This paper is on a novel use of lighting or signaling devices constructed by light-emitting diodes(LEDs). The idea is on their concurrent use for simultaneous signaling and communications. The visible light from LEDs can be modulated and encoded with audio or data signal. Hence, an LED indicator lamp or traffic light can become an information broadcasting device. Such a system made up of high brightness visible LEDs can provide the function of open space, wireless broadcasting of audio or data signals. An implemented system with experimental results is shown. A portable receiver is designed to demodulate the optically transmitted information. The distance for audio transmission of an LED traffic light can reach over 20 m. The optical link employs intensity modulation with direct detection. The system is limited to line-of-sight communications. However, this concurrent use of LEDs will open up many new applications.
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