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    Noise Margin and disconnection issues

    This is a discussion on Noise Margin and disconnection issues within the Sky Broadband help forums, part of the Sky Broadband help and support category; Before my problems occurred the sat i dl around 3 gig, it was a warm day and before i found ...

    1. #11
      rakesh27's Avatar
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      Re: Noise Margin and disconnection issues

      Before my problems occurred the sat i dl around 3 gig, it was a warm day and before i found out, my router laid flat on the ground which became very hot.

      Since i got connected which was a week ago, my router laid flat got really hot, one week later problem started on the sun and i found out i should have used the legs for the router which i am now and it doesnt feel hot at all.

      Could i have damaged the router ? , one last thing i tested a BT Voyager wireless 2110 router and the same thing was happening, could it be that sky has confgured the line alittle differently then BT so there equipment would be best suited for the connection..


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    3. #12
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      Re: Noise Margin and disconnection issues

      These are my stats when using the test socket:

      /usr/sbin/adslctl: ADSL driver and PHY status
      Status: Showtime Channel: INTR, Upstream rate = 416 Kbps, Downstream rate = 7296 Kbps
      Link Power State: L0
      Mode: G.DMT
      Channel: Interleave
      Trellis: ON
      Line Status: No Defect
      Training Status: Showtime
      Down Up
      SNR (dB): 7.3 14.0
      Attn(dB): 43.0 28.0
      Pwr(dBm): 19.7 0.9
      Max(Kbps): 7904 1216
      Rate (Kbps): 7296 416
      G.dmt framing
      K: 229(0) 14
      R: 16 16
      S: 1 16
      D: 64 8
      ADSL2 framing
      MSGc: 1 1
      B: 229 14
      M: 1 16
      T: 1 1
      R: 16 16
      S: 1.0695 17.0666
      L: 1840 120
      D: 64 8
      Counters
      SF: 7762 7760
      SFErr: 0 0
      RS: 527828 32980
      RSCorr: 15 0
      RSUnCorr: 0 0

      HEC: 0 0
      OCD: 0 0
      LCD: 0 0
      Total Cells: 2269139 0
      Data Cells: 7071 0
      Drop Cells: 0
      Bit Errors: 0 0

      ES: 0 0
      SES: 0 0
      UAS: 28 0
      Total time = 2 min 57 sec
      SF = 7762
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Latest 1 day time = 2 min 57 sec
      SF = 7762
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Latest 15 minutes time = 2 min 57 sec
      SF = 7762
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Previous 15 minutes time = 0 sec
      SF = 0
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Previous 1 day time = 0 sec
      SF = 0
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0

      Noticed i'm getting the same noise margin, what is the problem?

    4. #13
      Steve case's Avatar
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      Re: Noise Margin and disconnection issues

      Quote Originally Posted by SniperwolfDX View Post
      These are my stats when using the test socket:

      /usr/sbin/adslctl: ADSL driver and PHY status
      Status: Showtime Channel: INTR, Upstream rate = 416 Kbps, Downstream rate = 7296 Kbps
      Link Power State: L0
      Mode: G.DMT
      Channel: Interleave
      Trellis: ON
      Line Status: No Defect
      Training Status: Showtime
      Down Up
      SNR (dB): 7.3 14.0
      Attn(dB): 43.0 28.0
      Pwr(dBm): 19.7 0.9
      Max(Kbps): 7904 1216
      Rate (Kbps): 7296 416

      etc


      G.dmt framing
      K: 229(0) 14
      R: 16 16
      S: 1 16
      D: 64 8
      ADSL2 framing
      MSGc: 1 1
      B: 229 14
      M: 1 16
      T: 1 1
      R: 16 16
      S: 1.0695 17.0666
      L: 1840 120
      D: 64 8
      Counters
      SF: 7762 7760
      SFErr: 0 0
      RS: 527828 32980
      RSCorr: 15 0
      RSUnCorr: 0 0

      HEC: 0 0
      OCD: 0 0
      LCD: 0 0
      Total Cells: 2269139 0
      Data Cells: 7071 0
      Drop Cells: 0
      Bit Errors: 0 0

      ES: 0 0
      SES: 0 0
      UAS: 28 0
      Total time = 2 min 57 sec
      SF = 7762
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Latest 1 day time = 2 min 57 sec
      SF = 7762
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Latest 15 minutes time = 2 min 57 sec
      SF = 7762
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Previous 15 minutes time = 0 sec
      SF = 0
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      Previous 1 day time = 0 sec
      SF = 0
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0

      Noticed i'm getting the same noise margin, what is the problem?
      It's true that your noise margin is the same - but that's because the router uses the same target value (7dB) to negotiate the best speed it can. Look at your connection speed - it's much higher than before. This means that your extension wiring is a large part of the problem.

      Now you need to find out what you need to do to your extension wiring to enable you to get similar results without using the test socket. If you haven't already done so, follow Koala's advice and disconnect the orange wire (N0. 3) at the master socket and every extension socket. If that doesn't work, or is only partially successful, then one answer is to get a filtered faceplate. See also "cabling & faceplate help" area of the forum.

      The other thing you need to bear in mind is that the stats you posted were only for a couple of minutes, which doesn't really tell us much about the quality of your connection. Noise variations may mean that you can't sustain the 7296 kbps speed through the busy period, without large errors and possible disconnections. You need to browse the internet for an hour or two (ideally during the evening) and then post your full stats again. If you start getting errors and/or disconnections it will be necessary to deal with that - but first things first.
      Last edited by Steve case; 04-07-07 at 12:04 AM.
      Useful Links
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    5. #14
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      Re: Noise Margin and disconnection issues

      Hi. Hope you don't mind me jumping into this thread, but I am having exactly the same problems with my Sky Broadband. I have only had it a few weeks, but I also get disconnections every evening - seemingly after the router has been on for a while. I notice the SNR decreases from around 6db to 4db before disconnecting. I am connecting to the master socket with a filtered faceplate, so I don't think internal wiring can be the issue? Full stats are posted below. Any ideas on what could be the problem?

      /usr/sbin/adslctl: ADSL driver and PHY status
      Status: Showtime Channel: INTR, Upstream rate = 416 Kbps, Downstream rate = 4320 Kbps
      Link Power State: L0
      Mode: G.DMT
      Channel: Interleave
      Trellis: ON
      Line Status: No Defect
      Training Status: Showtime
      Down Up
      SNR (dB): 5.1 13.0
      Attn(dB): 60.0 31.5
      Pwr(dBm): 19.3 3.1
      Max(Kbps): 4928 1024
      Rate (Kbps): 4320 416
      G.dmt framing
      K: 136(0) 14
      R: 16 16
      S: 1 16
      D: 64 8
      ADSL2 framing
      MSGc: 1 1
      B: 136 14
      M: 1 16
      T: 1 1
      R: 16 16
      S: 1.1167 17.0666
      L: 1096 120
      D: 64 8
      Counters
      SF: 1043199 1043197
      SFErr: 53659 328
      RS: 70937538 4433587
      RSCorr: 33850276 2338
      RSUnCorr: 317931 0

      HEC: 47716 176
      OCD: 188 190
      LCD: 0 8
      Total Cells: 180332375 0
      Data Cells: 3858989 0
      Drop Cells: 0
      Bit Errors: 0 0

      ES: 3770 0
      SES: 1100 0
      UAS: 21 0
      Total time = 4 hours 56 min 2 sec
      SF = 1043199
      CRC = 53659
      LOS = 787
      LOF = 0
      ES = 3770
      Latest 1 day time = 4 hours 56 min 2 sec
      SF = 1043199
      CRC = 53659
      LOS = 787
      LOF = 0
      ES = 3770
      Latest 15 minutes time = 11 min 2 sec
      SF = 38993
      CRC = 1617
      LOS = 1
      LOF = 0
      ES = 302
      Previous 15 minutes time = 15 min 0 sec
      SF = 52930
      CRC = 5875
      LOS = 3
      LOF = 0
      ES = 727
      Previous 1 day time = 0 sec
      SF = 0
      CRC = 0
      LOS = 0
      LOF = 0
      ES = 0
      15 minutes interval [-30 min to -15 min] time = 15 min 0 sec
      SF = 52930
      CRC = 24740
      LOS = 5
      LOF = 0
      ES = 881
      15 minutes interval [-45 min to -30 min] time = 15 min 0 sec
      SF = 52931
      CRC = 11769
      LOS = 1
      LOF = 0
      ES = 622
      15 minutes interval [-60 min to -45 min] time = 15 min 0 sec
      SF = 52930
      CRC = 7402
      LOS = 6
      LOF = 0
      ES = 627

    6. #15
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      Re: Noise Margin and disconnection issues

      Quote Originally Posted by StephenR View Post
      I also get disconnections every evening - seemingly after the router has been on for a while. I notice the SNR decreases from around 6db to 4db before disconnecting. I am connecting to the master socket with a filtered faceplate, so I don't think internal wiring can be the issue?
      Falling noise margin is a common if not universal problem. Please read the sticky in my signature at the bottom of this post for more info and two suggestion on how to deal with this.

      Looking at your stats your low noise margin is generating a large number of line errors. Considering your attenuation of 60db, your sync speed is very good but the errors will give you connection stability issues.

    7. #16
      Steve case's Avatar
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      Re: Noise Margin and disconnection issues

      Quote Originally Posted by StephenR View Post
      I notice the SNR decreases from around 6db to 4db before disconnecting. I am connecting to the master socket with a filtered faceplate, so I don't think internal wiring can be the issue?
      I don't believe the large downward shift you are experiencing is unusual. I for one have exactly the same problem. To get round it I used the Mognuts utility to set the target noise margin to a higher value (14 dB, assuming I do this in the "quiet" part of the day when the high line noise is not present). Of course that means that the router syncs at a somewhat lower speed (in my case about 6800 kbps compared with the 7800 I could get if I just use the default value of 7dB). However it means that my connection is stable through the evening period.

      Using the RouterStats utility (see link in my signature) I have recorded my noise margin continuously for several weeks now. In the quiet part of the day it is typically 14-15 dB, but it can jump suddenly down by 3db at any part of the day, and then jump back up several hours later. Then during the evening (from about 8.30 onwards it starts to fall, until around 11pm it reaches a minimum, having fallen - sometimes by about 6dB. You can probably understand from this why the default value of 7db is hopelessly inadequate to handle the changing noise levels on my line. This changing noise is totally outside my control. (Originally it was made even worse due to noise associated with my extension wiring, but I sorted that out by using an ADSL Nation flitered faceplate). I think the evening noise problems are caused mainly by cross-talk in the exchange, as more and more broadband users go online. I have said before in this forum that I am sure others will experience similar problems, and you appear to be in that catergory. Based on my own experience my advice is:-

      1. Sort out any problems associated with your wiring. (You already appear to have done this but others subscribing to this thread need to do likewise. The reason we ask people to plug into the test socket and post full stats is to determine how much of the noise problem is related to extension wiring issues).

      2. Use the Mognuts utility to set your target noise margin to 14 dB (assuming it is not during the high-noise problem period) and see if your connection remains stable, and your errors acceptable. Note that if you power off your router, you will need to re-set the target noise margin, because it defaults to the 7 dB value.

      3. Use the RouterStats utility to record your noise margin - ideally from early morning until late at night and see how it changes.

      You may subsequently find you can reduce the target noise margin below 14 dB, and get a slightly higher connection speed. In my case I could probably reduce it to about 12dB. However my theory (as yet unproven) is that noise on my line is increasing generally as more and more people take up broadband and get connected to my exchange. I also suspect that weather-related issues may cause some variation (e.g. the recent heavy rain). I am therefore leaving it at 14 db, because the additional improvement in speed of 2 or 3 hundred kbps is not that important to me.
      Last edited by Steve case; 04-07-07 at 08:46 AM.
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    8. #17
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      Re: Noise Margin and disconnection issues

      Quote Originally Posted by Steve case View Post
      It's true that your noise margin is the same - but that's because the router uses the same target value (7dB) to negotiate the best speed it can. Look at your connection speed - it's much higher than before. This means that your extension wiring is a large part of the problem.

      Now you need to find out what you need to do to your extension wiring to enable you to get similar results without using the test socket. If you haven't already done so, follow Koala's advice and disconnect the orange wire (N0. 3) at the master socket and every extension socket. If that doesn't work, or is only partially successful, then one answer is to get a filtered faceplate. See also "cabling & faceplate help" area of the forum.

      The other thing you need to bear in mind is that the stats you posted were only for a couple of minutes, which doesn't really tell us much about the quality of your connection. Noise variations may mean that you can't sustain the 7296 kbps speed through the busy period, without large errors and possible disconnections. You need to browse the internet for an hour or two (ideally during the evening) and then post your full stats again. If you start getting errors and/or disconnections it will be necessary to deal with that - but first things first.
      Why would my extension wiring only become a problem with the noise margin after 5 months of a steady connection? I have a feeling they have bumped me up from Connect to Mid without telling me, thus giving me a faster speed that my line cannot handle, could this be the case?

      There are three wires in my master socket: an Orange one in number 2, a Green one in number 3, and a Blue one in number 5. Are these in the wrong ones, or did you mean Orange should be in 2, and not 3? Also from looking at them I don't think removing them myself would be a very clever idea, because they don't look like they reconnect easy.

      I will try and get some stats for a longer connection period but it seems my connection is currently intent on dying every few minutes at the moment, which makes this difficult to do.

    9. #18
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      Re: Noise Margin and disconnection issues

      Quote Originally Posted by SniperwolfDX View Post
      Why would my extension wiring only become a problem with the noise margin after 5 months of a steady connection? I have a feeling they have bumped me up from Connect to Mid without telling me, thus giving me a faster speed that my line cannot handle, could this be the case?
      It's possible they have increased the limit. But at least as likely an explanation is that although your connection has appeared to be OK, it has in fact been running close to the bone in terms of noise margin. A slight increase of noise (which could happen for a number of reasons) would then start to give you problems.

      Quote Originally Posted by SniperwolfDX View Post
      There are three wires in my master socket: an Orange one in number 2, a Green one in number 3, and a Blue one in number 5. Are these in the wrong ones, or did you mean Orange should be in 2, and not 3? Also from looking at them I don't think removing them myself would be a very clever idea, because they don't look like they reconnect easy.

      I'll leave somebody else to comment on this one because I've never come across this combination of colours - it looks non-standard to me. This may be further reason to suppose that yiour wiring could be contributing to the problem.
      Useful Links
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    10. #19
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      Re: Noise Margin and disconnection issues

      Thanks for the info, very interesting. I feel better knowing I'm not alone! I have only been connecting in the evenings i.e. busiest part of the day, so I think I will have to use that utility to set my SNR higher and sacrifice a bit of speed. Sounds like 4Mbps is a bit too fast for my line length anyway, as 60dB attenuation should be giving around 3Mbps if I understand correctly.

      Just as an aside, is it more the problem of the Sky router or the Sky service? I have a spare router I could try, but I am reluctant to change too many things at a time. If a different router wouldn't help I won't bother trying it.

    11. #20
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      Re: Noise Margin and disconnection issues

      Quote Originally Posted by StephenR View Post
      Just as an aside, is it more the problem of the Sky router or the Sky service? I have a spare router I could try, but I am reluctant to change too many things at a time. If a different router wouldn't help I won't bother trying it.
      I suppose it's a matter of opinion - but personally would say neither. It's more a fact of life associated with trying to get high speed broadband to multiple users down copper circuits, many of which are quite old. I doubt if using your spare router will make any difference.

      Let us know whether increasing your target noise margin has the desired effect.
      Useful Links
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