In reply to a post by BatBoy:

In reply to a post by Anonymous:

I know sometimes the DSLAM backs off the output power on a connection to avoid cross talk.

Does it? I've only seen 19.5 dBm except where there's a problem.

It changes (only by small amounts) with the sync/connection speed.
18.8dBm here (currently connected at 4818kbps).

it often looks to be a constant per tone in use, which sort of makes sense anyway. So low sync speed due to less tones in use = less power output.

In reply to a post by Anonymous:

http://www.kitz.co.uk/adsl/adsl_technology.htm#power...

Cutting back on power reduces the signal strength, which in turn reduces the SNR. The above line is very good with little noise, therefore without this cut back the above line would likely 'drown out' neighbouring lines at the DSLAM causing cross-talk for other lines.

Given the target noise margin and the tweak to 12dB, and your statement that the SNRM now is 9dB, as BatBoy says - you have a problem.

Please post the full stats from the router, including error counts.

The power can vary right down to 0dBm and I have seen locations where this happens.

In reply to a post by MHC:

The power can vary right down to 0dBm and I have seen locations where this happens.

Yes line problems cause this.

Receive power at 20.3 dBm - you must be joking.

Transmit power might be 20.3 dBm but that will be significantly attenuated by the time it reaches the customer premises.

Stop talking rubbish.

The DSLAM can back off power from the normal maximum - line issues have nothing to do with the power level.

In reply to a post by MHC:

Stop talking rubbish.

The DSLAM can back off power from the normal maximum - line issues have nothing to do with the power level.

Start talking sense - the power is transmitted down the line.

I am talking sense, you are just posting incorrect statements. A line problem will not directly cause the transmitted power to vary.

Yes, the power is transmitted down the line, but the level at the DSLAM can and will be varied.

The DSLAM will manage the power level based on several parameters - do you not understand that?

In reply to a post by MHC:

The DSLAM will manage the power level based on several parameters

...including line faults.