Nbs Technical Note 674 National Bureau of Standards
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
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. -
The BPL Dilemma
Reprinted with permission from CQ VHF Magazine, Spring 2004 issue. Copyright CQ Communications 2004 The BPL Dilemma Hams claim Broadband over Power Lines will interfere with their on-the-air operations. The utility companies claim not. Read how they are both right . sort of. By Gary Pearce,* KN4AQ still academic. They haven’t encountered Because of the importance of the it yet. I will provide a quick tutorial. Broadband over Power Lines (BPL) The basics of BPL are simple. It is a issue, “FM” columnist Gary Pearce, method of delivering high-speed internet KN4AQ, devotes his space this time to the to homes and small businesses using the investigation of a BPL test site and the local power lines that crisscross neigh- surrounding area. He will be back in the borhoods either overhead or under- next issue of CQ VHF with his regular ground. This is a brilliantly obvious idea column material. —N6CL (“the wires are already there!”) that was delayed because the AC power grid is a really noisy, crappy signal-delivery ince last fall, I’ve been up to my medium for anything above 60 Hz. The eyeballs in BPL—Broadband over march of technology, however, is mak- Power Lines—and its effect on ing it feasible. It is the third method of Samateur radio. If you’re up on current TV doing that, following DSL (Digital culture, you can call it “HF Eye for the FM Subscriber Line) on the phone lines and Guy.” Our area has been “lucky” enough cable TV (nobody’s come up with a cute to host one of the few BPL trials, courtesy name or acronym for broadband over of my local power company, Progress cable TV; they just call it “cable”). -
A Century of WWV
Volume 124, Article No. 124025 (2019) https://doi.org/10.6028/jres.124.025 Journal of Research of the National Institute of Standards and Technology A Century of WWV Glenn K. Nelson National Institute of Standards and Technology, Radio Station WWV, Fort Collins, CO 80524, USA [email protected] WWV was established as a radio station on October 1, 1919, with the issuance of the call letters by the U.S. Department of Commerce. This paper will observe the upcoming 100th anniversary of that event by exploring the events leading to the founding of WWV, the various early experiments and broadcasts, its official debut as a service of the National Bureau of Standards, and its role in frequency and time dissemination over the past century. Key words: broadcasting; frequency; radio; standards; time. Accepted: September 6, 2019 Published: September 24, 2019 https://doi.org/10.6028/jres.124.025 1. Introduction WWV is the high-frequency radio broadcast service that disseminates time and frequency information from the National Institute of Standards and Technology (NIST), part of the U.S. Department of Commerce. WWV has been performing this service since the early 1920s, and, in 2019, it is celebrating the 100th anniversary of the issuance of its call sign. 2. Radio Pioneers Other radio transmissions predate WWV by decades. Guglielmo Marconi and others were conducting radio research in the late 1890s, and in 1901, Marconi claimed to have received a message sent across the Atlantic Ocean, the letter “S” in telegraphic code [1]. Radio was called “wireless telegraphy” in those days and was, if not commonplace, viewed as an emerging technology. -
N O T I C E This Document Has Been Reproduced From
N O T I C E THIS DOCUMENT HAS BEEN REPRODUCED FROM MICROFICHE. ALTHOUGH IT IS RECOGNIZED THAT CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED IN THE INTEREST OF MAKING AVAILABLE AS MUCH INFORMATION AS POSSIBLE r^i 44 The University of Tennessee Department of Electrical Engineering Knoxville, Tennessee 37916 (NASA-C,9-1bu791) A SIULY OF LNIYEASA.I N82--2! MODULATICN TECHN101 S APPL11 D TO SA?ELLI;TE 4 DATA COLLECTION Final Report (Tennessee tFn v.) 176 p HC A09/MF A01 CSCL 1711 Uncla G3/32 21917 A STUDY OF UNIVERSAL MODULATION TECHNIQUES APPLIED TO SATELLITE DATA COLLECTION If ^^ tit Final Report Y December 1980 Contract No. NAS5-24250 Prepared for National Aeronautics and Space Administration Goddard Space Flight Center r Greenbelt, Maryland 20771 f i PRECEDING PAGE BLANK NOT FILMED .Osp* Abstract A scheme for a universal modulation and frequency control system for use with data-collection platform (DCP) transmitters is examined. The final design discussed can, under software/firmwave control, generate all of the specific digital data modulation formats currently used in the NASA satellite data-collection service and can simultaneously synthesize the proper RF carrier frequencies employed, A novel technique for DCP time and frequency control is presented, The emissions: of NBS rad o station WW/WWVH are received, detected, and finally decoded in microcomputer software to generate a highly accurate time base for the platform; with the assistance of external hardware, the microcomputer also directs the recalibration of all DCP oscillators to achieve very high frequency accuracies and low drift rates versus tem perature, supply voltage, and time. -
Unclassified NEA/RWM/RF(2004)6 RWMC Regulators' Forum (RWMC
Unclassified NEA/RWM/RF(2004)6 Organisation de Coopération et de Développement Economiques Organisation for Economic Co-operation and Development 30-Sep-2004 ___________________________________________________________________________________________ English - Or. English NUCLEAR ENERGY AGENCY RADIOACTIVE WASTE MANAGEMENT COMMITTEE Unclassified NEA/RWM/RF(2004)6 RWMC Regulators' Forum (RWMC-RF) REMOVAL OF REGULATORY CONTROLS FOR MATERIALS AND SITES National Regulatory Positions Issues with the removal of regulatory controls are very important on the agenda of the regulatory authorities dealing with radioactve waste managemnt (RWM). These issues arise prominently in decommissioning and in site remediation, and decisions can be very wide ranging having potentiallly important economic impacts and reaching outside the RWM area. The RWMC Regulators Forum started to address these issues by holding a topical discussion at its meeting in March 2003. Ths present document collates the national regulatory positions in the area of removal of regulatory controls. A summary of the national positions is also provided. The document is up to date to April 2004. English - Or. English JT00170359 Document complet disponible sur OLIS dans son format d'origine Complete document available on OLIS in its original format NEA/RWM/RF(2004)6 FOREWORD Issues with the removal of regulatory controls are very important on the agenda of the regulatory authorities dealing with radioactive waste management (RWM). These issues arise prominently in decommissioning and in site remediation, and decisions can be very wide ranging having potentially important economic impacts and reaching outside the RWM area. The relevant issues must be addressed and clearly understood by all stakeholders. There is a large interest in these issues outside the regulatory arena. -
The RWM Benefit Cost Analysis Compendium
The Road Weather Management Benefit Cost Analysis Compendium Quality Assurance Statement The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement. Notice This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. The Road Weather Management Benefit Cost Analysis Compendium TECHNICAL REPORT DOCUMENTATION PAGE 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. FHWA-HOP-14-033 4. Title and Subtitle 5. Report Date Road Weather Management Benefit Cost Analysis Compendium August 2014 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Michael Lawrence, Paul Nguyen, Jonathan Skolnick, Jim Hunt, Roemer Alfelor N/A 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Leidos 11251 Roger Bacon Drive Reston, Virginia 20190 11. Contract or Grant No. Jack Faucett Associates 4915 St. Elmo Ave, Suite 205 DTFH61-12-D-00050 Bethesda, Maryland 20814 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered U.S. Department of Transportation Federal Highway Administration Office of Freight Management and Operations 14. Sponsoring Agency Code 1200 New Jersey Avenue, SE Washington, DC 20590 HOP 15. Supplementary Notes Far right image on cover source: Idaho Transportation Department Bottom image on cover source: Paul Pisano, Federal Highway Administration 16. -
Species Selection in a Global Change Scenario Francesco Ferrini and Alessio Fini
Planning the Green City of 2050: Species Selection in a Global Change Scenario Francesco Ferrini and Alessio Fini Department of Agri-Food Production and Environmental Sciences University of Florence – Italy Viale delle Idee, 30 – 50019 Sesto Fiorentino (Florence) - Italy Abstract The presentation will focused on the technical and practical solutions for the selection of trees that might be the best choice in the urban environments for the next 100 years, given differences in urban sites (infrastructures, climate, soils etc), species attributes, management requirements and climate change. The presentation will be divided in the following parts: • Trees and climate change in the urban environment (main characteristics of the urban areas. Tree physiology as influenced by typical environmental constraints of urban stands). • Trees and infrastructure (Improving relations between technical infrastructures and vegetation. • Selection of planting material in a global change scenario Presenter Biography Francesco Ferrini, Ph.D. Full Professor at the Department of Agri-Food and Environmental Sciences – University of Florence (Italy). Scientific activity focused on: Impact of plant selection and nursery production practices on root regeneration and tree growth after planting Physiological and growth aspects of different species as affected by different cultivation techniques after planting in the urban environment Evaluation of morpho-physiological and biochemical parameters to study urban stress tolerance on tree species. Evaluation of the ability of shrub and tree species to mitigate the effect of pollution in the urban and periurban environment Planning the green city in the global change era: urban tree functions and suitability for predicted future climates (TreeCity) From 1990 he has published more than 210 scientific and technical papers in Italian (112) and in English (101) in international referred and nationwide journals. -
KHF 950/990 HF Communications Transceiver PILOT’S GUIDE and DIRECTORY of HF SERVICES
KHF 950/990 HF Communications Transceiver PILOT’S GUIDE AND DIRECTORY OF HF SERVICES A Table of Contents INTRODUCTION KHF 950/990 COMMUNICATIONS TRANSCEIVER . .I SECTION I CHARACTERISTICS OF HF SSB WITH ALE . .1-1 ACRONYMS AND DEFINITIONS . .1-1 REFERENCES . .1-1 HF SSB COMMUNICATIONS . .1-1 FREQUENCY . .1-2 SKYWAVE PROPAGATION . .1-3 WHY SINGLE SIDEBAND IS IMPORTANT . .1-9 AMPLITUDE MODULATION (AM) . .1-9 SINGLE SIDEBAND OPERATION . .1-10 SINGLE SIDEBAND (SSB) . .1-10 SUPPRESSED CARRIER VS. REDUCED CARRIER . .1-10 SIMPLEX & SEMI-DUPLEX OPERATION . .1-11 AUTOMATIC LINK ESTABLISHMENT (ALE) . .1-11 FUNCTIONS OF HF RADIO AUTOMATION . .1-11 ALE ASSURES BEST COMM LINK AUTOMATICALLY . .1-12 SECTION II KHF 950/990 SYSTEM DESCRIPTION. .2-1 KCU 1051 CONTROL DISPLAY UNIT . .2-1 KFS 594 CONTROL DISPLAY UNIT . .2-3 KCU 951 CONTROL DISPLAY UNIT . .2-5 KHF 950 REMOTE UNITS . .2-6 KAC 952 POWER AMPLIFIER/ANT COUPLER .2-6 KTR 953 RECEIVER/EXITER . .2-7 ADDITIONAL KHF 950 INSTALLATION OPTIONS .2-8 SINGLE KHF 950 SYSTEM CONFIGURATION .2-9 KHF 990 REMOTE UNITS . .2-10 KAC 992 PROBE/ANTENNA COUPLER . .2-10 KTR 993 RECEIVER/EXITER . .2-11 SINGLE KHF 990 SYSTEM CONFIGURATION . .2-12 Rev. 0 Dec/96 KHF 950/990 Pilots Guide Toc-1 Table of Contents SECTION III OPERATING THE KHF 950/990 . .3-1 KHF 950/990 GENERAL OPERATING INFORMATION . .3-1 PREFLIGHT INSPECTION . .3-1 ANTENNA TUNING . .3-2 FAULT INDICATION . .3-2 TUNING FAULTS . .3-3 KHF 950/990 CONTROLS-GENERAL . .3-3 KCU 1051 CONTROL DISPLAY UNIT OPERATION . -
Time Signal Stations 1By Michael A
122 Time Signal Stations 1By Michael A. Lombardi I occasionally talk to people who can’t believe that some radio stations exist solely to transmit accurate time. While they wouldn’t poke fun at the Weather Channel or even a radio station that plays nothing but Garth Brooks records (imagine that), people often make jokes about time signal stations. They’ll ask “Doesn’t the programming get a little boring?” or “How does the announcer stay awake?” There have even been parodies of time signal stations. A recent Internet spoof of WWV contained zingers like “we’ll be back with the time on WWV in just a minute, but first, here’s another minute”. An episode of the animated Power Puff Girls joined in the fun with a skit featuring a TV announcer named Sonny Dial who does promos for upcoming time announcements -- “Welcome to the Time Channel where we give you up-to- the-minute time, twenty-four hours a day. Up next, the current time!” Of course, after the laughter dies down, we all realize the importance of keeping accurate time. We live in the era of Internet FAQs [frequently asked questions], but the most frequently asked question in the real world is still “What time is it?” You might be surprised to learn that time signal stations have been answering this question for more than 100 years, making the transmission of time one of radio’s first applications, and still one of the most important. Today, you can buy inexpensive radio controlled clocks that never need to be set, and some of us wear them on our wrists. -
Response of Parameters of HF Signals at the Long Radio Paths on Solar Activity
URS I AP -RASC 2019, New Delhi, India, 09 - 15 March 2019 Response of parameters of HF signals at the long radio paths on solar activity Andriy Zalizovski (1, 2) *, Yuri Yampolski (1) , Alexander Koloskov (1, 2), Sergey Kashcheyev (1) , Bogdan Gavrylyik (1) (1) Institute of Radio Astronomy, NASU, Kharkiv, Ukraine; e-mail: [email protected] (2) National Antarctic Scientific Center, Kyiv, Ukraine A technique for multiposition Doppler HF sounding of the ionosphere that use the emission of broadcasting radio-stations as probing signals is developed in the Institute of Radio Astronomy of National Academy of Sciences of Ukraine (IRA NASU) during some last decades. At present the Internet-controlled receiving sites designed by IRA NASU are located in Arctic, Scandinavia, Europe, Africa, and Antarctica. The analysis of HF signal propagation on the super long radio paths is one of the major tasks of this network. This paper discusses the results of the analysis of signal propagation from Europe and Northern America to Antarctica. The signals of time and frequency services were used as probe because of the excellent stability of their parameters. The radiation of RWM (Moscow, carrier frequencies 4996, 9996, and 14996 kHz) and CHU (Ottawa, frequencies 3330, and 7850 kHz) stations are recorded round-the-clock at the Ukrainian Antarctic Station (UAS, 65.25S, 64.27W) Akademik Vernadsky since 2010. Time and spectral analysis of the RWM pulse signals allowed to detect experimentally four different pathways: the direct and reverse paths lying on the great circle, and trajectories outside the great circle formed by focusing along the solar terminator and scattering on the ionospheric irregularities of auroral ovals. -
Radio Navigational Aids
RADIO NAVIGATIONAL AIDS Publication No. 117 2014 Edition Prepared and published by the NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY Springfield, VA © COPYRIGHT 2014 BY THE UNITED STATES GOVERNMENT NO COPYRIGHT CLAIMED UNDER TITLE 17 U.S.C. WARNING ON USE OF FLOATING AIDS TO NAVIGATION TO FIX A NAVIGATIONAL POSITION The aids to navigation depicted on charts comprise a system consisting of fixed and floating aids with varying degrees of reliability. Therefore, prudent mariners will not rely solely on any single aid to navigation, particularly a floating aid. The buoy symbol is used to indicate the approximate position of the buoy body and the sinker which secures the buoy to the seabed. The approximate position is used because of practical limitations in positioning and maintaining buoys and their sinkers in precise geographical locations. These limitations include, but are not limited to, inherent imprecisions in position fixing methods, prevailing atmospheric and sea conditions, the slope of and the material making up the seabed, the fact that buoys are moored to sinkers by varying lengths of chain, and the fact that buoy and/or sinker positions are not under continuous surveillance but are normally checked only during periodic maintenance visits which often occur more than a year apart. The position of the buoy body can be expected to shift inside and outside the charting symbol due to the forces of nature. The mariner is also cautioned that buoys are liable to be carried away, shifted, capsized, sunk, etc. Lighted buoys may be extinguished or sound signals may not function as the result of ice or other natural causes, collisions, or other accidents. -
STANDARD FREQUENCIES and TIME SIGNALS (Question ITU-R 106/7) (1992-1994-1995) Rec
Rec. ITU-R TF.768-2 1 SYSTEMS FOR DISSEMINATION AND COMPARISON RECOMMENDATION ITU-R TF.768-2 STANDARD FREQUENCIES AND TIME SIGNALS (Question ITU-R 106/7) (1992-1994-1995) Rec. ITU-R TF.768-2 The ITU Radiocommunication Assembly, considering a) the continuing need in all parts of the world for readily available standard frequency and time reference signals that are internationally coordinated; b) the advantages offered by radio broadcasts of standard time and frequency signals in terms of wide coverage, ease and reliability of reception, achievable level of accuracy as received, and the wide availability of relatively inexpensive receiving equipment; c) that Article 33 of the Radio Regulations (RR) is considering the coordination of the establishment and operation of services of standard-frequency and time-signal dissemination on a worldwide basis; d) that a number of stations are now regularly emitting standard frequencies and time signals in the bands allocated by this Conference and that additional stations provide similar services using other frequency bands; e) that these services operate in accordance with Recommendation ITU-R TF.460 which establishes the internationally coordinated UTC time system; f) that other broadcasts exist which, although designed primarily for other functions such as navigation or communications, emit highly stabilized carrier frequencies and/or precise time signals that can be very useful in time and frequency applications, recommends 1 that, for applications requiring stable and accurate time and frequency reference signals that are traceable to the internationally coordinated UTC system, serious consideration be given to the use of one or more of the broadcast services listed and described in Annex 1; 2 that administrations responsible for the various broadcast services included in Annex 2 make every effort to update the information given whenever changes occur.