Please note that the notes are given as a guide, and this site takes no responsibility for any alterations you make in the shell.

Details of how to over-ride the Target SNR on the DSLAM using the DG834GT

The Netgear DG834GT and DG834 v4 have a busybox shell which can be accessed using telnet. It also allows the user to set their own Target SNR in order to try improve stability issues that may be caused through loss of sync.

~ Enable debug via the web interface
http://192.168.0.1/setup.cgi?todo=debug

~ Then telnet the router
or click --> 192.168.0.1

~ when logged in type the following command
adslctl configure --snr N

where N is the figure that you wish to change your target SNR by - (see table below)

Clarification of 'N'

• N should be between 1 and 200 with the default value being 100.
• Values > 100 increase the target noise margin
• Values < 100 reduce the target noise margin, and a value of 1 reduces it by about 5.5 dB.

To reduce it further you would need to use negative values of N, but the command rejects negative values. This is where the hack comes in: internally, the value of N is stored as a 16-bit signed integer (supports values between -32768 and +32767) and we can trick the command into accepting negative values by using high positive values. Values between about 65400 and 65535 would be possible; this is equivalent to a range between -136 and -1.

Examples

If your target SNR is 9dB and you wish to reduce this by 3dB to 6dB, then try 50

         adslctl configure --snr 50

Your target SNR is 15dB and you wish to reduce it to approx 5.6dB, then try 65480

adslctl configure --snr 65480

All lines vary slightly, but as a rough indication the following figures may be used as a guide.

Notes

This setting is not saved after a reboot. (Unless you are using DGTeam Firmware).

Default Target SNR on the BTw DSLAM is 6dB and go in 3dB increments, up to 15dB.

Thanks to roseway for bringing attention to the overflow hack that allows SNR tweaking of more than -5.5dB and the suggested values. His post and further discussion on the subject of amending the target SNR for Broadcom chipsets be viewed on the Forum.