Design of an Automotive Visible Light Communications Link using an Off-The-Shelf LED Headlight

We present a transmitter circuit to drive a commercial Light Emitting Diode (LED)-based headlight for automotive Visible Light Communication (VLC). Based on the design of the presented transmitter (TX), we provide a design methodology for VLC TXs and make it available as Open Hardware. Furthermore, a complete wireless VLC link is built using the GNU Radio signal processing tool chain and demonstrated on an Universal Software Radio Peripheral (USRP). The Total Harmonic Distortion (THD) of the system is below 5% for a wide input voltage range and the 1 dB compression point (P1dB) is at 1.02V, which makes the circuit attractive for more advanced modulation formates like Orthogonal Frequency Division Multiplexing (OFDM) or Pulse-Amplitude Modulation (PAM).