Interference from LED Lighting Systems
Light Emitting Diode (LED)
LED lighting is set to revolutionise the way we light our homes, businesses, vehicles, trains, boats, aircraft, and more. The humble LED uses a fraction of the energy of incandescent lamps and offers thousands of hours of lifetime. Sadly, the control and power electronics are proving to be less than reliable, and when poorly designed, can generate a considerable amount of radio interference. This interference has been shown to wipe out ￼ Band II VHF Stereo and ￼ Band III DAB radio. As the safety-of-life aircraft band sits in the middle of those two, poorly designed LED lighting also posses a danger to aircraft communications, navigation beacons, and ￼ Instrument Landing Systems. Boat and car owners, who have retro-fitted LED lamps to existing lighting systems have also experienced interference from some types of lamps.
There are two known generators of interference: The first source is the switched-mode power-supply. Due to the size constraints, some manufacturers are missing out the necessary filter components and this results in a great deal of conducted emissions.
The second source can come from a device known as a buck-driver – a type of switched-mode power-supply that regulates lower voltages (typically 12V) to provide a constant-current to the Light Emitting Diode. These devices typically operate with a switching-frequency of 5000 Hz, but they can produce harmonics (mixing of multiple frequencies) that extend up to 30MHz, and higher. Some are making it to 220MHz, where they cause serious degradation to any nearby DAB radios.
The following are known to be affected by LED lighting interference:
Digital Audio Broadcast (DAB)174 – 240 MHz
Marine VHF156 – 162.025 MHz
Amateur Radio 2 metre band144 – 146 MHz
Airband118 – 136.975 MHz
FM Stereo broadcast88 – 108 MHz
Baby monitors49.30 – 49.89 MHz
High frequency services, inc. long range marine & airband, Shortwave broadcasts, Amateur radio allocations, Citizens’ Band radio, plus wireless devices operating on 27MHz3 – 30 MHz
EMC industry investigates
The EMC industry has published concerns over the proliferation of LED lighting that fails to meet any standardised testing and the essential requirements of the EMC Directive. The European Union is also concerned and has published a Cross Border Surveillance Report on the issue. Publishing a report is only helpful if member state’s Market Surveillance authorities are actually doing their job!
We are gratefully indebted to the EMC testing house METECC for sharing their finding after testing a large number of off-the-shelf LED lamps.
Submitted by KD4WX