Fig. 1. The schematic diagram of band-pass DSM

Fig. 2. The architectural diagram of a real-time FSO transmission system

Fig. 3. Experimental setup diagram of a real-time FSO transmission system

Fig. 4. Spectrum and constellation diagram of the transmitting signal

Fig. 5. 50 m FSO link

Fig. 6. Real-time coherent transceiver physical diagram

Fig. 7. DSP flow

Fig. 8. Received signal

Fig. 9. The graph of BER versus ROP for the FSO system