strange line problem even SFI are stumped

I have had a fault on my line since last September following an overnight storm which damaged my router and PC. I live on a rural site 3.9Km from the exchange about 1.5Km is overhead the rest buried some of it just done last year. The last 150Mtrs is overhead to my house some of it on an electricity pole. The line has been solid since I had broadband nearly two years ago. With max it used to normally sync at about 4500 with downloads between 420-380 . Since the storm now sync at 2800 with downloads at 240 although this has now gone down to 60 The problem is the line dropping as soon as it rains, which seems to be every day.Four BT guys have looked at this and cannot find any problem. Today the SFI guy could see the snr go from 15 to 0 and drop the line as soon as the shower started, it happened three times in a row but his meters showed no fault. With continuous rain the line stays up it is just the initial shower and it drops within 30 seconds. the line attenuation is 49 so it is not a marginal line. Anyone have any ideas. Done all the usual things looking for noise, faceplate, wiring etc although the SFI guy checked all that anyway and found nothing.

thanks

What's the SFI guy using to measure the SNR? I imagine he's interrogating the dslam while your modem is connected, therefore measuring the entire length of the line, correct? So if we deem the SNR drop of 15 to be indicative of the fault, we could try to break the line down and find out where this is happening. That means him going out to the halfway point, cutting the line and looking for this drop; if it occurs the fault is towards the exchange, otherwise it's behind him. Simply a matter of repeating until a manageable / replaceable piece of cable is implicated.

Good luck.

Yes that is the principal, he was here seven hours and did exactly as you say but can find no problems with the line. He said if it was water causing the problems his equipment should be able to see it and give an indication how far away it is. The fault is real and repeatable but they don,t know what it is. The constant disconnections have now lowered my profile from 4 meg to 1/2meg.I think the fault is in the last 150mtrs up to the house the wire is over 25 years old, goes through a load of trees is on the same poles as the electricity supply and gets buffeted by the wind every day. The last line fault (intermittent) was eventually traced to a broken wire in this section.

Edited by titan (Wed 17-Jan-07 19:34:10)

Bare possiblity - TV aerials pointed towards trees can cause ghosting, perhaps trees can pass on AM interference into your line. If so, would need a rerouting of the phone line.

Might be something in that as his noisemeter went from hiss to radio 2 as he put it near the wires on the electricity post but the broadband was fine until the storm.

Bit different but similar, my satellite picture was breaking up and freezing intermittently whenever we had a storm (quite often here on the west coast of Scotland!). Tried the wire into the dish, cleaned, dried, all that, nothing. One night I was out watching a loose loop of cable swinging under the dish in the gale, looped it over the pole, doesn't swing now, no problem since including tonight at about 5 gusting to 7.

Your telephone wire was probably put in when the trees were saplings or not there, and the repairmen aren't planners, and don't think of trees, but it could also be branches blowing in the wind, tugging the wires tight and testing a slighly poor connection. I see a lot of trees near phone lines getting lopped or cut down, so I guess it's a known problem by BT.

Has anyone done anything tangible, like replace the dropwire, or swap the E and D sides ? You can sit and monitor it to your blue in the face (very likely in this weather), but really, you just got to try fixing it. Why was the SFI wallah checking for RFI, if it's rainfall that makes the fault apparent ?

Well I live in hope that they know what they are doing but I am getting a little despondent now.Two of the engineers have witnessed the line drop within 30 seconds of a shower but can offer no explanation. They say tree rub or any interference would show up on their equipment.

Just because it doesn't show ..... TBH some of these faults can be truly horrendous to locate. It seems that sometimes swapping a whole length is quicker than actually trying to locate the exact fault. I had a punter about 6 weeks ago who's broadband 'dropped sync when wet and windy' the cause, an unfiltered Sky box why, according to him, it had always been worse in bad weather .

>>They say tree rub or any interference would show up on their equipment.

Presumably this would only show up when it was rubbing or interfering, respectively, unless their test instruments are made from crystal, allowing a precognition of a tree about to rub.

The poster zarzab? (I can't recall his name) made a couple of good points. One, if the fault appears to be correlated to rainfall, there is little merit in testing for interference, unless one would rather not find the fault. Two, are you sure there is an association with the weather and you're not just grasping at straws in frustration; does it happen every time it rains, and does it work flawlessly whenever it's doesn't?