Lightweight Pilot Estimation on LEO Satellite Signals for Enhanced SOP Navigation

TL;DR

This paper presents a method for estimating satellite signals from LEO satellites like Starlink to improve SOP-based navigation, achieving around 268 meters positioning accuracy.

Contribution

It introduces a practical receiver implementation for capturing and analyzing LEO satellite signals for SOP measurements, including symbol estimation and PVT computation.

Findings

Successfully identified recurring symbols from Starlink satellites.

Collected Doppler shift data over 600 seconds for positioning.

Achieved approximately 268 meters positioning error after refinement.

Abstract

The computation of positioning, navigation and timing (PNT) via signal of opportunity (SOP), where signals originally transmitted for communication, such as 5G, Wi-Fi, or DVB-S, are exploited due to their ubiquity and spectral characteristics, is an emerging research field. However, relying on these signals presents challenges, including limited knowledge of the signal modulation and the need to identify recurring sequences for correlation. We offer a guide to implement a receiver capable of capturing broadband downlink Ku-band signals from low Earth orbit (LEO) satellites (e.g., Starlink and OneWeb) and estimating the recurring symbols for SOP measurements. The methodology integrates recent approaches in the literature, highlighting the most effective aspects while guiding the replication of experiments even under limitations on the front-end gain and bandwidth. Using the proposed model, we can identify recurring symbols transmitted by Starlink satellites, which are then used to collect Doppler shift measurements over a 600 s interval. A position, velocity, and time (PVT) solution is also computed via least squares (LS), which achieves a positioning error of approximately 268 m after a post-fit refinement.