An ultraviolet laser communication system using frequency-shift keying modulation scheme

A communication system based on an ultraviolet (UV) laser at 266 nm is presented to improve the communication distance. The pulse frequency-shift keying (FSK) modulation scheme is studied and improved in order to reduce the bit error rate (BER), and is put into practice on a field programmable gate array (FPGA). The mathematical models of the modulation and demodulation are established. A test platform is set up to measure the energy density and pulse response under different distances and receiver elevation angles. It is shown that the omnibearing communication can be realized, and the bit rate is limited to 12.5 Mbit/s. The BER is estimated to be less than 10−7 at distance of 300 m in line-of-sight (LOS) communication model and to be less than 10−6 at distance of 80 m in non-line-of-sight (NLOS) communication model.