These are data systems over power mains.

  In the  UK these  systems are  now being  extended after  a trial  period in Manchester. Last week an international  conference on power mains data systems was held.

  The system works by the data  signals being inserted onto the power mains at the substation and distributed around the  district on the power lines. It  is radiation from the  power lines that  is the cause  of the problem  as well as feeding the HF  RF into your  own premises. A  further problem is likely to be interference  caused by  amateur transmissions  corrupting data  on the  power line.

  In Australia United Energy, a  Melbourne electricity supply company has made a commercial arrangement with Nortel a partner with the North West Electricity Board of the UK.

  So it is starting to happen. Those  of you with internet access do a  search on NORWEB COMMUNICATIONS and you will get lots of info.

  There is not much technical  information available excpt one paper  from the Queensland University of Technology. I hope to put it up on packet soon.

  The problem of interference from  these systems is being investigated by the RSGB EMC committee and a number  of reports have been published in RADCOM over the last six months or so. The signals are in the band 2 Mhz to about 20 Mhz. My understanding is  that the modulation  method results in  a raising of  the noise floor in that range. This makes  it difficult to realise that you may be suffering from this interference. As far as I am aware there are no systems in use in Australia.

   If anyone  is aware  of the  existance of  one of  these systems  would you please let me know via packet or email.

   73 Barry VK2AAB @ VK2AAB   email: bewhite@tpg.com.au