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Japanese show BPL generates
spurious RF emissions
Measurements carried out in Japan have clearly demonstrated
that interference from a broadband power line (BPL) system generates spurious
RF emissions beyond 300 MHz according to this story from VK2's Roger Harrison
If you haven't heard about it, BPL systems send broadband RF between
2 MHz and 30 MHz down local electricity distribution lines, to provide
high-speed internet access. Some proposed systems extend to 80 MHz.
In the most common BPL system, the broadband RF comprises tens of thousands
of modulated carriers at intervals of about 1 kHz.
As the electricity distribution lines were never designed to carry RF,
they act like an antenna system, and the 2-30 MHz signal can be readily
heard 100s of metres away. HF spectrum users are up in arms about it,
naturally enough. However, because the electricity grid has imperfections,
intermodulation products and harmonics are created and also radiated.
Japanese tests detected these spurious BPL emissions between 310 MHz and
340 MHz at distances of 35 metres and 55 metres from a 54 metre length
of BPL-enabled power line. At 35 metres, BPL spurious emissions were up
to 10
dB above local ambient noise, while at 55 metres they were still 7-8 dB
above ambient.
Apart from HF communications, BPL has the potential to interfere with
TV and FM broadcast reception, low band VHF land mobile operations, aircraft
VHF communications, maritime VHF communications as well as amateur 6m
and
2m operation.
The Japanese technical report is available here:
( Roger Harrison VK2ZRH )
Source: Wireless
Institute of Australia
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