OCC (Optical Camera Communication) has been proposed in recent years as a new technique for visible light communications.This paper.introduces the implementation and experimental demonstration of an OCC system.Phase uncertainty and phase slipping caused by camera sampling are the two major challenges for OCC.In this paper,we propose a novel modulation scheme called undersampled differential phase shift on-off keying to encode binary data bits without exhibiting any flicker to human eyes.The phase difference between two consecutive samples conveys one-bit information,which can be decoded by a low-frame-rate camera receiver.Error detection techniques are introduced to enhance the reliability of the system.We present the hardware and software design of the proposed system,which is implemented with a Xilinx FPGA and a Logitech commercial camera.Experimental results demonstrate that a bit-error rate of 10-5 can be achieved with 7.15 mW received signal power over a link distance of 15 cm.
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