Large variation in noise margin

Hi,

Have noticed quite large drops in my downstream SNR margin recently. Am now connected directly to the test socket of the NTE5 with no extension wiring in place and am still noticing large drops in SNR. Line syncs at 15bd margin during the day and sits steadily at this until usually between 4pm and 5pm when it starts to fluctuate quite a bit - anything from 2db up to around 12db. Had put this down to street lights coming on etc but now they aren't on until a few hours after that each day. It will continue fluctuating until the next morning. Are such large drops common place? Do I just have a noisy for which nothing can be done? Currrent line stats are below in case they are of any use.

Thanks

Brian


ADSL Line Type GDMT
ADSL Line CodingADSL Line Coding INTERLEAVED
Line Attenuation (Down):46 (Up):26
Noise Margin (Down):4 (Up):23
Total Output Power (Down):0 (Up):0
Current State DownStr: 4256(K) UpStr: 448(K)

Your line is probably picking up MW radio stations which are always stronger as darkness falls. If you have no extension wiring, then it's BT's wiring doing it, and the only option with that is to pay them to shield it or run it underground if it is fed overground from a pole. Incidentally, you are not doing too bad with a 4256kbps sync speed with a 46dB attenuation - my line has the same attenuation and barely scrapes 3648kbps during the day.

Hmmm, I thought it might be a bit of MW interference but I'm not convinced its the only factor.

Since original post, I noticed an increasing audible noise on my line - worse during the evenings. BT accepted there was a noise fault and despatched an engineer who swapped over pairs from the hole at the end of the street. Noise fault cured, but no change in broadband performance. From around 4.30pm every day* noise margin jumps from steady 15 down to 2, up to 13, down to 1, to 10...etc....with occasional resync (* Noticed this weekend that Friday and Saturday evenings didn't appear to produce the same 'jumpiness' - just a gradual decrease to 8 or 9 db.

Now, the even more confusing thing is that i have a second line into the house along the same physical underground cable which doesn't appear to suffer from these noise variations. Stats for the second line.....

ADSL Line Type GDMT
ADSL Line CodingADSL Line Coding INTERLEAVED
Line Attenuation (Down):47 (Up):26
Noise Margin (Down):6 (Up):25
Total Output Power (Down):0 (Up):0
Current State DownStr: 7232(K) UpStr: 448(K)

Resyncs on this line are few and far between. Neither line has extensions running on it and both use a filtered faceplate. Can cable routing from the green cabinet back to the exchange be the only explanation here for the different noise levels? Could something be wrong in the exchange? Is there anything I can do? Any thoughts much appreciated.

Brian