noise margin and attenuation help

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kasper112

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noise margin downstream: 10 db
output power upstream: 14 db
attenuation downstream: 4 db
------------------------------------------
noise margin upstream: 31 db
output power downstream: 17 db
attenuation upstream: 4 db
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WAN Port Statistics:
Link Status: Up
Upstream Speed: 1023 kbps
Downstream Speed: 20477 kbps
Node-Link Status TxPkts RxPkts Errors Tx B/s Rx B/s Up Time
1-ENET Up 661341 996972 0 55778 151932 1:42:

--------------------------------------------------
is sean i only can download wht 1.8MB/sec why ??
 
Do you live above the exchange with a direct line to the DSLAM?

4db attenuation ? damn. You should be getting 8MB/s...
 
i live like 200 meter away from my IPS
i think is kinda wierd i only get like 85 % of my line uset..


sorry for my bad english
 
Telkom is limiting your line, you have to phone them and sort it out ;)

Afrikaans: Bel vir telskuim, hulle maak 'n boggerop van die lyn, jy behoort beter spoed as dit te kry.
 
Mine is 29, but I'm quite a distance from the exchange, so I don't know actually ;)
 
Looks like you have some kind of problem with your line. Your noise margin downstream should be much higher if you are so close to the exchange. See below. Can you post a bits per tone or an SNR per tone plot using something like Zyxmon or DMT? Alternatively a plot from Routerstats may also be helpful.

"Noise Margin (AKA Signal to Noise Margin or Signal to Noise Ratio)
Relative strength of the DSL signal to Noise ratio. The higher the number the better for this measurement. In some instances interleaving can help raise the noise margin to an acceptable level.

6dB or below is bad and will experience no synch or intermittent synch problems
7dB-10dB is fair but does not leave much room for variances in conditions
11dB-20dB is good with little or no synch problems* (but see note below)
20dB-28dB is excellent
29dB or above is outstanding

* Note that there may be short term bursts of noise that may drop the margin, but due to the sampling time of the management utility in your modem, will not show up in the figures.

Line Attenuation
Measure of how much the signal has degraded between the DSLAM and the modem. This is largely a function of the distance from the exchange. The lower the dB the better for this measurement.

20dB and below is outstanding
20dB-30dB is excellent
30dB-40dB is very good
40dB-50dB is good
50dB-60dB is poor and may experience connectivity issues
60dB or above is bad and will experience connectivity issues"

http://www.kitz.co.uk/tute/voyager2100_DMT.htm (find DMT link here)
http://zyxmon.3daffex.com/downloade.php
 
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What is interleaving exactly Yotch? Can I accomplish this myself, or is it best not to fiddle?

Thanks for the info, I really appreciate it ;)
 
@teraside: Same to you. Could have been a lot better though if the cricket had gone according to plan ...
 
The forum seems busted, this is probably going to be double posted too, for those reading, I said thanks Yotch, enjoy your weekend, wanted to delete one double post and it deleted both, I probably deleted both ;) :D :p
 
@kasper112, what country are you in? BTW the link you tried to post was blocked by the forum's automated spam-blocker.

@teraside, that is normal at that time of early mornings, I know why but will not elaborate.
 
@Yotch, any idea which program I can use to check the noise margin and attenuation on a Marconi Premium Combo modem?
 
ic said:
@teraside, that is normal at that time of early mornings, I know why but will not elaborate.
Click to expand...

Thanks for telling me ic, I won't be frustrated next time ;)
 
@MrH: Most routers can usually provide the noise and attenuation figures via one of their screen menus. In many cases there is also a telnet command that you can issue to get this information. If you are looking for something more advanced there is also software like routerstats and ADSL monitor which might or might not work with Marconi routers. You'll have to look at the help files. [Oupa]MrNutz has been using Routerstats on his Telkom 5102G so it might be a good idea to ask him about this.

Routerstats
http://www.vwlowen.co.uk/internet/files.htm

ADSL monitor
http://adslm.dohrenburg.org/index-old.php

Why cable is better than ADSL
http://adslm.dohrenburg.net/

Zyxmon (Zyxel) & Dlmon (D-Link)
http://zyxmon.streamclub.ru/indexe.php

This method works with a Billion 7202GR2 router. Not sure about a Marconi. Maybe you can fiddle a bit using telnet if nobody else can help.

"Go to the dos prompt and type " telnet 192.168.1.254 " or whatever your routers IP is. Next you will be asked for your username and password.
Type in the following command " wan adsl linedatan " and this will give you ur SNR margin and attenuation......"

Explanation of bits per tone and SNR per tone plots
"If slow service is indicated, technicians can look at the bits per tone measurement. Dips in the bit per tone graph indicate interference. Checking the frequency of the interference often makes it possible to identify its cause. The accompanying chart shows the frequencies associated with common interference sources, such as T1,E1 and HDSL. If the bits per tone are taking a hit and it is determined that noise is not the cause, then the cause could be a DC fault, such as a bridge tap or a wet section. Very low or nonexistent bits per tone in the high frequency band indicate the presence of a long loop. If there is a major dip in the bits-per-tone graph but the noise power-per-tone graph does not show any abnormalities, the most likely troubles are bridged taps or wet sections on the span. Use a loop-troubleshooting tool with a TDR to find and fix these problems. If the bits per tone are low across the whole bandwidth, the cause is most likely DC troubles on the loop, such as shorts or grounds. A major dip in bits per tone indicates AC trouble on the loop. To verify the type of AC trouble, compare the bits per tone to SNR. If the noise influence and bits-per-tone dip occur at the same frequency, the degraded performance is most likely due to a transmission influence. The particular frequency will help identify the source of influence or crosstalk. An example of possible shared frequency zones could be T1 centered at 770 kHz or HDSL at 196 kHz."

DMT plots can help to give a visual indication of line problems etc. Take a look at these plots to get an idea about line quality noise and attenuation. (Also look at some of the other pages of plots in this thread).
http://www.dslreports.com/forum/r17718637-SpeedTouch-516-Tweaking-~start=220

How to determine position of bridge taps (scroll down to see graph)
http://www.dslreports.com/forum/r18967859-Comparison-of-spectrum-beforeafter-bridge-tap-removed

Information about the hybrids used in some routers and location of line faults
http://www.dslreports.com/faq/14333
 
@Yotch, thanks for the info, I'll take a look a bit later or by tomorrow.

For some reason I'm now only getting sync at 2048 and telkom say there is nothing wrong on their side.
Even though it is slower than it was before it is still very stable when downloading.
 
yeah - u know...this is really a stuff-up...i spoke to a good friend of mine at saix.

telkom NEVER did their homework properly when deploying ADSL.

they were 200% supposed to use optics from the exchange to your local green/blue telkom street box..and only FROM THERE use copper..

now i bet ya...we wouldn't be having this "up-to-4meg" BS if their infrastructure had been correctly planned and deployed.

that means to say - i my situation specifically alone - i would sit with a distance of .7km from the UMC and not 3.7km and the tons of issues.

pretty good example of a 3rd world country and a monopoly going hand in hand.
 
@kasper112: Thought that you were posting about Telkom's ADSL service - should have realised that your attenuation figures were too good to be true!

If your modem supports DMT you might be able to change some of the internal modem settings like the upstream/downstream Tx powers etc. to optimise your speed. From the modem options you could try to change your SNR until your RCO is around 85% to 90% and increase the downstream Tx power to 19.5. Take a look at the dslreports link to get more information. Alternatively I see from the image that you posted that your router can supply bits per tone data so you should be able to plot this data from a spreadsheet etc. or possibly using ADSL monitor or Zyxmon etc. to see if there are any noise problems on the line.

ADSL performance tweaking
http://www.dslreports.com/forum/r17718637-SpeedTouch-516-Tweaking-~start=220

ADSL monitor
http://adslm.dohrenburg.org/index-old.php
 
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