Ionospheric delay is a signal propagation delay that occurs when GNSS signals pass through the Earth’s ionosphere, a layer of charged particles in the atmosphere. This effect introduces positioning errors in GNSS-aided Inertial Navigation Systems (INS) by causing signal refraction and travel time variations, affecting high-precision navigation in aerospace, military, and maritime applications.
How Ionospheric Delay Affects INS?
Signal Refraction & Delay – GNSS signals slow down and bend when passing through the ionosphere, leading to range errors.
Positioning Errors in GNSS-Aided INS – Since INS relies on GNSS updates for error correction, ionospheric delay can reduce positioning accuracy.
Increased Errors During Solar Activity – Solar flares and geomagnetic storms amplify ionospheric disturbances, worsening navigation errors.
Methods to Mitigate Ionospheric Delay in INS
✔ Dual-Frequency GNSS Receivers – By comparing L1 & L2 signals, INS can estimate and correct ionospheric delay.
✔ Ionospheric Models (Klobuchar, NeQuick, IRI) – These predictive models help compensate for delay effects.
✔ INS Dead Reckoning – In GNSS-denied environments, INS continues navigation autonomously, reducing reliance on affected GNSS signals.
