Speaking at the second annual Powerline Communications Conference, South African Radio League's president Graham Hartlett called on ICASA and the power line communications (PLC) industry to be more transparent when piloting PLC systems.
"As it stands, power line communication systems spell the death of radio communication ranging from AM radio to short-wave broadcasting, amateur radio, marine radio and many other essential communication services", he said. "Radio amateurs are by nature experimenters and understand the need for researching and testing new developments. Much of the work to develop PLC systems is, however, behind closed doors with little or no interference testing."
Sharing the platform, the Amateur Radio Satellite Association's Hans van de Groenendaal said that the latest tests carried out in the UK showed that current PLC systems are incompatible with radio communications. He cited four areas of major concern: interference to reception of radio signals; immunity of PLC systems to nearby RF sources; intermodulation products; propagation of power line telecommunications generated signals via the ionosphere.
The interference of PLC to radio signals has shown to cover a wide area of the radio spectrum from medium-wave to well into the VHF spectrum. While industry has come up with a system to notch out certain frequencies, he said recent studies by the British Regulator, Ofcom, have shown that it is ineffective in the case of weak signals.
Immunity of PLC systems to strong nearby RF fields has also received little attention he said. Radio amateurs who live and operate their transmitters in the midst of their community may be unfairly accused of interference and the same would apply to other nearby transmitting stations such as community radio, two radio systems used by the police, ambulance and other emergency services.
Hartlett called on industry and ICASA to work together with users of the radio spectrum and suggested that the following be implemented:
By industry - pilot studies and PLC trials should include:
* Impact studies on the radio spectrum.
* Interference to radio reception.
* Increase in local noise floor.
* Electromagnetic compatibility of PLC systems with respect to signals generated by radio amateurs in close proximity.
* Open communication with users of the radio spectrum.
* Disclosure of trial and pilot details.
By ICASA:
* Registration of all trials and pilot studies.
* Monitoring of adherence to current and future standards.
* Ability to stop pilots and trials should interference in the spectrum impede operation by radio amateurs and other radio spectrum users.
* Develop regulations that will protect users of the radio spectrum against interference from PLC systems.
"There are many well documented cases that show that the current PLC systems are a major problem for radio communication. There is also no internationally-accepted standard. The standard issue must be resolved before any further pilot systems are installed," Hartlett said.
For more information contact Hans van de Groenendaal, +27 (0)12 991 4662, hans@intekom.co.za
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