Auto-Alignment and TIA Module: Increasing Visible Light Communication Reception Performance Under Low Light

The development of edge computing has promoted synaesthesia and intelligence integration. Visible light communication (VLC) systems as the broad communication medium, it focuses on the channel characteristics or the transmission rate limit. There is little research on VLC under low light conditions. This is because weak light signals are challenging to detect. Therefore, we propose an indoor low-light VLC system for emergency communication, robot tracks, and other scenarios. First, we design a dual-photodiode automatic alignment module (DPAAM), which places dual symmetrical positive-intrinsic negative diodes (PIN) on the demo board. When the transmitter is not aligned with the receiver, the dual-PIN generates different photocurrents. According to the photocurrents, the receiver adjusts its position to increase valid signal light intensity. For better signal reception at the receiver under low light conditions, we further design a low-noise, high-gain trans-impedance amplifier (TIA) module based on the avalanche photon diode (APD). This module consists of a boost circuit that allows the APD to operate in avalanche mode and a high-gain amplifier circuit. Finally, the results show that the designed VLC system can perform low error auto-alignment and receive undistorted light signals within 100cm under low light conditions.