A Low-cost Approach towards Ionospheric Probing Using Compact GNSS Receivers

Besides core services like Positioning, Navigation and Timing (PNT), Global Navigation Satellite System (GNSS) is used for atmospheric and ionosphere probing since the deployment of the systems. Costly and high data rate geodetic receivers are usually used for such research. These receivers may not be affordable for many users and cost reduction of probing systems may be useful for ongoing research. Low cost, compact, multi-frequency and multiple constellation enabled GNSS modules are recently being increasingly available in market those may be used for atmospheric or ionospheric research. In this manuscript, study results on suitability of such compact, cost-efficient GNSS modules for GNSS-based ionospheric research is presented. Low-cost single board computers (Raspberry Pi, RPi) interfaced with the module may be used for data recording. Approximate cost for such complete prototype unit would be around USD 360 (around INR 26,000) Signal strengths of GNSS satellites in terms of C/NO values may be extracted from the recorded NMEA data sentences and related atmospheric parameters can be derived from the C/NO values. This low cost, compact setup may be deployed at a fixed location or multiple such units may be deployed over a distributed geographical region for realtime, networked monitoring purpose. A comparative study on signal strength obtained from standard survey grade GNSS receivers and such low-cost receivers is made. For the module used in this effort, 6dB-Hz difference is witnessed between the values, but both the types show similar signature of signal strength variation. A properly calibrated system may be useful for designing cost- effective, GNSS-based ionospheric research.