VDSL interference on 10MHz

I’m being plagued by broadband hash right across the 10MHz band apart from one small gap.  (ignore the yellow swooshy thing, that is a real signal).  There are 4kHz wide blocks of the hash, mostly light blue in the waterfalls (which are upwards-moving, with newest at the bottom).

I suspect local copper broadband, we recently got FTTC in the village, however, the noise doesn’t change at all when I disconnect and power off my VDSL modem….

vdsl1

Time for a little experiment.  10s of a 50 watt carrier around 10115kHz.  Interesting, a wide swathe of the noise just disappears for 5-6 seconds, to be replaced with tones at roughly 4kHz intervals.  Then a few segments of hash come back, then more at 12s, and after 20s, some of the pilot tones go away, but not the close-in ones, they stay around for a long time.

vdsl2

It seems to be repeatable, but shorter transmissions don’t get rid of the noises for 12s, just 6s, and under a second of carrier has no visible effect.

So, let’s try calling CQ for a minute or so, with some 5-6 second gaps to listen.  Hmm, looks like I can knock quite a decent hole in the noise.

vdsl3

The hash stops at 12MHz.

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