Evaluation of an AGC for a Solar Panel as a Receiver in a VLC System Applied to Access Control

Visible light communication (VLC) technology allows data to be transmitted using the optical power emitted by light-emitting diodes (LEDs). The optical receiver usually employs light sensors such as photodiodes, image sensors, photoresistors or solar panel. In the last decades, VLC technology has explored the use of solar panels as data receivers, since they offer the service of power generation, in addition to, a larger surface area to capture the light beam. In this paper, we present the performance evaluation of a VLC system based on solar panel and automatic gain control (AGC) with application in access control systems. Three experiments are proposed to evaluate the uses of the solar panel as information receiver in VLC systems: bandwidth (BW) estimation, VLC system performance and panel viewing angle variation. As a result, we were able to determine a BW of 10 kHz and 190 kHz considering the panel without AGC and with AGC. In the context of digital modulation, a RS-232 module of an Arduino UNO development system was used in order to execute the technique of intensity modulation and direct detection IM/DD. The NRZ line code of the serial interface was used to modulate the electric current of the LED with a maximum symbol rate of 38400 baud with a data effectiveness of 91%. Furthermore, we found that AGC improves the dynamic range of the solar panel's viewing angle and the performance of the VLC system.