Attenuation Problem ?

Associate
Joined
18 Oct 2002
Posts
463
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
 
Soldato
Joined
18 Oct 2009
Posts
11,175
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?
 
Caporegime
Joined
8 Sep 2005
Posts
29,917
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 :(
 
Associate
OP
Joined
18 Oct 2002
Posts
463
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.
 
Soldato
Joined
10 Jun 2005
Posts
2,605
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.

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.
 
Soldato
Joined
18 Oct 2009
Posts
11,175
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?
 
Associate
Joined
3 Dec 2006
Posts
428
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
 
Associate
Joined
17 Jan 2004
Posts
483
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.
 
Associate
OP
Joined
18 Oct 2002
Posts
463
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...
 
Back
Top Bottom