Undersampled-PAM with subcarrier modulation for camera communications

Abstract

In this paper, a novel undersampled pulse amplitude modulation with subcarrier modulation (UPAMSM) is proposed to supporting high efficiency non-flickering visible light camera communication (CamCom). A post-compensation technique is employed to reduce nonlinear effects caused by camera gamma correction. In order to eliminate phase uncertainty between transmitter and camera, and obtain the built-in gamma correction function of a camera, a dedicated framing structure is designed and applied. A test-bed with a light emitting diode (LED) and a commercial digital single-lens reflex (DSLR) camera is built to evaluate the performance of the proposed UPAMSM CamCom system. Experiment results show that this system can achieve a data rate of 250 bps (5 (bit/s)/Hz/LED) with a 50 fps camera at a distance of 1.5 m.