Development of an autonomous Global Navigation Satellite System ground station and its calibration for monitoring of local ionospheric perturbations

A state-of-the-art monitoring global navigation satellite system (GNSS) system has been originally designed and developed for various positioning and atmosphere-sensing purposes by the authors and updated to fulfil the challenging requirements for monitoring of ionospheric perturbations. The paper discusses various scientific and technically challenging issues, such as the requirement for an autonomous operating ground GNSS station and how this can be fulfilled. Basic algorithms for monitoring of local ionospheric perturbations with GNSS receivers are described. The algorithms require that inter-frequency hardware biases be known. Although the satellite transmitter biases can be obtain from the IGS services, the user takes responsibility for the estimation of frequency dependent receiver hardware biases and for the control of their variations. The instrumental signal delays are important for timing applications and GNSS monitoring of the ionosphere and are also required for recovering of the integer carrier-phase ambiguities. The paper presents an algorithm for calibration of inter-frequency biases of global positioning system (GPS) receivers and validates the first set of results.