Experimental Study on Chromaticity Control in Visible-Light Communication Systems

To apply visible-light communication (VLC) systems in different scenarios, this study utilizes a temperature-adjustable light source equipped with RGB light-emitting diodes (LEDs) and applies it to a visible-light communication system. It utilizes color-division multiplexing technology to achieve three-channel communication, thereby improving the communication bandwidth of the system. The communication system adopts three constant-current driving circuits to control the duty cycle of the pulse-width modulation (PWM) of each channel, thereby changing the proportion of RGB LEDs and obtaining different color temperatures to control the color for mixed-color LEDs. The experimental results show that when adjusting the color temperature, the change in luminous flux is very small, with fluctuations of less than 2.24%. When adjusting the brightness, the color-temperature fluctuation is within 40 K, which is less than the 50-K color-temperature limit that the human eye can distinguish, and the average color-temperature error is 0.609%. A color tolerance less than 5.5 × 10−3 indicates a good dimming effect. The communication performance of the system is better in the high color-temperature range, which is significantly superior to the low color-temperature range. When the error rate is below 3.8 × 10−3, the total modulation bandwidth of the three channels reaches 11.7 MHz.