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Attenuation Problem ?

Discussion in 'Networks & Internet Connectivity' started by philhoole, 24 Apr 2010.

  1. philhoole

    Gangster

    Joined: 18 Oct 2002

    Posts: 466

    Location: Cambridgeshire

    Hi,

    While I am happy with my BT Broadband connection, I wonder if I should perhaps be getting better download speeds.

    I have a Netgear DG834N and it reports the stats below.


    ADSL Link Downstream Upstream
    Connection Speed 8821 kbps 446 kbps
    Line Attenuation 40.0 db 19.7 db
    Noise Margin 9.6 db 17.8 db



    I presume it's the 40dB attenuation which is limiting my download speeds. Is this quite high given that I am exactly 1Km away from the exchange as the crow flies?

    As far as I know my exchange is 20Mb enabled.

    So, the question is, can I do anything to improve matters or am I stuck as it's the copper path to the exchange which is basically responsible for this.

    Should I try the test socket and see if it makes a difference ?

    Thanks
     
  2. Marsman

    Capodecina

    Joined: 18 Oct 2009

    Posts: 11,173

    Your attenuation is quite high in comparison to the noise margin. In short too much noise on the line, not much signal = slower connection. Friend of mine has 8mb package, he has 44db attenuation and 11db noise margin, his connection speed is 2.3kbps.

    Do you have internal phone wiring from the master socket, or do you connect directly to it?
     
  3. Efour

    Caporegime

    Joined: 8 Sep 2005

    Posts: 26,873

    Location: Norrbotten, Sweden.

    i had a belkin adsl modem that could hold a signal all the way down to 2db and that gave me a huge 2mbit boost.

    Not been on adsl for yonks tho so ive forgotten nearly everything useful sorry lol :(
     
  4. philhoole

    Gangster

    Joined: 18 Oct 2002

    Posts: 466

    Location: Cambridgeshire

    I connect directly to the master socket with about a 1m cable to my modem. There is just a single phone in the house is on another socket in another room.

    I guess if the attenuation is high then there's probably not much I can do about it.

    I am still getting almost 9Mb/s so it isn't a big deal.
     
  5. Bane

    Mobster

    Joined: 10 Jun 2005

    Posts: 2,612

    Have you tried removing the faceplate from the master socket to use the test socket, as per this Kitz guide? This will disconnect the phone extension cable that your single telephone uses, so only any good for a brief test.
     
  6. philhoole

    Gangster

    Joined: 18 Oct 2002

    Posts: 466

    Location: Cambridgeshire

    I tried it directly into the test socket but the line stats didn't change at all.

    So I guess there's not much I can do ?
     
  7. Marsman

    Capodecina

    Joined: 18 Oct 2009

    Posts: 11,173

    Not really. It's on BT's side of the master socket. It could just be the consequence of living a certain distance from the telephone exchange. Have you an idea how far you are from it?
     
  8. [email protected]

    Gangster

    Joined: 3 Dec 2006

    Posts: 431

    Location: Somewhere I shouldn't be!

    You can flash the firmware of your router with the DGTeam firmware, then you will be able to tweak your SNR (noise margin) down towards 6db, see if it is stable, keep going down until it is too unstable and move it back up.... it is all trial and error on finding the fastest speed for your connection.

    My line attenuation is about 50db and I sync at between 5.5 and 7 meg at various times of the week, that is with my SNR set to 55% (which is about 4db), it is stable too.

    edit.... my current stats:

    Down Up
    SNR (dB): 4.8 6.2
    Attn(dB): 49.5 27.9
    Pwr(dBm): 19.1 12.4
    Max(Kbps): 7766 1114
    Rate (Kbps): 6364 1113
     
  9. ncjok

    Gangster

    Joined: 17 Jan 2004

    Posts: 482

    philhoole,

    An 8.8 Mbps sync is actually quite reasonable for a 40 dB line with 9 dB target SNR. There is probably nothing wrong with your line to the exchange.

    As suggested, adjusting your router's target SNR by using modified firmware, or getting the ISP to adjust the corresponding setting on the exchange hardware* may result in an improvement of up to a few Mbps.

    * I have no idea if your ISP is responsive to this type of request.
     
  10. philhoole

    Gangster

    Joined: 18 Oct 2002

    Posts: 466

    Location: Cambridgeshire

    Thanks everyone - I think I will leave it as it is.

    I had heard of the DGTeam custom firmware and I may give it a try at some point.

    Marsman - I live exactly 1Km from the exchange measured in a direct line but who knows how long the copper path is...