A novel method using signals of opportunity from Low Earth Orbit (LEO) satellites is redefining what’s possible in satellite-based navigation. Researchers have developed a joint pseudo-range and Doppler positioning technique that taps into signals from constellations like Starlink and Iridium NEXT—without relying on traditional navigation signal structures. By employing low-cost, wide-beam antennas and a specially designed time–frequency inversion algorithm, the team achieved remarkable accuracy: 3.6 meters in 2D and 6.2 meters in 3D, surpassing Starlink positioning approaches based on parabolic antennas by 35%.
Global Navigation Satellite Systems (GNSS), such as Global Positioning System (GPS), often struggle in dense urban settings or under heavy foliage, where signal blockage and reflection compromise accuracy. In response, researchers are turning to Signals of Opportunity (SOP)—ambient radio emissions not originally intended for navigation, including those from Low Earth Orbit (LEO) satellites. Among these, Starlink stands out for its dense coverage and global reach. Yet, technical barriers remain: unknown signal transmission times, low signal power, and imprecise orbital data all hinder accurate positioning. Addressing these challenges demands a new approach to extracting usable navigation data from LEO constellations.
In 2025, a study published in Satellite Navigation. Researchers from the Aerospace Information Research Institute introduced a joint pseudo-range and Doppler positioning method using wide-beam antennas to receive LEO satellite SOPs. The approach centers on a signal time–frequency inversion algorithm that reconstructs key signal parameters, alongside a novel accuracy metric called Equivalent Position Dilution of Precision (EPDOP). Real-world experiments combining Starlink Doppler data and Iridium NEXT pseudo-range signals confirmed strong performance, especially in long-baseline conditions—reinforcing the method’s global applicability.
To overcome the cost and complexity of existing satellite tracking equipment, the team employed Low-Noise Block (LNB) wide-beam antennas capable of simultaneously receiving signals from multiple Starlink satellites. The core innovation lies in a signal processing algorithm that estimates transmission time and frequency from the received code phase and Doppler shifts—enabling both pseudo-range and Doppler observations without needing exact satellite clock data or real-time ephemeris. To quantify system performance under real-world errors, the researchers developed the EPDOP metric, adapted to mixed measurement inputs. Tests demonstrated the method’s robustness: 3.6 m 2D and 6.2 m 3D positioning using Starlink Doppler signals, and up to 24 m (2D) and 41 m (3D) accuracy using Iridium NEXT SOPs over a 40 km baseline. Compared to Doppler positioning techniques, the algorithm reduced positioning errors by over one-third and successfully suppressed the impact of orbital inaccuracies inherent in public Two-Line Element set (TLE) datasets.
“This work marks a key step toward accessible, accurate navigation using commercial satellite constellations,” said lead author Dr. Ying Xu. “By integrating Doppler and pseudo-range measurements and introducing a flexible precision metric, we can now harness Starlink and Iridium NEXT signals for high-precision positioning, even without access to proprietary signal structures. The proposed low-cost architecture opens new possibilities for resilient navigation in GPS-denied environments.”
Because of its ability to operate with low-cost antennas and weak, unstructured signals, the technique is poised to support a wide range of applications: from autonomous driving and Unmanned Aerial Vehicle (UAV) navigation in remote regions to emergency response and IoT asset tracking. Its resilience to satellite orbital prediction errors and adaptability across different LEO constellations make it a strong contender for next-generation positioning systems. As LEO deployments continue to expand globally, this approach offers a scalable and practical solution for real-time, high-accuracy navigation—promising enhanced capabilities for both civilian infrastructure and defense operations.
