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Author Topic: Low SNR  (Read 4304 times)

muon

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Low SNR
« on: May 23, 2006, 10:24:47 PM »

Hi there people.

Have had nothing but trouble with ADSL since having it installed 3ish years ago. Recently parted company with Pipex over their laughable tech support and am now sadly seemingly trapped with talktalk.

Anyway, have a look at this:



I assume this is down to the issues outlined above. It's fine(ish) during the day, but as the evening wears on, the SNR figure drifts down and down until at about 12:30 every night it reaches 0 and refuses to connect at all until the next morning.

Talktalk don't want to know, they claim it must be a hardware issue at my end, despite my telling them that I have replaced every piece of kit here. BT won't even talk to me, they tell me I have to get my ISP to raise some kind of fault.

Starting to get really annoyed :)
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muon

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Low SNR
« Reply #1 on: May 23, 2006, 10:26:31 PM »

By the way, does anyone know what that ANNEX_A means?
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kitz

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Low SNR
« Reply #2 on: May 24, 2006, 11:36:22 AM »

Hi

That SNR Margin doesnt look to good Im afraid. :/
On traditional adsl anything below 10dB and you can start to see problems, below 6dB and thats when most users will start to see frequent disconnects.
Noise always is worst in the evenings because thats when more users are at home and online.

Ironically your Attenuation is quite good and indicates that your line should theoretically be able to support 2Mb.
and therefore your SNR Margin is lower than what I would normally expect to see.

Have you tried plugging your router/modem in at the master socket?
Theres also a test socket behind the master socket which you could try using to see if it improves your SNR Margin.
(Details and image half way down Low SNR page. )
If when using the test socket your SNR Margin improves, then you would likely benefit by purchasing an NTE5 adsl faceplate.

As regards to contacting your ISP, I should image the likes of Talk Talk are well used to trying to fob users off if they can.
Contact them again clearly stating that your modem is showing that you have a very low SNR Margin, despite your attenuation showing that the line is capable of 2Mb speeds.

Ask if they would arrange to send a BT engineer out to check the quality of your phone line.
You could even request that they carry out a WOOSH test which will show them that you are reporting a low SNR Margin figure.

However, before you do this.. please carry out the master socket test, because when an engineer comes and if he finds that things are fine at the master socket then it does indicate that the problem is either with your equipment or internal wiring and may make a charge.

Therefore it would be good if you could also report to your ISP that you have tested from the master socket without any improvement.
Let us know how you go on with the master socket test and reporting it to your ISP.
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kitz

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Low SNR
« Reply #3 on: May 24, 2006, 12:12:44 PM »

Quote from: "muon"
By the way, does anyone know what that ANNEX_A means?


All I knew is that its something to do with one of the G.DMT standards.

G.DMT full-rate ADSL expands the usable bandwidth of existing copper telephone lines, delivering high-speed data communications at rates up to 8 Mbit/s downstream and 1 Mbit/s upstream.

http://en.wikipedia.org/wiki/G.DMT

However after a heck of a lot of googling (all refs to annex a seemed to bring up line stats from peoples routers)..  I found this....

http://neasia.nikkeibp.com/archive_magazine/nea/200011/inst_115955.php

Quote
There are three specifications that are becoming widely used standards in Asia at this time: Annex A (both G.dmt and G.lite), Annex C (including G.dmt and G.lite), and Annex H.

Annex A is the most common type of ADSL deployed in the world today. G.dmt Annex A has replaced ANSI T1.413 Issue 2, an early version of discrete multi-tone (DMT) line coding, as the most widely used form of ADSL. Since that time, G.dmt has been adopted as one of two worldwide standards for ADSL, given 24 gauge copper wires with loops not exceeding 18,000 feet. In other words, if the most common quality level of copper wire exists in a market, G.dmt Annex A is the most efficient method today for providing DSL services to end users.
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