of 7000k, but is now only around 2800k.
Attenuation and noise margin seem fine, and the Openreach engineer informed me that the line quality was very good when he installed the new phone line.
The distance to the exchange (that the phone line takes) is around 1000m, so I should be seeing sync rates of at least 7000k.
In diagnosing the issue, I've changed between routers (Thomson as supplied by PN) and a Netgear DG834G that used to sync at my old address (another few hundred meters away) at speeds in excess of 7000k.
An isolation test using only the master / test socket did not show any improvement in sync rates, which suggests the issue is not in the property, but between the exchange and house, or with some equipment at the exchange itself.
I did raise a fault with PN, and they are investigating - but no matter what I do, and when I connect I simply cannot get a sync speed higher than around 3000k (which means my IP profile is set to 2500k).
Now, the modem and phone are plugged into a microfilter connected to a new BT iPlate, and my attenuation and noise margin stay constant with the results I had in the test socket with just the modem (and nothing else connected).
Neighbors are getting speeds around 6000k and I barely see half that.
I've asked whether a lift and shift at the exchange could help, but still waiting on PN's response.
What is even more strange is the fact that the broadband availability checker (6th Jan) showed that I should get an ADSL max broadband line speed speed of 7000, but checking today, it shows that I should get an line speed of 2000.
What on earth could be going on?

21 REPLIES
Community Veteran
Posts: 38,460
Thanks: 1,031
Fixes: 62
Registered: ‎15-06-2007

Re: Close to exchange - very low sync speed

The only thing to do is let the fault process take its course.
Basically there is a very high level of noise on the line.
Did you try the quiet line test - dial 17070 option 2 and is there any noise
The 2000 expected line speed is because it is now working off what you are getting
lexhamilton
Grafter
Posts: 47
Registered: ‎26-09-2010

Re: Close to exchange - very low sync speed

That is an interesting observation - what is the figure that indicates high levels of noise on the line?  
If it's the noise margin, I thought that the 6db downstream value was ok.  For this figure is higher better?
I did try the quiet test (17070), and there is no line noise I can discern whatsoever.  Pops, crackles, snaps or other sounds all conspicuous in their absence.
I dug up some old stats from my last property (another 200m further from the exchange) and the router stats were similar, but I had a massively improved line speed.
The only difference is the attenuation (12 vs 15) with the noise margin being 6db (as I get here).
But I think you are right - have to let the faults process take it's course...
Community Veteran
Posts: 38,460
Thanks: 1,031
Fixes: 62
Registered: ‎15-06-2007

Re: Close to exchange - very low sync speed

With that attenuation and a 6dB noise margin your speeds should be much faster which indicates that there is noise  which is restricting the speeds in order to get a noise margin over it - if that makes any sense at all
lexhamilton
Grafter
Posts: 47
Registered: ‎26-09-2010

Re: Close to exchange - very low sync speed

Thanks Oldjim - I <think> I understand what you mean.
Would a better microfilter help, or does it possibly suggest line noise that I cannot filter or mitigate?
It's a real puzzle.
Community Veteran
Posts: 38,460
Thanks: 1,031
Fixes: 62
Registered: ‎15-06-2007

Re: Close to exchange - very low sync speed

The filter doesn't filter the broadband signal it filters the other signals so I am afraid not.
All you can do is wait impatiently for the fault system to ruin its course and BT Openreach do their stuff
198kHz
Aspiring Champion
Posts: 3,516
Thanks: 437
Fixes: 13
Registered: ‎30-07-2008

Re: Close to exchange - very low sync speed

Possibly a split pair? ie two 'A' legs or two 'B' legs instead of a proper A & B twisted pair.
Remember you are unique - just like everyone else
lexhamilton
Grafter
Posts: 47
Registered: ‎26-09-2010

Re: Close to exchange - very low sync speed

Quote from: Oldjim
The filter doesn't filter the broadband signal it filters the other signals so I am afraid not.
All you can do is wait impatiently for the fault system to ruin its course and BT Openreach do their stuff

Agreed - it seems to be going that way - will have to place faith in the the Plusnet faults process to get this rectified.
It's just irritating that moving to a newer place, closer to the exchange (which was a major factor in our purchase) and we get far lower speeds.
Will update if PN manage to solve.
Community Veteran
Posts: 1,412
Thanks: 4
Registered: ‎29-01-2009

Re: Close to exchange - very low sync speed

Quote from: lexhamilton
It's just irritating that moving to a newer place, closer to the exchange (which was a major factor in our purchase) and we get far lower speeds.

The router stats are reporting the opposite - that the old connection (with 12dB attenuation) has a shorter line length than the new property (at 15dB attenuation).
Kitz, at this page thinks the old line is 200m shorter.
It could well be that your line appears worse to the router because of whatever fault it has. But it could be that your street cabinet is now actually further away!
But either way, you should be able to get full ADSL1 speeds with either level of attenuation. I get 8128 with a value of 30.5dB.
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
jojopillo
Grafter
Posts: 9,786
Registered: ‎16-06-2010

Re: Close to exchange - very low sync speed

Hi lexhamilton,
Glad to see that one of the guys has managed to book an engineer for you. Let me know how the visit goes.
Jojo Smiley
lexhamilton
Grafter
Posts: 47
Registered: ‎26-09-2010

Re: Close to exchange - very low sync speed

@JoJo: Yes - we have an engineer booked, so very happy about that.  Thank you.
The one thing that I really do like about Plusnet is their focus on customer service.  Having a bunch of knowledgeable people, in the call center, online and in the forums really sets them apart.  I know problems like this are hard to deal with, but I am extremely happy that I'm dealing with people who know their stuff and (being part of BT) are able to take direct action.
It's really easy to complain about bad service, and not many people post when broadband works as expected (me included).  I'd rather deal with Plusnet than pretty much any other 'customer service'  company I can think of.  

Issue update:
I'd plugged the router into the test socket yesterday afternoon at about 1300, and have just grabbed the logs - it looks like there is a flurry of activity at about 0400 with LCP up and down - maybe this is a clue to the problem.
Sun, 2002-09-08 12:00:24 - Initialize LCP.
Sun, 2002-09-08 12:00:24 - LCP is allowed to come up.
Sun, 2002-09-08 12:00:28 - CHAP authentication success
Sun, 2002-09-08 12:00:37 - Send out NTP request to time-g.netgear.com
Mon, 2011-01-24 13:04:43 - Receive NTP Reply from time-g.netgear.com
Mon, 2011-01-24 13:05:07 - Administrator login successful - IP:192.168.0.3
Mon, 2011-01-24 13:04:06 - Router start up
Mon, 2011-01-24 18:32:53 - Administrator login successful - IP:192.168.0.5
Mon, 2011-01-24 19:39:19 - Administrator login successful - IP:192.168.0.5
Mon, 2011-01-24 20:36:13 - Administrator login successful - IP:192.168.0.5
Tue, 2011-01-25 00:19:10 - Administrator login successful - IP:192.168.0.5
Tue, 2011-01-25 04:00:41 - LCP down.
Tue, 2011-01-25 04:00:44 - Initialize LCP.
Tue, 2011-01-25 04:00:44 - LCP is allowed to come up.
Tue, 2011-01-25 04:01:44 - Initialize LCP.
Tue, 2011-01-25 04:01:44 - LCP is allowed to come up.
Tue, 2011-01-25 04:02:45 - Initialize LCP.
Tue, 2011-01-25 04:02:45 - LCP is allowed to come up.
Tue, 2011-01-25 04:03:46 - Initialize LCP.
Tue, 2011-01-25 04:03:46 - LCP is allowed to come up.
Tue, 2011-01-25 04:04:46 - Initialize LCP.
Tue, 2011-01-25 04:04:46 - LCP is allowed to come up.
Tue, 2011-01-25 04:05:47 - Initialize LCP.
Tue, 2011-01-25 04:05:47 - LCP is allowed to come up.
Tue, 2011-01-25 04:06:48 - Initialize LCP.
Tue, 2011-01-25 04:06:48 - LCP is allowed to come up.
Tue, 2011-01-25 04:07:48 - Initialize LCP.
Tue, 2011-01-25 04:07:48 - LCP is allowed to come up.
Tue, 2011-01-25 04:08:49 - Initialize LCP.
Tue, 2011-01-25 04:08:49 - LCP is allowed to come up.
Tue, 2011-01-25 04:09:50 - Initialize LCP.
Tue, 2011-01-25 04:09:50 - LCP is allowed to come up.
Tue, 2011-01-25 04:10:51 - Initialize LCP.
Tue, 2011-01-25 04:10:51 - LCP is allowed to come up.
Tue, 2011-01-25 04:11:51 - Initialize LCP.
Tue, 2011-01-25 04:11:51 - LCP is allowed to come up.
Tue, 2011-01-25 04:12:52 - Initialize LCP.
Tue, 2011-01-25 04:12:52 - LCP is allowed to come up.
Tue, 2011-01-25 04:13:53 - Initialize LCP.
Tue, 2011-01-25 04:13:53 - LCP is allowed to come up.
Tue, 2011-01-25 04:14:53 - Initialize LCP.
Tue, 2011-01-25 04:14:53 - LCP is allowed to come up.
Tue, 2011-01-25 04:15:54 - Initialize LCP.
Tue, 2011-01-25 04:15:54 - LCP is allowed to come up.
Tue, 2011-01-25 04:16:55 - Initialize LCP.
Tue, 2011-01-25 04:16:55 - LCP is allowed to come up.
Tue, 2011-01-25 04:17:55 - Initialize LCP.
Tue, 2011-01-25 04:17:55 - LCP is allowed to come up.
Tue, 2011-01-25 04:18:56 - Initialize LCP.
Tue, 2011-01-25 04:18:56 - LCP is allowed to come up.
Tue, 2011-01-25 04:19:57 - Initialize LCP.
Tue, 2011-01-25 04:19:57 - LCP is allowed to come up.
Tue, 2011-01-25 04:20:58 - Initialize LCP.
Tue, 2011-01-25 04:20:58 - LCP is allowed to come up.
Tue, 2011-01-25 04:21:58 - Initialize LCP.
Tue, 2011-01-25 04:21:58 - LCP is allowed to come up.
Tue, 2011-01-25 04:22:59 - Initialize LCP.
Tue, 2011-01-25 04:22:59 - LCP is allowed to come up.
Tue, 2011-01-25 04:24:00 - Initialize LCP.
Tue, 2011-01-25 04:24:00 - LCP is allowed to come up.
Tue, 2011-01-25 04:25:00 - Initialize LCP.
Tue, 2011-01-25 04:25:00 - LCP is allowed to come up.
Tue, 2011-01-25 04:26:01 - Initialize LCP.
Tue, 2011-01-25 04:26:01 - LCP is allowed to come up.
Tue, 2011-01-25 04:27:02 - Initialize LCP.
Tue, 2011-01-25 04:27:02 - LCP is allowed to come up.
Tue, 2011-01-25 04:28:02 - Initialize LCP.
Tue, 2011-01-25 04:28:02 - LCP is allowed to come up.
Tue, 2011-01-25 04:29:03 - Initialize LCP.
Tue, 2011-01-25 04:29:03 - LCP is allowed to come up.
Tue, 2011-01-25 04:30:04 - Initialize LCP.
Tue, 2011-01-25 04:30:04 - LCP is allowed to come up.
Tue, 2011-01-25 04:31:05 - Initialize LCP.
Tue, 2011-01-25 04:31:05 - LCP is allowed to come up.
Tue, 2011-01-25 04:32:05 - Initialize LCP.
Tue, 2011-01-25 04:32:05 - LCP is allowed to come up.
Tue, 2011-01-25 04:33:06 - Initialize LCP.
Tue, 2011-01-25 04:33:06 - LCP is allowed to come up.
Tue, 2011-01-25 04:34:07 - Initialize LCP.
Tue, 2011-01-25 04:34:07 - LCP is allowed to come up.
Tue, 2011-01-25 04:35:07 - Initialize LCP.
Tue, 2011-01-25 04:35:07 - LCP is allowed to come up.
Tue, 2011-01-25 04:36:08 - Initialize LCP.
Tue, 2011-01-25 04:36:08 - LCP is allowed to come up.
Tue, 2011-01-25 04:37:09 - Initialize LCP.
Tue, 2011-01-25 04:37:09 - LCP is allowed to come up.
Tue, 2011-01-25 04:38:09 - Initialize LCP.
Tue, 2011-01-25 04:38:09 - LCP is allowed to come up.
Tue, 2011-01-25 04:39:10 - Initialize LCP.
Tue, 2011-01-25 04:39:10 - LCP is allowed to come up.
Tue, 2011-01-25 04:40:11 - Initialize LCP.
Tue, 2011-01-25 04:40:11 - LCP is allowed to come up.
Tue, 2011-01-25 04:41:12 - Initialize LCP.
Tue, 2011-01-25 04:41:12 - LCP is allowed to come up.
Tue, 2011-01-25 04:42:12 - Initialize LCP.
Tue, 2011-01-25 04:42:12 - LCP is allowed to come up.
Tue, 2011-01-25 04:43:13 - Initialize LCP.
Tue, 2011-01-25 04:43:13 - LCP is allowed to come up.
Tue, 2011-01-25 04:44:14 - Initialize LCP.
Tue, 2011-01-25 04:44:14 - LCP is allowed to come up.
Tue, 2011-01-25 04:45:14 - Initialize LCP.
Tue, 2011-01-25 04:45:14 - LCP is allowed to come up.
Tue, 2011-01-25 04:46:15 - Initialize LCP.
Tue, 2011-01-25 04:46:15 - LCP is allowed to come up.
Tue, 2011-01-25 04:46:54 - CHAP authentication success
Tue, 2011-01-25 09:08:37 - Administrator login successful - IP:192.168.0.7

lexhamilton
Grafter
Posts: 47
Registered: ‎26-09-2010

Re: Close to exchange - very low sync speed

@WWWombat -
You make a very good point about the line length - I did check with the neighbours on their attenuation levels and they are around 14/15db.  Maybe the distance is closer, but line is longer as you suggest.
But you are right, I'd expcect much higher sync speeds based on those numbers.
I'm sure PN and BT will get to the bottom of this (and get it resolved).
lexhamilton
Grafter
Posts: 47
Registered: ‎26-09-2010

Re: Close to exchange - very low sync speed

Well, the Openreach engineer has just left, and instead of having a sync speed of <3000k, I'm now seeing the full 8128k.
Turns out there was a cabling issue between either the house and the junction box in the street or between that box and the cabinet.
All credit to the Openreach engineer for being methodical and getting to the bottom of the issue.
When he checked the line, he was seeing 8218k at the cabinet, but <3000k as the line went into the house.
Replacing the pairs in both sections got the speed up immediately, and then he's also added an Openreach faceplate with the separate ADSL and phone connectors.  The Netgear DG834g is now syncing 8128k which is great.
The engineer then called BT Wholesale who were going to amend the IP Profile, but that can take between 5 minutes and a few hours to take effect(when requested directly).
The slow sync speed was down to the cable pairs not being right - once that was changed, line speeds leapt up to the maximum they should be.
Glad to have this resolved - big thanks to all PN staff and also to Openreach.
lexhamilton
Grafter
Posts: 47
Registered: ‎26-09-2010

Re: Close to exchange - very low sync speed

One thing that I forgot to ask - how long should it take for my IP profile to lift from the 2500k it's set at currently?
The Openreach engineer said a few hours - or should I be waiting the standard 72 or so to get speed hike?

From what I can see here in the router stats, it looks like a pretty decent connection now - it doesn't look like there are errors, and the logs don't indicate that the router has lost sync or dropped a connection.
I understand that the line attenuation of 12db is pretty good (indicating a short distance to the exchange), but what about the noise margin?
Is 12db good / bad when I am syncing at 8128 (using Netgear DG834G)?
If the profile hasn't lifted after the weekend (72 elapsed hours), I'll ask the PN team to see if they can intervene and get it moving the right way.
Stats below:
AR7 DSL Modem Statistics:
--------------------------------
[DSL Modem Stats]
       US Connection Rate:     448     DS Connection Rate:     8128
       DS Line Attenuation:    12      DS Margin:              12
       US Line Attenuation:    5       US Margin:              26
       US Payload :            24768768        DS Payload:             180829008
       US Superframe Cnt :     1481902 DS Superframe Cnt:      1481902
       US Transmit Power :     0       DS Transmit Power:      0
       LOS errors:             0       SEF errors:             0
       Errored Seconds:        0       Severely Err Secs:      0
       Frame mode:             3       Max Frame mode:         0
       Trained Path:           0       US Peak Cell Rate:      1056
       Trained Mode:           3       Selected Mode:          1
       ATUC Vendor Code:       54535443        ATUC Revision:  2
       Hybrid Selected:        1       Trellis:                1
       Showtime Count:         1       DS Max Attainable Bit Rate: 10080 kbps
       BitSwap:                1       US Max Attainable Bit Rate:     n/a
       Annex:                  AnxA    psd_mask_qualifier: 0x0000
       Power Management Status: L0     DS HLINSC: 0
       US ACTPSD:              -345    DS ACTPSD: -365
       Total init. errors:     0       Total init. timeouts: 0
       Showtime init. errors:  0       Showtime init. timeouts: 0
       Last showtime init. errors: 0   Last showtime init. timeouts: 0
       ATUC ghsVid:  b5 00 54 53 54 43 00 00
       T1413Vid: 00 00         T1413Rev: 00            VendorRev: 00
       ATUR ghsVid:  b5 00 54 53 54 43 00 00
       T1413Vid: 00 00 T1413Rev: 00    VendorRev: 00
       [Upstream (TX) Interleave path]
       CRC:    0       FEC:    0       NCD:    1
       LCD:    0       HEC:    0
       [Downstream (RX) Interleave path]
       CRC:    0       FEC:    0       NCD:    0
       LCD:    0       HEC:    0
       [Upstream (TX) Fast path]
       CRC:    0       FEC:    0       NCD:    0
       LCD:    0       HEC:    0
       [Downstream (RX) Fast path]
       CRC:    0       FEC:    0       NCD:    0
       LCD:    0       HEC:    0
[ATM Stats]
       [Upstream/TX]
       Good Cell Cnt:  516016
       Idle Cell Cnt:  26102299
       Tx Packets Dropped Count:       0
       Tx Bad Packets Count:   0
       [Downstream/RX)]
       Good Cell Cnt:  3767271
       Idle Cell Cnt:  479165005
       Bad Hec Cell Cnt:       0
       Overflow Dropped Cell Cnt:      0
       Rx Packets Dropped Count:       0
       Rx Bad Packets Count:   0

[SAR AAL5 Stats]
       Tx PDU's:       115726
       Rx PDU's:       159129
       Tx Total Bytes: 20294906
       Rx Total Bytes: 176107675
       Tx Total Error Counts:  0
       Rx Total Error Counts:  0

[OAM Stats]
       Near End F5 Loop Back Count:    0
       Near End F4 Loop Back Count:    0
       Far End F5 Loop Back Count:     0
       Far End F4 Loop Back Count:     0
       SAR OAM Ping Response Drop Count=0
Superuser
Superuser
Posts: 9,926
Thanks: 1,265
Fixes: 71
Registered: ‎06-04-2007

Re: Close to exchange - very low sync speed

On longer lines connection speed and noise margin are inversely dependent upon each other, and the sync speed is set at the value which will just achieve the target noise margin (normally 6dB on well-behaved lines).
However the maximum sync speed on maxDSL is 8128kbps and once that speed is reached there is noise margin to spare and its value rises above 6dB. A healthy margin is good but specific values are immaterial.
David