The following information is given as a guide only and you make any changes at your own risk.

Version 8 of the DMT tool works for the following routers:
Speedport 500V/W500V, Siemens SL2-141-I/SLI-5300-I/CL-110-I, Speedtouch 716g, Belkin 7633, T-Sinus 1054 DSL, BT Voyager 2091/2100/2110, BT Voyager 240, Linksys WAG54GS, US Robotics 9107/9108, Netgear DG834GT/DG834NB/DG834PNB, Hitachi AH4222, BCM 6338/6348/6358

The DMT Tool can be downloaded from http://dmt.mhilfe.de/ - you need v8.
The site is German but when you install DMT you have the option to select English.
A translation of the page can be viewed here.

Running DMT

• Download and unzip into a folder.
• Click DMT.exe to start the program.
• Select "English"
• Select "Annex A"

Configuring DMT

• Insert your routers IP address (normally 192.168.1.1)
• Insert your router login and password (default = admin, admin)
• Click "Connect".

Your Line stats

DMT shows you your current line stats from your router. With adsl the figures we are normally the most interested in are the first 3 downstream figures.

• Bit rate - Your sync or connection speed.
• Attenuation - reduction in signal strength quality and directly related to the length of your line. The lower the figure the better the line. This figure should stay static.
• SNRM - Signal to Noise Ratio Margin. This figure is subject to fluctuations of Noise. The higher your SNR Margin, the better the signal strength to background noise.
• tx pwr - transmit power
• RCO - Routers estimation of maximum achievable sync speed on adsl.
• ADSL fast path - Will either be fast or interleaved, depending if interleaving is switched on or not.

SNR Monitoring

Your SNR Margin plays a big part in the condition of your line particularly with maxdsl/radsl. If your SNR Margin drops too low then your connection starts to become unstable. You will likely see CRC etc errors and errored seconds and your connection may drop. You can monitor your SNR Margin over a period of time using DMT tool, and the graph will show any fluctuations in your SNR Margin.

For more information on SNR see my line stats page.

Changing your Target SNR.

Each time you connect, your router will try and sync at the highest speed it can whilst still allowing a safe margin of SNR to allow for normal noise fluctuations that occur over the course of the day. The default Target SNR is 6dB, but the DLM at the exchange can also set your Target SNR to 6, 9, 12 or 15dB.

Possibly the easiest way of finding out the Target SNR set on your line is checking your SNR Margin immediately after a resync. Generally speaking if your SNR Margin is 6dB then your Target SNR is likely to be 6dB.
Please note that this method is not fool-proof because lines that have a good overhead of SNR and are able to sync at the full 8128 kbps (or 7616 with Interleaving), will show a higher figure anyhow.

Sometimes your Target SNR may not be perhaps quite the best for your line and you may wish to change this yourself, by either increasing your Target SNR to improve stability of your line. Or it may be that your SNR Margin is normally very stable and you want to see if by bringing your Target SNR down you can perhaps get a bit more speed.

Enabling the Hidden 5th Tab to change your Target SNR From the top toolbar select Special Misc. Options A new window will open Misc. Options/Settings From Expert Settings - Tick the checkbox "unlock experimental area Panel/Last Tab Click the "Save/Close" Button The slider allows you to adjust your SNR with 100% being your existing the BT set figure. The slider is not entirely accurate, and because each line is different then you will have to experiment. But as a guide:- Default Target SNR New Target SNR Slider value %       6dB 3dB 50 6dB 9dB 150 6dB 12dB 200