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hey (looking back at my previous posts on my SNR/atten)
before ring wire removal
Attenuation (dB): 44.5 / 31.5
SNR Margin (dB): 13.5 / 7.5 (17-19 nights)
500-900kb synch rate
after removal
Attenuation (dB): 60 <<<<
SNR: 12
1.5-1.6mb synch rate
i still am question what has happened, i thaught attenuation was not surpose to change, but i have got + 15 all of a sudden
if this didnt increase so much, then i could be getting 3mb shouldnt i?
any ideas on what has caused this huge jump
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There's no way that removal of the ring wire can increase attenuation, so either your router is reporting wrongly or (more likely) there's something wrong with your wiring. The wire you should have disconnected is the one on pin 3 in the NTE5 faceplate. Pins 2 and 5 (only) should be connected. Check that they are correctly connected to pins 2 and 5 in all the extension sockets.
Eric
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In reply to:
then i could be getting 3mb shouldnt i?
More than that actually, there's someone on this board that has a 57db attenuation line and gets 4mb sync. You should get at least 4.5-5mb i'd say.
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Packet loss, High pings, High Attenuation, Low noise margins, and high contention courtesy of BT
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In reply to:
any ideas on what has caused this huge jump
Yes, you've got a dodgy connection on one of the other 2 wires.
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In reply to:
More than that actually, there's someone on this board that has a 57db attenuation line and gets 4mb sync. You should get at least 4.5-5mb i'd say.
There's more to line speed than just the attenuation figure. The SNR of the line is just as important. To demonstrate, I have 2 lines in this office, and here are the current stats:
Line 1: Attn: 46dB, sync speed 3360, SNR 5dB
Line 2: Attn: 42dB, sync speed 6112, SNR 4dB
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ADSL uses a range of frequencies (bins), each of which has an attenuation figure. The higher frequencies will have a higher attenuation. To get a single figure displayed on a router some kind of average is used.
When the noise on a line decreases more of the higher frequency bins can be used and hence the overall attenuation may rise.
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I think you are getting confused. The displayed SNR is the average of all the frequencies used, but the line attenuation is always measured at 300kHz for reference purposes. My SNR goes up and down like a yo-yo, but my line attenuations have stayed static for months.
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My SNR gets worse by about 5dB in the evenings. If I re-sync then my speed decreases and the SNR increases again as expected. I also see an increase in my attenuation of between 0.5 and 1 dB.
I only have a basic knowledge about how ADSL works so assumed that the change in my attenuation was due to it being measured at different frequencies. Does the changing attenuation indicate a problem with my line or router?
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SNR changes in the evenings are due to the fact that the source of the noise (broadcast stations in the MW band) are much stronger at night, because the layer in the ionosphere which reflects these signals is destroyed by daylight. ADSL uses the same frequencies as MW radio. All you can do is to keep unfiltered wiring above ground as short as possible, to stop it acting as an aerial. I think the variations you're seeing in the attenuation are more to do with the innacuracy of the measurement as anything else.
Edited by deleted (Wed 25-Oct-06 15:12:50)
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Yes, I was aware why SNR gets worse in the evenings. The information that lead me to believe that attenuation was measured at different frequencies came from this post. Perhaps different routers derive the figures in different ways, or perhaps it is just an inaccuracy as you suggest.
So would a 5dB drop in SNR from day to night be typical?
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Well, I've seen other people argue that the attenuation was averaged, but since BT based the ability to receive fixed rate services based on line attenuation, I really don't see how it could be based on something which would inevitably change every time the modem sync'd, if it were to be measured this way.
I don't think that you can give a typical change in SNR figure, since every installation is unique. It certainly isn't unusual.
Edited by deleted (Wed 25-Oct-06 16:55:54)
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Yes, it shouldn't, but my attenuation went up from 26db to 27db, with the removal of the ring wire in my one extension. This was pre max, and has stayed the same ever since. This is also testing the attenuation from an external source, so not using the routers own stats.
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lol well i can read ( im using a voyager 105)
i checked all my forum post's on my ISP all siad me saying 45 Attenaution
removed ring wire, went upto 60
plus.net are now sending an engineer over to me this week
and YES! IT WAS! after i removed the ring wire 100% certain with this
p.s. ordered a router should be here next week or so, will this increase synch ?
Edited by iLLegaL (Wed 25-Oct-06 21:52:47)
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We don't doubt you, but I hope you know that BT can charge you if the fault was your fault (like you've dislodged a wire, or caused a stress fracture in the copper).
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ye ive been told about this 
being that im 17 and no1 else even uses intnet in our house i think my parents aint gunna be to happy :P
any idea of the price ?
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I think it's about
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0mFg well surely my isp couldve told me first ^^
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Don't worry too much - BT rarely charge. As long as you haven't interfered with the wiring behind the back part of the NTE5.
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will they care that i took out the ring wire ?
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reported attenuation does change in response to the frequencies in use, as several posting demonstrate. I don't know how its defined but it appears to be some sort of average. BT and others use a 300 kHz reference if doing a two-ended test and you can find papers on the net about how reported attenuation relates to the 300 kHz figure.
The odd dB of increase is to be expected if you sort out problems and get better speeds, changing a microfilter I saw sync speed go from 600 to 3600 and attenuation went up about 5 dB. 15 dB would be excessive and suggests a possible wiring fault (like the wire removed was one half of the pair !)
Phil
666 kbytes/s with Demon
MaxDSL speeds - what do they all mean. |
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In reply to:
There's more to line speed than just the attenuation figure. The SNR of the line is just as important.
SNR = Tx power - Attenuation - Noise
I would say the SNR and hence the speed are a result of the attenuation and the noise level, so good speeds can be if the noise is low. Your line 1 looks noisy.
Phil
666 kbytes/s with Demon
MaxDSL speeds - what do they all mean.
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BT don't care what you do to your extension wiring.
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In reply to:
Your line 1 looks noisy.
It is. It goes for about half a mile overground, and it then travels about a mile over aluminium. Line 2, on the other hand, goes underground all the way, and over copper all the way. It's a great example of what overground cables and aluminium cables can do to your broadband.
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Agreed.
A low noise line is the key to getting higher and more stable syncs with a high attenuation long line, and is more important than line attenuation alone (I'm able to hold sync for longer than many with much shorter lines, and end up on a good IP profile because of the good stability allowed by my line).
I consider myself to be very lucky, in being able to sync at 4096kbps (at 6db noise margin) on a 6.9km line with an attenuation of 57db.
Admittedly, if I want a stable sync (to hold for more than a few days) I have to deliberately sync during medium to high noise periods (resulting in a sync around 3600kbps, which will hold for weeks if I leave it alone).
Ade
Giving UKFSN/Entanet a try
DL Sync 4096kbps
UL Sync 448
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It is. It goes for about half a mile overground, and it then travels about a mile over aluminium. Line 2, on the other hand, goes underground all the way, and over copper all the way. It's a great example of what overground cables and aluminium cables can do to your broadband.
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was that talking about my line ? sorry i missed these to posts
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hey i got this reply from plus.net
The only way in which a charge was incurred by yourself would be of the fault was due to your equipment or setup. The tests that we have completed so far would indicate that this is not the case.
any idea of what the "tests indicated" ?
p.s. i am synching at an all time high tonight of 1.9mb :O with an SNR or 10 (3am :') i should get some sleep )
do you think they are lowering my target SNR. (which my isp said they would ask BT to do )
Edited by iLLegaL (Fri 27-Oct-06 03:43:29)
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No, it was a reply to Yarwell. Read the header, or don't use flat mode.
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my Line attenuation has been up and down over last few days
peaking at 63.5 (apprently max. figure that modem will report)
and right now, it is at 56db
is this a wiring fault or something, because i heard people saying a change of 1db is big
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An increase of 3 dB means half the signal strength, so it is a bit sensitive. Dodgy connection in plug, poorly terminated wires, line fault etc.
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