Increase transmit power?

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

Does anyone know it it is possible to alter this in any router firmware (as you can with the SNR target), or is it controlled soley by the DSLAM?

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.

You say transmit power ,are you referring to up steam from your router to exchange ? or from exchange to router?
the Rx power ( from exchange to router is 20.3 dBm
on my connection the tx is lower

Im the OP.

Your right - im actually talking downstream (mine is currently 12dbm)

.....as in downstream (rx) from exchange to router.

I'd guess there 's a line problem.

Do you have the rest of the stats?

There isnt a fault per 'se - i just live fairly close to the exchange which means my power levels have been backed off - this is normal.

Ive found myself with a target snr of 15db (dmt tweaked to 12db) and an actual snr of 9db - and consequently I sync at lower than the the full speed.

I could probably get in touch with my isp and, after a fight, get this reset (and go through the training period again) - but out of interest, i'd still like an answer to the question.... does anyone know if power is adjustable in firmware of the dsl modem? (maybe a DG834GT or similar with custom firmware).

thanks

In reply to a post by Anonymous:

There isnt a fault per 'se - i just live fairly close to the exchange which means my power levels have been backed off - this is normal.

Doubt it. You have a problem. Post all your stats.
imho

Edited by deleted (Wed 10-Nov-10 21:24:18)

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.

Kitz

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.

In reply to a post by MHC:

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.

from my router :
# adsl margin
adsl margin
Downstream Noise Margin : 4.00 dB
Downstream Attenuation : 33.0 dB
Downstream Power : 20.3 dBm
Upstream Noise Margin : 6.0 dB
Upstream Attenuation : 14.5 dB
Upstream Power : 12.4 dBm

as you can see that's what it reports it as ?

Where does it report it as receive power? It gives the DOWNSTREAM power and attenuation so the power level at the customer premises will be -12.7dBm

If the received power was at 20dBm then the power at the DSLAM would be 53dBM or 200W.

In reply to a post by MHC:

The DSLAM will manage the power level based on several parameters

...including line faults.

"including"?
This kind of contradicts your opening statement "Does it? I've only seen 19.5 dBm except where there's a problem." (in response to the post "I know sometimes the DSLAM backs off the output power on a connection to avoid cross talk."
You seem unaware that DSLAMs can reduce power, on full speed lines, to reduce cross-talk.
You've also forgotten about effective power falling as sync speed decreases (as pointed out by myself and Phil).

It's just one of the parameters included in the list of several.

In reply to a post by BatBoy:

It's just one of the parameters included in the list of several.

I know that; I was just pointing out the appearance you didn't (from your post "Does it? I've only seen 19.5 dBm except where there's a problem.").

In reply to a post by adebov:

In reply to a post by BatBoy:

It's just one of the parameters included in the list of several.

I know that; I was just pointing out the appearance you didn't (from your post "Does it? I've only seen 19.5 dBm except where there's a problem.").

That's me saying what I have personally experienced, like tommy45 did. Not posting theories and trying to justify them.

HINT: If you get corrected and it seems a reasonable correction, shrug shoulders and take it as constructive criticism.

Your battling attitude is resulting in people not being constructive with you, and your retorts are very troll like at times, almost like you plan this course for a thread to de-rail them all into two and thro matches rather than helping users. As such if it continues then no choice but to help those seeking help and suspend your account for a short while so you can take a break.