1,720,971 research outputs found
Positioning Techniques in Indoor Environments Based on Stochastic Modeling of UWB Round-Trip-Time Measurements
No full textIn this paper, a technique for modeling propagation of ultrawideband (UWB) signals in indoor or outdoor environments is proposed, supporting the design of a positioning systems based on round-trip-time (RTT) measurements and on a particle filter. By assuming that nonlinear pulses are transmitted in an additive white Gaussian noise channel and are detected using a threshold-based receiver, it is shown that RTT measurements may be affected by non-Gaussian noise. RTT noise properties are analyzed, and the effects of non-Gaussian noise on the performance of an RTT-based positioning system are investigated. To this aim, a classical least-squares estimator, an extended Kalman filter, and a particle filter are compared when used to detect a slowly moving target in the presence of the modeled noise. It is shown that, in a realistic indoor environment, the particle filter solution may be a competitive solution, at a price of increased computational complexity. Experimental verifications validate the presented approach. © 2016 IEEE
Validation and comparison of circular coils’ inductive coupling models
No full textIn this paper, modeling of inductive coupling between circular coils is analyzed. We present a system for measuring the mutual inductance and the magnetic flux between resonant coils. We investigate the accuracy and precision against data obtained through the FastHenry2 simulation software and through experiments, when these are available (Pasku et al., 2017). The theoretical background is discussed, theoretical models are presented, and their properties are compared to those of other published models. A practical implementation is illustrated and employed to validate the considered numerical models. Obtained results demonstrate that the proposed modeling and experimental setup provide high-accuracy measurements of the induced voltage. Field measurements validate the considered numerical models with a discrepancy of less than 10% with respect to measurement results
Parallel PN code acquisition for wireless positioning in CDMA handsets
No full textThis paper proposes a simplified acquisition system for finding and identifying Base Stations (BSs) in visibility in the framework of a CDMA wireless positioning system, based on IS-95 cellular standard. The problem of having more than one BS in the same PN code acquisition system makes it necessary to discriminate between correct detection and false alarm events. Since IS-95 uses the same PN sequence for all BSs, but with different code offsets, it is possible to use a cross-correlation technique to estimate both code and frequency offsets of several BSs at once. Time-Difference-Of-Arrival (TDOA) technique is used by the Mobile Station (MS) to geolocate itself. The positioning estimate is found to be stable in time and with a precision compatible with that required by emergency services, such as Enhanced 911 (E911)
An Indoor AC Magnetic Positioning System
No full textThis paper describes the design and realization of a magnetic indoor positioning system. The system is entirely realized using off-the-shelf components and is based on inductive coupling between resonating coils. Both system-level architecture and realization details are described along with experimental results. The realized system exhibits a maximum positioning error of <10 cm in an indoor environment over a 3 × 3 m2 area. Extensive experiments in larger areas, in nonline-of-sight conditions, and in unfavorable geometric configurations, show submeter accuracy, thus validating the robustness of the system with respect to other existing solutions
A 5.6-GHz UWB Position Measurement System
No full textThis paper describes the design and realization of a 5.6-GHz ultrawide-bandwidth-based position measurement system. The system was entirely made using off-the-shelf components and achieves centimeter-level accuracy in an indoor environment. It is based on asynchronous modulated pulse round-trip time measurements. Both system level and realization details are described along with experimental results including estimates of measurement uncertainties
An Experimental System for Tightly Coupled Integration of GPS and AC Magnetic Positioning
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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