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DG834GT and the DMT Tool

baldrick
Grafter
Posts: 128
Registered: ‎07-08-2007

DG834GT and the DMT Tool

As discussed elsewhere I have been suffering from a jump in SNR to 15dB with a resulting loss of speed. In desperation I have gone out and bought a Netgear DG934GT with the purpose of seeing what's going on and tweeking the SNR with the DMT Tool.
The router I have bought has Firmware version V1.02.09. When I run the DMT Tool I get the message 'Error: can not identify modemtype: DMT Version 8.07 for BCM6338/6348/6358'.
I have rechecked and the DMT website shows version 8 as being correct for this router.
I have therefore tried using telnet to tweek the SNR. I did not manage to get up to my full speed until entering /usr/sbin/adslctl configure --snr 1 (yes number one), which again is at odds with what I read.This gives a reported speed of 8128kbps with a SNR of 9.8dB.
Does any-one know what is different here, for example have Netgear started using a new chipset? If so does any-one know if there is a compatible DMT tool?
20 REPLIES
Community Veteran
Posts: 6,735
Thanks: 12
Registered: ‎02-02-2008

Re: DG834GT and the DMT Tool

That's the right version, use it myself.
Have you ticked "special logon"?
baldrick
Grafter
Posts: 128
Registered: ‎07-08-2007

Re: DG834GT and the DMT Tool

Ah, where do I find that?
baldrick
Grafter
Posts: 128
Registered: ‎07-08-2007

Re: DG834GT and the DMT Tool

Sorry, I've just found it, it now works!
Community Veteran
Posts: 6,735
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Registered: ‎02-02-2008

Re: DG834GT and the DMT Tool

Excellent. It is in the instructions........ Wink
VileReynard
All Star
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Registered: ‎01-09-2007

Re: DG834GT and the DMT Tool

Did you have to adjust the DMT slider for the speed down to 10% ?
Also telneting /usr/sbin/adslctl configure --snr 1 is required.
I've just been hit with an increase from 6dB to 15dB - I've managed to reduce that to 9dB - but I don't know how to improve on that.
Unfortunately, I really need a 6dB noise margin to achieve a 6.5 - 7.0Mbits profile.

Community Veteran
Posts: 6,735
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Registered: ‎02-02-2008

Re: DG834GT and the DMT Tool

I'm sure I read somewhere that the most you could normally achieve was 50%.
baldrick
Grafter
Posts: 128
Registered: ‎07-08-2007

Re: DG834GT and the DMT Tool

No, When I set the snr to 1 via Telnet the speed increased to 8128 kbps. When later I got the DMT Tool working courtesy of HPsauce (thanks again) reference to the SNR slider showed it set to 100%. As my connection is already working flat out I have not touched it. I assume that DMT thinks that the Telnet tweeked figure is that set by BT.
It may be that I would also be stopped at 9dB but just fortunate that I live near the exchange and can achieve 'full chat' with 9.8dB in hand, so I don't get to the limit.
Community Veteran
Posts: 6,735
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Registered: ‎02-02-2008

Re: DG834GT and the DMT Tool

Maybe the exchange has decided your 15dB was a blip and has reverted?
(we'll probably never know)
VileReynard
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Registered: ‎01-09-2007

Re: DG834GT and the DMT Tool

Correction - the increase was to 12dB, not 15dB.
It's still a drastic increase though.
If you look at the attached graph (sr-day.png), you will see that from 9pm - 10pm on 9th July BT gradually increased my noise margin a lot.
You can see that it is a normally stable line if you look at the monthly graph (sr-month.png).
I monitor noise margin every 5 minutes, whilst my PC is switched on.
Just by way of coincindence  Crazy
I received an email today that says that my local exchange has been upgraded to 21CN WBC status=yes
See http://www.samknows.com/broadband/exchange/LWMIL
Coincidence?
Or have they been replacing DSLAM's?

VileReynard
All Star
Posts: 11,212
Thanks: 307
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Registered: ‎01-09-2007

Re: DG834GT and the DMT Tool

A bit more on this 21CN...
Quote
Exchange History
Subscribe to RSS Feed RSS Updates
09/07/2008 BT Wholesale has enabled the Mill Hill exchange for their 21CN Wholesale Broadband Connect (WBC) service
29/03/2008 BT Wholesale has set an enablement date of 30/06/2008 for their 21CN Wholesale Broadband Connect product at the Mill Hill exchange
...

Community Veteran
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Thanks: 443
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Registered: ‎31-08-2007

Re: DG834GT and the DMT Tool

DMT SNRM target slider - if 100% <=> 15dB, then 10% <=> ~9dB (just over). Normally achievable without a problem.
MickKi
Grafter
Posts: 543
Registered: ‎30-09-2007

Re: DG834GT and the DMT Tool

Notwithstanding the fact that tweaking the SNR at router level gets you what you want (or not in this case) can't you raise a ticket for PN to ask BT to release your SNR at the BT exchange?
The drawback is that if your line continues to play up then the SNR may well increase again.
VileReynard
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Registered: ‎01-09-2007

Re: DG834GT and the DMT Tool

I could raise a ticket for my router.
But I know that I will have to get it raised to a certain level of attention at PlusNet.
PN then have to struggle to get BT to accept that they should do this action.
Couple of months (or so) it is necessary to repeat the process.
I have hopes that if I run at an elevated 9dB for a month or two, that BT will let me reset my noise margin back to its standard 6dB.

Community Veteran
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Registered: ‎01-08-2007

Re: DG834GT and the DMT Tool

Quote from: axisofevil
I've just been hit with an increase from 6dB to 15dB - I've managed to reduce that to 9dB - but I don't know how to improve on that.
Unfortunately, I really need a 6dB noise margin to achieve a 6.5 - 7.0Mbits profile.

That's exactly the same for me. I can only force mine down to 9 or 10dB, with a resulting speed of between 4000 and 4500 even though I've set the SNR to 1 via Telnet. It's really annoying as I know I can get much better speeds even with interleaving on (as I found it is).
P.S. 21C info for my exchange is still showing as
"WBC Rollout Status
BT have announced a ready for service date for this exchange. The estimated go live date of 30th June 2008 and was last updated 29th March 2008."
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