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Chapter 4, Current Status, Knowledge Gaps, and Research Needs Pertaining to Firefighter Radio Communication Systems
NIOSH Firefighter Radio Communications CHAPTER IV: STRUCTURE COMMUNICATIONS ISSUES Buildings and other structures pose difficult problems for wireless (radio) communications. Whether communication is via hand-held radio or personal cellular phone, communications to, from, and within structures can degrade depending on a variety of factors. These factors include multipath effects, reflection from coated exterior glass, non-line-of-sight path loss, and signal absorption in the building construction materials, among others. The communications problems may be compounded by lack of a repeater to amplify and retransmit the signal or by poor placement of the repeater. RF propagation in structures can be so poor that there may be areas where the signal is virtually nonexistent, rendering radio communication impossible. Those who design and select firefighter communications systems cannot dictate what building materials or methods are used in structures, but they can conduct research and select the radio system designs and deployments that provide significantly improved radio communications in this extremely difficult environment.4 Communication Problems Inherent in Structures MULTIPATH Multipath fading and noise is a major cause of poor radio performance. Multipath is a phenomenon that results from the fact that a transmitted signal does not arrive at the receiver solely from a single straight line-of-sight path. Because there are obstacles in the path of a transmitted radio signal, the signal may be reflected multiple times and in multiple paths, and arrive at the receiver from various directions along various paths, with various signal strengths per path. In fact, a radio signal received by a firefighter within a building is rarely a signal that traveled directly by line of sight from the transmitter. -
EHC 238 Front Pages Final.Fm
This report contains the collective views of an international group of experts and does not necessarily represent the decisions or the stated policy of the International Commission of Non- Ionizing Radiation Protection, the International Labour Organization, or the World Health Organization. Environmental Health Criteria 238 EXTREMELY LOW FREQUENCY FIELDS Published under the joint sponsorship of the International Labour Organization, the International Commission on Non-Ionizing Radiation Protection, and the World Health Organization. WHO Library Cataloguing-in-Publication Data Extremely low frequency fields. (Environmental health criteria ; 238) 1.Electromagnetic fields. 2.Radiation effects. 3.Risk assessment. 4.Envi- ronmental exposure. I.World Health Organization. II.Inter-Organization Programme for the Sound Management of Chemicals. III.Series. ISBN 978 92 4 157238 5 (NLM classification: QT 34) ISSN 0250-863X © World Health Organization 2007 All rights reserved. Publications of the World Health Organization can be obtained from WHO Press, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791 3264; fax: +41 22 791 4857; e- mail: [email protected]). Requests for permission to reproduce or translate WHO publications – whether for sale or for noncommercial distribution – should be addressed to WHO Press, at the above address (fax: +41 22 791 4806; e-mail: [email protected]). The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. -
Applied Engineering Using Schumann Resonance for Earthquakes Monitoring
applied sciences Article Applied Engineering Using Schumann Resonance for Earthquakes Monitoring Jose A. Gazquez 1,2, Rosa M. Garcia 1,2, Nuria N. Castellano 1,2 ID , Manuel Fernandez-Ros 1,2 ID , Alberto-Jesus Perea-Moreno 3 ID and Francisco Manzano-Agugliaro 1,* ID 1 Department Engineering, University of Almeria, CEIA3, 04120 Almeria, Spain; [email protected] (J.A.G.); [email protected] (R.M.G.); [email protected] (N.N.C.); [email protected] (M.F.-R.) 2 Research Group of Electronic Communications and Telemedicine TIC-019, 04120 Almeria, Spain 3 Department of Applied Physics, University of Cordoba, CEIA3, Campus de Rabanales, 14071 Córdoba, Spain; [email protected] * Correspondence: [email protected]; Tel.: +34-950-015396; Fax: +34-950-015491 Received: 14 September 2017; Accepted: 25 October 2017; Published: 27 October 2017 Abstract: For populations that may be affected, the risks of earthquakes and tsunamis are a major concern worldwide. Therefore, early detection of an event of this type in good time is of the highest priority. The observatories that are capable of detecting Extremely Low Frequency (ELF) waves (<300 Hz) today represent a breakthrough in the early detection and study of such phenomena. In this work, all earthquakes with tsunami associated in history and all existing ELF wave observatories currently located worldwide are represented. It was also noticed how the southern hemisphere lacks coverage in this matter. In this work, the most suitable locations are proposed to cover these geographical areas. Also, ELF data processed obtained from the observatory of the University of Almeria in Calar Alto, Spain are shown. -
Spectrum and the Technological Transformation of the Satellite Industry Prepared by Strand Consulting on Behalf of the Satellite Industry Association1
Spectrum & the Technological Transformation of the Satellite Industry Spectrum and the Technological Transformation of the Satellite Industry Prepared by Strand Consulting on behalf of the Satellite Industry Association1 1 AT&T, a member of SIA, does not necessarily endorse all conclusions of this study. Page 1 of 75 Spectrum & the Technological Transformation of the Satellite Industry 1. Table of Contents 1. Table of Contents ................................................................................................ 1 2. Executive Summary ............................................................................................. 4 2.1. What the satellite industry does for the U.S. today ............................................... 4 2.2. What the satellite industry offers going forward ................................................... 4 2.3. Innovation in the satellite industry ........................................................................ 5 3. Introduction ......................................................................................................... 7 3.1. Overview .................................................................................................................. 7 3.2. Spectrum Basics ...................................................................................................... 8 3.3. Satellite Industry Segments .................................................................................... 9 3.3.1. Satellite Communications .............................................................................. -
Through-The-Earth Electromagnetic Trapped Miner Location Systems. a Review
Open File Report: 127-85 THROUGH-THE-EARTH ELECTROMAGNETIC TRAPPED MINER LOCATION SYSTEMS. A REVIEW By Walter E. Pittman, Jr., Ronald H. Church, and J. T. McLendon Tuscaloosa Research Center, Tuscaloosa, Ala. UNITED STATES DEPARTMENT OF THE INTERIOR BUREAU OF MINES Research at the Tuscaloosa Research Center is carried out under a memorandum of agreement between the Bureau of Mines, U. S. Department of the Interior, and the University of Alabama. CONTENTS .Page List of abbreviations ............................................. 3 Abstract .......................................................... 4 Introduction ...................................................... 4 Early efforts at through-the-earth communications ................. 5 Background studies of earth electrical phenomena .................. 8 ~ationalAcademy of Engineering recommendations ................... 10 Theoretical studies of through-the-earth transmissions ............ 11 Electromagnetic noise studies .................................... 13 Westinghouse - Bureau of Mines system ............................ 16 First phase development and testing ............................. 16 Second phase development and testing ............................ 17 Frequency-shift keying (FSK) beacon signaler .................... 19 Anomalous effects ................................................ 20 Field testing and hardware evolution .............................. 22 Research in communication techniques .............................. 24 In-mine communication systems .................................... -
What Is Rf? It's Like Magic
Originally appeared in the December 2011 issue of Communications Technology. WHAT IS RF? IT’S LIKE MAGIC By RON HRANAC The cable industry has, since the very first systems in the late 1940s, embraced and been based on radio frequency (RF) technology. These days, we’ve also embraced the digital world — and a subset of digital technology called Internet protocol (IP) — but RF still is needed in most cable networks to transport digital data to and from devices in our subscribers’ homes. The answer to the question in the title of this month’s column is far more complicated than it seems initially. A good place to start is with an explanation of “R” and “F.” What’s radio frequency? Here’s one high-level perspective: It’s that portion of the electromagnetic spectrum from a few kilohertz to about 300 gigahertz. The radio-frequency part of the electromagnetic spectrum is further broken down into two chunks: radio waves and microwaves. Some references define radio waves as those with a frequency starting at about 3 kHz (the beginning of the very low frequency [VLF] band) and extending to 300 MHz (the beginning of the ultra high frequency [UHF] band), with microwaves covering roughly 300 MHz to 300 GHz. The latter is the beginning of the far infrared (FIR) portion of the electromagnetic spectrum. Other references have microwaves starting at frequencies higher than 300 MHz; indeed, many RF engineers consider the microwave spectrum to be higher than about 1 GHz. Radio frequency also can be defined as a rate of oscillation within the 3 kHz to 300 GHz range (more on this in a moment). -
The Effect of the Ionosphere on Ultra-Low-Frequency Radio-Interferometric Observations? F
A&A 615, A179 (2018) Astronomy https://doi.org/10.1051/0004-6361/201833012 & © ESO 2018 Astrophysics The effect of the ionosphere on ultra-low-frequency radio-interferometric observations? F. de Gasperin1,2, M. Mevius3, D. A. Rafferty2, H. T. Intema1, and R. A. Fallows3 1 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands e-mail: [email protected] 2 Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany 3 ASTRON – the Netherlands Institute for Radio Astronomy, PO Box 2, 7990 AA Dwingeloo, The Netherlands Received 13 March 2018 / Accepted 19 April 2018 ABSTRACT Context. The ionosphere is the main driver of a series of systematic effects that limit our ability to explore the low-frequency (<1 GHz) sky with radio interferometers. Its effects become increasingly important towards lower frequencies and are particularly hard to calibrate in the low signal-to-noise ratio (S/N) regime in which low-frequency telescopes operate. Aims. In this paper we characterise and quantify the effect of ionospheric-induced systematic errors on astronomical interferometric radio observations at ultra-low frequencies (<100 MHz). We also provide guidelines for observations and data reduction at these frequencies with the LOw Frequency ARray (LOFAR) and future instruments such as the Square Kilometre Array (SKA). Methods. We derive the expected systematic error induced by the ionosphere. We compare our predictions with data from the Low Band Antenna (LBA) system of LOFAR. Results. We show that we can isolate the ionospheric effect in LOFAR LBA data and that our results are compatible with satellite measurements, providing an independent way to measure the ionospheric total electron content (TEC). -
Methods and Experiments for Sensing Variations in Solar Activity and Defining Their Impact on Heart Variability
sensors Article Methods and Experiments for Sensing Variations in Solar Activity and Defining Their Impact on Heart Variability Michael Hanzelka 1,*, Jiˇrí Dan 2, Zoltán Szabó 1 , ZdenˇekRoubal 1, PˇremyslDohnal 1 and Radim Kadlec 1 1 Department of Theoretical and Experimental Electrical Engineering, Brno University of Technology, 616 00 Brno, Czech Republic; [email protected] (Z.S.); [email protected] (Z.R.); [email protected] (P.D.); [email protected] (R.K.) 2 Department of Psychology, Faculty of Arts and Letter, Catholic University in Ružomberok, 034 01 Ružomberok, Slovakia; [email protected] * Correspondence: [email protected]; Tel.: +420-54114-6280 Abstract: This paper evaluates variations in solar activity and their impact on the human nervous system, including the manner in which human behavior and decision-making reflect such effects in the context of (symmetrical) social interactions. The relevant research showed that solar activity, manifesting itself through the exposure of the Earth to charged particles from the Sun, affects heart variability. The evaluation methods focused on examining the relationships between selected psychophysiological data and solar activity, which generally causes major alterations in the low-level electromagnetic field. The investigation within this paper revealed that low-level EMF changes are among the factors affecting heart rate variability and, thus, also variations at the spectral level of the rate, in the VLF, (f = 0.01–0.04 Hz), LF (f = 0.04–0.15 Hz), and HF (f = 0.15 až 0.40 Hz) bands. The results of the presented experiments can also be interpreted as an indirect explanation of sudden Citation: Hanzelka, M.; Dan, J.; Szabó, Z.; Roubal, Z.; Dohnal, P.; deaths and heart failures. -
UNIT -1 Microwave Spectrum and Bands-Characteristics Of
UNIT -1 Microwave spectrum and bands-characteristics of microwaves-a typical microwave system. Traditional, industrial and biomedical applications of microwaves. Microwave hazards.S-matrix – significance, formulation and properties.S-matrix representation of a multi port network, S-matrix of a two port network with mismatched load. 1.1 INTRODUCTION Microwaves are electromagnetic waves (EM) with wavelengths ranging from 10cm to 1mm. The corresponding frequency range is 30Ghz (=109 Hz) to 300Ghz (=1011 Hz) . This means microwave frequencies are upto infrared and visible-light regions. The microwaves frequencies span the following three major bands at the highest end of RF spectrum. i) Ultra high frequency (UHF) 0.3 to 3 Ghz ii) Super high frequency (SHF) 3 to 30 Ghz iii) Extra high frequency (EHF) 30 to 300 Ghz Most application of microwave technology make use of frequencies in the 1 to 40 Ghz range. During world war II , microwave engineering became a very essential consideration for the development of high resolution radars capable of detecting and locating enemy planes and ships through a Narrow beam of EM energy. The common characteristics of microwave device are the negative resistance that can be used for microwave oscillation and amplification. Fig 1.1 Electromagnetic spectrum 1.2 MICROWAVE SYSTEM A microwave system normally consists of a transmitter subsystems, including a microwave oscillator, wave guides and a transmitting antenna, and a receiver subsystem that includes a receiving antenna, transmission line or wave guide, a microwave amplifier, and a receiver. Reflex Klystron, gunn diode, Traveling wave tube, and magnetron are used as a microwave sources. -
Super-High-Frequency Two-Port Aln Contour-Mode Resonators for RF Applications
University of Pennsylvania ScholarlyCommons Departmental Papers (ESE) Department of Electrical & Systems Engineering 1-2010 Super-High-Frequency Two-Port AlN Contour-Mode Resonators for RF Applications Matteo Rinaldi University of Pennsylvania, [email protected] Chiara Zuniga University of Pennsylvania, [email protected] FChengjieollow this Z anduo additional works at: https://repository.upenn.edu/ese_papers University of Pennsylvania, [email protected] Part of the Acoustics, Dynamics, and Controls Commons, Electrical and Electronics Commons, ElectrGianlucao-Mechanical Piazza Systems Commons, Electronic Devices and Semiconductor Manufacturing Commons, NanoscienceUniversity of P andennsylv Nanotechnologyania, [email protected] Commons, Nanotechnology Fabrication Commons, Signal Processing Commons, and the Systems and Communications Commons Recommended Citation Matteo Rinaldi, Chiara Zuniga, Chengjie Zuo, and Gianluca Piazza, "Super-High-Frequency Two-Port AlN Contour-Mode Resonators for RF Applications", . January 2010. Copyright 2010 IEEE. Reprinted from: Rinaldi, M.; Zuniga, C.; Zuo, C.; Piazza, G., "Super-high-frequency two-port AlN contour-mode resonators for RF applications," Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on , vol.57, no.1, pp.38-45, Jan. 2010 Publisher URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=5361520&isnumber=5361508 Digital Object Identifier: 10.1109/TUFFC.2010.1376 This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Pennsylvania's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. -
A Novel Database of Bio-Effects from Non-Ionizing Radiation
A Novel Database of Bio-Effects From Non-Ionizing Radiation by Leach VA, Weller S and Redmayne M. ORSAA paper ID: 3088 OPEN SOURCE: https://www.degruyter.com/view/journals/reveh/33/3/article-p273.xml Rev Environ Health 2018; aop Review Victor Leach*, Steven Weller and Mary Redmayne A novel database of bio-effects from non-ionizing radiation https://doi.org/10.1515/reveh-2018-0017 Received March 18, 2018; accepted May 6, 2018 Introduction Abstract: A significant amount of electromagnetic field/ The environmental profile of man-made electromagnetic electromagnetic radiation (EMF/EMR) research is availa- field (EMF) and associated radiation [electromagnetic ble that examines biological and disease associated end- radiation (EMR)] over the last several decades has grown points. The quantity, variety and changing parameters in by 12 orders of magnitude (1012) [1] and is now considered the available research can be challenging when under- one of the major sources of environmental pollution. taking a literature review, meta-analysis, preparing a During more recent years, the use of mobile phones study design, building reference lists or comparing find- in close proximity to the brain has become a major focus ings between relevant scientific papers. The Oceania of much research. Successful marketing and subsequent Radiofrequency Scientific Advisory Association (ORSAA) uptake have necessitated an on-going increase in the has created a comprehensive, non-biased, multi-cate- number of mobile phone base stations being deployed, gorized, searchable database of papers on non-ionizing contributing to increasing levels of background, environ- EMF/EMR to help address these challenges. It is regu- mental non-ionizing radiation. -
An Agile Laser with Ultra-Low Frequency Noise and High Sweep Linearity
An agile laser with ultra-low frequency noise and high sweep linearity Haifeng Jiang 1,* , Fabien Kéfélian 2, Pierre Lemonde1, André Clairon 1 and Giorgio Santarelli 1 1Laboratoire National de Métrologie et d’Essais–Système de Références Temps-Espace, Observatoire de Paris, UPMC and CNRS, 61 Avenue de l’Observatoire, 75014 Paris, France 2Laboratoire de Physique des Lasers, Université Paris 13 and CNRS, 99 Avenue Jean-Baptiste Clément, 93430 Villetaneuse, France *[email protected] Abstract: We report on a fiber-stabilized agile laser with ultra-low frequency noise. The frequency noise power spectral density is comparable to that of an ultra-stable cavity stabilized laser at Fourier frequencies higher than 30 Hz. When it is chirped at a constant rate of ~ 40 MHz/s, the max non-linearity frequency error is about 50 Hz peak-to-peak over more than 600 MHz tuning range. The Rayleigh backscattering is found to be a significant frequency noise source dependent on fiber length, chirping rate and the power imbalance of the interferometer arms. We analyze this effect both theoretically and experimentally and put forward techniques to reduce this noise contribution. OCIS codes: (140.0140) Lasers and laser optics; (140.3425) Laser stabilization; (140.3518) Lasers, frequency modulated; (140.3600) Lasers, tunable; (290.5870) Scattering, Rayleigh. References and links 1. M. Harris, G. N. Pearson, J. M. Vaughan, D. Letalick, and C. Karlsson, “The role of laser coherence length in continuous-wave coherent laser radar,” J. Mod. Opt., 45 , 1567-1581, (1998). 2. R. W. Fox, C. W. Gates, and L. W. Hollberg, in Cavity-Enhanced Spectroscopies, R.