Research on a CDMA-based integrated single-terminal detection system for laser communication networking with micrometer-level disturbance error

The large-scale constellation networking is an inevitable trend in the development of free-space optical communication, and the demand for multiple optical terminals to simultaneously establish links with and transmit data to a single optical terminal has driven the integration of optical terminals. The technological development of phased arrays and rotating parabolic mirrors has effectively addressed the challenges in the transmission and reception control of multi-node beams. The multi-beacon co-domain detection technology based on Code Division Multiple Access (CDMA) also provides an effective solution for the integrated detection of single optical terminals. This paper further investigates the influence mechanism of the cross-correlation values of pseudo-codes on multi-spot detection, deduces the impact model of cross-correlation values on the relative error and detection accuracy of spot position detection under the multi-spot co-domain mechanism, and proposes a parallel interference cancellation method based on channel estimation, which further enhances the accuracy of multi-spot detection under asynchronous clock sources. Desktop verification experiments were conducted and closed-loop control was performed with the servo system, verifying the engineering feasibility of multi-spot detection. The results show that after parallel interference cancellation, under the condition of asynchronous clock sources at the transmitter and equal power interaction of two spots, the maximum perturbation position deviation error is about 2.81 μm, representing a 96.1 % reduction in the maximum positional deviation error compared to the case without interference cancellation under heterogeneous clock sources.