Global Navigation Satellite Systems Engineering, Policy, and Design
There are interesting tradeoffs to consider in placing navigation satellites at various orbital heights, including signal power, availability, cost, orbit prediction, receiver computational load and manufacturer motivation.
By Inside GNSS
Innovative European developers use emerging GNSS-based Internet of Things technologies to create more power-efficient solutions for a range of logistics, maintenance and other applications.
By Peter Gutierrez
It has become fashionable of late in U.S. government circles to undermine the U.S. defense forces. The General Accounting Office (GAO), the Federal Communication Commission (FCC) and the White House (POTUS) have all pitched in, doing their share to weaken the capability and downgrade the tools with which our warfighters enter conflict.
A favorable GAO ruling discounted Congressional allegations that the FCC skipped a key legal step before granting Ligado’s controversial application. This positions the broadband company closer to its target and to ongoing interference with GPS signals.
By Dawn M.K. Zoldi (Colonel, USAF, Ret.)
The digital outputs of a four-channel antenna processing chain consisting of a four-element squared phased array and a 4-coherent channels front-end are processed to identify the presence of a jamming signal. The processing unit then implements a spatial filter to minimize jammer impact. The reconstructed signal is input to a COTS/SDR receiver designed to work in a typical railway environment.
Galileo will provide a High Accuracy Service (HAS) with positioning performance in the 20-cm range, disseminating Precise Point Positioning (PPP) corrections through the Galileo E6-B signal. Test results of a data encoding and dissemination scheme in different user environments demonstrate a reception time of the corrections in a few seconds in good channel conditions, and less than half a minute with severe channel impairments.
By Inside GNSS
When we find ourselves in times of trouble, it can help to take the long view. Pull back, zoom out, range free. Consider a vastly enlarged scope and sequence.
That’s why I find this month’s NTS-3 story so welcome. “Next-generation technologies across space,” I keep repeating.
By Alan Cameron
This advanced geosynchronous satellite from the Air Force Research Laboratory will mature next-generation technologies across space, ground control, and user equipment segments. NTS-3 will experiment with multiple integrated technologies.
Future telecom, finance and energy sector applications may require time synchronization of tens or hundreds of nanoseconds. A joint time and composite MIMO channel estimation method for indoor receivers can meet these stringent requirements.
GPS satellites usually transmit their signals with constant power. However, a so-called “Flex Power” is foreseen to increase the strength of individual signals to better fulfill operational constraints. Flex power operations can be detected in carrier-to-noise density ratio (C/N0) observations provided by GNSS receivers of the global tracking network of the International GNSS Service (IGS).
By Peter Steigenberger, et al.
We trace back through time to witness the progress in anti-spoofing solutions and describe how we arrived at the designs being implemented today; principally GPS’ CHIMERA, Galileo’s OSNMA, and ICAO’s SBAS data scheme.
Critical infrastructure has a compelling need to infer the assurance of PVT estimates—as do users in general. However, traditional PNT platforms do not offer a principled way to infer assurance from multiple anti-spoofing (A-S) techniques, situational awareness (SA) information, and other auxiliary sources such as network data. Here we introduce, a PNT Trust Inference Engine (PNTTING) that can assess PNT trust according to probabilistic models with rigorous semantics.
Researchers in the PRoPART project developed a 10-centimeter accurate and robust position determination system for autonomous vehicles, demonstrating a safe merge of a fully automated heavy truck between two cars driving at speed in an adjacent lane.
By Peter Gutierrez
