The Importance of Human Motion for Simulation Testing of GNSS

Human motion is generally considered benign to the performance of global navigation satellite system (GNSS) and other positioning sensors. This study proves that this is not the case, even for typical human behaviour involving GNSS user equipment, e.g. in smartphones. Using recorded human motion, it is shown that phase-lock loops (PLLs) in GNSS receivers are sensitive to jerk dynamics induced by user motion, resulting in carrier cycle slips. To test the effects of human dynamics on GNSS carrier tracking, real human motion profiles were captured. These profiles comprised typical types of movements using a mobile phone, e.g. holding, answering and texting, different types of activities, e.g. walking or jogging, as well as different phone locations on the human body, e.g. in a hand, pocket, backpack and on an arm band. The data were captured outdoors using an Xsens MTi-G MEMS (Micro-Electronic Mechanical Systems) Inertial Measurement Unit (IMU) aided by a Global Positioning System (GPS) receiver with a 100Hz output rate. Then the captured motion (MoCap) was processed and input into a simulated PLL in Matlab with different tracking loop bandwidths (BL_CA) and carrier power-to-noise density ratios (C/N0). The results show that pedestrian gestures and type of activity, e.g. walking or jogging, affect the performance of the simulated PLL more adversely than the location of the phone on the human body. Also, to track pedestrian motion encompassing these gestures, activities and receiver locations, a minimum of 15Hz tracking bandwidth is required. Consequently, receiver manufacturers should exercise caution before reducing tracking bandwidths to compensate for the reduction in C/N0 resulting from GNSS antenna design, human body masking and the effects of buildings, trees and other environmental features. This paper also proposes and describes a pedestrian motion model (PMM) that simulates the GNSS antenna trajectory in 3D, when it is held by or attached to a pedestrian. The PMM will be validated using real MoCap scenarios and will enable Spirent to increase their product offering in the area of simulation-based testing of positioning sensors for pedestrian applications by generating human motion profiles which affect realistically the performance of GNSS user equipment

Quantum mechanical effect of path-polarization contextuality for a single photon

Using measurements pertaining to a suitable Mach-Zehnder(MZ) type setup, a curious quantum mechanical effect of contextuality between the path and the polarization degrees of freedom of a polarized photon is demonstrated, without using any notion of realism or hidden variables - an effect that holds good for the product as well as the entangled states. This form of experimental context-dependence is manifested in a way such that at \emph{either} of the two exit channels of the MZ setup used, the empirically verifiable \emph{subensemble} statistical properties obtained by an arbitrary polarization measurement depend upon the choice of a commuting(comeasurable) path observable, while this effect disappears for the \emph{whole ensemble} of photons emerging from the two exit channels of the MZ setup.Comment: To be published in IJT

Modern introductory physics

Modern Introductory Physics, 2nd Edition, by Charles H. Holbrow, James N. Lloyd, Joseph C. Amato, Enrique Galvez, and Beth Parks, is a successful innovative text for teaching introductory college and university physics. It is thematically organized to emphasize the physics that answers the fundamental question: Why do we believe in atoms and their properties?  The book provides a sound introduction to basic physical concepts with particular attention to the nineteenth- and twentieth-century physics underlying our modern ideas of atoms and their structure.  After a review of basic Newtonian mechanics, the book discusses early physical evidence that matter is made of atoms.  With a simple model of the atom Newtonian mechanics can explain the ideal gas laws, temperature, and viscosity.  Basic concepts of electricity and magnetism are introduced along with a more complicated model of the atom to account for the observed electrical properties of atoms. The physics of waves---particularly light and x-rays---and basic features of relativity are explored and used to reveal further details of atomic structure.  Following the discovery of radioactivity, transmutation, and the atomic nucleus, Bohr’s model of the hydrogen atom sets the stage for a view of the atom that becomes fully modern with the introduction of the ideas of quantum mechanics.  This book presents these ideas in terms of the Heisenberg uncertainty principle and Feynman’s rules of quantum mechanics and also discusses the intriguing topics of entanglement, non-locality, and Bell’s inequalities.  Here, as everywhere in this book, there is strong emphasis on experiments and observable phenomena that have shaped and confirmed the concepts of physics. To help students make a good transition from high-school physics to university physics, this book fosters quantitative skills: There is much use of order-of-magnitude calculations, scaling arguments, proportionalities, approximations, and other basic tools of quantitative reasoning, progressing from simple and direct applications in the early parts of the book to more elaborate ones later.   The book shows how new physics and new ideas are inferred from experimental data and quantitative reasoning.  A large number of exercises and problems help students clarify their understanding. Modern Introductory Physics, 2nd Edition, is an extensive revision of the original influential and innovative introductory text.  This new edition includes: - improved exposition of some difficult topics - two new chapters that explore important and intriguing ideas of quantum mechanics in the context of real experiments - many updated problems for students - new questions added to many chapter