Estimation of ionospheric gradients and vertical total electron content using dual-frequency NAVIC measurements

  • M. Ravi Kumar
  • M. Sridhar
  • D. Venkata RatnamEmail author
  • P. Babu Sree Harsha
  • S. Navya Sri
Original Article


Indian Space Research Organization is being developing a regional satellite radio navigation system known as Navigation with Indian Constellation (NAVIC) satellite system to cater positioning, navigation and timing application. NAVIC has the capability to transmit dual frequency measurements on L5 and S band signals. Ionospheric gradients are one of the pre-dominant error sources with huge impact at the time of geomagnetic disturbed ionospheric conditions in low-latitude region. The large ionospheric gradients can degrade the positional accuracy of NAVIC system. In this paper, ionospheric temporal gradient analysis is carried out in east, west, north and south directions using a Weighted Least Squares (WLS) algorithm for NAVIC L5 signals. The ionospheric gradient algorithm is tested with NAVIC receiver data located at Koneru Lakshmaiah Education Foundation (KLEF) University campus, Guntur, India (16.42 N, 80.62 E) during geomagnetic storm time conditions (27th–29th May 2017). The results confirmed the increments in VTEC along with longitudinal (E-W) and latitudinal (N-S) gradient magnitudes accordingly with geomagnetic storm effects. The WLS based VTEC model is able to detect E and W ionospheric gradients during the transition period from main phase to recovery phase of the geo-magnetic storm.


NAVIC VTEC Gradient measurements Dual frequency code and carrier phase measurements 



This work was supported in part by the Department of Science and Technology, New Delhi, India, through the FIST Program under Grant SR/FST/ESI-130/2013. The present work has been carried out under the project titled ‘Development of Ionospheric TEC Data Assimilation Model based on Kalman Filter using Ground and Space based GNSS and Ionosonde Observations’ sponsored by Science and Engineering Research Board (SERB)/ECR/2015/000410.


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Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.Koneru Lakshmaiah Education FoundationGunturIndia

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