Real-time frequency transfer system over ground-to-satellite link based on carrier-phase compensation at 10⁻¹⁶ level*

Abstract

We demonstrate a novel and stable frequency transfer scheme over ground-to-satellite link based on real-time carrier-phase detection and compensation. We performed a zero-baseline measurement with the designed system, an uninterrupted frequency standard signal is recovered in the reception station without additional post-correction of delay error caused in the route, which is because the phase error of the entire route is tracked and compensated continuously in real-time. To achieve this goal, we employed two carriers in the system and the differential signal is transferred in order to eliminate the instability results from the local oscillator at the satellite transponder as well as the common-mode noise induced in the transfer route and microwave components. The stability of 3 × 10−16 with an integration time of 1 day was achieved and the time fluctuation during one day was measured to be about ±20 ps. Error sources and possible solutions are discussed. Our zero-baseline method shows a promising result for real-time satellite-based time and frequency transfer and deserves further research to find whether it works between long-baseline stations.

A New Device for Two-Way Time-Frequency Real-Time Synchronization

“…In the next step, we will partially inherit of satelliteground time synchronization technology [15][16][17][18][19] and analyse the errors from seven aspects, including spatial distance error, transmission and reception channel delay error, receiving measurement error, multipath effect error, frequency synthesis error, antenna phase centre error, and clock error correction model error, aiming to further Improve the time synchronization performance of the system. In addition, more optimized estimation models for synchronization results may be further extended to quantum optimization algorithm [20].…”