Methods for Improving User Position Accuracy in IRNSS (NavIC) Receiver

Abstract

Indian Regional Navigation Satellite System (IRNSS) named as NavIC is ISRO’s initiative to build an independent regional satellite navigation system based on a constellation of geostationary and geosynchronous satellites to find the user receiver position. There are three segments involved such as space segment, control segment and user segment to provide PVT solutions. For Standard Positioning Service (SPS) Receiver, to find out the user position, computational process is involved between IRNSS space segment and user segment. The receiver position is calculated in two steps: which involves baseband processing and navigation processing. In this paper, overview of the navigation processing, method for user position computation and accuracy improvement methods are discussed. This includes decoding of satellite sub-frames, parsing of satellites ephemeris data, pseudo-range measurements to compute the user and satellite positions. To improve the user position accuracy, the entire computation of navigation process can be further refined by incorporating various error correction algorithms. Error correcting algorithms such as ionospheric error correction, tropospheric error correction, earth rotation error correction algorithms are discussed. Matlab-based simulations are carried out. The proposed methods are developed and implemented FPGA-based hardware platform. The results with and without error corrections algorithms are enclosed.