Chapter 2 (Radio Time Signals)
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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. -
Quantitative Analysis and Correction of Temperature Effects On
sustainability Article Quantitative Analysis and Correction of Temperature Effects on Fluorescent Tracer Concentration Measurement Zhihong Zhang 1,2, Heping Zhu 2,* and Huseyin Guler 3 1 College of Agriculture and Food, Kunming University of Science and Technology, Kunming 650500, China; [email protected] 2 USDA-ARS Application Technology Research Unit, Wooster, OH 44691, USA 3 Department of Agricultural Engineering and Technology, Ege University, 35040 Izmir, Turkey; [email protected] * Correspondence: [email protected]; Tel.: +1-330-263-3871 Received: 20 March 2020; Accepted: 27 May 2020; Published: 2 June 2020 Abstract: To ensure an accurate evaluation of pesticide spray application efficiency and pesticide mixture uniformity, reliable and accurate measurements of fluorescence concentrations in spray solutions are critical. The objectives of this research were to examine the effects of solution temperature on measured concentrations of fluorescent tracers as the simulated pesticides and to develop models to correct the deviation of measurements caused by temperature variations. Fluorescent tracers (Brilliant Sulfaflavine (BSF), Eosin, Fluorescein sodium salt) were selected for tests with the solution temperatures ranging from 10.0 ◦C to 45.0 ◦C. The results showed that the measured concentrations of BSF decreased as the solution temperature increased, and the decrement rate was high at the beginning and then slowed down and tended to become constant. In contrast, the concentrations of Eosin decreased slowly at the beginning and then noticeably increased as temperatures increased. On the other hand, the concentrations of Fluorescein sodium salt had little variations with its solution temperature. To ensure the measurement accuracy, correction models were developed using the response surface methodology to numerically correct the measured concentration errors due to variations with the solution temperature. -
1 Diocese of Harrisburg Geography of Pennsylvania
7/2006 DIOCESE OF HARRISBURG GEOGRAPHY OF PENNSYLVANIA Red Italics – Reference to Diocesan History Outcome: The student knows and understands the geography of Pennsylvania. Assessment: The student will apply the geographic themes of location, place and region to Pennsylvania today. Skills/Objectives Suggested Teaching/Learning Strategies Suggested Assessment Strategies The student will be able to: 1a. Using student desk maps, locate and highlight the 1a. On a blank map of the U.S., outline the state of state, trace rivers and their tributaries and circle Pennsylvania, label the capital, hometown and two 1. Locate and identify the state of Pennsylvania, its major cities. largest cities. capital, major cities and his hometown. On a blank map of the U.S. outline the state of 1b. Using the globe, determine the latitude and longitude Pennsylvania; within the state of Pennsylvania, outline of the state. the Diocese of Harrisburg. Label the city where the cathedral is located. 1c. Using a Pennsylvania highway map, design a road tour visiting major Pennsylvania cities. 1b. Using the desk map, identify the latitude line closest Using a Pennsylvania highway map with the counties to the hometown and two other towns of the same within the Diocese of Harrisburg marked, do the parallel of latitude. Identify the longitude nearest the following: first, in each county, identify a city or town state capital and two other towns on the same with a Catholic church; then design a road tour visiting meridian of longitude. each of these cities or towns. Using a desk map, place marks on the most-western, the most-northern, and the most-eastern tips of the Diocese 1d. -
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. -
AN 307: Altera Design Flow for Xilinx Users Supersedes Information Published in Previous Versions
Altera Design Flow for Xilinx Users June 2005, ver. 5.0 Application Note 307 Introduction Designing for Altera® Programmable Logic Devices (PLDs) is very similar, both in concept and in practice, to designing for Xilinx PLDs. In most cases, you can simply import your register transfer level (RTL) into Altera’s Quartus® II software and begin compiling your design to the target device. This document will demonstrate the similar flows between the Altera Quartus II software and the Xilinx ISE software. For designs, which the designer has included Xilinx CORE generator modules or instantiated primitives, the bulk of this document guides the designer in design conversion considerations. Who Should Read This Document The first and third sections of this application note are designed for engineers who are familiar with the Xilinx ISE software and are using Altera’s Quartus II software. This first section describes the possible design flows available with the Altera Quartus II software and demonstrates how similar they are to the Xilinx ISE flows. The third section shows you how to convert your ISE constraints into Quartus II constraints. f For more information on setting up your design in the Quartus II software, refer to the Altera Quick Start Guide For Quartus II Software. The second section of this application note is designed for engineers whose design code contains Xilinx CORE generator modules or instantiated primitives. The second section provides comprehensive information on how to migrate a design targeted at a Xilinx device to one that is compatible with an Altera device. If your design contains pure behavioral coding, you can skip the second section entirely. -
5G; 5G System; Binding Support Management Service; Stage 3 (3GPP TS 29.521 Version 15.3.0 Release 15)
ETSI TS 129 521 V15.3.0 (2019-04) TECHNICAL SPECIFICATION 5G; 5G System; Binding Support Management Service; Stage 3 (3GPP TS 29.521 version 15.3.0 Release 15) 3GPP TS 29.521 version 15.3.0 Release 15 1 ETSI TS 129 521 V15.3.0 (2019-04) Reference RTS/TSGC-0329521vf30 Keywords 5G ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N° 348 623 562 00017 - NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88 Important notice The present document can be downloaded from: http://www.etsi.org/standards-search The present document may be made available in electronic versions and/or in print. The content of any electronic and/or print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI deliverable is the one made publicly available in PDF format at www.etsi.org/deliver. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the current status of this and other ETSI documents is available at https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx If you find errors in the present document, please send your comment to one of the following services: https://portal.etsi.org/People/CommiteeSupportStaff.aspx Copyright Notification No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm except as authorized by written permission of ETSI. -
Report on the 1975 Survey of Users of the Services of Radio Stations Wwv and Wwvh
'JM ^^ t*.;: .,-.;, .'-ti ^^#' • J* .^: '•^i'-^v'-' '- \ • REFERENCE N B S V U) NBS TECHNICAL NOTE 674 ^''fff AU O* * U.S. DEPARTMENT OF COMMERCE/National Bureau of Standards Report On The 1975 Survey of Users of the Services of Radio Stations WWY and WWYH /OO ' .6/5753 . no,(o7i . /975, NATIONAL BUREAU OF STANDARDS The National Bureau of Standards' was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Institute for Computer Sciences and Technology, and the Office for Information Programs. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of the Office of Measurement Services, the Office of Radiation Measurement and the following Center and divisions: Applied Mathematics — Electricity — Mechanics — Heat — Optical Physics — Center for Radiation Research: Nuclear Sciences; Applied Radiation — Laboratory Astrophysics ° — Cryogenics" — Electromagnetics" — Time and Frequency". -
International Earth Rotation and Reference Systems Service (IERS) Provides the International Community With
The Role of the IERS in the Leap Second Brian Luzum Chair, IERS Directing Board Background The International Earth Rotation and Reference Systems Service (IERS) provides the international community with: • the International Celestial Reference System and its realization, the International Celestial Reference Frame (ICRF); • the International Terrestrial Reference System and its realization, the International Terrestrial Reference Frame (ITRF); • Earth orientation parameters (EOPs) that are used to transform between the ICRF and the ITRF; • Conventions (i.e., standards, models, and constants) used in generating and using reference frames and EOPs; • Geophysical data to study and understand variations in the reference frames and the Earth’s orientation. The IERS was created in 1987 and began operations on 1 January 1988. It continued much of the tasking of the Bureau International de l’Heure (BIH), which had been created early in the 20th century. It is responsible to the International Astronomical Union (IAU) and the International Union of Geodesy and Geophysics (IUGG). For more than twenty-five years, the IERS has been providing for the reference frame and EOP needs of a variety of users. Time The IERS has an important role in determining when the leap seconds are to be inserted and the dissemination of information regarding leap seconds. In order to understand this role, it is important to realize some things regarding time. For instance, there are two different kinds of “time” being related: (1) a uniform time, now based on atomic clocks and (2) “time” based on the variable rotation of the Earth. The differences between uniform time and Earth rotation “time” only became apparent in the 1930s with the improvements in clock technology. -
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. -
Bulletin of the DANISH SHORT WAVE CLUB INTERNATIONAL for Short Wave Listeners and Dxers No 9 December 2009 Volume 52
Bulletin of the DANISH SHORT WAVE CLUB INTERNATIONAL for short wave listeners and DXers No 9 December 2009 Volume 52 Our German member, no. 3700 Dieter Sommer The equipment is Yaesu FT840, Sangean ATS-909 modifed, a T2FD antenna and a GP horizontal antenna. Dieter writes that he prefers Utility, Pirate and BC DX-ing Dieter has more than 200 countries verified He is 56 years old and have been DX-ing in about 43 years Editorial Staff: ISSN 0106-3731 Danish Short Wave Club International Shortwave Tips: Tavleager 31, DK-2670 Greve, Denmark Klaus-Dieter Scholz, Home page: http://www.dswci.org Postfach 45 02 34, D-99052 Erfurt, Germany Board: Tel.: +49 (0)361 –- 21 68 96 5, Fax: +49(0) 69 - 13 30 63 72 07 8 Chairman and representative to the EDXC: Web::http://www.dswci-sw-logs.dxer.info/yourlogs.htm Anker Petersen, E-mail: [email protected] Udbyvej 11, DK-2740 Skovlunde, Denmark Utility Shack: E-mail: [email protected] Tor-Henrik Ekblom, Treasurer: Solvindsgatan 7 A 20, FI-00990 Helsingfors, Finland Bent Nielsen, E-mail: [email protected] Egekrogen 14, DK-3500 Vaerloese, Denmark World News: E-mail: [email protected] Sakthi Jaisakthivel, Bank: Danske Bank, 59,Annai Sathya Nagar, Arumbakkam, Chennai-600106,India.: Holmens Kanal 2-12, DK 1092 Copenhagen K. E-mail:[email protected] BIC: DABADKKK. Account: DK 44 3000 4001 528459. QSL Corner: Danish members use: Reg. 3001- account no. 4001528459 Andreas Schmid, The treasurer accepts bank notes! Lerchenweg 4, D-97717 Euerdorf, Germany Editor-in-Chief and Distribution: E-mail: [email protected] Kaj Bredahl Jørgensen, Tel. -
NIST Time and Frequency Services (NIST Special Publication 432)
Time & Freq Sp Publication A 2/13/02 5:24 PM Page 1 NIST Special Publication 432, 2002 Edition NIST Time and Frequency Services Michael A. Lombardi Time & Freq Sp Publication A 2/13/02 5:24 PM Page 2 Time & Freq Sp Publication A 4/22/03 1:32 PM Page 3 NIST Special Publication 432 (Minor text revisions made in April 2003) NIST Time and Frequency Services Michael A. Lombardi Time and Frequency Division Physics Laboratory (Supersedes NIST Special Publication 432, dated June 1991) January 2002 U.S. DEPARTMENT OF COMMERCE Donald L. Evans, Secretary TECHNOLOGY ADMINISTRATION Phillip J. Bond, Under Secretary for Technology NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY Arden L. Bement, Jr., Director Time & Freq Sp Publication A 2/13/02 5:24 PM Page 4 Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the entities, materials, or equipment are necessarily the best available for the purpose. NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY SPECIAL PUBLICATION 432 (SUPERSEDES NIST SPECIAL PUBLICATION 432, DATED JUNE 1991) NATL. INST.STAND.TECHNOL. SPEC. PUBL. 432, 76 PAGES (JANUARY 2002) CODEN: NSPUE2 U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 2002 For sale by the Superintendent of Documents, U.S. Government Printing Office Website: bookstore.gpo.gov Phone: (202) 512-1800 Fax: (202) -
NASS 2011Seattle Conference Retrospective
NASS Conference Retrospective: Seattle, August 2011 Roger Bailey Reception: Thursday 18 September: We gathered between 4:30 and 6:00 pm in the University of Washington Physics and Astronomy Building to register and meet old friends and welcome newcomers. A total of 51 people participated. Fred had gathered a good collection of sundial-related books and paraphernalia as door prizes. Tickets were used to allow choices to maximize the chance of reward. You could plunk all your allotted tickets on one prize or you could spread your tickets to increase your chances of winning something. Prizes included: a Nocturnal Geocoin; a reproduction Pewter Sundial; Sharon Gibbs’ book Greek and Roman Sundials, Frank Cousins’ book Sundials: The Art & Science of Gnomonics; Christopher St. J. H. Daniel’s Sundials and Gerald Jenkins & Magdalene Bear’s Sundials and Timedials; Mike Cowham’s A Study Of Altitude Dials; Hester Higton’s Sundials: An Illustrated History of Portable Dials; Stephenson, Bolt & Friedman’s The Universe Unveiled; Winthrop W. Dolan’s A Choice of Sundials; a recent reprint of T. Geoffrey W. Henslow’s 1914 Ye Sundial Booke; two Perspex Sundials designed for latitude 40° by Hendrik Hollander; two sets of Sundial Note Cards; laser-engraved wood Differential Dialing Scales developed by Fred Sawyer; and copies of Ramona Maher’s Secret of the Sundial, and Eugenia Desmond’s Shadow At Dunster Hall. The doorprizes were followed by a showing of Gino and Judith Schiavone’s video on the design and construction of the Bowie Portal Sundial. Then Woody Sullivan took us around the building to show his large vertical declining sundial on the southwest wall of the Physics and Astronomy Building.