Help & Advice! [Stats & SNR]

[dandiscoboy]

Hi All,

Couple of weeks ago I began looking at my ADSL G.DMT speed in a little more detail (no other ADSL services available unfortunately) - part of this was buying a 7800DXL (firmware 2.32c) with the aim of improving m,y speed. I have gone through numerous forums and performed noise reduction and general domestic performance tweaks i.e. ADSLNation faceplate, plugging router directly into master, no telephone extensions etc. Having done all this I also requested my ISP reset my line so am currently into day 4 of the training period.

I'm hoping some of you guys with a little more experience can help me understand my router stats (attached) - I believe I should be able to achieve better speed than I'm currently getting (~5.5-5.8 Mbps)

From BT Wholesale speed test, IP Profile currently 6Mbps. System uptime at time of screenshot 4D 9H 19M 1S.

[-] In the Statistics -> xDSL screen, is the 'SNR Margin' in fact the target SNR? (i.e. BT's 6db default target). I've read a few posts where people have been tweaking their SNR in order to change this value.
[-] If this value is the target SNR and not the 'margin' over the default 6db, it looks like I have some headroom (although my ISP says BT have set it at 15db due to the line condition). If I tweak the SNR in the router config, will the BT DLM override my changes?
[-] Should any tweaks only be done after the training period?
[-] Can the IP Profile be changed? i.e. if I perform SNR tweaks which improve the stable connection, will the profile go higher?

Any advice based on my router stats would be really helpful!! Im not expecting light speed but I'd like to think that with the exchange being under 1km away I can achieve better speeds!

Thank-you for any help/advice in advance!

[RandomGeeza]

I have my SNR set by the DLM to 6. However, I have it tweaked to 4... I've had a stable connection throughout and no issues, since using the Billion product. The SNR margin is what your line is currently set at. So, yes you can tweak it. If you do tweak the SNR your profile will change in accordance, but if the DLM amends it back then your profile changes back also.

However, I have seen, especially on my old router (NetGear DGN2200v3) the DLM freak out, when tweaked. The router would constantly drop and the DLM believed there was a fault on the line, pushing my SNR up to 15/16. Although, it became clear that it was a router fault and not line, when I was out of the country for a month. During that time not a single drop occurred and yet when I was back in the country, within two days of using my kit as I normally would the connection became unstable. Indicating a heat, throughput issue with the NetGear. Hence the reason for buying the 7800DXL.

Give it a go and monitor accordingly. At the worst if the DLM goes mental, call your ISP and request a line reset. If they ask why, tell them you've installed a new router and the constant on and offs have compromised your speed.

[tinytim]

I would definitely advise not tweaking whilst in the training period , also no resets,disconnects or power offs of the router.

Are you only on an 8meg service? I ask as normally on G dmt I'd expect your upstream max to be 448kbps not around a meg.

[billion_fan]

Once the training period has ended, you can refer to the attached SNR table to tweak your SNR

[BadMelonFarmer]

I have tried to tweak the SNR on BT ADSL Max and gave up.

from what I can see it will be a continuous process of tweaking, unless you have a fixed SNR target ... which is something BT seem reluctant to do. The reason is that the DLM will ALWAYS try to get the SNR target back to 6.

So lets say you have a SNR of 6.1 and you tweak it to reduce it by 2 this will give the actual SNR of 4.1

over time the DLM will increase the 4.1 back to what it sees is 6.1 (Really 8.1 as you have the added 2) so you have to subtract 4 .... to get it back to 4.1

then over time the DLM will see this as 12.1 and will adjust it to 6.1 ... so you then have to subtract 6. and so it will go on.

took me a while to figure out what was going on, but i tested this twice and others have confirmed they have seen the same issue.

So if you are on BT ADSL max or ADSL2+ .... unless you are tweaking for a temporary reason OR you have a fixed SNR target then I can not see any point in tweaking the number...it just seems to cause more problems that it fixes in my opinion.