Fiber-based ultra-stable frequency synchronization using client-side,   1f-2f active compensation method
  We demonstrate a frequency synchronization scheme with the phase noise compensation function placed at the client site. One transmitting module hence can be linked with multiple client sites. As a performance test, using two separate 50 km fiber spools, we recover the 100 MHz disseminated reference frequencies at two remote sites, separately. Relative frequency stabilities between two recovered frequency signals of 2.8E-14/s and 2.5E-17/day are obtained. This scalable scheme is suitable for the applications of frequency dissemination with a star-topology, such as SKA and DSN. 
Bo Wang, Xi Zhu, Chao Gao, Yu Bai, Jing Miao and Lijun Wang
physics.optics