Assessing Thermal Noise in GNSS Frequency Transfer: Insights from a Temperature Chamber Experiment

authored by

Ahmed Mohamed Abdelhalim Elmaghraby, Thomas Krawinkel, Tobias Kersten, Steffen Schön

Abstract

Time and frequency transfer networks based on Global Navigation Satellite Systems (GNSSs) are essential for scientific applications, including fundamental physics, metrology, and time-frequency comparison. Achieving frequency stability at the 10^(−16) to 10^(−18) level over one day averaging time in terms of Allan deviation is
crucial for testing fundamental constants, and validating general relativity, for example. Enhancing GNSS error modeling improves frequency stability and leverages well-established infrastructure of GNSS stations. However, temperature variations can introduce frequency fluctuations into the GNSS signal processing chain at various points, e.g., receiver, antenna, cables or signal splitters. This makes it essential to assess and correct for such thermal effects.

Based on a common-clock zero baseline setup, our study quantifies thermal effects on different geodetic receivers (one Septentrio PolaRx5TR, two JAVAD OMEGA) placed in a controlled laboratory environment, in his case a temperature chamber. In a first experiment, we tested Septentrio PolaRx5TR receivers individually, and in a second one we included both receiver types and a signal splitter to examine inter-receiver correlations. The temperature curves consisted of four cycles ranging from 10°C to
36°C over two days with a gradient of 6.5°C/h, while maintaining consistent conditions for both the receivers and the signal splitter. We developed an algorithm to estimate differential receiver clock parameters from single difference carrier phase observations. In this case, we used multi-frequency GPS and Galileo data. First results with only the JAVAD receiver inside the chamber show temperature variations affecting GPS L1, L2 and L5 by up to 2.3, 2.7 and 3.4 mm/°C, respectively. When only the splitter is in the chamber, thermal sensitivity varies significantly, showing gradients
of 0.2 mm/°C for the Septentrio-JAVAD baseline and 0.02 mm/°C for the JAVAD-JAVAD baseline, respectively, for GPS L1 observations. This shows that a baseline formed by two receivers of the same type experiences distinctly smaller temperature-
induced variations than a baseline formed by different receiver types. Conclusively, we will also compare our findings with results derived from a standard PPP approach, both with and without integer ambiguity resolution.

Organisation(s)

Institute of Geodesy
CRC 1464: Relativistic and Quantum-Based Geodesy (TerraQ)

Type

Slides to presentation

Publication date

04.09.2025

Publication status

E-pub ahead of print

ASJC Scopus subject areas

Engineering (miscellaneous)

Research Area (based on ÖFOS 2012)

Navigation systems, Satellite-based coordinate measuring

Sustainable Development Goals

SDG 9 - Industry, Innovation, and Infrastructure