Ambient Light Rejection Using a Novel Average Voltage Tracking in Visible Light Communication System

The quality of a received signal is one of the most important factors to be considered when designing a receiver for visible light communication (VLC) systems. Therefore, it is necessary to evaluate the robustness of the VLC receiver circuit in low-signal-to-noise ratio (SNR) communication. The SNR is the quantity characterized by the ratio of the signal power to the noise power of the received signal. The noise generates an offset voltage and distorts the desired signal waveform. Thus, a low SNR makes it difficult to retrieve the data. Among the sources of noise, ambient light has the most negative impact on the VLC data signal. Therefore, the novel receiver proposed by us acts as an ambient light rejection circuit. As our average-voltage tracking circuit is insensitive to the sunlight and indoor fluorescent light, our design could be a solution to enhance the performance of low-SNR VLC systems. Several experiments are conducted using light of same intensity, but with different distances and semi-angles. Experimental results demonstrate that robust interference rejection is possible to send an error-free communication with an On-Off Keying modulation base on microcontroller up to 1 Mbps at an SNR of −2.7 dB.