Authors : Timi V. Nagberi; Iyemeh Uchendu

Volume/Issue : Volume 11 - 2026, Issue 1 - January

Google Scholar : https://tinyurl.com/54e2cywb

Scribd : https://tinyurl.com/ybft63hv

DOI : https://doi.org/10.38124/ijisrt/26jan229

Note : A published paper may take 4-5 working days from the publication date to appear in PlumX Metrics, Semantic Scholar, and ResearchGate.

Abstract : Land Mobile Satellite Service (LMSS) terminals operating over geostationary (GEO) links experience persistent challenges in maintaining pointing continuity under vehicular motion, urban shadowing, and signal blockage. Conventional GNSS/INS-only predictors suffer from drift during outages, while monopulse tracking introduces prohibitive RF complexity for compact mobile terminals. This paper presents a low-complexity, comparator-assisted tracking architecture for real- time realignment of vehicle-mounted GEO LMSS terminals. The proposed system integrates a four-facet power-difference comparator that supplies residual pointing correction to an Extended Kalman Filter (EKF)–assisted estimator. The EKF fuses GNSS and inertial measurements to jointly estimate attitude, Doppler, and bias states, while a dual-axis PID controller performs coarse antenna actuation. A hysteretic beam-selection logic stabilizes sector handover, and an adaptive frequency/phase-locked loop (FLL/PLL) hybrid preserves carrier lock under rapid signal-to-noise ratio (SNR) fluctuations. The entire tracking loop is formulated in unified state-space form, enabling analytical derivation of stability limits and tuning laws. The architecture achieves reduced realignment latency and improved pointing robustness without the calibration overhead of monopulse systems, making it well suited for small S-band LMSS terminals operating in dynamic environments.

Keywords : Land Mobile Satellite Service, GEO Tracking, EKF, Comparator Tracking, Antenna Realignment, Satellite-on-the- Move.

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