Comparison of TEC Estimation Techniques using S1 and L5 Signals of IRNSS

Resumo

Indian Regional Navigation Satellite System (IRNSS) is a satellite based navigation system developed by Indian Space Research Organization (ISRO). The positional accuracy of IRNSS is limited by several errors including ionospheric delay. Ionospheric delay can be estimated with precise calculation of total electron content (TEC). However, TEC is biased by multipath and thermal noise. Therefore, multipath and thermal noise free relative TEC measurements are made and compared with two other methods, namely, code TEC and IRNSS Receiver Software (IRS) techniques. In this investigation L5 (1176.45 MHz) and S1 (2492.028 MHz) signals from IRNSS 1A to 1G satellites are considered. The results indicate that relative TEC estimation technique removes the multipath and thermal noise from the TEC measurements. Further, the TEC for signals coming from various IRNSS satellites are evaluated by calculating the standard deviation (SD). In the analysis the data is divided into segments with duration of 1 h each. The results indicate that SDs for the relative TEC estimation (2.5 TECU in case of IRNSS 1B) are lesser than the other two techniques indicating the relative TEC can be used in the receiver for the estimation of ionospheric delay. Further, the high ratio of the operating frequencies indicates a better TEC estimation.