Tweak Signal To Noise Target Margin on a TP-LINK TD-W8968

Modifying the Signal to Noise Margin can increase the speed of an ADSL connection at the potential detriment of stability.

One analogy I’ve read is that you can think of the Signal to Noise Margin is like the altitude at which a plane flies over the sea. As expected, the sea will have waves, and an ADSL connection will also have waves of noise (radio interference) that could cause instability. Just as flying a plane higher over the sea would protect it from colliding with a wave in the sea, the Signal to Noise Margin is the level of noise the modem is configured to be able to tolerate before disconnecting.

Here in the UK, British Telecom and its affiliates set the Signal to Noise margin at 6db if the line is performing as expected, and it will automatically adjust this to be higher during periods of instability, or when there is a fault on the line.

Some routers allow you to manually override the Signal to Noise margin. One of my routers, the TP-LINK TD-W8968 allows me to do so using the command line.

To modify the Signal to Noise margin on a TP-LINK TD-W8968:

  • Telnet to the router using a tool like Putty or Window’s command line telnet. (i.e. telnet 23) and log in with your username and password
  • Type command adsl configure –snr 50
  • Your ADSL will drop and reconnect at a higher sync rate.

When doing this, I am able to gain 1.5mbit of downstream from my 13mbit ADSL connection, however the connection becomes a bit too unstable for online gaming.

Use at your own risk!