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[kezzaman]

Incidentally, you have very tasty looking limbs, kezzaman.  Do you strictly need them all?!

I would like to keep all my limbs but after reading ur post i suppose u could eat my head because i dont think its working anymore. 

Cheers.

[kezzaman]

The transmitting device only needs to use sufficient power for the receiving device to obtain a clear signal. There is a dialogue between the two ends: "Eh? What? Speak up, I can't hear you!" . . . "Stop shouting, I'm not that deaf, you know" . . . etc, etc.

This is what my modem/router reports --

Current Output Power:    18.6 dBm (Downstream) 12.5 dBm (Upstream)

The DS output power is the level that the DSLAM/MSAN is transmitting to my modem/router (the value is only known by the DSLAM/MSAN and is sent in a data packet so that the modem/router can display it), the US output power is the level that my modem/router is transmitting to the DSLAM/MSAN.

Hi,

So by US do you mean upstream?
The only place i can get a reading of output power on my router stats is in the upstream catagory, thats where i got the 9dBm from, so then its that what power my router is transmitting?

[kitz]

The only place i can get a reading of output power on my router stats is in the upstream catagory, thats where i got the 9dBm from, so then its that what power my router is transmitting?

Your upstream power output is usually way less than the downstream power. (unless you have a problem)...  The upstream tones use lower frequencies.

Its not strictly true.... but very roughly and as a guide only,  it should be somewhere in the region of about half the downstream adsl2+ output power.

[kitz]

Incidentally, you have very tasty looking limbs, kezzaman.  Do you strictly need them all?!

Excellent and informative post asbokid...  however that one line made me laugh 

[kezzaman]

The only place i can get a reading of output power on my router stats is in the upstream catagory, thats where i got the 9dBm from, so then its that what power my router is transmitting?

Your upstream power output is usually way less than the downstream power. (unless you have a problem)...  The upstream tones use lower frequencies.

Its not strictly true.... but very roughly and as a guide only,  it should be somewhere in the region of about half the downstream adsl2+ output power.

I have an issue with my connection which sometimes goes away, most recently was about 2 weeks ago when it went away and liturally the only thing i could see different with my stats was that the upstream output power was 0.5 higher at 9.5, since then its been at 9 and hasnt budged. Do u think an increase of 0.5 could have an affect on someones connection?

[kitz]

I just noticed that c6em mentioned in his post about some routers not reporting the downstream power on adsl2+

>> the only thing i could see different with my stats was that the upstream output power was 0.5 higher at 9.5

The 2 figures are independent..  A shift in the upstream could indicate problems in those lower frequencies....  or it is also possible that it could indicate some low level noise across the whole adsl2+ frequency range.  Without having the downstream power output though, its impossible to say.

If you are having connection problems though, I wouldnt focus too much on the output power..  The SNRM figures (and fluctuations in them) are more telling.

[kitz]

My interpretation of this was that BTOR did not want to use full power on short lines as
a) they did not need it to function fully and
b) excess power on the lines means increased cross talk between the cable pairs with other broadband customers. 

Thats correct - power cut back is applied on short lines.
You wont see it so much on adsl2+, as even short lines may need near full power to get up to the 24Mbps region.

It can however be clearly seen on adsl1 where the max sync speed is 8128kbps and the shorter lines dont need the additional power and power cut back comes into play to reduce crosstalk by removing any 'surplus power' and thereby reducing the risk of surplus noise from these shorter lines drowning out the longer lines.  Why give a line more power than it needs?

I believe sky are currently 'playing' with new power management equipment on their MSANs..  However they dont appear to have got things quite right yet and some lines are finding themselves not being able to sync to their full potential due to the power management module being a bit overzealous with the cutback on shorter lines.... as they appear to be using data obtained during the training period, before the line has fully settled to its full capability :/

[burakkucat]

So by US do you mean upstream?

Yes, spot-on. DS and US are relative to the observer which, in this discussion, is either you or me. Some devices won't report the DS power level purely because it hasn't asked the DSLAM / MSAN, at the other end of the link, to report the value.

[kezzaman]

If you are having connection problems though, I wouldnt focus too much on the output power..  The SNRM figures (and fluctuations in them) are more telling.

Hi,
Cheers for all the input.
Would you be able to elaborate abit more on the fluctuations in the noise margin, because mine changes everytime i refresh the stats page, usually within a 3db range. Im on 12snr profile at the moment and the DLM isnt active.

[kezzaman]

... Is it possible that i could be experiencing gaming online issues because my upstream is suffering from crosstalk at the exchange?

[kitz]

Its can be normal for SNR to fluctuate a bit..  but it depends on how much its fluctuating and and if theres a pattern to it.

routerstats is a good tool for being able to record your SNRm and it will do all the hard work for you, by taking regular snapshots of stats from your router and outputting it as a graph.   
Results from a routerstat graph can often be quite telling as whats going on on your line.  Its one of the tools we use most to help troubleshoot problematic lines.


>> Is it possible that i could be experiencing gaming online issues because my upstream is suffering from crosstalk at the exchange?

This doesnt sound like crosstalk..  its impossible to say without seeing whats happening to your SNR..  but its probably more likely to be internal wiring,  EMI/REIN or a line fault.  Crosstalk doesnt cause SNRM's of 12-15dBm

[kezzaman]

Theres was another thing that i just thought was a router mistake, for the last 2 days its been reporting my downstream attenuation as 3.7db when its deffinately not, its about 9db. Could this be anything significant?

[kezzaman]

Lets just say, if someone did have an issue with crosstalk would an increase in snr fix it?

[burakkucat]

Lets just say, if someone did have an issue with crosstalk would an increase in snr fix it?

The crosstalk is the noise. So for noise at a constant level, an increase in the ratio of signal to noise implies that the power of the (wanted) signal has been increased. So in basic terms, yes is the answer to your question.

However the SNR is not the same thing as the SNRM, which is what all modem/routers will report.

[kezzaman]

Does the DSLAM tell the modem what output power to use or does the router decide itself?