A quasi-real-time on-chip ionospheric TECKalman filtering algorithm

An on-chip quasi-real-time algorithm is proposed for monitoring the ionospheric total electron content (TEC). The algorithm can run on a standard commercial chip. In this way, the cost, power consumption, size and data to be transferred of TEC monitor are reduced. To minimize the cache capacity needs and computational load, the algorithm collects the GNSS dual-frequency pseudorange and phase measurements in 20 minutes. The TEC, based on phase measurements, is fitted to the TEC derived from pseudorange measurements to achieve high-precision TEC along the line-of-sight path (slant TEC, STEC) within 20 minutes. A 5-min step is employed to compute the subsequent set of STEC. A thin-shell ionospheric model and VTEC polynomial model are used to construct the measurement equation of Kalman filter and acquire the quasi-real-time VTEC above the monitor. These VTEC values are compared with the results based on STEC from 1-day measurements. The results show that the quasi-real-time algorithm is effective. The algorithm is implemented on i.MX283 (Arm9™ Core).