Ionospheric Delay

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?

  1. Signal Refraction & Delay – GNSS signals slow down and bend when passing through the ionosphere, leading to range errors.

  2. Positioning Errors in GNSS-Aided INS – Since INS relies on GNSS updates for error correction, ionospheric delay can reduce positioning accuracy.

  3. Increased Errors During Solar ActivitySolar 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.