One for Kelly, Mike et al - Radio Communications.

Near many centres of population in the UK the HF band is quite badly jammed by leakage from telephone lines carrying ADSL and VDSL , and in many houses also from poorly suppressed electronics such as electronic transformers or LED lights etc.. As the 'DSLs in particular sound quite noise like to the untrained ear, it is often mistakenly assumed that HF is unused, and that  the noise floor is very high. (For those so equipped, specialist software, Lelantos, is available that can automatically  distinguish VDSL noise from other sources, but it is not a trivial thing to set up, and requires the right sort of digitising receiver.)

As you get further out of town and away from the Open Reach wide area jamming networks, the noise falls away and you realise that at the sub microvolt per metre E field level it was indeed quite busy out there, and there are lots of interesting things going on, not just local Amateurs and a few  really loud broadcasters like Voice of America or China Radio International and Radio Taiwan trying to drown each other out.

If you are ever lucky enough to have a HF directional array at your disposal that does elevation and Azimuth is quite fun to see what you can pull out from under the noise coming in from the quiet directions and indeed also sobering  to see where the noise is coming from and how much of it there is too.

Hopefully if broadband moves to using fibre to the house this will clean things up in the coming years.

Near many centres of population in the UK the HF band is quite badly jammed by leakage from telephone lines carrying ADSL and VDSL , and in many houses also from poorly suppressed electronics such as electronic transformers or LED lights etc.. As the 'DSLs in particular sound quite noise like to the untrained ear, it is often mistakenly assumed that HF is unused, and that  the noise floor is very high. (For those so equipped, specialist software, Lelantos, is available that can automatically  distinguish VDSL noise from other sources, but it is not a trivial thing to set up, and requires the right sort of digitising receiver.)

As you get further out of town and away from the Open Reach wide area jamming networks, the noise falls away and you realise that at the sub microvolt per metre E field level it was indeed quite busy out there, and there are lots of interesting things going on, not just local Amateurs and a few  really loud broadcasters like Voice of America or China Radio International and Radio Taiwan trying to drown each other out.

If you are ever lucky enough to have a HF directional array at your disposal that does elevation and Azimuth is quite fun to see what you can pull out from under the noise coming in from the quiet directions and indeed also sobering  to see where the noise is coming from and how much of it there is too.

Hopefully if broadband moves to using fibre to the house this will clean things up in the coming years.