Digital cartography and automated mapping techniques based on GNSS positioning have transformed our relationship to the physical world. The convergence of these complementary technologies are supporting the growth of commercial and consumer location-based applications that benefit from the coupling of real-time information with maps that are more current than ever — at least in environments tha...

Successful integer estimation of carrier phase ambiguities of Global Navigation Satellite Systems (GNSS) is the key to many high precision positioning applications. In order to describe the quality of the positioning results rigorously, one needs to know the probabilistic properties of both the integer and noninteger parameters in the GNSS model. In this contribution these probability distribut...

Forest mapping, one of the main components of performing a forest inventory, is an important driving force in the development of laser scanning. Mobile laser scanning (MLS), in which laser scanners are installed on moving platforms, has been studied as a convenient measurement method for forest mapping in the past several years. Positioning and attitude accuracies are important for forest mappi...

The technique of the orthogonal projection of ionosphere electronic content variations for mapping total electron content (TEC) allows us to visualize ionospheric irregularities. For the reconstruction of global ionospheric characteristics, numerous global navigation satellite system (GNSS) receivers located in different regions of the Earth are used as sensors. We used dense GNSS networks in c...

Self-aggregated Li4Ti5O12 particles sandwiched between graphene nanosheets (GNSs) and single-walled carbon nanotubes (SWCNTs) network are reported as new hybrid electrodes for high power Li-ion batteries. The multi-layer electrodes are fabricated by sequential process comprising air-spray coating of GNSs layer and the following electrostatic spray (E-spray) coating of well-dispersed colloidal L...

For outdoor and global navigation satellite system (GNSS) challenged scenarios, collaborative positioning algorithms are proposed to fuse information from GNSS satellites and terrestrial wireless systems. This paper derives the Cramer-Rao lower bound (CRLB) and algorithms for the angle-of-arrival (AOA)-assisted GNSS collaborative positioning. Based on the CRLB model and collaborative positionin...

The coming decade will bring a proliferation of Global Navigation Satellite Systems (GNSS) that are likely to revolutionize society in the same way as the mobile phone has done. The promise of a broader multi-frequency, multi-signal GNSS “system of systems” has the potential of enabling a much wider range of demanding applications compared to the current GPS-only situation. In order to achieve ...

Global Navigation Satellite System (GNSS) Receiver Autonomous Integrity Monitoring (RAIM) is essential for safety-of-life and liability critical applications. This paper discusses two fundamentally different ways to assess the integrity risk of an operation with RAIM, based on a different amount of information available : the expected (or average) performance that is computed using the GNSS mod...

Todd E. Humphreys is a research assistant professor in the department of Aerospace Engineering and Engineering Mechanics at the University of Texas at Austin. He will join the faculty of the University of Texas at Austin as an assistant professor in the Fall of 2009. He received a B.S. and M.S. in Electrical and Computer Engineering from Utah State University and his Ph.D. in Aerospace Engineer...

The use of space-time processing methods in GNSS interference mitigation is of great interest due to their effectiveness in both narrowband and wideband interference suppression. Techniques to reduce the distortion and bias on the cross correlation function due to space-time filtering are also very important especially for high precision GNSS applications. In this paper, different types of spac...