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    Noise Margin

    This is a discussion on Noise Margin within the Sky Broadband help forums, part of the Sky Broadband help and support category; Dang it's late and i can't take this much info, lol. I been reading forums for past hour and it ...

    1. #11
      DEADLY9996's Avatar
      DEADLY9996 is offline Junior Member
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      Dang it's late and i can't take this much info, lol. I been reading forums for past hour and it feels like my head is gonna explode .

      I tried alstairs suggestion it it went to 11db with a sync speed loss of 1000Kbps ish.

      From 6500Kbps - 5376Kbps

      I leave it for now, 1000Kbps makes a difference for d/ling but less in gaming in my opinion.
      I had a 300k NTL cable connection it it ran better than their 1-4Mb Connections in gaming. Until they ******ed it up somehow, so i had to upgrade to 4mb but no change so sky has provided me with a much better internet for a cheaper price.
      Not to shabby in my opinion . (Still sky hasn't beaten ye ole 300k on Gaming Yet, soon find out now though )


      Thanks for all help people, once again i appreciate it


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    3. #12
      Alistair S's Avatar
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      Quote Originally Posted by Saturday View Post
      @alistair s

      setting your noise margin to 15db is a rather aggressive and will suppress your connection speed unnecessarily.

      In my experience the Sky router should function perfectly OK with a margin of 6.2 or more with Sky ADSL2+. Connect (ADSL Max) may be different.

      If your noise margin is plummeting from 15db down to 6db during the day then you have some serious line issues.

      Improving your line quality (better filtering) may well reduce the drop to manageable levels.

      Setting your noise margin to ~7db at the time of highest noise will give the best compromise between stability and speed.

      http://www.skyuser.co.uk/forum/showthread.php?t=5969

      BTW being very pedantic the SNR change you refer to is not a percentage and is not advisable for Connect customers
      All true, I agree - and thanks for the input, especially for Connect customers.

      I am on max and was/am getting very high sync speeds, but the line would seem to go into what seemed like mass error correction at certain times of day and slow to a crawl. I started to get some disconnects as well, and tried this as an experiment to discover whether capping my sync speed would help.

      I'm still syncing at around 12 meg with a 15db noise margin and have far fewer issues (no major slowdowns, few disconnects if any). That is plenty fast enough for me, so I never bothered to optimise it. To be honest, stability is far more important to me (so that other family members don't get too frustrated).

      I am sure other people's experience will vary, but it is nice to have something you can do yourself that doesn't involve talking to Sky (a fast route to despair in my experience). This allows for some experimentation.

      Deadly, I am sure that you know that (as far as gaming is concerned) download speed won't matter too much. Ping is what counts, and ideally you want a stable line and no interleaving (interleaving helps with robustness but will add to ping times). I don't know whether Sky applies it or not, but you will want it off your line if you want gaming in my opinion.
      Last edited by Alistair S; 18-11-06 at 03:05 AM.

    4. #13
      Saturday's Avatar
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      12meg with a noise margin of 15db is brilliant! In your circumstances forcing the change makes sense - sorry about the lecture.

      For Deadly9996 I hope the change is beneficial. I've no idea what forcing a noise margin change will do to his BRAS profile (the change in downstream line rate parameter will be picked up by the Max part of RAMBo) or his DLM target margin.

      I guess he'll either get away with it or he won't.

      Sorry to go back into lecture mode but for any Connect customers contemplating manipulating your noise margin, please be aware that this is not recommended. To quote BT "this bypasses DLM and could cause very serious performance issues".

    5. #14
      DEADLY9996's Avatar
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      hmm what performance issues could it cause?, cause i can barly use my internet otherwise

    6. #15
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      anything?

    7. #16
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      A real low noise margin can cause disconnects - Frequent disconnects!

    8. #17
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      @deadly9996

      I don't know - however, that quote came from a BTWholesale guide for ISPs. My guess is there would be some justification for the warning?

      ADSL Max is fundamentally different from ADSL2+ in how it handles rate adaption. With ADSL Max this is handled by RAMBo at the exchange. RAMBo is made up of two parts - MAX and DLM. MAX monitors the line rate and adjusts BRAS and also notifies BBCR of any changes in the BRAS profile. DLM analyses the performance statistics for the line DSLAM and adjusts the line profile.

      MY guess is that if DLM sees a noise margin change then this results in a rate change which will be passed to MAX which will adjust the BRAS profile. The router has to agree a downstream rate with the DSLAM for a given noise margin. However, if the router is "locked" to a high noise margin then maybe the balance between MAX and DLM is screwed up?

      At the end of the day if it has worked for you then great

    9. #18
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      Re: Noise Margin

      Hi,

      Can you please send me that link again, it's been edited now i lost it i need it =(. It started working fine without it but my internets gone down the hill latly, so i really need it!!

      Thanks!!!

      One thing that I have found can be helpful is to use the following to adjust your noise margin.

      First, a couple of points. You will get a slightly lower sync speed, but you may get more robust connection and faster, more reliable throughput.

      Can I Use my own Router with Sky Broadband?

      This will not cause a permanent change in your router. If it helps, you will have to do it again if you reboot. However, you may then be able to ask Sky to cap your sync speed at their end for the same effect.

      The last number (200 in this case) is the percent you want to increase your noise margin by. If you make this 100, it will be the standard noise margin. A setting of 200 basically doubles your noise margin.. kinda. If you don't like the result, just enter a new figure and try again.

      I found that setting it so my noise margin was around 15 during the day was very helpful. Anything that avoids you dropping below around 8 seems robust.

      I think the issues I had were due to my syncing at a speed that was faster than the line could really handle without huge error correction activity during busy times when SNR dropped.

      I hope it helps. It helped me.

      (Edited to rename SNR to noise margin and fix some typos)

    10. #19
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      Re: Noise Margin

      As I said before my strong advice is not to try and control a Connect service through manipulation of the router.

      However, if you are determined to then the easiest way would be to use Mognut's utility. You will find details in one of the Tech forum stickies.

    11. #20
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      Re: Noise Margin

      Ok I've tried everything I can think of, mognuts, mossywell, even ubergt firmware and I still can't change my noise margin.

      No matter what I do it is always around 15. Am I misunderstanding something??? Every post I read people talk about how they rebooted this time and synced at xxxxkpbs and later on synced at whateverkpbs, mine has never changed EVER.

     

     
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