Absolute Calibration of Dual Frequency Timing Receivers for Galileo

The timing service of Global Navigation Satellite Systems (GNSS) is being steadily improved. Generally, this fact traces back to increasing accuracy of the provided ephemeris data, improvements in Precise Point Positioning, continuous refinement of time transfer techniques, the utilization of modern signals, the use of wider bandwidth, and a growing number of available satellites—the latter particularly due to the coexistence of an increasing number of independent GNSSs available. The accuracy achievable by the GNSS common view time transfer method is within range of nanoseconds. In particular the upcoming Galileo in combination with the Global Positioning System is expected to improve that accuracy even further. In this paper, we present results for an approach for absolute calibration of Galileo timing receivers operating in the L1BC and E5 signal bands. The internal receiver delays for Galileo E1 and GPS L1 signals of the institute’s Septentrio PolaRx4 TR PRO are assessed. The approach utilizes a hardware simulator, which is an expanded version of a GSS7790 GNSS simulator from Spirent Communications. The simulator, the receiver under test, as well as the utilized measurement equipment use the 10 MHz signal from the same cesium clock as reference. Keywords—Receiver calibration, multi frequency, GNSS, synchronization, time transfer