Testing the product quality of Galileo and GPS on-board oscillators

Abstract

The final clock product provided by the IGS (International GNSS Service) with a 30/300 s sampling interval for satellites and stations respectively is characterized by accuracy of 75 ± 20 ps RMS (Root Mean Square). Since mid-2012, the MGEX (Multi-GNSS Experiment) experiment provides full products containing all available GNSS (Global Navigation Satellite Systems) satellite signals. In this paper, the phase, frequency and stability of Galileo and GPS (Global Positioning System) on-board oscillators based on the MGEX data are analysed. Moreover, the authors also determined the noise type for specific on-board oscillators depending on GNSS type and frequency standard. The analysis showed different characteristics of clock correction phase and frequency for both satellite systems. Also, each system and clock type has different noise for each averaging time. In order to distinguish more types of noises, three different variants of stability analysis were conducted: Allan deviation (ADEV), modified Allan deviation (MDEV), and Hadamard deviation (HDEV).