Global Navigation Satellite Systems Engineering, Policy, and Design
Will the network, which some are still fighting, be ready for a September rollout, and if so, what are the implications for GPS and the people who rely on it?
By Dawn M.K. Zoldi (Colonel, USAF, Ret.)
A factor-graph optimization-based GNSS positioning method uses GNSS pseudorange and Doppler observations to estimate position, velocity, and receiver clock biases. Added constraints on past and current graph nodes of the graph using time-difference observations of the GNSS carrier phase improve the accuracy, and a robust optimization method excludes multipath outliers. Experimental results reduce horizontal positioning error from 5 to 10 meters to 1.37 meters.
By Inside GNSS
In this second column we consider fundamental principles of inertial navigation that derive position, velocity and angular orientation from measurements of accelerometers and gyroscopes.
By Andrey Soloviev
The European Geostationary Navigation Overlay Service (EGNOS) will soon launch a new maritime solution that will make legacy and costly coastal ground-based augmentation systems redundant. Meanwhile, the next generation EGNOS V3, featuring dual-frequency, multi-constellation (DFMC) services, is set to come online by 2028, once GPS L5 is declared operational.
By Peter Gutierrez
A novel method for improving the positioning accuracy of GNSS receivers exploits a machine learning (ML) algorithm. The ML model uses the post-fit residuals, which are readily available after the position computation from the position, velocity and timing (PVT) engine, adoptable by existing receivers without requiring any modification. The performance of this method, demonstrated using data collected with mass-market receivers as well as a Google public dataset collected with Android smartphones, shows the practicality of the concept.
By Inside GNSS
The concept of autonomous driving has generated a lot of interest and attention in the past decades as it is believed to provide numerous benefits for individuals and society: increased road safety, reduced traffic congestion, accidents and death, and saving time and pollution on commuting. There is a lot of ongoing work on this topic, much research and many experiments have been conducted on how to make cars learn the environment, make human-like decisions and drive on their own.
By Inside GNSS
Warfighting systems rely on GPS to provide cyber-secure and accurate positioning, navigation and timing (PNT). A recent Department of Defense Operational Test and Evaluation (DOT&E) report examined, along with all U.S. tactical weaponry, the adequacy of current GPS equipment, test strategies and plans for future operational effectiveness. It found some causes for concern.
By Dawn M.K. Zoldi (Colonel, USAF, Ret.)
Inside GNSS’s resident inertial expert examines coasting over GNSS outages, navigation in challenged environments and interference mitigation in a sensor-fusion environment.
By Andrey Soloviev
Speaking at a special EGNOS Workshop, Fiametta Diani, head of marketing at the EU Agency for the Space Program (EUSPA), described where Europe’s GNSS augmentation system is going, in the air, on land and at sea.
By Peter Gutierrez
Difficult GNSS environments and adverse weather conditions require a fusion of many sensors to maintain lane-level accuracy for autonomous platforms, without incurring high costs that would inhibit widespread adoption. Radars are an attractive option in a multi-sensor integration scheme due to being robust to adverse weather and insensitive to lighting variations.
By Inside GNSS
The following is a partial transcript of a talk given to the National PNT Advisory Board Executive Committee (PNTAB ExCom) on December 9, 2021. It connects GNSS signal authentication, by both Galileo’s OSNMA and the proposed GPS Chimera signal, with developing PNT capabilities in 5G telecom technology, and further, with software-defined radio (SDR) capabilities aboard some GNSS satellites that could place GPS in the second tier.
By Inside GNSS
With a Low-cost Single-frequency Multi-GNSS Receiver
Although precise point positioning (PPP) has been largely limited to applications in open environments using high-end GNSS receivers, recent test results demonstrate that a new PPP system with a mass-market receiver can significantly improve positioning accuracy in urban environments.
By Inside GNSS Cryptographic techniques can optimize the trade-off between authentication integrity (minimizing the probability of authenticating a modified message), ease of modification of existing signals (for operator and user acceptance), and minimal impact on existing users who will form the vast majority of the GNSS user population for some time to come.
By Sam Pullen
