[aprssig] [OT] "Silence Of The Hams" ?
dave at uk-ar.co.uk
Mon Nov 23 06:54:48 CST 2009
> Let us hope we never witness the "Silence Of The Hams"
Coming to a neighbourhood near you sometime soon (if not already there)
PLT! And it might just silence you...
In the US, a similar system (with all to similar problems) is known as
"PLA". Or how to radiate huge ammounts of QRM from your domestic power
http://www.ukqrm.org Read and learn. Not nice if you've got this
Currently two main types, one burbles away 24/7 regardless of if it's
got data to transfer, or a single unit will scream away all to itself,
waiting for it's partner in crime to wake up. This is what's
illustrated on that site as the "BT Vision" or Comtrend adapters. Some
of these are "notched" dramaticaly reducing the data carier levels in
the US ham bands, but not the background noise..
The other type, known as "Homeplug", are quiet when no data is needed to
be moved, but tick away to themselves like an electric cattle fence.
Only waking up and obliterating most of HF when they have traffic to
send. No "notching" of them at all.
Most of these domestic systems are currently using 2 to 30MHz or
thereabouts, but we are aware of the industries wishes and plans to move
into VHF, up towards 300MHz!
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