Implementation of continuous VLC modulation schemes on commercial LED spotlights

When modulated with a continuous signal, the intensity of light emitted by a Light Emitting Diode needs to be adjusted such that linearity is maintained between the modulating voltage and the intensity of the emitted light. This paper presents a low-cost solution that is able to maintain linearity over virtually the entire intensity range. Extending the range of linearity is accomplished by incorporating a feedback loop that compensates for the non-linear parameters of the circuit´s active components, including the LED. The technique is applied to convert a commercially available LED spotlight into a device that allows for the transmission of continuous Visible Light Communication schemes.