VDSL - The Great RSGB Campaign

I'm frequently a critic of the RSGB, mainly because it has tended not to adequately address the real concerns of typical operators in the UK, such as planning and RFI.

But, progress is underway!

Yesterday, the May edition of RadCom, the RSGB's magazine, carried a full-page letter from the President, calling every member who suffers from VDSL interference - previous surveys suggest up to 50% of operators do - to measure their spectrum and complain to OFCOM, the UK regulator.

I have done a simple 'by ear' test of the bands here when the RSGB last took an interest in this topic, and there was no real sign of VDSL noise.

This time, the RSGB has a spectrum analysis tool ('Lelantos') which anyone - including non-members - can download for free and use it to analyse very short (~0.5s) I/Q recordings made using any SDR device.  You can find it, and plenty of information on the methodology and software, here.

This is what we expect to see where VDSL RFI is present - two timing signals that are very prominent:

Image: RSGB.

I'm glad to say that none of the amateur bands show any evidence of VDSL interference here.  With fibre optics, and not copper wire now providing all telecoms in the locality, all the way to each property, it would also appear that it will never become a problem here.

Here is the analysis of my 20m band recording, and the random noise in the lower right graph panel shows no timing signals: