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Low attenuation but high SNR, can speed be improved?

Mathias
Grafter
Posts: 242
Registered: 21-08-2008

Low attenuation but high SNR, can speed be improved?

LONG POST WARNING!
I have recently learnt what the attenuation and SNR stats on the router information page mean and believe that as my attenuation is pretty low i should get a higher speed than i currently do. Unfortunately the SNR is around 12 rather than the optimum of 6 so this probably explains it. I have been doing some tests and have some data to share in order that some action can be taken to hopefully increase my speed and reduce the noise.
First some background info:
I live in a 3 storey 1900 terrace house and my local exchange is Acomb (in York), which is about 500m away. The master socket is on the ground floor, but my games room where i use my xbox and pc is in the attic room on the 2nd floor. As this is quite a distance away vertically, as well as being through old house style thick floors etc, i tend to keep the router connected to a secondary socket on the first floor, just below the games room. The games room itself unfortunately does not have any phone sockets, otherwise i would have the router up there and conenct things via adsl cables. As it currently stands i have to rely on wireless tech.
The router stats from the router on its normal first floor location in the secondary socket is given below:
Uptime: 0 days, 0:07:35 
DSL Type: G.992.5 annex A 
Bandwidth (Up/Down) [kbps/kbps]: 1,179 / 12,411 
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00 
Output Power (Up/Down) [dBm]: 12.0 / 0.0 
Line Attenuation (Up/Down) [dB]: 10.5 / 21.0 
SN Margin (Up/Down) [dB]: 6.5 / 12.5 
Vendor ID (Local/Remote): TMMB / IFTN 
Loss of Framing (Local/Remote): 10 / 0 
Loss of Signal (Local/Remote): 3 / 0 
Loss of Power (Local/Remote): 0 / 0 
Loss of Link (Remote): 0 
Error Seconds (Local/Remote): 2 / 0 
FEC Errors (Up/Down): NA / 0 
CRC Errors (Up/Down): NA / 1 
HEC Errors (Up/Down): 0 / 0 
As you can see I am on ADSL2+, not sure why it was only connected for 7 mins before the test, i hadn't turned the router off and i leave it on all day. I don't experience any noticeable disconnects in the router when streaming HD youtube or online gaming. The attenuation is low at 21 db so i should expect a line speed of ~16mbps, but the noise is quite high at 12.5db, so i can see why i don't get that.
Here is a bt speedtest conducted wirelessly (as this is how i normally connect to the net) with the router in that position:
1. Best Effort Test:
Download speed 7288 Kbps
For your connection, the acceptable range of speeds 4000-21000 Kbps.
Additional Information:
Your DSL Connection Rate :12411 Kbps(DOWN-STREAM), 1179 Kbps(UP-STREAM)
IP Profile for your line is - 10949 Kbps
2. Upstream Test:
Upload speed 950 Kbps
Additional Information:
Upstream Rate IP profile on your line is - 1179 Kbps
So you can see i normally get over 7mbps, whilst fine for streaming, lets me down when playing online on the xbox as i often get a fair amount of lag (for whatever reason). My ping from other speedtests is around 20, but interleaving is still turned on so not sure how much this impacts it. I wish the sbox itself had a speedtest option to give me an indication if that experiences significantly different results to my pc. Both are connected via wireless g to the thomson 585v7, which annoyingly doesn't support wireless n.
I then plugged into the master test socket and repeated the tests to see if internal wiring made any difference:
Uptime: 0 days, 0:01:43 
DSL Type: G.992.5 annex A 
Bandwidth (Up/Down) [kbps/kbps]: 1,203 / 12,791 
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00 
Output Power (Up/Down) [dBm]: 12.0 / 0.0 
Line Attenuation (Up/Down) [dB]: 10.0 / 21.0 
SN Margin (Up/Down) [dB]: 6.5 / 12.5 
As you can see the SNR has not changed, so i presume this means that internal wiring is fine.
Here are the bt speedtest results with the router in the test socket, but the test conducted wirelessly in the acticon my pc:
Download speed 7979 Kbps
For your connection, the acceptable range of speeds4000-21000 Kbps.
Additional Information:
Your DSL Connection Rate :12791 Kbps(DOWN-STREAM), 1203 Kbps(UP-STREAM)
IP Profile for your line is - 11284 Kbps
Upload speed 997 Kbps
Additional Information:
Upstream Rate IP profile on your line is - 1203 Kbps
You can see that the speed has increased by 700kbps.
Does this mean i need a simple reset of the SNR to 6db and see if that helps improve speed if the connection is stable?If so please action this.
Also does removal of interleaving really have much impact ofor online gaming. If so is my line currently stable enough to have it turned off?
Cheers.

28 REPLIES
lexusuk
Grafter
Posts: 567
Registered: 20-10-2009

Re: Low attenuation but high SNR, can speed be improved?

Quote from: Mathias
Does this mean i need a simple reset of the SNR to 6db and see if that helps improve speed if the connection is stable?If so please action this.

I have submitted a request for your line to be manually changed to 6dB target SNR profile.  This will likely be picked up tomorrow as the team that process these changes close at 6pm.
Quote from: Mathias
Also does removal of interleaving really have much impact ofor online gaming. If so is my line currently stable enough to have it turned off?

The wireless link between your PC and router will likely have a greater effect than the interleaving.  Best way to check is to try the connection with a wire if possible and compare the two.  Besides, interleaving is currently off on your line at the moment.
Any questions just ask.
Community Veteran
Posts: 2,568
Thanks: 176
Fixes: 2
Registered: 27-05-2011

Re: Low attenuation but high SNR, can speed be improved?

Have you considered Homeplugs  Huh
http://www.solwise.co.uk/net-powerline-gig-pl-1000m.htm
To do is to be - Neitzsche
To be is to do - Kant
do be do be do - Sinatra
Mathias
Grafter
Posts: 242
Registered: 21-08-2008

Re: Low attenuation but high SNR, can speed be improved?

Thanks for actioning the reset of the SNR Alex.
Thanks for the recommendation Peter, will see what effect the reset has. If gaming is no better on the xbox i may consider the homeplugs as there are no phone points in the attic and running an adsl cable from the floor below is not very practical for me.
Cheers.
Mathias
Grafter
Posts: 242
Registered: 21-08-2008

Re: Low attenuation but high SNR, can speed be improved?

Hi,
Have checked the router stats this morning before leaving for work. Noticed that the SNR was at 13.5.
Does this mean that the reset hasn't been actioned/taken effect yet, or if it has is that the best i can expect? Can you therefore please confirm whether the reset has gone through yet and when i can expect to see a change in the level?
Cheers.
lexusuk
Grafter
Posts: 567
Registered: 20-10-2009

Re: Low attenuation but high SNR, can speed be improved?

The line profile is showing at 6dB target SNR for both upstream and downstream and I've also had an email confirmation that the profile change has gone through.  Our test also shows that the current SNR is at 13dB.  Does the SNR reduce to 6dB if you power down and back up your router.  I'm just thinking that the sync may not have dropped when the profile change went through.
Mathias
Grafter
Posts: 242
Registered: 21-08-2008

Re: Low attenuation but high SNR, can speed be improved?

Thanks for the confirmation Alex. Will reset the router when i return home this evening and check the SNR again.
Mathias
Grafter
Posts: 242
Registered: 21-08-2008

Re: Low attenuation but high SNR, can speed be improved?

Hi, have reset and turned the router of then back on again on Friday evening. The SNR did not change back to 6 and has remained at 12.5. Checked last night and it was still at 12.5. Can you please find out why the SNR has not dropped and advise if i need to do anything else?
Cheers.
lexusuk
Grafter
Posts: 567
Registered: 20-10-2009

Re: Low attenuation but high SNR, can speed be improved?

Our line tester also shows the SNR at 12dB.  I have therefore sent a request for a line reset to see if we can get this to move.  Bear in mind this will restart the line 10 day training period that normally occurs during the first 10 days that your connection is active.  You may see some fluctuations in speed and connectivity.  Please monitor over the next few days and let us know if you need us to take another look.
Mathias
Grafter
Posts: 242
Registered: 21-08-2008

Re: Low attenuation but high SNR, can speed be improved?

thanks Alex. Am away for a couple of days, but will check when i return, hopefully will avoid the fluctuations that you referred to above.
Will i need to reset the router again?
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: 18-07-2007

Re: Low attenuation but high SNR, can speed be improved?

You shouldn't need to, though if it's synced at lower than normal speeds it'd be worth disconnecting via the interface then powering off and on again to resync at a higher speed (if you do this around lunchtime you'll usually get a better speed than other times of the day) - I'd only do that once a day though. If it's a good speed though best to leave it on if possible.
Hope that helps,
Mathias
Grafter
Posts: 242
Registered: 21-08-2008

Re: Low attenuation but high SNR, can speed be improved?

Hi Alex,
Have now returned. Haven't noticed any noticeably drop in sync speeds so have not reset the router. Unfortunately the SNR (when checked last night) was still at 12db. Is something not working, please let me know what else can you do?
Cheers.
lexusuk
Grafter
Posts: 567
Registered: 20-10-2009

Re: Low attenuation but high SNR, can speed be improved?

I have re-requested the 6dB profile.  This can take a few hours to take effect.
Let us know if the SNR does not change.
Mathias
Grafter
Posts: 242
Registered: 21-08-2008

Re: Low attenuation but high SNR, can speed be improved?

Cheers Alex, will monitor over the weekend
Mathias
Grafter
Posts: 242
Registered: 21-08-2008

Re: Low attenuation but high SNR, can speed be improved?

Hi Alex, that seems to have worked. The SNR is now 6.5 and DL speeds have increased to ~ 10mbps, which is nice.
It seems that the line reset has re-imposed the cap on my upload speed as it has decreased from ~1mbps to 440kbps. Could you therefore please request that the cap on upload speed is removed so i can get close to 1mbps again?
Cheers.