Wide-Range and High-Precision Doppler Simulation for Inter-Satellite Coherent Optical Communications

Coherent free-space optical communication has emerged as a critical technology for high-speed data transmission between satellites. However, the significant relative velocities between satellites result in substantial Doppler shifts, making signal synchronization and demodulation challenging. A Doppler simulation method based on changing the signal clock frequency is proposed. This method reproduces the Doppler effect caused by relative motion during satellite operations, enabling the verification of Doppler tracking and compensating algorithms. The proposed method allows for the flexible generation of Doppler shifts based on satellite orbit information. The designed hardware platform allows for a performed Doppler range of [-20, 20] km/s and a simulation accuracy of 1.8 × 10-<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup>m/s, encompassing the Doppler between various orbital altitudes.