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Author Topic: ADSL2 Attenuation & speed Survey  (Read 7136 times)

Jonnyteg

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ADSL2 Attenuation & speed Survey
« on: October 08, 2012, 04:50:07 PM »

As above what is your stats so we can compare.    Include your target SNR also and ISP.

 Im sure we will see divergence  :graduate: 

Im 50.1db, SNR 6db, sync speed 4.1meg.   ;)

Forgot to add cp is BT Retail  ;)
« Last Edit: October 08, 2012, 05:50:16 PM by Jonnyteg »
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toulouse

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Re: ADSL2 Attenuation & speed Survey
« Reply #1 on: October 08, 2012, 05:19:53 PM »

Hello Jonnyteg,

It would appear that I still have some kind of fault on my line, advised to O2 this morning, so at present I'm at :

Attenuation - 29.5, Target SNR - 15 (currently at 13.1), Sync Speed - 7834

TTFN

toulouse
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Utility Warehouse (via TalkTalk)
FTTC 40/10
ZyXEL VMG8924-B10A
ECI (approx 750 metres)

People tell me that I ought to get out more. But in the words of the great Homer J Simpson, "Yeah, but what ya gonna do ?"

Jonnyteg

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Re: ADSL2 Attenuation & speed Survey
« Reply #2 on: October 08, 2012, 05:48:40 PM »

Hello Jonnyteg,

It would appear that I still have some kind of fault on my line, advised to O2 this morning, so at present I'm at :

Attenuation - 29.5, Target SNR - 15 (currently at 13.1), Sync Speed - 7834

TTFN

toulouse

Your Snr is holding back your sync speed.   Did you not have a engineer out the other day to fix your issue?  What fault is your ISP claiming?
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c6em

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Re: ADSL2 Attenuation & speed Survey
« Reply #3 on: October 08, 2012, 06:07:31 PM »

Total real line length 2.4Km, (approx 2.25Km E side, 125m D side, 75 yards overhead dropwire)
ADSL2+, router reported DS attenuation: 36dB
DS Target margin 3.0dB, Sync 14100kbps.
However the line sometimes re-sync's overnight at this setting so by judicious timing of a re-sync in the evening I actually run the line lower at approx 13800kbps sync at around 3.8 daytime margin where it will hold in continuously for months.

The clue to the good line performance seems to be the short D side length - which is on aluminium incidentally.  Those fellow villagers with a longer D side have very marked poorer performance. Presumably due to the cable joins at each joint box where the cable is cut for next house group to be split out from the main cable and run up a pole).
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Jonnyteg

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Re: ADSL2 Attenuation & speed Survey
« Reply #4 on: October 08, 2012, 06:13:12 PM »

Total real line length 2.4Km, (approx 2.25Km E side, 125m D side, 75 yards overhead dropwire)
ADSL2+, router reported DS attenuation: 36dB
DS Target margin 3.0dB, Sync 14100kbps.
However the line sometimes re-sync's overnight at this setting so by judicious timing of a re-sync in the evening I actually run the line lower at approx 13800kbps sync at around 3.8 daytime margin where it will hold in continuously for months.

The clue to the good line performance seems to be the short D side length - which is on aluminium incidentally.  Those fellow villagers with a longer D side have very marked poorer performance. Presumably due to the cable joins at each joint box where the cable is cut for next house group to be split out from the main cable and run up a pole).

Are you interleaved at all?   D sides can be good on a long stretch on a newer network or upgraded.   E sides can also have aluminium.   

With your stats i would expect a high CRC count?
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toulouse

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Re: ADSL2 Attenuation & speed Survey
« Reply #5 on: October 08, 2012, 06:35:09 PM »

Hello Jonnyteg,

It would appear that I still have some kind of fault on my line, advised to O2 this morning, so at present I'm at :

Attenuation - 29.5, Target SNR - 15 (currently at 13.1), Sync Speed - 7834

TTFN

toulouse

Your Snr is holding back your sync speed.   Did you not have a engineer out the other day to fix your issue?  What fault is your ISP claiming?

Yes, indeed I did have an engineer last Thursday afternoon. He was very thorough checking my wiring up to the DP in the building. He found a loose or disconnected wire at the DP and reconnected that. He then went to the street cabinet, and apparently found something else 'of concern' as he put it, and then on to the exchange where I think he found something else that 'wasn't quite right'. He assured me that everything to do with the phone side of things was A OK, and that if I had further problems, I should insist that a specialist Broadband engineer gets involved. My ISP ( O2 ) insist on running a further 24 Hour test on the line and I have got to call them again in the morning. I did explain that this 24 monitoring malarkey has already been carried out twice to my knowledge, but I think I was talking to a script reader rather than a proper 'techie'.
They set the target SNR to 15,as part of this monitoring. At least the line has stayed up all day so far.

Bring back my 15M sync with 6db NM @ 29.5 Attenuation.

I think something is seriously BROKEN, but convincing an ISP of that ain't easy. They told me this morning that as far as they could see from their end I had had no disconnections, but the line was up and down like the proverbial lady of the nights 'underthings' from around 3:30am. Sometimes it would stay up for around 2 or 3 minutes, other times up / down / up / down.........

Any advice would be most welcome

toulouse
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Utility Warehouse (via TalkTalk)
FTTC 40/10
ZyXEL VMG8924-B10A
ECI (approx 750 metres)

People tell me that I ought to get out more. But in the words of the great Homer J Simpson, "Yeah, but what ya gonna do ?"

Jonnyteg

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Re: ADSL2 Attenuation & speed Survey
« Reply #6 on: October 08, 2012, 07:00:13 PM »


Yes, indeed I did have an engineer last Thursday afternoon. He was very thorough checking my wiring up to the DP in the building. He found a loose or disconnected wire at the DP and reconnected that. He then went to the street cabinet, and apparently found something else 'of concern' as he put it, and then on to the exchange where I think he found something else that 'wasn't quite right'. He assured me that everything to do with the phone side of things was A OK, and that if I had further problems, I should insist that a specialist Broadband engineer gets involved. My ISP ( O2 ) insist on running a further 24 Hour test on the line and I have got to call them again in the morning. I did explain that this 24 monitoring malarkey has already been carried out twice to my knowledge, but I think I was talking to a script reader rather than a proper 'techie'.
They set the target SNR to 15,as part of this monitoring. At least the line has stayed up all day so far.

Bring back my 15M sync with 6db NM @ 29.5 Attenuation.

I think something is seriously BROKEN, but convincing an ISP of that ain't easy. They told me this morning that as far as they could see from their end I had had no disconnections, but the line was up and down like the proverbial lady of the nights 'underthings' from around 3:30am. Sometimes it would stay up for around 2 or 3 minutes, other times up / down / up / down.........

Any advice would be most welcome

toulouse

The explination from the engineer sounds suspect to me  :( .    On a IDC connection you cant have a loose wire if dry (apart from a quante krone), its either terminated or not if it was dis then your phone service wouldnt work.   

My guess is the engineer ran the pqt test from the cab for a pass so he can prove he fixed the circuit. 

Did the engineer bring a next gen tester into your premises, or his laptop and hawk?

You may need a SFI visit which the engineer will be broadband trained.

The 15db snr will be more stable with a fault. 

To add your metalic pathways 'pair' quality may pass a basic line test, however an in depth test from a BB engineer will look for issues that the basic tests will show.   The important parameters on a pair for adsl2 would be Resistance balance >97-98%, AC balance >55db, Capacitance balance > 98%, DC voltage < 3v & Insulation resistance > 1 meg ohm.

So you can ask the engineer next visit  ;) 

« Last Edit: October 08, 2012, 07:44:06 PM by Jonnyteg »
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Browni

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Re: ADSL2 Attenuation & speed Survey
« Reply #7 on: October 08, 2012, 07:13:47 PM »

This went off-topic in post #2  :D

Anyhow

Bandwidth (Up/Down) [kbps/kbps]:   1.429 / 15.827
Line Attenuation (Up/Down) [dB]:   19,9 / 33,0
SN Margin (Up/Down) [dB]:   5,1 / 2,8

Target SNR 3db on O2.

Are you going to do some sort of analysis of the figures posted here?

Jonnyteg

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Re: ADSL2 Attenuation & speed Survey
« Reply #8 on: October 08, 2012, 07:23:46 PM »

This went off-topic in post #2  :D

Anyhow

Bandwidth (Up/Down) [kbps/kbps]:   1.429 / 15.827
Line Attenuation (Up/Down) [dB]:   19,9 / 33,0
SN Margin (Up/Down) [dB]:   5,1 / 2,8

Target SNR 3db on O2.

Are you going to do some sort of analysis of the figures posted here?

Yes, I will do if i can get enough data  ;)
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Bald_Eagle1

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Re: ADSL2 Attenuation & speed Survey
« Reply #9 on: October 08, 2012, 07:37:07 PM »


Bandwidth (Up/Down) [kbps/kbps]:   1.429 / 15.827


Is that a typo, or is the router misreporting the speeds?

It looks as though it should either be Mbps or the decimal point should be omitted (or replaced by a comma).
« Last Edit: October 08, 2012, 07:39:15 PM by Bald_Eagle1 »
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c6em

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Re: ADSL2 Attenuation & speed Survey
« Reply #10 on: October 08, 2012, 07:37:58 PM »

In reply to the query above.
D side is direct buried in ground ie not ducted installed as I recall in early ?1970's? when the old separate two overhead incoming phone line wire supply was removed.

My Line has always been interleaved DS at depth of 64 both on ADSLmax and now on ADSL2+.
The cumulative RS corrected count certainly mounts up into the multiple millions over time so the error correction routines certainly work.
See typical sort of graph below of CRC count /15minute interval over a 24 hour period. During the day its pretty well zero so I can achieve somewhere near to the IP setting in speed tests.
Normally computer is off overnight though I can recall seeing CRC counts/15min higher than this and in the thousands in the middle of the night - though what do I care if they are - I'm asleep then, nothing is being down/up loaded, the router is idle and remaining in sync and all has returned to normal the next morning. Sure if you were doing lots over overnight downloading of stuff then it would probably be an issue.

This is a largish rural exchange hence the ADSL2+ upgrade but frankly even if fibre arrived (it's not planned) I would not be currently interested given the present line performance which is actually far more than I need.
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Jonnyteg

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Re: ADSL2 Attenuation & speed Survey
« Reply #11 on: October 08, 2012, 07:49:41 PM »

In reply to the query above.
D side is direct buried in ground ie not ducted installed as I recall in early ?1970's? when the old separate two overhead incoming phone line wire supply was removed.

My Line has always been interleaved DS at depth of 64 both on ADSLmax and now on ADSL2+.
The cumulative RS corrected count certainly mounts up into the multiple millions over time so the error correction routines certainly work.
See typical sort of graph below of CRC count /15minute interval over a 24 hour period. During the day its pretty well zero so I can achieve somewhere near to the IP setting in speed tests.
Normally computer is off overnight though I can recall seeing CRC counts/15min higher than this and in the thousands in the middle of the night - though what do I care if they are - I'm asleep then, nothing is being down/up loaded, the router is idle and remaining in sync and all has returned to normal the next morning. Sure if you were doing lots over overnight downloading of stuff then it would probably be an issue.

This is a largish rural exchange hence the ADSL2+ upgrade but frankly even if fibre arrived (it's not planned) I would not be currently interested given the present line performance which is actually far more than I need.

Due to the 'ali' in your dside I would bet thats the reason for your int delay, the joints are terrible and should be replaced.
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Jonnyteg

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Re: ADSL2 Attenuation & speed Survey
« Reply #12 on: October 08, 2012, 07:58:20 PM »

What will be of interest, different CP's performance with similar attenuation.
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Browni

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Re: ADSL2 Attenuation & speed Survey
« Reply #13 on: October 08, 2012, 09:05:43 PM »


Bandwidth (Up/Down) [kbps/kbps]:   1.429 / 15.827


Is that a typo, or is the router misreporting the speeds?

It looks as though it should either be Mbps or the decimal point should be omitted (or replaced by a comma).

It's not a typo as that was just a straight copy & paste from the router stats page.

I'm using the O2 Wireless box 5 which by default uses the European convention for displaying numbers (IE commas & decimal points are transposed)

You can see that in the attenuation and noise margin figures.

Black Sheep

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Re: ADSL2 Attenuation & speed Survey
« Reply #14 on: October 08, 2012, 09:07:33 PM »

I think the BT Home Hub (from memory) use the decimal point as well ??
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