In reply to a post by ggremlin:

I did see something suggesting they were also testing about interference from radio stations, and the arkley ones are very close to the 'Saffron Green' transmitter.

Right.

I think the perceived solution is to set the vectoring process to ignore the affected frequencies. But it should be a good test to see if that happens automatically, or needs to be done manually.

I also wonder if we have any subscribers in the area, so we can get some graphs from unlocked modems during the trial

I suspect the Hadley Wood cabinet was selected because it is beside the East Coast Main Line.

In reply to a post by ggremlin:

I suspect the Hadley Wood cabinet was selected because it is beside the East Coast Main Line.

are BT hoping for miracles?

vectoring is for crosstalk noise not external

I would guess that they believe Vectoring works OK when the only noise around is crosstalk. What they probably want to see is how it performs when significant external noise is present too.

RF and electrical noise from electrified rail lines, radio transmitters and aircraft beacons/radar all sound like good test locations to me.

yeah that would be a valid reason.

External noise *IS* crosstalk noise. If it's affecting a line from a known stable baseline, vectoring will try to filter it out just like noisecancelling does on some mobile phones to block out road traffic noise etc.

Edited by LeJimster (Thu 04-Jul-13 23:23:17)

By "external", I'd normally expect it to mean from a source outside the cable.

Crosstalk is very firmly just from within the cable - other subscribers to DSL. FTTC subscribers mainly, as the ADSL crosstalk (from the exchange) is considered "alien" and cannot be removed by vectoring. Luckily it is a small-ish portion of the spectrum (and smaller, the further the cabinet is from the exchange).