Photonics-assisted high-precision free space RF synchronization technology

In this paper, a high-precision frequency synchronization scheme in free space based on microwave photonic architecture is proposed, which can be used between multi-nodes in relative motion or in a motionless state. The reference frequency is modulated to high frequency through microwave photon up-conversion, and the reference signal is recovered at the receiver through photonics self-mixing technology. The experiment over free space in the laboratory in 4m, shows that the performance of Allen variance is 1.88 x 10((-11))/1s under the noise floor is 6.48 x 10((-12))/1s, and it is better than that of the electrical generation method with the Allen variance is 5.70 x 10((-10))/1s. The impact of system signal-to-noise ratio (SNR) on frequency stability is analyzed, and the experimental results are consistent with the theoretical value. At the same time, a functional experiment based on free space RF synchronization is conducted, compared to the direct synchronization method, the phase degradation of this method is only 0.25 rad, and the degradation of peak side lobe ratio (PLSR) of pulse compression loss is 0.29 dB. The good, coherent result further verifies the correctness of this synchronization method. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement