Low SNR Margin - Tried Everything

  TicTacToc 18:34 27 Aug 2006
Locked

Hi all,

I recently bought a Voyager 2100. I also got a speed upgrade to '3mbps'.(as Bt said)

I looked into my Voyagers Broadband Line stats page.

My line rate varies from 4,000kbps up to 7,000kbps.

When I do some Broadband Speed tests I rarely get above 3000kbps.
When the line rate is greather the noise margin is smaller (I know why this is :))

When the noise margin drops below about 6.5db I get dropping connections. The noise margin is normally smaller in the evenings along with the line rate being normally greater. I never have problems with the line in the mornings till about 5pm. (high noise margin)

I have tried taking the front of the phone socket and plugging the connector into the test socket, negating the extension wiring: no change.

I have tried calling BT about 6 times but get various responses:

Firstly I struggle to be able to get the Indian representative to understand what noise margin and SNR is at all!

When I mention the speed seems far too much and maybe it should be slowed down they get me to run speedtester.bt.com which shows about 2,600kbps speed rate, so they say the speed is what i should get and thats fine.

And then I get lots of questions like 'How long does it take to disconnect' to which the answer is it changes everytime. . (I went a day recently, but then had 5 disconnections in like 30 minutess).

So I'm just not getting anywhere.

Anything for me to try?
Thanks

  woodchip 19:54 27 Aug 2006

Yes go back to peddle power. ]

I had to put that in to push your thread up

  CurlyWhirly 20:08 27 Aug 2006

"When the noise margin drops below about 6.5db I get dropping connections."

What is your target SNR?

When I first went on to Max, I found that 6 dB (the default) was too low as even though it used to be fine through the day, I used to get dropped connections at night due to the sinking SNR.
When it used to get to 3 dB my connection would drop.

It is sorted now as I asked my ISP to get BT to increase it to 9 dB and I also asked to have interleaving (error correction) enabled as I'm not into online gaming and don't mind having (slightly) increased latency.

p.s. your connection shouldn't drop at 6.5 dB as that SNR should be high enough to maintain a stable connection.

  TicTacToc 20:21 27 Aug 2006

thanks for the info.

Generally, 5db+ doesn't drop but there have been a few random occurences.

I don't know how to find out my target SNR, is there a simple way?

When you say you aksed BT to increase it to 9db, how does this work? Do they do things their end to help you raise your SNR?

  CurlyWhirly 20:38 27 Aug 2006

"I don't know how to find out my target SNR, is there a simple way?"

Yes check your SNR through the day when it should be at it's highest. For example in my case it varies from 9 dB through the day and sinks to around 5.5 dB in the evening which is just enough to maintain a stable connection.


"When you say you aksed BT to increase it to 9db, how does this work?"

You don't actually ask BT itself but get your ISP to ask BT Wholesale to do this for you but once it is raised it is very difficult to get it reversed so make sure you definently want to go ahead with it first.

  TicTacToc 21:26 27 Aug 2006

oh sorry, I i mistranslated the target SNR bit.

My SNR margin reaches about 13db at best in the day, and gets down to 3db in the night. I've never had problems at 6db or above.

My ISP is Bt Total Broadband. What disadvantages are there to raising that margin? I don't get quite what it is and is involved. .

THanks very much for the help so far

  CurlyWhirly 17:46 28 Aug 2006

"My SNR margin reaches about 13db at best in the day, and gets down to 3db in the night. I've never had problems at 6db or above."


It sounds like a line fault to me as your SNR margin shouldn't vary by 10 dB as that's a huge margin!

If it reaches 13 dB at best then this would suggest that you are already on the highest margin that Max supports (15 dB) and so it isn't possible to raise it any higher anyway.

The only thing you can try is to get interleaving switched on (if it isn't already on) and as a last resort contact your ISP to raise a fault with BT assuming that your house wiring is in order first?

  CurlyWhirly 17:56 28 Aug 2006

Oops, it looks like you are on a 12 dB margin so that you *could* get it raised to 12 dB if need be as that is the highest margin available but it looks like a fault to me.

As you said in your original post that your line can sync at 7 Mb, you should have an attenuation in the region 30 to 40 dB I guess?

If so you shouldn't need a noise margin as high as that as mine is only set to 9 dB and my line is over 5 km long with an attenuation of 54 dB!

  CurlyWhirly 17:57 28 Aug 2006

raised to 15 dB I mean - doh.

  TicTacToc 19:05 28 Aug 2006

My line attenuation is 39.5db now, and I think it is always about that.

click here - I used this guide, and my connetion and noise margin did not improve during step 3. I guess this means my house wiring is fine?

As high as 13db and as low as 3db was the absolute extremes, that my noise margin has only reached a few times, normally its 10db in the day, and 4-5db at night.

Maybe theres a way to make my voyager 2100 a bit stabler, as it sounds like it shouldnt be dropping very often at 4-6db. .

Sorry for my stupidity, but what does raising the margin to 15db achieve? Why aren't all lines set to 15db if it is likely to make the line the most stable? Is there any reason I should consider not doing it?

Thanks again for all the help, it is much apprecitaed.

  CurlyWhirly 20:15 28 Aug 2006

"but what does raising the margin to 15db achieve? Why aren't all lines set to 15db if it is likely to make the line the most stable?"

It is the margin most likely to give you a stable line.
The reason why ALL lines aren't set to 15 dB is because in most cases it isn't needed and in any case it wouldn't be Max DSL if this was the default setting as the idea of Max is to give you the fastest speed your line can handle while still being STABLE.


"Is there any reason I should consider not doing it?"

Yes if you want the extra speed.

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