Strong line stats?

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.

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?).

Hmmmm.

I advise against setting your expectations that high. Sorry .

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!

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)

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.

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.}

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

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.

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.

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.

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.

Not strong no, but it seems you line is quiet. I'd say upto 25db attenuation is a 'strong' line.

I reckon you will probably get 9Mb ish - the only way of telling what kind of gain you will get by moving to ADSL2+ is by you uploading a DMT tool graph of the available bins.

I'm on a 48db line, a bit longer than yours and I gain 2Mb on ADSL1 using ADSL2, not 2+ but my line is noisy. My attenuation jumps to 51db on ADSL2+.

On a good day, without interleaving I used to sync at 7120kbps on ADSL1 with a 1db SNR. Unfortunately soon as the sun goes down my line goes wild.

Haven't tried ADSL2/2+ without interleaving but on the BT 3db default SNR it's around 6700kbps - interleaved.

I believe someone on here managed 10Mb on a 40db line but they were on UKOnline LLU with SRA enabled.

Edited by wolvesmad (Thu 02-Aug-12 10:58:10)

Mine is 39dB and I manage 12Mb but I am running at 3dB noise margin because my line is incredibly stable (and because I chose a provider where I can do that). On Sky with a 7dB margin I used to get around 10Mb.

So, provider, noise margin and stability all make a big difference around these numbers. I consider my line to be very stable for its attenuation and therefore would be surprised if a higher attenuation would be able to easily beat my line stats.

So you are tweaking like crazy because of a DLM setting of 15dB?

Your efforts would be better directed to establishing the cause, (possibly the tweaking itself forcing the line too fast in the past), and getting it back to 6dB. Then tweak more gently.

Edited by RobertoS (Thu 02-Aug-12 22:06:54)

In reply to a post by RobertoS:

So you are tweaking like crazy because of a DLM setting of 15dB?

Your efforts would be better directed to establishing the cause, (possibly the tweaking itself forcing the line too fast in the past), and getting it back to 6dB. Then tweak more gently.

It was originally 6dB but the router wasn't particularly good so I needed to reboot it a few times which forced the SNR up to 15dB.

In reply to a post by Toonshorty:

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.

Are you really sure about that? You can get that speed on 40dB as you have already shown.

In reply to a post by Toonshorty:

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.

Your attenuation has already been reported as 43dB and it ain't going down unless you move closer to the exchange or make sure your internal wiring is top notch! If anything it will rise by 2-3dB by changing to ADSL2+.

Edited by IanBB (Fri 03-Aug-12 00:17:32)

In reply to a post by Toonshorty:

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.

I would expect between 6.5 and 8.5 Mbps on ADSL2+

On your line I would expect 8.5 given that you are already syncing at 8000 but I wouldn't be shocked if there was little / no improvement.

I think we have established his 8Mbps was only by tweaking to below 6dB margin, and that is now difficult as he has caused a rise to a DLM setting of 15dB.

I agree with you that the estimates based on a 43-46dB attenuation on ADSL2+ of something under 9Mbps seem realistic. I've no idea what the effect of over-ambitious tweaking on TT could be. 11Mbps but unstable is possible.

My realistic expectation turns out to be bang on to be honest.

11Mb/s or a little less is what I guessed and it's currently sitting at 10500Kb/s.

I've always used my DGN2000 for my old connection since the TP-Link always synced a lot slower so naturally I connected to the network with the DGN2000 first.

It synced at around 9Mb/s with a 6dB SNR however reducing this to 3dB seemed to boost it up to 10.5Mb/s. The attenuation rose from 43dB to 44.5dB which isn't so bad.

I then tried my TP-W8961ND to see how that synced and was interested to see the same 10.5Mb/s sync speed but my attenuation was reported as 49dB! The SNR margin was originally 6dB however this has fallen to 4dB with no difference in sync speed.

I thought that 7.5Mb/s @ 43dB was impressive... 10.5Mb/s @ 49dB is crazy.

Any good speed tests to check my speed? I don't trust speedtest.net, it gave me a download of 10.69Mb/s when my sync speed is 10520Kb/s.

In reply to a post by Toonshorty:

Any good speed tests to check my speed? I don't trust speedtest.net, it gave me a download of 10.69Mb/s when my sync speed is 10520Kb/s.

I'm sure ThinkBroadBand's own speed test can be relied on!

Will do TBB test once H.A.W.X 2 has downloaded.

It's £1 at the Ubi Store for today only

SNR also seems to have fallen dramatically, down at 2.3dB right now! That said the line seems perfectly stable at that speed and the sync hasn't changed at all.

Try http://loki10.mpi-sws.mpg.de/bb/bb.php (don't select anything, just click 'start measurement')

On TalkTalk (direct) i'm getting a sync of 18.3 meg on a 29 db attenuation @ 6db noise margin...this is using a infineon modem (draytek 120). Yet using a broadcom router (billion 7800n) gives me 15.5 meg and even tweaking the noise margin on that to 3db still doesn't give me 18 meg. Since TalkTalk have just LLU'd your exchange, your exchange MSAN is almost certain to have an Infineon chipset...i'd strongly recommend you go for a Infineon chipset router for the highest sync speeds eg Netgear DGN1000, DGN3500, Dryatek 120, 2820, 2830 etc.

SNR margin at 1.9dB now, found it as low as 1.7dB before.

It seems to be falling quite a bit, is this normal behaviour?

If I were to resync should I expect a higher sync but less stability?

I'm used to the BT Wholesale setup where the noise margin would hang around 6dB and fluctuate by ~±1dB. Here it doesn't seem to have a target and will just go as low as it can before it gets unstable.

ADSL2+, using double the frequency range of ADSL Max, is more susceptible to noise, as the higher frequencies are more likely to get hit. Yes, a greater variation over 24 hours is likely. Not always the case though.

If I were to resync should I expect a higher sync but less stability?

If you resync when the margin is low, i.e. the ambient noise is high, the result is the opposite of that. Your noise margin returns to your (tweaked) value, hence stability improves, but the sync speed falls.

But are you lowering the SNR yourself? If so, i'd suggest leaving it 6db and getting an infineon router and then just enjoy using your connection

In reply to a post by RobertoS:

ADSL2+, using double the frequency range of ADSL Max, is more susceptible to noise, as the higher frequencies are more likely to get hit. Yes, a greater variation over 24 hours is likely. Not always the case though.

If I were to resync should I expect a higher sync but less stability?

If you resync when the margin is low, i.e. the ambient noise is high, the result is the opposite of that. Your noise margin returns to your (tweaked) value, hence stability improves, but the sync speed falls.

I always thought lower SNR was faster. Should have read a little closer.

So if I find the noise margin higher at say 7-8dB for example it may increase speeds slightly?

Will probably get a Vigor 120 anyway.

Read all about it .

I think you are confusing the "target" noise margin used at sync-time, which is what you are tweaking, with the behaviour of the margin thereafter. You may also be confusing noise margin with noise, but I don't really think so. The figure you see is the margin at that time you look.

Edited by RobertoS (Thu 16-Aug-12 21:59:18)

A 6dB SNRM is good for a 13143Kbps sync, interleaved, with a 37.5dB attenuation using uno partial LLU (CPW) is absolutely fine for me.

As you say baby_frogmella: "...just enjoy using your connection."

Not sure that getting an infineon router is essential though? I just use a tg585v7, although I believe the TT kit at the exchange may have been previously installed by Tiscali and uses Broadcom...

Edited by 4M2 (Thu 16-Aug-12 22:07:48)

In reply to a post by 4M2:

Not sure that getting an infineon router is essential though? I just use a tg585v7, although I believe the TT kit at the exchange may have been previously installed by Tiscali and uses Broadcom...

Matching router + exchange chipsets will almost certainly result in the best sync speed. Exchanges which TalkTalk have LLU'd in the last few years use Infineon chip in their dslam so it makes sense for the OP to use an Infineon router (not tweakable). However some exchanges such as yours (ex tiscali) use a broadcom chip which is why a broadcom router is best suited.

In reply to a post by baby_frogmella:

Matching router + exchange chipsets will almost certainly result in the best sync speed.

Fair enough