Hello Tristan,
The RF interference from AM broadcast radio looks dramatic, but when quantified by the number of tones affected by the ingress, it probably doesn't impact the overall DSL performance that badly.
Channel bandwidth in Europe for AM broadcast radio is only 9kHz, meaning that ingress from an AM radio station should only impact two or three DSL subcarriers.
Using a re-purposed wavelet-based peak-det algorithm: [1]
$ R
library(MassSpecWavelet)
# Loading required package: waveslim
qlnDAT <- read.table("qln.txt", colClasses = c(rep("NULL",1), rep("numeric",1)), header=TRUE)
qlnMAT <- data.matrix(qlnDAT)
wCoefs <- cwt(qlnMAT, scales=seq(1,31,1), wavelet='mexh')
localMax <- getLocalMaximumCWT(wCoefs)
ridgeList <- getRidge(localMax)
majorPeakInfo <- identifyMajorPeaks(qlnMAT, nearbyPeak=TRUE, ridgeList, wCoefs, SNR.Th=1)
peakIndex <- majorPeakInfo$peakIndex
#
The tones notably affected by AM broadcast ingress (and other RFI) are the following. From a total of some 4000 tones, it's not that many, really. The line attenuation is the real service killer...
peakIndex
127 167 188 211 238 253 282 311 451 562 763
777 858 1216 1324 1391 1405 1430 1506 1604 1687 1704
1736 1791 1885 1962 2799 2819 2913 2970 3006 3099 3192
3286 3324 3380 3433 3472 3537 3567 3763 3959
And plotted..
plotPeak(qlnMAT, peakIndex, main=paste("identified QLN peaks"))
Suggesting that the real problem, as Paul has already said, is the high attenuation on the line. A consequence, as you mentioned before, of suffering a loop of considerable length. An unfortunate property of the twisted pair. As such, even if every joint was re-made between your home and the cabinet, it still might not result in an improvement.
What can be done? It's optimistic to hope that any more tweaking by Openreach is going to improve the performance - short of running fibre to your doorstep. As such, I would be tempted to ditch DSL and look for another solution.
What about establishing a private point-to-point microwave link from your community to the nearest town? It sounds very expensive or complicated but it's neither. Just a few hundred pounds and an afternoon's work can result in a surprisingly good job.
There is a specialist firm,
Stella Doradus, in Waterford, [2] who sell all the kit needed. Helpful people too
With a pair of high gain (22dBi) parabolic dishes and good quality transceivers, it is possible to form a decent microwave link of some miles. With the right antennas, a point-to-point wi-fi bridge of 25 miles even using domestic 802.11 kit, isn't unheard of
cheers, a
[1]
http://forum.kitz.co.uk/index.php/topic,11503.msg221918.html#msg221918[2]
http://www.stelladoradus.com/