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Standard User Toonshorty
(newbie) Wed 01-Aug-12 22:35:07
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Strong line stats?


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I've always considered my line to be fairly average however recently after looking at several checkers and other people's stats it would appear that my line is actually particularly good.

Here are my current statistics on ADSL Max (Will have ADSL2+ in 2 weeks).

Sync: 8000 (Goes down to 7500 during heavy noise periods)
Attenuation: 43dB
Noise Margin: 5.5dB

While most calculators aren't always accurate, to find that on the Kitz speed checker an attenuation of 43dB would normally result in a sync of around 6300 was quite impressive. For the checker to report a figure around the 8000Kb/s you'd need an attenuation of ~30dB. While the checker could possibly be fairly conservative it is based on a 6dB target SNR so it's probably not too far away.

Since TalkTalk have just unbundled my exchange I'm looking to move to XILO's Pro 24 package. I currently have an attenuation of 43dB so I expect this to reach 46dB after a switch to ADSL2+ however the checker reckons a sync of around 6800Kb/s would be the norm for 46dB attenuation. However if I use that 30dB figure that would almost appear to be what my attenuation represents then a 33dB attenuation would sync me at 13,000Kb/s. I'm genuinely quite excited and curious to see what on earth I'll sync at with ADSL2+. Realistically I'm expecting around 11,000Kb/s sync, maybe a little less.

I'd be interested to see what line stats other people are getting, maybe a 'Post your stats!' thread is in order.
Standard User camieabz
(sensei) Wed 01-Aug-12 23:14:21
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Re: Strong line stats?


[re: Toonshorty] [link to this post]
 
Prior to ADSL2+

Sync: 8128
Profile: 7150
Max Speed: 6750kbps
Typical speed: 6550kbps
Attn: 30.0 dB
SNR: 8.5 dB

Since ADSL2+ (max settings, not stable)

Sync: 16000
Profile: 14000
Max Speed: 13350kbps
Typical Speed: 13000kbps
Attn: 32.5 dB
SNR: 3.0 dB

Stable settings are generally 500kbps less on sync, profile and speeds. 12.5 Meg is a typical stable speedtest result. BY stable, I generally mean that I can get the faster speeds between midnight and 8am, but the SNR drops to 2.5 or less and forces a resync to around 15500 or so.

IMHO, there's something screwy with your stats if you can get those speeds with that attenuation. There's certainly scope for some testing to confirm the data. As you can see, I get the almost stable speeds you hope for, and I have to go to 3.0 dB to get them. Maybe it's a short connection with high attenuation for some reason (bad link?).

~ Camieabz ~

All Connection Data ~ Some plusnet links

mod'er·a'tion n.
Synonyms: temperance, restraint, modesty.
Standard User RobertoS
(sensei) Wed 01-Aug-12 23:17:14
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Re: Strong line stats?


[re: Toonshorty] [link to this post]
 
Hmmmm.

I advise against setting your expectations that high. Sorry frown.

Quite how you are getting the speeds you are I'm not sure, but at 43dB I wouldn't expect over 10Mbps sync on ADSL2+, and at 46dB even the 8Mbps you see now would be high.

In addition, I think TalkTalk sync-time noise margins for most resellers are set at 9dB. That knocks 1Mbps or so off he 6dB speed. On the other hand there is no IP profile to apply.

having said that, I sincerely hope your calculations work out!

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - Plusnet Value Fibre FTTC 80/20 trial.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
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Standard User Toonshorty
(newbie) Wed 01-Aug-12 23:20:56
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Re: Strong line stats?


[re: camieabz] [link to this post]
 
In reply to a post by camieabz:
Prior to ADSL2+

Sync: 8128
Profile: 7150
Max Speed: 6750kbps
Typical speed: 6550kbps
Attn: 30.0 dB
SNR: 8.5 dB

Since ADSL2+ (max settings, not stable)

Sync: 16000
Profile: 14000
Max Speed: 13350kbps
Typical Speed: 13000kbps
Attn: 32.5 dB
SNR: 3.0 dB

Stable settings are generally 500kbps less on sync, profile and speeds. 12.5 Meg is a typical stable speedtest result. BY stable, I generally mean that I can get the faster speeds between midnight and 8am, but the SNR drops to 2.5 or less and forces a resync to around 15500 or so.

IMHO, there's something screwy with your stats if you can get those speeds with that attenuation. There's certainly scope for some testing to confirm the data. As you can see, I get the almost stable speeds you hope for, and I have to go to 3.0 dB to get them. Maybe it's a short connection with high attenuation for some reason (bad link?).


The connection certainly isn't short, I'd say the opposite actually.

The cable follows the road and the road from my street to exchange is 3.7km however BT's reported line length is 4.2km so maybe it loops around in some places.

43dB should only be around 3.1km though so I'd actually argue that the attenuation is really good considering the length. Then the line sync is really good for the attenuation.

IP Profile is actually set to 6Mb/s at the minute (Can't wait to be rid of this stupid profile system).

Edited by Toonshorty (Wed 01-Aug-12 23:22:11)

Standard User 4M2
(experienced) Wed 01-Aug-12 23:31:45
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Re: Strong line stats?


[re: Toonshorty] [link to this post]
 
Xilo Pro 24, partial LLU - TT broadcom kit at the exchange, currently gives me a downstream sync of 13076Kbps from a down attenuation of 37.5dB and down night-time SNRM of 5.5dB (daytime SNRM is 6 or 6.5dB.) This is a very stable interleaved connection and I get a downstream throughput of ~11Mbps 24/7.

However the other day the tg585v7 router resync'd after a power cut and the down SNRM lowered to 2.5dB and the down sync was 14657Kbps. The router did hold the connection for more than 24 hours but possibly due to a high FEC Error rate downstream throughput dropped to ~5Mbps and it didn't seem comfortable. Powering off the router for 30 minutes brought the connection back to normal though.

I think your choice of Xilo/uno Pro 24 SMPF should prove to be very satisfactory but I would be surprised if you can achieve a downstream sync of ~11000Kbps together with good stability if your current adsl1 attenuation is 43dB even though it is an exceptionally good line.
Standard User RobertoS
(sensei) Wed 01-Aug-12 23:47:31
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Re: Strong line stats?


[re: Toonshorty] [link to this post]
 
In reply to a post by Toonshorty:
IP Profile is actually set to 6Mb/s at the minute (Can't wait to be rid of this stupid profile system).
That means a sync of no more than 7360kbps, assuming a few days have elapsed since the connection was was made at 6816kbps or more.

As camieabz says, your router stats look dodgy. What does the BT speed test say your connection speed is, compared to what your router is reporting at the same time?

By the way, an attenuation of 35/36dB should get 8128kbps sync on a good line.

And in your favour, on O2 LLU at one time I got around 7Mbps sync on 49dB attenuation. Which is not supposed to be possible.
Edit - typos.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - Plusnet Value Fibre FTTC 80/20 trial.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Edited by RobertoS (Wed 01-Aug-12 23:54:41)

Administrator MrSaffron
(staff) Thu 02-Aug-12 09:05:32
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Re: Strong line stats?


[re: RobertoS] [link to this post]
 
What is dodgy about the original posters stats?

I have two ADSL lines that would on good days get 7Meg sync at same attenuation. I would urge caution since ADSL2+ made little difference, other than now getting closer to 8 Meg sync a lot more of the time.

If an area has less crosstalk then no reason to doubt a line could manage close to 8 Meg at that distance, it is not common, just at the top end of what I would expect.

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 RobertoS
(sensei) Thu 02-Aug-12 09:18:58
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Re: Strong line stats?


[re: MrSaffron] [link to this post]
 
8000kbps at 43dB is suspect. The probable current sync of under 7392kbps, (unless the IP Profile is due to rise), is more like a good line performance. However he also reports drops to 7500'ish at noisy times, and is probably still talking about sync.

That's why I've asked him to check the current sync/BT-reported sync/BT-reported IP Profile. To see if the three are in line. I did use the word "dodgy", not "wrong".

On reflection, I wonder if he is tweaking the noise margin at times and just not told us. That way he could get 8000kbps.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - Plusnet Value Fibre FTTC 80/20 trial.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Standard User Toonshorty
(newbie) Thu 02-Aug-12 09:29:00
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Re: Strong line stats?


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
8000kbps at 43dB is suspect. The probable current sync of under 7392kbps, (unless the IP Profile is due to rise), is more like a good line performance. However he also reports drops to 7500'ish at noisy times, and is probably still talking about sync.

That's why I've asked him to check the current sync/BT-reported sync/BT-reported IP Profile. To see if the three are in line. I did use the word "dodgy", not "wrong".

On reflection, I wonder if he is tweaking the noise margin at times and just not told us. That way he could get 8000kbps.


I forced a resync and it connected at 7560Kb/s. Waiting for 6.5Mb/s IP profile. Noise margin from BT is 15dB however after some telnet commands this is now effectively 6dB. 8Kb/s isn't stable but 7.5 is quite comfortable.
Administrator MrSaffron
(staff) Thu 02-Aug-12 09:30:51
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Re: Strong line stats?


[re: RobertoS] [link to this post]
 
There are very few absolute limits, no reason 50dB cannot do 8 Meg, over than at the distance signal level is attenuated so much that the bins are not available.

All it takes is an away with lower noise levels for a few extra bits to be available.

RF which is what ADSL is, has so many variables difficult to model with 99% certainty.

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.
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