My research interests involve the use of high-precision Global Navigation Satellite System (GNSS) measurements based on geodesy for the study of active deformation and to improve the understanding of earthquake fault systems. The study involves the collection of GNSS data and the processing of the raw data using GAMIT-GLOBK software. Multi-constellation systems (GPS, GLONASS, Galileo, BeiDou, IRNSS, and QZSS) signals are studied for comparative analysis such as positioning and multipath error analysis by using MATLAB computational package. GNSS reflectometry technique is used to measure the tide gauge by recording the data of signal-to-noise ratio (SNR). The study is also concerned with the ionosphere and troposphere error model by using the delay in GNSS signals.