DOCSLIB.ORG

NIST Time and Frequency Radio Stations: WWV, WWVH, and WWVB

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
NIST Time and Frequency Radio Stations: WWV, WWVH, and WWVB TECH NAT L INST. OF STAND & NIST PUBUCATtONS Nisr National Institute of Standards and Technology Technology Administration, U.S. Department of Commerce NIST Special Publication 250-67 NIST Time and Frequency Radio Stations WWV, WWVH, and WWVB Glenn K. Nelson Michael A. Lombardi Dean T. Okayama rhe National Institute of Standards and Technology was established in 1988 by Congress to "assist industry in the development of technology ... needed to improve product quality, to modernize manufacturing processes, to ensure product reliability ... and to facilitate rapid commercialization ... of products based on new scientific discoveries." NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S. industry's competitiveness; advance science and engineering; and improve public health, safety, and the environment. One of the agency's basic functions is to develop, maintain, and retain custody of the national standards of measurement, and provide the means and methods for comparing standards used in science, engineering, manufacturing, commerce, industry, and education with the standards adopted or recognized by the Federal Government. As an agency of the U.S. Commerce Department's Technology Administration, NIST conducts basic and applied research in the physical sciences and engineering, and develops measurement techniques, test methods, standards, and related services. The Institute does generic and precompetitive work on new and advanced technologies. NIST's research facilities are located at Gaithersburg, MD 20899, and at Boulder, CO 80303. Major technical operating units and their principal activities are listed below. For more information visit the NIST Website at http://www.nist.gov, or contact the Publications and Program Inquiries Desk, 301-975-3058. Office of the Director Chemical Science and Technology •National Quality Program Laboratory •International and Academic Affairs •Biotechnology •Process Measurements Technology Services •Surface and Microanalysis Science •Standards Services •Physical and Chemical Properties^ •Technology Partnerships •Analytical Chemistry •Measurement Services •Information Services Physics Laboratory •Weights and Measures •Electron and Optical Physics Advanced Technology Program •Atomic Physics •Optical Technology •Economic Assessment •Ionizing Radiation •Information Technology and Applications Time and Frequency' •Chemistry and Life Sciences •Quantum Physics' •Electronics and Photonics Technology Manufacturing Engineering Manufacturing Extension Partnership Laboratory Program •Precision Engineering •Regional Programs •Manufacturing Metrology •National Programs •Intelligent Systems •Program Development •Fabrication Technology •Manufacturing Systems Integration Electronics and Electrical Engineering Laboratory Building and Fire Research Laboratory •Microelectronics •Applied Economics •Law Enforcement Standards •Materials and Construction Research •Electricity Building Environment •Semiconductor Electronics Fire Research •Radio-Frequency Technology' •Electromagnetic Technology' Information Technology Laboratory Optoelectronics' •Mathematical and Computational Sciences^ •Magnetic Technology' •Advanced Network Technologies •Computer Security Materials Science and Engineering •Information Access Laboratory •Convergent Information Systems •Intelligent Processing of Materials •Information Services and Computing •Ceramics •Software Diagnostics and Conformance Testing •Materials Reliability' •Statistical Engineering •Polymers •Metallurgy •NIST Center for Neutron Research 'At Boulder, CO 80305 Some elements at Boulder, CO NIST Special Publication 250-67 NIST Time and Frequency Radio Stations: WWV, WWVH, and WWVB Glenn K. Nelson Michael A. Lombardi Dean T. Okayama Time and Frequency Division Physics Laboratory National Institute ofStandards and Technology 325 Broadway Boulder, Colorado 80305 January 2005 U.S. Department of Commerce Carlos M. Gutierrez. Secretary Technology Administration Phillip J. Bond, Under Secretaryfor Technology National Institute of Standards and Technology Hratch Semerjian, Acting Director Certain commercial entities, equipment, or materials may be identified in this document in order to describe a 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 250-67 Natl. Inst. Stand. Technol. Spec. Publ. 250-67, 160 pages (January 2005) CODEN: NSPUE2 01 Contents Contents Introduction vii Acknowledgements viii Chapter 1 . History and Physical Description 1 A. History of NIST Radio Stations 1 1. History of WWV 1 2. History of WWVH 6 3. History of WWVB 8 B. Physical Description of NIST Radio Station Facilities 10 1. WWVFaciHties 10 a) WWV and WWVB Land 1 b) WWV Buildings 13 c) WWV Transmitters 15 d) WWV Antennas and Transmission Lines 16 e) WWV Back-Up Generator 2 f) WWV Time and Frequency Equipment 22 g) Other Equipment (Satellite Systems) 22 2. WWVB Facilities 23 a) WWVB Land 23 b) WWVB Buildings 23 c) WWVB Transmitters 24 d) WWVB Antennas 26 e) WWVB Back-Up Generator 29 f) WWVB Time and Frequency Equipment 30 3. WWVH Facilities 31 a) WWVH Land 31 b) WWVH Buildings 32 c) WWVH Transmitters 33 d) WWVH Antennas 33 e) WWVH Back-Up Generator 35 f) WWVH Time and Frequency Equipment 37 C. Organizational Control of NIST Radio Stations 38 Chapter 2. Technical Description 39 A. How the NIST Radio Stations Work 39 B. Technical Description of WWV 40 1 . Timing system 40 2. Broadcast Format 41 /// Remote Frequency Calibrations: The NIST Frequency Measurement and Analysis Service a) Standard Carrier Frequencies 43 b) Voice Time Announcements 43 c) Standard Time Intervals 44 d) Standard Audio Frequencies 45 e) UTl Corrections 46 f) 100 Hz Time Code 46 g) Official Announcements 48 h) Modulations Levels and Spectrum Allocation 50 i) WWV Signal Monitoring 51 3. Frequencies and Power Levels 52 4. WWV Antennas 54 5. WWV and WWVB Broadcast Monitoring and Alarm Systems 55 6. Commercial Electrical Power Monitoring 58 7. UPS Monitors 58 C. Technical Description of WWVB 59 1 . Standard Carrier Frequency and Phase Signature 59 2. Time Code and Time Code Generators 59 3. Frequency and Power Level 62 4. Modes of Operation 62 5. Broadcast Control 63 6. RF Switch Matrix 64 7. Control Console 64 8. Automatic Tuning 64 9. Transmitters 64 10. Helix Houses 65 1 1 . Antennas 68 12. Monitoring and Alarm Systems 69 D. Technical Description of WWVH 70 1 . Timing System 70 2. Broadcast Format 71 a) Standard Carrier Frequencies 72 b) Voice Time Announcements 72 c) Standard Time Intervals 73 d) Standard Audio Frequencies 73 e) UTI Corrections 74 f) 100 Hz Time Code 74 g) Official Announcements 75 h) Modulation Levels and Spectrum Allocation 75 i) WWVH Signal Monitoring 76 3. Frequencies and Power Levels 76 4. WWVH Antennas 77 5. WWVH Broadcast Monitoring and Alarm Systems 79 6. Commercial Electrical Power Monitoring 80 7. UPS Monitors 81 iv Contents E. Telephone Time-of-Day Service 81 1. WWV Telephone Time-of-Day Service 81 2. WWVH Telephone Time-of-Day Service 82 Chapter 3. Operational Procedures 83 A. Hardware Maintenance 83 1 . Transmitters and Broadcast Equipment 83 2. Timing Equipment 84 B. Facilities Maintenance 84 C. Scheduled Tasks 85 1. WWV Task Lists 85 2. WWVB Task Lists 87 3. WWVH Task Lists 89 D. Repairs and Service of Equipment 93 1. Facility Service and Repairs at WWV and WWVB 93 2. Facility Service and Repairs at WWVH 93 3. Mission-Specific Service and Repairs at the Radio Stations 94 4. Spare Parts 94 5. Ongoing Tasks 94 E. Failure Modes 95 1. WWV/WWVH Failure Modes 95 a) Timing Failures 95 b) Broadcast Failures 95 c) Other Equipment Failure Modes 96 2. WWVB Failure Modes 97 a) Timing Failures 97 b) Broadcast Failures 97 c) Other Equipment Failure Modes 98 F. Quality Control of Broadcast Information 98 1 . Timing Control 98 2. Frequency Control 99 G. Recordkeeping 99 1 . Operational Recordkeeping 99 2. Equipment Records 100 3. Other Records 101 4. Software 101 5. Data Backup Procedures 101 H. Physical Security 102 1. Physical Security of WWV and WWVB 102 2. Physical Security of WWVH 102 Chapter 4. Customers 103 A. Estimated Number of Customers 103 1 1 . Estimated Number of Customers for WWV/WWVH 03 V 3581 Remote Frequency Calibrations: The NIST Frequency Measurement and Analysis Service 2 . Estimated Number of Customers for WWVB 1 04 3. Estimated Num. of Customers for the Telephone Time-of-Day Service 105 B. Coverage Area for Radio Broadcasts 105 1 . Coverage Area for WWV 1 06 2. Coverage Area for WWVH 107 3 . Coverage Area for WWVB 1 09 a) The Effect of Receiver Sensitivity on Coverage Area Size 1 1 b) Field Strength Readings (Radial Measurements) 1 1 c) Monitoring Field Strength in Near Real-Time 1 1 C. How the NIST Radio Stations are Used by their Customers 1 1 1. WWV/WWVH Customers 115 a) Time Customers 116 b) Frequency Customers 1 1 c) Voice Announcement Customers (Non-Timing) 1 19 2. WWVB Customers 120 a) Time Customers 1 20 b) Frequency Customers 1 2 D. Customer Interaction and Support 122 1 . Distribution of Information about the NIST Radio Stations 1 22 a) Web Site 122 b) Publications 122 c) Technical support (e-mail, phone, and postal mail) 124 d) HF Station Voice Announcements 124 Chapter 5. Measurement Uncertainties 125 A. Frequency Uncertainty of Transmitted Radio Signals
Load more

Recommended publications
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • QUICK REFERENCE GUIDE Latitude, Longitude and Associated Metadata
    QUICK REFERENCE GUIDE Latitude, Longitude and Associated Metadata The Property Profile Form (PPF) requests the property name, address, city, state and zip. From these address fields, ACRES interfaces with Google Maps and extracts the latitude and longitude (lat/long) for the property location. ACRES sets the remaining property geographic information to default values. The data (known collectively as “metadata”) are required by EPA Data Standards. Should an ACRES user need to be update the metadata, the Edit Fields link on the PPF provides the ability to change the information. Before the metadata were populated by ACRES, the data were entered manually. There may still be the need to do so, for example some properties do not have a specific street address (e.g. a rural property located on a state highway) or an ACRES user may have an exact lat/long that is to be used. This Quick Reference Guide covers how to find latitude and longitude, define the metadata, fill out the associated fields in a Property Work Package, and convert latitude and longitude to decimal degree format. This explains how the metadata were determined prior to September 2011 (when the Google Maps interface was added to ACRES). Definitions Below are definitions of the six data elements for latitude and longitude data that are collected in a Property Work Package. The definitions below are based on text from the EPA Data Standard. Latitude: Is the measure of the angular distance on a meridian north or south of the equator. Latitudinal lines run horizontal around the earth in parallel concentric lines from the equator to each of the poles.
    [Show full text]
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • Public Notice >> Licensing and Management System Admin >>
    REPORT NO. PN-2-210125-01 | PUBLISH DATE: 01/25/2021 Federal Communications Commission 45 L Street NE PUBLIC NOTICE Washington, D.C. 20554 News media info. (202) 418-0500 ACTIONS File Number Purpose Service Call Sign Facility ID Station Type Channel/Freq. City, State Applicant or Licensee Status Date Status 0000122670 Renewal of FM KLWL 176981 Main 88.1 CHILLICOTHE, MO CSN INTERNATIONAL 01/21/2021 Granted License From: To: 0000123755 Renewal of FM KCOU 28513 Main 88.1 COLUMBIA, MO The Curators of the 01/21/2021 Granted License University of Missouri From: To: 0000123699 Renewal of FL KSOZ-LP 192818 96.5 SALEM, MO Salem Christian 01/21/2021 Granted License Catholic Radio From: To: 0000123441 Renewal of FM KLOU 9626 Main 103.3 ST. LOUIS, MO CITICASTERS 01/21/2021 Granted License LICENSES, INC. From: To: 0000121465 Renewal of FX K244FQ 201060 96.7 ELKADER, IA DESIGN HOMES, INC. 01/21/2021 Granted License From: To: 0000122687 Renewal of FM KNLP 83446 Main 89.7 POTOSI, MO NEW LIFE 01/21/2021 Granted License EVANGELISTIC CENTER, INC From: To: Page 1 of 146 REPORT NO. PN-2-210125-01 | PUBLISH DATE: 01/25/2021 Federal Communications Commission 45 L Street NE PUBLIC NOTICE Washington, D.C. 20554 News media info. (202) 418-0500 ACTIONS File Number Purpose Service Call Sign Facility ID Station Type Channel/Freq. City, State Applicant or Licensee Status Date Status 0000122266 Renewal of FX K217GC 92311 Main 91.3 NEVADA, MO CSN INTERNATIONAL 01/21/2021 Granted License From: To: 0000122046 Renewal of FM KRXL 34973 Main 94.5 KIRKSVILLE, MO KIRX, INC.
    [Show full text]
  • 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.
    [Show full text]
  • A History of the Citizen Watch Company, from the Pages of Watchtime Magazine
    THE WORLD OF FINE WATCHES SPOTLIGHT www.watchtime.com A HISTORY OF THE CITIZEN WATCH COMPANY, FROM THE PAGES OF WATCHTIME MAGAZINE CCIITTIIZZEENN THe HisTory of ciTizen One of the original Citizen pocket watches that went on THE sale in December 1924 CITIZEN WATCH STORY How a Tokyo jeweler’s experiment in making pocket watches 84 years ago led to the creation of a global watch colossus n the 1920s, the young Emperor of Japan, than the imports. To that end, Yamazaki found - Goto. The mayor was a friend of Yamazaki’s. Hirohito, received a gift that reportedly de - ed in 1918 the Shokosha Watch Research Insti - When the fledgling watch manufacturer was I lighted him. The gift was from Kamekichi tute in Tokyo’s Totsuka district. Using Swiss ma - searching for a name for his product, he asked Yamazaki, a Tokyo jeweler, who had an ambi - chinery, Yamazaki and his team began experi - Goto for ideas. Goto suggested Citizen. A tion to manufacture pocket watches in Japan. menting in the production of pocket watches. watch is, to a great extent, a luxury item, he ex - The Japanese watch market at that time By the end of 1924, they began commercial plained, but Yamazaki was aiming to make af - was dominated by foreign makes, primarily production of their first product, the Caliber fordable watches. It was Goto’s hope that every Swiss brands, followed by Americans like 16 pocket watch, which they sold under the citizen would benefit from and enjoy the time - Waltham and Elgin. Yamazaki felt the time brand name Citizen.
    [Show full text]
  • Dynamics and Control of Resistive Wall Modes with Magnetic Feedback Control Coils: Experiment and Theory
    1 IAEA-CN-116 EX/P5-13 Dynamics and Control of Resistive Wall Modes with Magnetic Feedback Control Coils: Experiment and Theory M. E. Mauel, J. Bialek, A. H. Boozer, C. Cates, R. James, O. Katsuro-Hopkins, A. Klein, Y. Liu, D. A. Maurer, D. Maslovsky, G. A. Navratil, T. S. Pedersen, M. Shilov, and N. Stillits Department of Applied Physics and Applied Mathematics Columbia University, New York, NY 10027, USA e-mail contact of main author: [email protected] Abstract. Fundamental theory, experimental observations, and modeling of resistive wall mode (RWM) dynamics and active feedback control are reported. In the RWM, the plasma responds to and interacts with external current-carrying conductors. Although this response is complex, it is still possible to construct simple but accurate models for kink dynamics by combining separate determinations for the external currents, using the VALEN code, and for the plasma’s inductance matrix, using an MHD code such as DCON. These computations have been performed for wall-stabilized kink modes in the HBT-EP device, and they illustrate a remarkable feature of the theory: when the plasma’s inductance matrix is dominated by a single eigenmode and when the surrounding current-carrying structures are properly characterized, then the resonant kink response is represented by a small number of parameters. In HBT-EP, RWM dynamics are studied by programming quasi-static and rapid “phase-flip” changes of the external magnetic perturbation and directly measuring the plasma response as a function of kink stability and plasma rotation. The response evolves in time, is easily measured, and involves excitation of both the wall-stabilized kink and the RWM.
    [Show full text]
  • 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".
    [Show full text]
  • A Stability Analysis of Divergence Damping on a Latitude–Longitude Grid
    2976 MONTHLY WEATHER REVIEW VOLUME 139 A Stability Analysis of Divergence Damping on a Latitude–Longitude Grid JARED P. WHITEHEAD Department of Mathematics, University of Michigan, Ann Arbor, Ann Arbor, Michigan CHRISTIANE JABLONOWSKI AND RICHARD B. ROOD Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Ann Arbor, Michigan PETER H. LAURITZEN Climate and Global Dynamics Division, National Center for Atmospheric Research,* Boulder, Colorado (Manuscript received 24 August 2010, in final form 25 March 2011) ABSTRACT The dynamical core of an atmospheric general circulation model is engineered to satisfy a delicate balance between numerical stability, computational cost, and an accurate representation of the equations of motion. It generally contains either explicitly added or inherent numerical diffusion mechanisms to control the buildup of energy or enstrophy at the smallest scales. The diffusion fosters computational stability and is sometimes also viewed as a substitute for unresolved subgrid-scale processes. A particular form of explicitly added diffusion is horizontal divergence damping. In this paper a von Neumann stability analysis of horizontal divergence damping on a latitude–longitude grid is performed. Stability restrictions are derived for the damping coefficients of both second- and fourth- order divergence damping. The accuracy of the theoretical analysis is verified through the use of idealized dynamical core test cases that include the simulation of gravity waves and a baroclinic wave. The tests are applied to the finite-volume dynamical core of NCAR’s Community Atmosphere Model version 5 (CAM5). Investigation of the amplification factor for the divergence damping mechanisms explains how small-scale meridional waves found in a baroclinic wave test case are not eliminated by the damping.
    [Show full text]
  • 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.
    [Show full text]