Design and implementation of anti low-frequency noise in visible light communications

With the increasing popularity of light emitting diodes (LEDs), visible light communication (VLC) systems provide an attractive alternative method for wireless communication. To reduce complexity and achieve lower cost, the on-off keying (OOK) modulation has been widely adopted in implementation of VLC systems. Although the conventional minimum-voltage detection circuit can remove the interference from sunlight or ambient light, the low frequency noise problem is still unsolved. To overcome this drawback, we propose a novel OOK-based VLC receiver architecture consisting of a transimpedance amplifier, a fourth order high pass filter with Sallen-Key method, and a Schmitt trigger. Experiment results show that the proposed receiver not only can remove the interference from ambient lights, but also can reduce the interference effects from the low-frequency noise of ambient light or indoor fluorescent light.