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WWVB: a Half Century of Delivering Accurate Frequency and Time by Radio
Volume 119 (2014) http://dx.doi.org/10.6028/jres.119.004 Journal of Research of the National Institute of Standards and Technology WWVB: A Half Century of Delivering Accurate Frequency and Time by Radio Michael A. Lombardi and Glenn K. Nelson National Institute of Standards and Technology, Boulder, CO 80305 [email protected] [email protected] In commemoration of its 50th anniversary of broadcasting from Fort Collins, Colorado, this paper provides a history of the National Institute of Standards and Technology (NIST) radio station WWVB. The narrative describes the evolution of the station, from its origins as a source of standard frequency, to its current role as the source of time-of-day synchronization for many millions of radio controlled clocks. Key words: broadcasting; frequency; radio; standards; time. Accepted: February 26, 2014 Published: March 12, 2014 http://dx.doi.org/10.6028/jres.119.004 1. Introduction NIST radio station WWVB, which today serves as the synchronization source for tens of millions of radio controlled clocks, began operation from its present location near Fort Collins, Colorado at 0 hours, 0 minutes Universal Time on July 5, 1963. Thus, the year 2013 marked the station’s 50th anniversary, a half century of delivering frequency and time signals referenced to the national standard to the United States public. One of the best known and most widely used measurement services provided by the U. S. government, WWVB has spanned and survived numerous technological eras. Based on technology that was already mature and well established when the station began broadcasting in 1963, WWVB later benefitted from the miniaturization of electronics and the advent of the microprocessor, which made low cost radio controlled clocks possible that would work indoors. -
Reception of Low Frequency Time Signals
Reprinted from I-This reDort show: the Dossibilitks of clock svnchronization using time signals I 9 transmitted at low frequencies. The study was madr by obsirvins pulses Vol. 6, NO. 9, pp 13-21 emitted by HBC (75 kHr) in Switxerland and by WWVB (60 kHr) in tha United States. (September 1968), The results show that the low frequencies are preferable to the very low frequencies. Measurementi show that by carefully selecting a point on the decay curve of the pulse it is possible at distances from 100 to 1000 kilo- meters to obtain time measurements with an accuracy of +40 microseconds. A comparison of the theoretical and experimental reiulb permib the study of propagation conditions and, further, shows the drsirability of transmitting I seconds pulses with fixed envelope shape. RECEPTION OF LOW FREQUENCY TIME SIGNALS DAVID H. ANDREWS P. E., Electronics Consultant* C. CHASLAIN, J. DePRlNS University of Brussels, Brussels, Belgium 1. INTRODUCTION parisons of atomic clocks, it does not suffice for clock For several years the phases of VLF and LF carriers synchronization (epoch setting). Presently, the most of standard frequency transmitters have been monitored accurate technique requires carrying portable atomic to compare atomic clock~.~,*,3 clocks between the laboratories to be synchronized. No matter what the accuracies of the various clocks may be, The 24-hour phase stability is excellent and allows periodic synchronization must be provided. Actually frequency calibrations to be made with an accuracy ap- the observed frequency deviation of 3 x 1o-l2 between proaching 1 x 10-11. It is well known that over a 24- cesium controlled oscillators amounts to a timing error hour period diurnal effects occur due to propagation of about 100T microseconds, where T, given in years, variations. -
Revisions to Microwave Spectrum Utilization Policies in the Range of 1-20 Ghz
SP 1-20 GHz January 1995 Spectrum Management Spectrum Utilization Policy Revisions to Microwave Spectrum Utilization Policies in the Range of 1-20 GHz Notice No. DGTP-002-95 Amended by: DGTP-006-99 Amendments to the Microwave Spectrum Utilization Policies in the 1-3 GHz Frequency Range (October 1999) DGTP-006-97 Proposals to Provide New Opportunities for the Use of the Radio Spectrum in the 1-20 GHz Frequency Range (August 1997) DGTP-007-97 Spectrum Policy Provisions to Permit the Use of Digital Radio Broadcasting Installations to Provide to Non-Broadcasting Services (September 1997) DGTP-004-97 Licence Exempt Personal Communications Services in the Frequency Band 1910-1930 MHz (April 1997) DGTP-005-95 / Policy and Call for Applications: Wireless Personal Communications Services in the 2 GHz Range, Implementing PCS DGRB-002-95 in Canada (June 1995) DGTP-007-00 / Policy and Licensing Procedures for the Auction of the Additional PCS Spectrum in the 2 GHz Frequency Range DGRB-005-00 (June 2000) DGTP-003-01 Revisions to the Spectrum Utilization Policy for Services in the Frequency Range 2285-2483.5 MHz (June 2001) DGRB-003-03 Policy and Licensing Procedures for the Auction of Spectrum Licences in the 2300 MHz and 3500 MHz Bands (September 2003) DGRB-006-99 Policy and Licensing Procedures - Multipoint Communications Systems in the 2500 MHz Range (June 1999) DGTP-004-04 Revisions to Allocations in the Band 2500-2690 MHz and Consultation on Spectrum Utilization (April 2004) DGTP-008-04 Revisions to Spectrum Utilization Policies in the 3-30 GHz -
Radio Spectrum a Key Resource for the Digital Single Market
Briefing March 2015 Radio spectrum A key resource for the Digital Single Market SUMMARY Radio spectrum refers to a specific range of frequencies of electromagnetic energy that is used to communicate information. Applications important for society such as radio and television broadcasting, civil aviation, satellites, defence and emergency services depend on specific allocations of radio frequency. Recently the demand for spectrum has increased dramatically, driven by growing quantities of data transmitted over the internet and rapidly increasing numbers of wireless devices, including smartphones and tablets, Wi-Fi networks and everyday objects connected to the internet. Radio spectrum is a finite natural resource that needs to be managed to realise the maximum economic and social benefits. Countries have traditionally regulated radio spectrum within their territories. However despite the increasing involvement of the European Union (EU) in radio spectrum policy over the past 10 to 15 years, many observers feel that the management of radio spectrum in the EU is fragmented in ways which makes the internal market inefficient, restrains economic development, and hinders the achievement of certain goals of the Digital Agenda for Europe. In 2013, the European Commission proposed legislation on electronic communications that among other measures, provided for greater coordination in spectrum management in the EU, but this has stalled in the face of opposition within the Council. In setting out his political priorities, Commission President Jean-Claude Juncker has indicated that ambitious telecommunication reforms, to break down national silos in the management of radio spectrum, are an important step in the creation of a Digital Single Market. The Commission plans to propose a Digital Single Market package in May 2015, which may again address this issue. -
PSAD-79-48A an Unclassified Version of a Classified Report
STUDYBY THE STAFFOF THE‘U.S. General Accounting Office An Unclassified Version Of A Classified Report Entitled “The Navy’s Strategic Communications Systems--Need For Management Attention And Decisionmaking” Peacetime communications systems provide reliable day-to-day communications to the strategic submarine force. However, the Navy’s most survivable wartime communica- tions link to nuclear-powered strategic submarines--the TACAMO aircraft--has cer- tain problems which need attention. Also, the Navy should reconsider whether another peacetime communications system--the extremely low frequency system--is needed. COMPTROLLER GENERAL OF THE UNITED STATES WASHINGTON. O.C. 20548 B-168707 To the President of the Senate and the Speaker of the House of Representatives This report is an unclassified version of a SECRET report (PSAD-79-48, March 19, 1979) to the Congress that describes the various communications systems used by our strategic submarine force and questions the need for the extremely low frequency system. Also, the report addresses the need for support of the TACAMO comnunications system. We made this study because of widespread congressional interest in strategic communications systems, especially the TACAMO and proposed extremely low frequency systems. These issues are receiving increased recognition, and the Navy plans to spend millions of dollars to improve the TACAMO system and conduct research and development on the extremely low frequency system. Copies of this report are being sent to the Secretary of Defense and the Secretary of the Navy. Comptroller General of the United States COMPTROLLER GENERAL'S THE NAVY'S STRATEGIC REPORT TO THE CONGRESS COMMUNICATIONS SYSTEMS--NEED FOR MANAGEMENT ATTENTION AND DECISIONMAKING ------DIGEST Peacetime communications systems provide reliable day-to-day communications to the strategic submarine force. -
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. -
Analysis and Study the Performance of Coaxial Cable Passed on Different Dielectrics
International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 3 (2018) pp. 1664-1669 © Research India Publications. http://www.ripublication.com Analysis and Study the Performance of Coaxial Cable Passed On Different Dielectrics Baydaa Hadi Saoudi Nursing Department, Technical Institute of Samawa, Iraq. Email:[email protected] Abstract Coaxial cable virtually keeps all the electromagnetic wave to the area inside it. Due to the mechanical properties, the In this research will discuss the more effective parameter is coaxial cable can be bent or twisted, also it can be strapped to the type of dielectric mediums (Polyimide, Polyethylene, and conductive supports without inducing unwanted currents in Teflon). the cable. The speed(S) of electromagnetic waves propagating This analysis of the performance related to dielectric mediums through a dielectric medium is given by: with respect to: Dielectric losses and its effect upon cable properties, dielectrics versus characteristic impedance, and the attenuation in the coaxial line for different dielectrics. The C: the velocity of light in a vacuum analysis depends on a simple mathematical model for coaxial cables to test the influence of the insulators (Dielectrics) µr: Magnetic relative permeability of dielectric medium performance. The simulation of this work is done using εr: Dielectric relative permittivity. Matlab/Simulink and presents the results according to the construction of the coaxial cable with its physical properties, The most common dielectric material is polyethylene, it has the types of losses in both the cable and the dielectric, and the good electrical properties, and it is cheap and flexible. role of dielectric in the propagation of electromagnetic waves. -
Wireless Power Transmission
International Journal of Scientific & Engineering Research, Volume 5, Issue 10, October-2014 125 ISSN 2229-5518 Wireless Power Transmission Mystica Augustine Michael Duke Final year student, Mechanical Engineering, CEG, Anna university, Chennai, Tamilnadu, India [email protected] ABSTRACT- The technology for wireless power transfer (WPT) is a varied and a complex process. The demand for electricity is much higher than the amount being produced. Generally, the power generated is transmitted through wires. To reduce transmission and distribution losses, researchers have drifted towards wireless energy transmission. The present paper discusses about the history, evolution, types, research and advantages of wireless power transmission. There are separate methods proposed for shorter and longer distance power transmission; Inductive coupling, Resonant inductive coupling and air ionization for short distances; Microwave and Laser transmission for longer distances. The pioneer of the field, Tesla attempted to create a powerful, wireless electric transmitter more than a century ago which has now seen an exponential growth. This paper as a whole illuminates all the efficient methods proposed for transmitting power without wires. —————————— —————————— INTRODUCTION Wireless power transfer involves the transmission of power from a power source to an electrical load without connectors, across an air gap. The basis of a wireless power system involves essentially two coils – a transmitter and receiver coil. The transmitter coil is energized by alternating current to generate a magnetic field, which in turn induces a current in the receiver coil (Ref 1). The basics of wireless power transfer involves the inductive transmission of energy from a transmitter to a receiver via an oscillating magnetic field. -
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 .............................................................................. -
Five Years of VLF Worldwide Comparison of Atomic Frequency Standards
RADIO SCIENCE, Vol. 2 (New Series), No. 6, June 1967 Five Years of VLF Worldwide Comparison of Atomic Frequency Standards B. E. Blair,' E. 1. Crow,2 and A. H. Morgan (Received January 19, 1967) The VLF radio broadcasts of GBR(16.0 kHz), NBA(18.0 or 24.0 kHz), and NSS(21.4 kHz) have enabled worldwide comparisons of atomic frequency standards to parts in 1O'O when received over varied paths and at distances up to 9000 or more kilometers. This paper summarizes a statistical analysis of such comparison data from laboratories in England, France, Switzerland, Sweden, Russia, Japan, Canada, and the United States during the 5-year period 1961-1965. The basic data are dif- ferences in 24-hr average frequencies between the local atomic standard and the received VLF radio signal expressed as parts in 10"'. The analysis of the more recent data finds the receiving laboratory standard deviations, &, and the transmission standard deviation, ?, to be a few parts in 10". Averag- ing frequencies over an increasing number of days has the effect of reducing iUi and ? to some extent. The variation of the & with propagation distance is studied. The VLF-LF long-term mean differences between standards are compared with the recent portable clock tests, and they agree to parts in IO". 1. Introduction points via satellites (Steele, Markowitz, and Lidback, 1964; Markowitz, Lidback, Uyeda, and Muramatsu, Six years ago in London, the XIIIth General Assem- 1966); improvements in the transmission of VLF and bly of URSI adopted a resolution (No. 2) which strongly LF radio signals (Milton, Fey, and Morgan, 1962; recommended continuous very-low-frequency (VLF) Barnes, Andrews, and Allan, 1965; Bonanomi, 1966; and low-frequency (LF) transmission monitoring US.