Browsing by Subject "Pesyna"
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Item Centimeter Positioning with a Smartphone-Quality GNSS Antenna(2014-09) Pesyna, Kenneth M. Jr; Heath, Robert W. Jr.; Humphreys, Todd E.This paper demonstrates for the first time that centimeteraccurate positioning is possible based on data sampled from a smartphone-quality Global Navigation Satellite System (GNSS) antenna. Centimeter-accurate smartphone positioning will enable a host of new applications such as globally-registered fiduciary-marker-free augmented reality and location-based contextual advertising, both of which have been hampered by the several-meterlevel errors in traditional GNSS positioning. An empirical analysis of data collected from a smartphone-grade GNSS antenna reveals the antenna to be the primary impediment to fast and reliable resolution of the integer ambiguities which arise when solving for a centimeter-accurate carrierphase differential position. The antenna’s poor multipath suppression and irregular gain pattern result in large timecorrelated phase errors which significantly increase the time to integer ambiguity resolution as compared to even a low-quality stand-alone patch antenna. The time to integer resolution—and to a centimeter-accurate fix—is significantly reduced when more GNSS signals are tracked or when the smartphone experiences gentle wavelength-scale random motion.Item Collaborative Opportunistic Navigation(2012) Kassas, Zak; Pesyna, Kenneth M. Jr; Humphreys, Todd E.Item Constructing a Continuous Phase Time History from TDMA Signals for Opportunistic Navigation(2012-04) Pesyna, Kenneth M. Jr; Kassas, Zaher M.; Humphreys, Todd E.A technique is developed for reconstructing a continuous phase time history from the noncontinuous phase bursts of time division multiple access (TDMA) signals. A continuous phase time history facilitates exploitation of TDMA signals as signals of opportunity (SOPs) within an opportunistic navigation framework. Because of their widespread use and availability in today’s wireless communication market, TDMA signals are attractive candidate SOPs for opportunistic navigation. The phase reconstruction technique presented here combines an integer least squares technique for estimating phase ambiguities at the beginning of each TDMA phase burst with a Kalman filter and smoother for removing these ambiguities and optimally “stitching” the bursts together. A Monte-Carlo-type simulation and test environment has been developed to investigate the sensitivity of the proposed phase reconstruction technique to various system parameters, namely, carrier-to-noise ratio, receiver clock quality, TDMA transmitter clock quality, line-of-sight acceleration uncertainty, and TDMA burst structure. Simulation results indicate that successful carrier phase reconstruction is most strongly dependent on the TDMA burst period and on the combined phase random walk effect of the receiver and transmitter clocks, the propagation effects, and the range errorsItem Dense RTK: Mass-Market Positioning for Automated Vehicles(2016-09-15) Humphreys, Todd E.; Pesyna, Ken; Shepard, Daniel; Murrian, Matthew; Kerns, AndrewItem GPS-assisted Femtocell Synchronization and Localization Through Tightly-Coupled OpportunisticNavigation(2011) Pesyna, Ken; Wesson, Kyle; Heath, Robert; Humphreys, ToddItem Indoor GPS: Tightly Coupled Opportunistic Navigation(2010) Pesyna, Ken; Wesson, Kyle; Bhatti, Jahshan A.; Humphreys, ToddItem Low-Cost Precise Urban Positioning(2016-09-14) Humphreys, Todd; Pesyna, Ken; Shepard, Daniel; Murrian, Matthew; Kerns, AndrewItem On the Feasibility of cm-Accurate Positioning via a Smartphone’s Antenna and GNSS Chip(2016-04) Humphreys, Todd E.; Murrian, Matthew; Pesyna, Kenneth M. Jr; Sergei Podshivalov, Frank van DiggelenThe feasibility of centimeter-accurate carrier-phase differential GNSS (CDGNSS) positioning using a smartphone’s internal GNSS antenna and GNSS chip is investigated. Precise positioning on a mass-market platform would significantly influence the world economy, ushering in a host of consumer-focused applications that have so far been hampered by the several-meter-level errors in traditional GNSS positioning. Previous work has shown that GNSS signals received through a mass-market smartphone’s GNSS antenna can be processed to yield a centimeter-accurate CDGNSS position solution, but this earlier work processed all GNSS signals externally to the smartphone. The question remains whether a smartphone’s internal oscillator and GNSS chip can produce observables of sufficient quality to support centimeteraccurate carrier-phase-based positioning. This paper answers the question by accessing and processing the raw code- and carrierphase observables produced by a mass-market smartphone GNSS chip—observables that have heretofore been unavailable to the research community. The phone’s carrier phase measurements are shown to suffer from five anomalies compared to those from a survey-grade GNSS receiver, four of which are readily fixed in post-processing. The remaining anomaly, an error in the phase measurement that grows approximately linearly with time, currently prevents the phone’s phase measurements from satisfying the conditions for CDGNSS positioning. But the phone’s measurements seem otherwise fully capable of supporting cmaccurate carrier-phase differential GNSS positioning. A separate analysis of a smartphone’s GNSS signal strength dependency on azimuth and elevation reveals that multipath-induced deep fading and large phase errors remain a significant challenge for centimeter-accurate smartphone positioning.Item Opportunistic Frequency Stability Transfer for Extending the Coherence Time of GNSS Receiver Clocks(2010) Wesson, Kyle D.; Pesyna, Kenneth M. Jr; Bhatti, Jahshan A.; Humphreys, Todd E.A framework is presented for exploiting the frequency stability of non-GNSS signals to extend the coherence time of inexpensive GNSS receiver clocks. This is accomplished by leveraging stable ambient radio frequency signals, called “signals of opportunity,” to compensate for the frequency instability of the reference oscillators typically used in inexpensive handheld GNSS receivers. Adequate compensation for this frequency instability permits the long coherent integration intervals required to acquire and track GNSS signals with low carrier-to-noise ratios. The goal of this work is to push the use of GNSS deeper indoors or into environments where GNSS may be subject to interference.Item Precise Augmented Reality Enabled by Carrier-Phase Differential GPS(2012) Shepard, Daniel P.; Pesyna, Kenneth M. Jr; Humphreys, Todd E.A prototype precise augmented reality (PAR) system that uses carrier phase differential GPS (CDGPS) and an inertial measurement unit (IMU) to obtain sub-centimeter level accurate positioning and degree level accurate attitude is presented. Several current augmented reality systems and applications are discussed and distinguished from a PAR system. The distinction centers around the PAR system’s highly accurate position estimate, which enables tight registration, or alignment of the virtual renderings and the real world. Results from static and dynamic tests of the PAR system are given. These tests demonstrate the positioning and orientation accuracy obtained by the system and how this accuracy translates to remarkably low registration errors, even at short distances from the virtual objects. A list of areas for improvement necessary to create a fully capable PAR system is presented.Item Precision Limits of Low-Energy GNSS Receivers(2013) Pesyna, Kenneth M. Jr; Heath, Robert W. Jr.; Humphreys, Todd E.Limitations on position-time precision are analyzed in energy-constrained GNSS receivers. The goal of this work is to determine the combination of sampling rate, number of quantization bits, number of satellites tracked, and coherent integration time that maximizes the position-time precision under a fixed low-energy constraint. In this paper, only the measurement errors due to spectrally flat Gaussian thermal noise are considered. Analytical expressions relating the foregoing parameters to precision and energy consumption are developed. Based on these expressions, a constrained optimization problem is formulated. Optimal solutions indicate that under a tight energy constraint energy should be allocated toward increasing the sampling rate at the expense of the other parameters. Moreover, the quantization resolution should be set above 1-bit only under an energy surplus. Interestingly, optimum settings under tight energy constraints approximately match those chosen by the designers of energyefficient commercial GNSS receivers.