Distributed Sensing of Space Weather Phenomena using Satellite Navigation Signals

Satellite navigation signals have been widely used for ionosphere and space weather monitoring.  There will be an anticipated over 160 global and regional satellites broadcasting over 400 signals by 2023. With their well-defined signal structures, high spatial density and spectral diversity, these signals offers low cost and distributed passive sensing of ionosphere and space weather effects. 

There are, however, some major challenges to utilize satellite navigation signals to study and forecast space weather.  Two major obstacles are the lack of accuracy and availability of measurements generated by stations equipped with commercial GPS/GNSS receivers during severe space weather events.  These obstacles exist because these receivers are designed for navigation purposes. For navigation applications, space weather and other propagation effects are nuisances and every effort has been made to minimize these effects.  Errors from receiver environmental interferences, hardware imperfections, and software processing artifacts also degrades the accuracy. Finally, strong space weather events are often characterized by turbulent structures in ionosphere, causing simultaneous deep amplitude fading and abrupt carrier phase changes.  The combined weak signal and high carrier dynamics imposes conflicting requirements for receiver design, leading to discontinuities in measurements. 

To overcome these challenges, high quality, raw satellite navigation signals bearing space weather signatures and robust receiver algorithms designed to capture these signatures.  We have designed and deployed space weather event-driven, reconfigurable data collection system to achieve this purpose. To date, our global network has collected ~250TB of raw satellite navigation data during space weather events.  A suite of novel algorithms has been developed by exploiting these disturbed signals spatial, frequency, temporal, and constellation diversity to process signals experiencing space weather impact.  This presentation will summarize progress and current state of the data collection systems, receiver architectures designed to capture and preserve space weather signatures, and space weather observations derived from this unique set of data and processing algorithms.