Stable Radio Frequency Transfer Over Free Space by Passive Phase Correction

Yaqing Chen,Yanguang Sun,Fei Yang,Fufei Pang,Mingyu Jiang,Nan Cheng,Youzhen Gui,Haiwen Cai,Jialiang Wang,Rui Wu

doi:10.1109/jphot.2019.2945753

Abstract

The frequency transmission over free-space link can effectively overcome the dependence of existing optical fiber time-frequency transmission technology on optical fiber network. In this paper, we demonstrate a passive phase correction technique over a 124 m long indoor atmospheric radio frequency (RF) dissemination. This scheme simplifies the system, and suppresses the effects of Rayleigh backscattering. We verify the feasibility of the scheme by transmitting 1 GHz RF signals over the atmospheric link. After timing fluctuation compensation, the relative frequency stability can reach 6.8 × 10−15 for 1 s and 3.2 × 10−17 for 103 s, the RMS timing fluctuation is 186 fs in 5000 s. It can be proved that the scheme is very effective in eliminating phase noise caused by atmospheric link.

Highlights

Precise time-frequency signal dissemination has significant applications in scientific research such as navigation and positioning, very long baseline interferometry, deep space network and time-frequency measurement [1]–[3]
The maximum drift of the propagation delay is 760 fs and the RMS value is 186 fs for 5000 s, where the main sources are the asymmetry of the free-space link, the asymmetry introduced by EDFA and the thermal drift of the electrical amplifier
We have demonstrated a passive phase correction technique over a 124 m long indoor atmospheric radio frequency (RF) frequency dissemination

Summary

Introduction

Precise time-frequency signal dissemination has significant applications in scientific research such as navigation and positioning, very long baseline interferometry, deep space network and time-frequency measurement [1]–[3]. Fiber-based time-frequency transmission has been widely developed and achieved unprecedented accuracy, this technology is limited to be transmitted in a fixed optical fiber network and many applications require more flexible free-space links between remote sites and possibly portable optical clocks and oscillators. Many teams have carried out important research on time-frequency transmission across a turbulent air path. Sprenger has firstly conducted 100 m atmospheric optical frequency and 80 MHz RF frequency transmission experiment. The relative stability of the optical frequency

Methods

Discussion

Conclusion