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Standard User blinky
(committed) Wed 05-Jan-11 18:45:44
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Graph Analysis from DMT Tool


[link to this post]
 
Hi All,

Long time since I posted. We are having problems with our broadband. We are on Orange LLU (ADSL2+) and have been for quite some time.We used to get 2272kbs stable downsteam but since the summer it has dropped to ~463kbs and last night dropped to 336kbs.

I used DMT Tool on our 834PN to manually reduce the SNR from the 12.5-14.5dB set by Orange to a lower figure and managed to get ~1Mb connection.

So I have two questions:

How to we interpret the graph from DMT Tool?
DMT Graph

How do we improve the connection? (if at all)

I have already fitted an iplate, changing to XF-1e, different routers, using the test socket but none of these have done

The upstream always seems to sync well at around 448-463 but in tests I always get very poor speeds ~0.1Mb/s upload. This seems to be borne out by the HEC errors...

BT's predictor reckons on 2Mb now and 3Mb later this year when ADSL2+ is installed by BT,.
Standard User BatBoy
(eat-sleep-adslguide) Wed 05-Jan-11 19:14:50
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Re: Graph Analysis from DMT Tool


[re: blinky] [link to this post]
 
Can you reboot the router and post another picture? May give a hint what the problem is...



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Standard User blinky
(committed) Wed 05-Jan-11 19:56:42
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Re: Graph Analysis from DMT Tool


[re: BatBoy] [link to this post]
 
I've rebooted the router. The DSLAM seems to have reduced the downstream SNR slightly based on the settings I put in to DMT Tool. It still rather high at 11.5dB

As requested here's the new graph. New Graph

I've also tried using a radio tuned to 612Khz but didn't notice anything significant.


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Standard User BatBoy
(eat-sleep-adslguide) Wed 05-Jan-11 21:53:10
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Re: Graph Analysis from DMT Tool


[re: blinky] [link to this post]
 
Wow, lots of noise. If the wiring is in a good condition like you say, I'd suspect a line fault unfortunately.



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Standard User blinky
(committed) Wed 05-Jan-11 22:05:34
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Re: Graph Analysis from DMT Tool


[re: BatBoy] [link to this post]
 
Thanks, that's what I suspected. It's getting BT or Orange to take action about it....

Any tips?
Standard User 5km
(knowledge is power) Wed 05-Jan-11 22:49:22
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Re: Graph Analysis from DMT Tool


[re: blinky] [link to this post]
 
If you are given a morning appointment, be prepared to wait in all day.

Offer the engineer tea and biscuits.

O2 Broadband Premium LLU
Now on twitter @timmay2
Standard User Chrysalis
(eat-sleep-adslguide) Thu 06-Jan-11 03:44:18
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Re: Graph Analysis from DMT Tool


[re: blinky] [link to this post]
 
surprised noone suggested it yet but first force adsl1 mode.

not sure how you can do it on your router but if possible you should try that.

also your sync is very bad for your attenuation. either massive noise or a line fault.

Edited by Chrysalis (Thu 06-Jan-11 03:44:38)

Standard User WWWombat
(newbie) Thu 06-Jan-11 09:36:17
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Re: Graph Analysis from DMT Tool


[re: Chrysalis] [link to this post]
 
In reply to a post by Chrysalis:
also your sync is very bad for your attenuation. either massive noise or a line fault.

Can only agree with this. Kitz (http://www.kitz.co.uk/adsl/max_speed_calc.php) estimates 5kbps on ADSL and 5.5kbps on ADSL2+.

My parents have a simiar attenuation, and hit disconnect problems a year ago when Kcom swapped from ADSL to ADSL2+. Forcing ADSL definitely helped them, alongside a filtered faceplate, removal of ring wire, removal of master components fitted in secondary socket, and moving DECT handset away from the router (so router was plugged into master socket, and DECT station plugged in to an extension 20 feet away). This improved the noise margin by around 4dB, and restored stability.

They also recently got a new DECT handset/base, which caused extra interference on the line in the evenings (a BT Graphite) - dropping 3-5dB. I mostly solved this by adding double-filtering to the extension socket (for the DECT station), even with the extension wiring already being filtered by the faceplate at the master.
Standard User blinky
(committed) Thu 06-Jan-11 21:08:40
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Re: Graph Analysis from DMT Tool


[re: WWWombat] [link to this post]
 
Thanks guys.
The line is generally pretty stable with my DG834PN (I believe this has a Broadcomm chipset which is allegedly more compatible with Orange's DSLAM's).

The line achieves a lower sync using ADSL or ADSL2 as opposed to ADSL2+ but without any stability benefits, therefore it makes sense from my point of view to stick on ADSL2+ at the moment).

I have pulled wires 3 and 4 from the NTE5's front plate but I haven't looked at the upstairs sockets. Whoever installed the cable didn't use BT's colour coding on the cables. I've have to check again to see if 2 and 5 are wired the right way around.

After removing 3 and 4 from NTE front plate

I did a SNR test in DMT Tool and there is an awful lot of bit swapping going on.
SNR Test
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