Experimental Demonstration of a Self-Clocking Pulse-Amplitude Modulation for Optical Camera Communication in Artificial Ambient Light

Abstract

The synchronization of symbols in Optical Camera Communication (OCC) is crucial for systems in both global and rolling shutter operations. Global shutter OCC systems sample the received data using a frame acquisition mechanism that presents particularly high jitter while rolling shutter OCC systems are based on a line acquisition mechanism that is commonly synchronized to a closed hardware clock switching at a fixed period. Thus, all OCC systems require regular clock detection for correct demodulation. In this paper, we test a m-ary Pulse Amplitude Modulation (PAM) with m = 8 with a novel line code denominated self-clocking constant-power (SCCP)-PAM. The system was implemented using a global shutter operation, utilizing small scale Light Emitting Diode (LED) and camera, at a distance of 15 m with artificial constant ambient light, showing bit-error rate (BER) values under 1% at data rates of 50 bps per node, and a high node capacity given the small scale of the optical devices. The BER obtained can be further improved using matched filters given the clock-extraction capability of the system.