Global Navigation Satellite Systems Engineering, Policy, and Design
Ambiguity resolution combined with multiple constellations and multiple frequencies proves very effective in reducing Precise Point Positioning convergence time. Such a solution with a 30° mask has a shorter convergence than a float multi-GNSS solution without any obstructions, despite the latter using more satellites.
By Inside GNSS
Research has focused on methods to analytically determine bounding probability distributions and parameters and identify the conditions under which such bounds are guaranteed to hold. This column summarizes several important examples from this research to highlight the most useful principles and techniques.
By Sam Pullen
As a significant number of people and robotics venture into space, infrastructures providing critical services such as GNSS must be considered on a large extra-terrestrial scale to support these explorations and settlements.
By Inside GNSS
Laboratory tests explore how commercially available receivers respond to meaconing and spoofing, with the goal of developing useful test methodologies and metrics to assess receiver robustness and resilience to real-world spoofing threats.
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.
