Line noise problems

Hi all. I'm having what appears to be intermittent line noise problems which are screwing up my ADSL and driving me crazy. I work from home so it's important to me to get this sorted.

Problems started on a specific day - last Monday. All fine before then and no kit changes at home at that point. Symptoms are that the connection drops or dramatically slows down at frequent but irregular intervals. Ran a speed test on this site last Monday, getting 500k. Previous months was getting 4.5 to 5.5 Mb. Zen have confirmed nothing changed and agree with my drop-out observations. If I listen to the phone line while the connection is poor I can hear audible noise on the line - sort of like faint hissing interspersed with fax/modem like noises, but faint. Sometimes it happens every minute or so, other times it goes for an hour without dropping.

I've called the BT engineers in, but I want to make sure I've eliminated everything at my end first. I've disconnected everything except a plain phone and haven't heard the noise, but then it's intermittent as I've mentioned. I've tried 2 different routers and 3 different microfilters.

It feels to me like they've connected something up at the exchange which is interfering with my line. my worry is the engineer is going to turn up, listen for 30 minutes and not hear anything then charge me

If you have an NTE5 then read this
http://www.kitz.co.uk/adsl/troubleshooting.htm

Probably a high resistance joint (HR) or water ingress in your line to the exchange. I had similar a while back. Fairly common problem but a nightmare to solve, and the online testers normally fail to show anything. If you can hear noises on your normal phone best to do it via BT phone faults (151) rather than through your ISP.

In reply to:

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If you can hear noises on your normal phone best to do it via BT phone faults (151) rather than through your ISP.

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Agree, but make sure you can still hear them with your router or modem disconnected from the line first

Thanks all - lots of help as usual on these forums.

I currently have the front plate off my NTE5 socket and the router is connected directly to it without a filter. I'm monitoring the line and will run it all day without anything else connected (with the front plat off the extensions are disconnected if I have it right).

For interest, the router is showing downstream line attentuation of 23.0 db and Noise Margin of 4.8 db with a connection speed of 6784 kbps. Upstream is 26.0, 15.0 and 448 kbps respectively. The router is a Netgear DG834PN RangeMax.

The speed test on here shows 5.9 Mb (!!!) downstream and normal upstream (450 ish). yesterday afternoon I checked it and got similar results. I was on the verge of cancelling the engineer visit, when it dropped out on me and I couldn't reconnect for 10 minutes. I picked up the phone line and there were the noises again. I'm going to try to catch the noises, rush over to the master plate and plug a phone in place of the router to see if I can catch them on a normal phone and nothing else connected.

I've also ordered a filtered NTE5 faceplate from ADSLnation - just seems to make sense.

Those figures are not great. The majority of lines with ~24dB downstream attenuation will easily manage the full 8mbits, but yours is abit short wth a very low noise margin.
Dosnt in itself indicate a line fault , could just be a `noisy' environment.

Thanks - was about to ask how that compares.

Will sort out the faceplate and continue to monitor. Figures are remaining constant, with noise hovering between 4.9 and 5.1

Sorry to be dumb, but the term "Noise Margin" is a bit ambigous. Am I better off with a higher or lower figure here ? Does it mean the amount of noise on the line or (as I assume) the headroom between signal level and noise level ?

You want a higher noise margin figure, it is, as you surmise the headroom between signal and noise (albeit in a slightly simplified way).

It just changed to the following

System Up Time 03:53:52
Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 21159 29045 0 589 4468 01:50:41
LAN 10M/100M 60138 46957 0 3859 636 03:53:50
WLAN 11M/54M 1191 0 0 27 0 03:53:47


ADSL Link Downstream Upstream
Connection Speed 8128 kbps 448 kbps
Line Attenuation 11.0 db 6.0 db
Noise Margin 7.4 db 23.0 db

Speed test, however, shows lower throughput downstream at 4.8.