First of all please excuse me for a catchy title- it's meant to attract attention therefore it's not exactly sincere
This post describes and SNR tweak that might speed up your ADSL connection under certain circumstances- otherwise it's useless.
It also has some limitations. All of those are addressed below.
- SNR tweak works on modems based on Broadcom chipset (some or most made by Netgear, Billion, TP-Link, or branded Speedtouch)
- It doesn't work on those Broadcom-based modems that had the command deliberately disabled
- The tweak will keep working only until modem reboot
Some theory on what you are about to do |
SNR is Signal to Noise Ratio- a parameter that describes ratio that the ADSL signal has to maintain "over" background noise of the line.
Typically it is set to 6db (on a normal good quality line) although it might be significantly higher on poor lines with lots of noise.
Since no one is interested in technical jargon- let me describe it in a different way. Imagine that the ADSL signal is a plane flying over the sea and the sea would be the noise. 6db SNR is the hight over the sea that the plane maintains. For the sake of argument let's assume the lower the plane flies the faster if flies (your connection is faster with a lower SNR margin).
Now- if the sea is calm you can fly at very low altitude and therefore fly faster and everything is fine, however if the sea gets choppy there is a risk of a big wave hitting the plane and which ends the flight (meaning the ADSL disconnects). That's why with a high noise aka wave you need higher margin (you need to farther from the wave) which in turn reduces speed.
Some lines tend to have a constant noise- it's always the same- in which case you can lower SNR so it was just above the noise level and maintain higher speed. Other lines get choppy- for example after the rain has fallen noise might increase- so if you keep you SNR too low the line will keep disconnecting.
Another point is that with lines that are very choppy- modem sometimes sets SNR ratio too high, just to be on the safe side- that may mean SNR of even 18db which will cost you a good few mbps. That might or might not be relevant depending on how fast your connection speed is.
This tweak is particularly helpful for those who have slow connections- in such a case another 2 or 3mbps might almost double the connection speed- again assuming the SNR is set too high.
Now onwards- how to implement the tweak. Remember that it vanishes once modem is rebooted so if you overdo it an your modem keeps disconnecting, you don't have to worry about reversing the procedure- just reboot the modem.
First you need a
Putty or a similar app.
Type in an IP of your modem, click OPEN and once the connection is granted type username and password (note that it might not be the same username and password you use to log in to the modem via the browser- that depends on a device and manufacturer)
Once you've logged in type in a command
adsl configure --snr XX or
adslctl configure –snr XX (depending on a modem- both do the same thing)
Instead of XX is the percentage value of your normal 6db margin. So 6db is 100%. If you type 60 like I did you should get SNR of roughly 3.6db
(in my case I started with 6.1db and went down to 3.8db)
The percentage denominator works for 6db SNR margin which is normal one however if your SNR is significantly higher it might or might not work just like that.
If it doesn't work use these values:
To decrease SNR by 6db type
adsl configure --snr 65550
To decrease it by 9db type
adsl configure --snr 65500
To decrease it by 12db type
adsl configure --snr 65450
Once you type the command and press enter you get no confirmation (as seen on the screen above) but the ADSL connection will disconnect and synchronize again.
Results and final thoughts |
This is what I started with- standard SNR of 6.1db and connection speed according to speedtest of
12.99mbps
And that is whiat I ended up by changing the margin- SNR of 3.8db and speed according to speedtest of
14.09mbps
While I realize that 1.1mbps increase (or 8.5%) is not a dramatic one, you have to consider the fact that it is a free tweak, it takes only a minute to implement it's risk-free as it's very easy to revert (by rebooting the modem) and mostly- that it's not really meant to benefit people like me.
I've had normal SNR to start with so I did not have too much to gain. If yours is significantly higher for some reason (i.e. 12db) and your connection is still stable with much lower SNR (i.e. 6db), you are going to gain a lot more than I did especially relative to your connection speed (but also more in terms of mbps).
Please remember that setting SNR too low will result in frequent disconnections. This is far more annoying than a slower connection but still doesn't mean the tweak is not for you- it just means that you went too low with SNR setting and you should change the value (i.e. going from 18db to 9db might be too much, but going "only" to 12db might be stable, yet faster).
Last but not least- there are few modems that allow this tweak to be applied from firmware level (Billion) and there are apps that might make it easier for you for example
DMT Tools or
RouterStats. These tools don't work on all modems though- while doing it manually works on every one that runs a busybox and allows these commands.
Last edited by a moderator:
May 7, 2015