Optical inter-satellite links based on homodyne BPSK modulation: Heritage, status and outlook

For a number of reasons homodyne BPSK (binary phase shift keying) is superior to all other optical modulation schemes. Since BPSK has been verified as a reliable technique for space applications, laser communication terminals based on this modulation scheme are ready for in-orbit verification, which is the goal of the running LCTSX program. With this, an optical satellite-to-ground link shall be established to verify the impact the atmosphere has on a homodyne BPSK based communication link as well as the pointing and tracking performance of a laser communication terminal. In a follow-on program, an optical inter-satellite link will be established to verify the communication performance.