Inter-Satellite Integrated Laser Communication/Ranging Link with Feedback-Homodyne Detection and Fractional Symbol Ranging

The Integrated Laser Communication/Ranging System, which uses coded signal as the ranging information carrier, is of great importance to the next large-capacity inter-satellite information network. In this paper, the parallel FFT estimation is applied to improve the speed and range of tracking wavelength drift caused by both the trajectory estimation error and laser instability, it can handle dynamic wavelength drift up to 2.4 pm/s (300 MHz/s). Meanwhile, for clock sources with subtle dynamic frequency offset and sufficient stability, the proposed fractional symbol ranging method based on the timing offset compensation in the receiver is proven to achieve millimeter-level measurement accuracy. The Integrated Laser Communication/Ranging Link with high-sensitivity feedback-homodyne detection and fractional symbol ranging is demonstrated with real-time FPGA implementation and is shown to perform well in terms of both laser linewidth tolerance and noise resistance.