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Standard User NilSatisOptimum
(newbie) Thu 03-Feb-11 15:55:47
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attenuation


[link to this post]
 
Hi,


I had issue with my Isp some months back this has now been resolved, however i noticed when the line was bad my attenuation readings would increase to around 46 I supposed this was due to a poor line. For some months now it has been stable however depending what router I use It varies from 38-41


Is it normal to have varying line attenuation readings and how are they measured and could they be changed to suit ( The engineer hinted at persons fiddling).

Excuse what might appear to be paranoid thoughts, however just trying to understand the process and the reluctance of the ISP to sort it at the time
Standard User tommy45
(fountain of knowledge) Thu 03-Feb-11 16:39:02
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Re: attenuation


[re: NilSatisOptimum] [link to this post]
 
Attenuation is normally a measure of distance from exchange and the quality of the cables combined, there as far as i know no way end users can manipulate the attenuation on it's own, but as you have said routers that have different chipsets will report the values differently, and so will changing ADSL modes (G.DMT, Adsl 2, Adsl2 + Annex A & M)if supported by your isp,

Standard User NilSatisOptimum
(newbie) Thu 03-Feb-11 16:46:12
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Re: attenuation


[re: tommy45] [link to this post]
 
I aprreciate the end user cannot, however the engineer suggested that the ISP was increasing attenuation, if this is possible, why?


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Standard User MHC
(legend) Thu 03-Feb-11 17:05:29
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Re: attenuation


[re: NilSatisOptimum] [link to this post]
 
Absolute rubbish ... it could be done but there is no reason to as the power level can be managed if attenuation is not high enough.

The variation between router is normal and dependent on a lot of parameters including the termination impedance, bins in use and the algorithm used for calculating. Don't worry about it - I have three identical modems and they report different attenuation on the line





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M H C


taurus excreta cerebrum vincit
Standard User NilSatisOptimum
(newbie) Thu 03-Feb-11 17:38:40
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Re: attenuation


[re: MHC] [link to this post]
 
In reply to a post by MHC:
Absolute rubbish ... it could be done but there is no reason to as the power level can be managed if attenuation is not high enough.


I appreciate the difference in routers and attenuation, however what reasons could it be done.
Administrator MrSaffron
(staff) Thu 03-Feb-11 17:45:35
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Re: attenuation


[re: NilSatisOptimum] [link to this post]
 
The reasons are so rare that the attenuation is not played with by the ISP, and UK ISP's have no ability to do this, and have never known the suppliers do it either.

Only time I would expect anyone to even entertain it, is a line with under 1dB attenuation.

At your attenuation, what is more likely is ISP was flipping you between ADSL, ADSL2 and ADSL2+ modes which will see different attenuations reported.

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) Thu 03-Feb-11 17:50:23
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Re: attenuation


[re: NilSatisOptimum] [link to this post]
 
There is no reason for it to be done. Power control has the same effect.

If a customer has a very very short line with say 1dB of attenuation then a full power transmission will be received at +19dBm which could swamp the front end of the modem and degrade the signal. On a long line the received power can be as low as -50dBm and getting a modem to work reliably across such a dynamic range is difficult and expensive. To overcome that, an in-line attenuator could be installed to drop the received power down to 0 dBm. However, rather than installing attenuators the DSLAM can manage teh trnasmitted power and reduce it from teh maximum of 20dBm down to a more favourable level.





~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


M H C


taurus excreta cerebrum vincit
Standard User yarwell
(sensei) Thu 03-Feb-11 17:59:30
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Re: attenuation


[re: NilSatisOptimum] [link to this post]
 
attenuation is calculated from the downstream power output minus the received power. There's the potential for more than one definition, for example 2Wire routers have more than one attenuation including a figure at 300 kHz.

The "normal" figure is affected by the frequency bins in use. Fixing a fault may mean more higher frequencies are in use and thy'll have higher attenuation.

Phil

MaxDSL - goes as fast as it can and doesn't read the line checker first.

MaxDSL diagnostics
Are your kids pirates ? Limewire, Bearshare, Kazaa, BitTorrent, eMule are all tools of the trade.
Standard User NilSatisOptimum
(newbie) Thu 03-Feb-11 20:19:23
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Re: attenuation


[re: MrSaffron] [link to this post]
 
Many thanks to the three of you for your wisdom.

IT took me from June to September of last year to finally get it sorted, they appeared to try, every reading, statistic, set up and speedtest they could not go in the exchange and fix it, which they did in the end!!!

Again Many Thanks.
Standard User NilSatisOptimum
(newbie) Thu 03-Feb-11 20:26:12
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Re: attenuation


[re: yarwell] [link to this post]
 
In reply to a post by yarwell:
Yarwell -There's the potential for more than one definition, for example 2Wire routers have more than one attenuation including a figure at 300 kHz.


Regarding the the 2wire which or both attenuation reading would i use for distance purposes.
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