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Abstract: There has been resurgent interest in building low Earth orbiting (LEO) constellations of satellites on a new scale. Their aim is Internet for the world with plans for potentially thousands of satellites. Here, we explore how these LEO constellations can be utilized for navigation. Closer to Earth, LEO offers stronger signals, strengthening us against jamming and aiding in indoor and urban environments. Proximity is also its weakness, where satellites have a small Earth footprint requiring many to provide global coverage. We show that the strength of the Broadband LEO constellations is their numbers, where they offer threefold improvement in satellite geometry compared to navigation core‐constellations today. This allows for relaxation of the signal‐in‐space user range error, while still matching the position accuracy of GPS. Coupled with the more benign radiation environment in LEO compared to GPS in medium Earth orbit, this enables a navigation payload designed using commercial‐off‐the‐shelf components. © 2018 Institute of Navigation [ABSTRACT FROM AUTHOR]

Growing activity in the Arctic calls for high integrity navigation in this region. This can be achieved using Global Navigation Satellite Systems (GNSS) in conjunction with Satellite Based Augmentation Systems (SBAS) or Advanced Receiver Autonomous Integrity Monitoring (ARAIM). Single frequency GPS-only SBAS is in service in some regions today and is reliant on ground and space infrastructure. ARAIM will be more autonomous and will rely on the multitude of signals and core constellations coming in the future. Here, we examine both SBAS and ARAIM in the context of aviation and maritime requirements in the Arctic. Results demonstrate that the introduction of multi-frequency and multi-constellation to these systems enables navigation safety in the Arctic. SBAS brings aircraft precision approach as well as precise maritime operations such as mapping. ARAIM also supports precision approach in addition to autonomous ice navigation at sea but falls short of precision maritime requirements. Copyright © 2016 Institute of Navigation [ABSTRACT FROM AUTHOR]

Satellite navigation has been used for aircraft navigation for more than 50 years. In the last ten years, the capabilities of satellite navigation have been expanded to more demanding phases of flight, in particular vertical guidance down to 200 ft, thanks to the implementation of augmentation systems. In this paper, we attempt to predict the state of satellite navigation in the next 15 years. We will start by reviewing the challenges that must be addressed by satellite navigation for aircraft guidance. Then, we will describe the current techniques that enable satellite navigation for aviation and the level of performance they achieve today. This will be followed by a description of the upcoming changes to satellite navigation, which include the launch of new constellations and the introduction of new civil signals. Despite these developments, satellite navigation is inherently vulnerable to radio-frequency interference so that backup navigation systems are still necessary. Nonetheless, these improvements will have a great impact on the availability and level of service achieved by satellite navigation, in particular enabling worldwide coverage of vertical guidance. [ABSTRACT FROM PUBLISHER]

A unaugmented Global Positioning System (GPS)-based flight inspection system (FIS) that performs airborne inspection of the instrument landing system (ILS) is introduced. This novel system relies on a TV positioning system (TVPS) that measures the horizontal position over the runway threshold and a radar altimeter (RA) to determine a reference point that is able to remove the GPS biases. Because of the near-real-time nature of flight inspection, it is possible to reconstruct an accurate approach trajectory even though the reference point occurs after the completion of the trajectory. The precise relative positioning (PRP) algorithm is applied to achieve the desired results. It includes a first-order fit to the ionospheric error, based on code and carrier measurements, that enables a significant reduction in this error source. This system has an autonomous integrity feature, called FIS-RAIM (receiver autonomous integrity monitoring), that is equipped in this system to protect against GPS satellite failures that may cause significant positioning errors. The FIS-RAIM is specifically designed for a flight inspection problem, and much of its detail is also described. Experimental flight tests strongly suggest that the system architecture and algorithm could meet FIS accuracy requirements for CAT III ILS with better performance than current flight inspection systems in terms of cost and efficiency. The system is not dependent on any GPS augmentation system; therefore the unaugmented GPS-based FIS provides low cost and high efficiency with worldwide availability. [ABSTRACT FROM AUTHOR]

In the 2020 time frame, the Global Positioning System (6PS) will be fully modernized, and other satellite navigation systems will be operational. With an additional layer of fault detection, these systems will provide vertical guidance worldwide. This capability will be born of three important technologies. First and foremost, avionics will receive signals on two frequencies: LI/EI and L5/ESa. This frequency diversity will do much to obviate the impact of ionospheric storms that troubles aviation use of GPS today. Secondly, a multiplicity of data broadcasts will be available to convey integrity information from the ground to the airborne users. These will include the navigation satellites themselves, geostationary satellites, and possibly terrestrial transmitters. However, the most important change will be the most subtle. The fault monitoring burden will be split between the aircraft and the supporting ground systems in a new way relative to the fault-detection techniques used in 2008. This new integrity allocation and the associated architectures are the subject of this paper. [ABSTRACT FROM AUTHOR]

Strong ionospheric scintillation due to electron density irregularities inside the ionosphere is commonly observed in the equatorial region during solar maxima. Strong amplitude scintillation causes deep and frequent Global Positioning System (GPS) signal fading. Since GPS receivers lose carrier tracking lock at deep signal fading and the lost channel cannot be used for the position solution until reacquired, ionospheric scintillation is a major concern for GPS aviation in the equatorial area. Frequent signal fading also causes frequent reset of the carrier smoothing filter in aviation receivers. This leads to higher noise levels on the pseudo-range measurements. Aviation availability during a severe scintillation period observed using data from the previous solar maximum is analyzed. The effects from satellite loss due to deep fading and shortened carrier smoothing time are considered. Availability results for both vertical and horizontal navigation during the severe scintillation are illustrated. Finally, a modification to the upper bound of the allowed reacquisition time for the current Wide Area Augmentation System (WAAS) Minimum Operational Performance Standards (MOPS) is recommended based on the availability analysis results and observed performance of a certified WAAS receiver. [ABSTRACT FROM PUBLISHER]