Unification of global height system at centimeter level using precise frequency signal links

TL;DR

This paper proposes a satellite frequency signal transmission approach to unify local vertical height reference systems globally at centimeter accuracy, leveraging ultra-precise frequency links and atomic clock stability.

Contribution

It introduces a novel framework using satellite frequency signals to connect and unify local height systems without location restrictions, achieving centimeter-level accuracy.

Findings

Unification of China's and US's vertical height systems at centimeters level.

Simulation shows accuracy depends on atomic clock stability.

Approach offers a new method for global height datum unification.

Abstract

The realization of International Height Reference System (IHRS) is one of the major tasks of the International Association of Geodesy (IAG). A main component of the IHRS realization is the global vertical datum unification, which requires the connection of the existing local vertical height reference systems (VHS). However, it is difficult to estimate the offsets between two local height systems by conventional approaches when they are far apart. In this paper, we formulate a framework for connecting two local VHSs using ultra-precise frequency signal transmission links between satellites and ground stations, which is referred to as satellite frequency signal transmission (SFST) approach. The SFST approach can directly determine the geopotential difference between two ground datum stations without location restrictions, and consequently determine the height difference of the two VHSs. Simulation results show that the China's VHS and the US's VHS can be unified at the accuracy of several centimeters, provided that the stability of atomic clocks used on board the satellite and on ground datum stations reach the highest level of current technology, about $4.8\times 10^{-17}/\sqrt{\tau}$ for an averaging time {\tau} (in seconds). The SFST approach is promising to unify the global vertical height datum in centimeter level in future, and it also provide a new way for the IHRS realization.