Position, navigation, and time (PNT) distributed by the global navigation satellite system (GNSS) have become one of the most relied upon commodities of our civilization. GNSS relies on clocks on satellite, the timing signal of which is send to Earth. On ground both, the resulting position and the timing signal are used in various different cases on ground. We are reliant on the quality of the timing signal.
Quantum technologies offer novel methods of probing atoms or molecules to generate timing signals of higher quality. Additionally, optical cavities or resonators can provide precise timing signals. The main challenge involved with optical resonators is the long term stability in compatibility with the SWaP requirements of space. There are several works to prolong the stability of these systems and improve the quality of the received signal.
Regardless of the quality of the GNSS signal, it is subject to manipulation, such as jamming and spoofing. Additionally, areas of absence of GNSS exist, which need to be breached. In these cases (classical) inertial measurement units can be deployed. However, the inherent drift of these systems allow GNSS-free navigation for short periods.
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