Global Navigation Satellite Systems Engineering, Policy, and Design
Dr. Rui Hirokawa is Deputy General Manager, Space Systems Department, at Kamakura Works, Mitsubishi Electric Corporation. A fixture in today’s GNSS community, he manages several QZSS-related projects, including the centimeter-level augmentation service (CLAS), and has recently been deeply involved in the international standardization of high-accuracy GNSS.
By Peter Gutierrez
For years, both the Executive and Congress have expressed concerns over PNT vulnerabilities and clamored for solutions. Yet little has changed. Three important reports emerged at the tail end of the old regime. As new leadership takes the helm, in which direction will it take the PNT enterprise?
By Dawn M.K. Zoldi (Colonel, USAF, Ret.)
A new approach to facilitate fast and/or reliable reception and decoding of the navigation message in harsh radio propagation conditions derives from digital communications. Link-layer coding (LLC) techniques improve times-to-first-fix (TTFFs) over legacy carousel transmissions and achieve near-optimal performance with a limited complexity increase.
Innovative features of cellular fifth-generation (5G) signals enable the wireless system to play a major role in autonomous technologies. Test results of a ground vehicle navigating with signals from five 5G base stations (gNBs) over a trajectory of 773 m traversed in 110 seconds show a position root mean-squared error of 4.1 m.
The value of the GPS SPS PS goes far beyond the specific parameters that it contains. It has a great deal of information regarding how GPS operates and ideally should be read in full (including the appendices) by everyone who works with GPS at the measurement level.
Inertially-aided extended coherent integration makes a GNSS receiver more sensitive to directly received signals than to reflected signals whenever the receiver is moving. 3D-mapping-aided GNSS uses predictions of which signals are NLOS to enhance the positioning algorithms. Both techniques can improve positioning accuracy in dense urban areas by more than a factor of two. This article investigates the benefits of combining them.
By Inside GNSS
Alternative PNT from low-Earth orbit (LEO) satellites is being developed or proposed by various entities. Satelles delivers a fully operational Satellite Time and Location (STL) service to back up or augment GNSS, strengthening the resilience of critical infrastructure. This article details STL’s timing synchronization performance with different types of user equipment.
As 2020 ended, the Ligado project stood still. The FCC proceedings in the case had stagnated, while Congressional action, funds and filings flowed.
As 2020 comes to a close, the Ligado Networks LLC’s (Ligado) mobile satellite services (MSS) project remains at a standstill. While actions in the Federal Communication Commission (FCC) proceedings in the case have stagnated, Congressional action, funds and filings have flowed.
By Dawn M.K. Zoldi (Colonel, USAF, Ret.)
For decades, artificial intelligence and machine learning have advanced at a rapid pace. Today, there are many ways artificial intelligence and machine learning are used behind the scenes to impact our everyday lives, such as social media, shopping recommendations, email spam detection, speech recognition, self-driving cars, UAVs, and so on.
By Inside GNSS
The second of a two-part article explains how an initial system using existing Earth-GNSS constellations may be augmented with dedicated lunar orbiting satellites as well as lunar beacon ranging sources. A gradual deployment leads to a full autonomous lunar navigation system.
The advent of large LEO constellations is a game-changer for navigation. A key feature of these constellations is their potential to allow simultaneous measurement of Doppler shifts from a large number of satellites.
A framework to seamlessly navigate people from urban road traffic to indoor foot traffic uses the phone’s inertial measurement unit, GNSS chipset and camera, aided by an extended Kalman filter and ORB-SLAM. Tests show the framework performing well in both phases, guiding the phone’s user, behind the wheel on a city street, to a spot in an underground parking garage and walking to a meeting inside a large building.
