Wireless frequency synchronization and delay refinement methods for distributed array

Nowadays, distributed network such as coherent radar system has gained popularity due to better performance, flexibility, and stability. However, the independence of each node presents a significant challenge: clock synchronization, and in long-distance scenarios, we prefer to achieve it wirelessly. Clock synchronization consists of two parts: frequency and time. The traditional methods are mostly based on protocols, and the hardware requirements are very high to achieve high accuracy. So, we propose a novel frequency estimation and correction method based on signal processing for delay estimation, and further improve the accuracy by data refinement. Simulation results show that with a signal frequency of 100MHz and an SNR of 30dB, the accuracy of frequency difference estimation is 10 Hz. When the sampling rate is 1GHz, the accuracy of delay estimation can be improved by about 20 times after refinement.