6 Jun 2012

LED screens and RF Interference

Re : Richard Cadena’s blurb on RF interference from LED screens (read post HERE) is timely.

Australia, and in particular Sydney is having lots of problems with this lately. Only a few weeks ago, we had a routine visit from the ACMA (Australian Communications and Media Authority) technical guys at one of the transmitter sites we manage. Now this is incidental, but at the same time we got talking about the other work they were doing recently tracking down interference problems across the city and closing down illegal transmitters &c.

It seems half their time recently is spent investigating interference complaints caused by… LED display screens. These monsters are turning up everywhere – not just entertainment venues but just about anywhere a large advertising hoarding is required. The market is littered with poorly shielded units which act pretty much like a radio frequency jamming unit with an effectiveness that would make them attractive to the enemy in a field of war.


It’s easy to understand. Not too far from here, in Macquarie St Windsor (NSW) a local car dealership recently underwent a new retail fit out which included a new, bright LED screen in a prominent position outside the lot. The display has all but wiped out FM radio reception within a 200m radius of the car lot, effecting just about any FM broadcast in the immediate area. Ironically the display is often broken but still jams everything around it.

When they find them, ACMA have the legislative power to confiscate the transmitter or non compliant equipment if they feel it is necessary to stop the interference bei generated. This they often do. So while the users of these screens (on first offense) would likely escape a fine or court action, it’s very likely they would lose the screen, which would quickly become a expensive boat anchor.

Be warned. The ACMA van is out there – and you would be surprised at how much they know about what’s going on.


Paul Matthews.



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