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Standard User dneb
(regular) Wed 28-Mar-07 20:39:16
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Attenuation vs. Exchange Distance.


[link to this post]
 
According to samknows.com:

"You are approximately 1.20km from the exchange (straight line distance)."

That sounds about right. But surely an attenuation in excess of 30dB is *not*, given such a short distance?

Down Up
SNR (dB): 12.3 25.0
Attn(dB): 32.0 31.5
Pwr(dBm): 19.7 11.9
Max(Kbps): 9280 1248
Rate (Kbps): 7616 448

This attenuation level has been bugging me since I switched to an ADSL Max package last December. It was at 24dB until then.

FWIW:

1) There are no extension sockets (I use DECT phones plugged into the main socket).
2) The only cable running into the master socket, comes directly from BT's junction box on the wall outside. The cable is coated with a brown material, and very short (less than 20 inches).
3) I fitted an ADSL Nation faceplate a month or two ago.

dneb - Still trying to get from Demon to Be*
par
Standard User cahaddras
(experienced) Wed 28-Mar-07 21:12:07
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Re: Attenuation vs. Exchange Distance.


[re: dneb] [link to this post]
 
Does it really matter? You're getting what's probably the maximum speed you can get, and with 12.3dB margin to spare. What was your speed and margin before you switched to ADSLMax?
Standard User dneb
(regular) Wed 28-Mar-07 21:53:25
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Re: Attenuation vs. Exchange Distance.


[re: cahaddras] [link to this post]
 
Oh, no problems getting 2MB on regular DSL, and I've had a few difficulties with MaxDSL (dropped from 8Mbps first month to between 5-6Mbps). Not sure what my noise margin was before I switched to ADSLMax, I just made a note of my attenuation at 25dB up/ 24dB down. But having seen it increase to 31dB since switching to ADSLMax, my connection issues indicate that I'm no longer in an optimal place, and now I'm switching to Be* (ADSL2+) I hear that my attenuation stats are likely to increase some more. =(

dneb - Still trying to get from Demon to Be*
par


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Standard User deleted
(deleted) Thu 29-Mar-07 00:48:24
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Re: Attenuation vs. Exchange Distance.


[re: dneb] [link to this post]
 
The attenuation seems `reasonable' given the possible cable length.
The attenuation up and down are almost the same which is quite odd.
Did you change routers when you went to max?
Standard User dneb
(regular) Thu 29-Mar-07 00:54:09
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Re: Attenuation vs. Exchange Distance.


[re: deleted] [link to this post]
 
I've used two different routers and a dsl modem since I got ADSLMax. Attenuation and SNR is approx. the same on all three. Somebody said that about the attenuation before. Is it unusual but normal...or suggestive of an underlying problem?

dneb - Still trying to get from Demon to Be*
par

Edited by dneb (Thu 29-Mar-07 00:54:24)

Standard User cahaddras
(experienced) Thu 29-Mar-07 09:09:31
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Re: Attenuation vs. Exchange Distance.


[re: dneb] [link to this post]
 
Somebody else posted here recently with a similar issue - their modem had reported a 6dB increase in attenuation when changing from a 1Mbps to an 8Mbps service. They did happen to keep a note of their previous stats, and these showed that the reported attenuation change had made absolutely no difference - it appeared to be just a measurement anomally, not a physical change.

A similar change happens when you go to ADSL2+ - the modem does indeed report an increased attenuation but again there's nothing physically changing. What happens in this case is that because the reported figure is just an average, it is increased by including the higher attenuation of the additional higher frequencies introduced by ADSL2+. The attenuation of the original frequencies hasn't changed.
Standard User nredwood
(experienced) Thu 29-Mar-07 21:25:09
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Re: Attenuation vs. Exchange Distance.


[re: cahaddras] [link to this post]
 
I went from 35db down and 25.5db up on 2Mb ADSL to 37.5db down and 18.5db up when I moved to ADSL2+ on Be
BT recorded line length is 2.08km

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