Topic
Global Positioning System
About: Global Positioning System is a research topic. Over the lifetime, 53739 publications have been published within this topic receiving 697151 citations. The topic is also known as: GPS & Global Positioning System, GPS.
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01 Jan 2008
TL;DR: The next generation of positioning models for positioning and data processing will depend on the design of the satellite itself, as well as on the satellite orbits it is placed in.
Abstract: Reference systems.- Satellite orbits.- Satellite signals.- Observables.- Mathematical models for positioning.- Data processing.- Data transformation.- GPS.- Glonass.- Galileo.- More on GNSS.- Applications.- Conclusion and outlook.
893 citations
04 Nov 2009
TL;DR: A novel, principled map matching algorithm that uses a Hidden Markov Model (HMM) to find the most likely road route represented by a time-stamped sequence of latitude/longitude pairs, which elegantly accounts for measurement noise and the layout of the road network.
Abstract: The problem of matching measured latitude/longitude points to roads is becoming increasingly important This paper describes a novel, principled map matching algorithm that uses a Hidden Markov Model (HMM) to find the most likely road route represented by a time-stamped sequence of latitude/longitude pairs The HMM elegantly accounts for measurement noise and the layout of the road network We test our algorithm on ground truth data collected from a GPS receiver in a vehicle Our test shows how the algorithm breaks down as the sampling rate of the GPS is reduced We also test the effect of increasing amounts of additional measurement noise in order to assess how well our algorithm could deal with the inaccuracies of other location measurement systems, such as those based on WiFi and cell tower multilateration We provide our GPS data and road network representation as a standard test set for other researchers to use in their map matching work
887 citations
01 Jan 1999
835 citations
TL;DR: A theoretical model that describes the power of a scattered GPS signal as a function of geometrical and environmental parameters has been developed, suggesting mapping of the wave-slope probability distribution in a synthetic-aperture-radar (SAR) fashion to allow more accurate measurements of wind velocity and wind direction.
Abstract: A theoretical model that describes the power of a scattered Global Positioning System (GPS) signal as a function of geometrical and environmental parameters has been developed. This model is based on a bistatic radar equation derived using the geometric optics limit of the Kirchhoff approximation. The waveform (i.e., the time-delayed power obtained in the delay-mapping technique) depends on a wave-slope probability density function, which in turn depends on wind. Waveforms obtained for aircraft altitudes and velocities indicate that altitudes within the interval 5-15 km are the best for inferring wind speed. In some regimes, an analytical solution for the bistatic radar equation is possible. This solution allows converting trailing edges of waveforms into a set of straight lines, which could be convenient for wind retrieval. A transition to satellite altitudes, together with satellite velocities, makes the peak power reduction and the Doppler spreading effect a significant problem for wind retrieval based on the delay-mapping technique. At the same time, different time delays and different Doppler shifts of the scattered GPS signal could form relatively small spatial cells on sea surface, suggesting mapping of the wave-slope probability distribution in a synthetic-aperture-radar (SAR) fashion. This may allow more accurate measurements of wind velocity and wind direction.
826 citations