Global Navigation Satellite Systems Engineering, Policy, and Design
GeoOptics Inc. has upgraded its CICERO constellation of Earth-observation satellites to include advanced GNSS Reflectometry (GNSS-R).
By Inside GNSS
Trimble announced enhancements to its Trimble RTX correction services. Improvements in the high-accuracy correction service include convergence time reductions, more reliable and robust signals, and an easier workflow for surveyors.
By Inside GNSS
In-flight refueling requires sustained minimal separation between paired aircraft with little room for error. In or near combat zones, wide-area GPS-denial or spoofing means that an GPS-independent system must be available. Regardless of the selected sensor package, a common set of properties must be satisfied to facilitate mid-air docking: a high degree of accuracy, precision, and integrity.
UrsaNav and ADVA have conducted an enhanced long-range navigation (eLoran) field trial using UrsaNav’s eLoran receiver and ADVA’s Oscilloquartz grandmaster clock technology. The successful demo showed that eLoran offers a robust and reliable backup for GPS and other GNSS and could be used to provide an assured position, navigation, and timing (PNT) service.
By Inside GNSS
The addition of alternative sensors such as cameras, magnetometers, and small ranging radios increases the likelihood of a mismodeled and/or faulty sensor, affecting the accuracy and performance of the overall navigation solution. Unlike two-sensor systems such as GPS-inertial integration, systems of three or more sensors present the problem of ambiguity as to which sensor is adversely affecting the solution. This presents the need for a robust framework that can maintain navigation integrity despite the additional sensor modalities.
Testing of the first Galileo Second Generation (G2) hardware has begun, with versions of the satellites’ navigation payloads and antennas undergoing evaluation to check whether they meet the ambitious performance levels set for the coming generation of Europe’s GNSS.
By Inside GNSS
Interference mitigation techniques should protect GNSS receivers from interference and jamming without biasing their final position, velocity and timing solution. This column analyses five popular interference mitigation techniques, including the Adaptive Notch Filter (ANF) and Pulse Blanking (PB), evaluating their impact on pseudoranges and on the final position and timing solution. Several GNSS modulations are considered, showing the advantage of using GNSS signals with similar spectral characteristics.
There has been much discussion of the need for resilient PNT over the past few years as dependencies have grown and an evolving threat matrix has become more active. As a nation, we need a measured and cost-effective response commensurate with the level of threats and the possible consequences.
The European Commission and the European Space Agency (ESA) selected Leonardo’s hydrogen atomic clocks for Galileo Second Generation.
By Inside GNSS
Tallysman Wireless announced its new eXtended Filtering (XF) features to the TW3900 series of Accutenna precision antennas. The XF feature is designed to mitigate interference from all near-band signals.
By Inside GNSS
The future-oriented Navigation Technology Satellite-3 (NTS-3) spacecraft has taken one more step towards its in-space demonstration, scheduled for 2023. The satellite bus that will carry it has arrived at L3Harris Technologies of Palm Bay, Florida, delivered by Northrop Grumman Corporation.
By Inside GNSS
In the beginning, GPS was envisioned as a military program. A sign on the wall in the Joint Program Office where the system came into being during the early 1970s read: “The mission of this Program Office is to:
A Department of Homeland (DHS)-chartered May 2021 report concludes that PNT threat and resilience concerns are not as dire as some have made them out to be, and that funds for backup could be spent elsewhere. Why this runs counter to other recent government reports is not clear, nor is the fallout from this divergence of Congressionally mandated views. The Department of Transportation has distanced itself a bit from this report by the RAND Corporation—and even its issuer, the DHS, seems to have done so.
