Fig. 1. Block diagram of underwater wireless optical communication system

Fig. 2. Algorithm flowchart

Fig. 3. Instantaneous signal-to-noise ratio of branch signal and noise-added signal over time

Fig. 4. Performance comparison of EGC, MRC, SC and adaptive combining algorithms

Fig. 5. Selection of combining methods under different time conditions

Fig. 6. SNR variation with BER for two-path reception using SC, EGC, MRC and adaptive combining algorithms

Fig. 7. SNR variation with BER for three-path reception using SC, EGC, MRC and adaptive combining algorithms

Fig. 8. Outage probability variation with SNR for two-path reception using SC, EGC, MRC and adaptive combining algorithms

Fig. 9. Outage probability variation with SNR for three-path reception using SC, EGC, MRC and adaptive combining algorithms

Fig. 10. Transmitted signal frame format

Fig. 11. Underwater wireless optical communication experimental system. (a) Schematic diagram of underwater wireless optical communication experimental system; (b) installation diagram of underwater wireless optical communication experimental system

Fig. 12. Block diagram of the FPGA design modules at the receiving end

Fig. 13. PMT output signal waveform diagram with a heating rod installed. (a) Signal collected from branch 1; (b) signal collected from branch 2

Fig. 14. PMT output signal waveform diagram with two heating rods installed. (a) Signal collected from branch 1; (b) signal collected from branch 2

Fig. 15. PMT output signal waveform diagram with three heating rods installed. (a) Signal collected from branch 1; (b) signal collected from branch 2