NavIC Pseudorange Bias Estimation and Analysis Using Double Difference Method with Different Baseline Lengths

NavIC (Navigation with Indian Constellation) is an essential and indigenous positioning system developed by ISRO (Indian Space Research Organization) for all the location and navigation requirements in India. Before the deployment of NavIC in navigation and communication devices, it requires measuring and analyzing the residual bias remains in pseudorange and carrier phase observations when removing the atmospheric errors, satellite and receiver based errors. In this article we analyze the bias in NavIC pseudorange measurements on L5 band (1176.45 MHz) by using Double Difference (DD) method with different base lengths viz. zero base length, 1 meter base length, 3.56 meter base length, 5 meter base length, 7 meter base length and 9 meter base length. For all baseline lengths, the experiments were carried out in static position by using two multi-GNSS receivers at Kurnool (15. 79°N, 78.07°E), India. The pseudorange bias results were presented for a Geostationary orbit(GEO) satellite, IRNSS-1G (I07) and a Geosynchronous orbit (GSO) satellite, IRNSS-1D (I04). The satellite IRNSS-1C (I03) was considered as a reference in DD computation because of its highest elevation angle. The outcome of this research work shows that the pseudorange bias on L5 is in the range of - 0.606 m to 7.169 m and -0.019 m to 4.331 m for I04 satellite and for I07 satellite. Further the pseudo range bias increases significantly as the baseline length increases for both I04 satellite and I07.