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Standard User Kaltern
(regular) Thu 29-Sep-11 11:37:53
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ADSL Max - Attenuation too high?


[link to this post]
 
I've been having problems with my line dropping throughput now for a few years, with no resolution despite various engineers visiting.

Just now, I took a look at my line stats - I'm sure that my downstream attenuation is way too high for my line?

DSL Modulation Mode: GDMT
DSL Path Mode: INTERLEAVED
Downstream Rate: 8128 Kbps
Upstream Rate: 448 Kbps
Downstream Margin: 12db
Upstream Margin: 22db
Downstream Line Attenuation: 30
Upstream Line Attenuation: 16
Downstream Transmit Power: 19
Upstream Transmit Power: 12

My downstream margin also fluctuates a lot - between 8 and 13 db - now I know that fluctuation is normal, but I didn't think it was by that much.

When the connection is working, I get a very stable 6.5-7mb line speed, which is exactly right.

If it is the attenuation, what exactly can I do about it?

--Edit: Just read up more on it, and it turns out it's fine. Oh well, back to the drawing board frown

Edited by Kaltern (Thu 29-Sep-11 12:13:14)

Administrator MrSaffron
(staff) Thu 29-Sep-11 12:14:04
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Re: ADSL Max - Attenuation too high?


[re: Kaltern] [link to this post]
 
Attenuation is a measure of how long the phone line is. Around 2km of phone cable between you and the phone exchange one would suggest from figure.

If the modem holds the 8128Kbps all the time, then throughput drop is probably nothing to do with the ADSL line, and more to do with congestion on the network beyond the exchange

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User MHC
(legend) Fri 30-Sep-11 00:29:00
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Re: ADSL Max - Attenuation too high?


[re: Kaltern] [link to this post]
 
In reply to a post by Kaltern:
My downstream margin also fluctuates a lot - between 8 and 13 db - now I know that fluctuation is normal, but I didn't think it was by that much.


a 5dB swing is reasonable - I have seen some as low as 3dB and others at 7 or 8 dB.

Get a copy of RouterStats Lite and monitor the SNR over three consecutive days. If you removing teh sample to sample spikiness and drawing a simple curve along the centre, it should match almost perfectly day to day





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