Ultra-Stable RF Transmission Over Coaxial Cables via Phase Fluctuation Compensation

Synchronous radio frequency (RF) signals are essential for a number of applications including time and frequency metrology, coherent communications, and signal processing. The stability of frequency synchronization is vulnerable to phase fluctuations induced through in transmission link. To mitigate this effect, we propose a stable RF transmission solution using coaxial cable as the medium in short-distance frequency synchronization. The phase fluctuations caused by the coaxial cable are detected and compensated in real-time by a proportional-integral (PI) servo controller. Laboratory experiments performed through a 100-m coaxial cable confirmed the scheme and showed that compensating transmission-medium-induced fluctuations effectively improves the frequency synchronization stability. Laboratory experiments performed using a 100-m coaxial cable confirmed the scheme and demonstrated that compensating for fluctuations induced by the transmission medium effectively improves frequency synchronization stability.