Performance of miniaturized atomic clocks in static laboratory and dynamic flight environments
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ORIGINAL ARTICLE
Performance of miniaturized atomic clocks in static laboratory and dynamic flight environments Ankit Jain1 · Thomas Krawinkel1 · Steffen Schön1 · Andreas Bauch2 Received: 25 May 2020 / Accepted: 18 September 2020 © The Author(s) 2020
Abstract Miniaturized atomic clocks with high frequency stability as local oscillators in global navigation satellite system (GNSS) receivers promise to improve real-time kinematic applications. For a number of years, such oscillators are being investigated regarding their overall technical applicability, i.e., transportability, and performance in dynamic environments. The shortterm frequency stability of these clocks is usually specified by the manufacturer, being valid for stationary applications. Since the performance of most oscillators is likely degraded in dynamic conditions, various oscillators are tested to find the limits of receiver clock modeling in dynamic cases and consequently derive adequate stochastic models to be used in navigation. We present the performance of three different oscillators (Microsemi MAC SA.35m, Spectratime LCR-900 and Stanford Research Systems SC10) for static and dynamic applications. For the static case, all three oscillators are characterized in terms of their frequency stability at Physikalisch-Technische Bundesanstalt, Germany’s national metrology institute. The resulting Allan deviations agree well with the manufacturer’s data. Furthermore, a flight experiment was conducted in order to evaluate the performance of the oscillators under dynamic conditions. Here, each oscillator is replacing the internal oscillator of a geodetic-grade GNSS receiver and the stability of the receiver clock biases is determined. The time and frequency offsets of the oscillators are characterized with regard to the flight dynamics recorded by a navigation-grade inertial measurement unit. The results of the experiment show that the frequency stability of each oscillator is degraded by about at least one order of magnitude compared to the static case. Also, the two quartz oscillators show a significant g-sensitivity resulting in frequency shifts of − 1.2 × 10−9 and + 1.5 × 10−9, respectively, while the rubidium clocks are less sensitive, thus enabling receiver clock modeling and strengthening of the navigation performance even in high dynamics. Keywords Allan variance · Miniaturized atomic clocks · Frequency stability · Flight navigation · GNSS
Introduction
The authors do not attempt to recommend any of the instruments under test. It is noted that the performance of the equipment presented in this paper depends on the particular environment and the individual instruments in use. Other instruments of the same type or the same manufacturer may show a different behavior. The reader is, however, encouraged to test his own equipment to identify the system performance with respect to a particular application. * Ankit Jain [email protected]‑hannover.de 1
Institut für Erdmessung, Leibniz Universität Hannover, Hannover, Germany
Physikalisch-Technis
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