Reception of Low Frequency Time Signals
Total Page:16
File Type:pdf, Size:1020Kb
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. -
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. -
Analog Clock Headway Movement FAQS
ANALOG CLOCK HEADWAY MOVEMENT FAQS The links below will work in most PDF viewers and link to the topic area by clicking the link. We recommend Adobe Reader version 10 or greater available at: http://get.adobe.com/reader CONTENTS Analog Clock Headway Movement FAQS .................................................................... 1 Batteries ............................................................................................................................. 2 Atomic Clock Factory Restart ...................................................................................... 2 Supported Time Zones .................................................................................................. 2 Time is Incorrect ............................................................................................................. 2 Clock is incorrect by Hours but minutes are correct .......................................... 3 Daylight Saving Time ..................................................................................................... 3 Manually Set Time ........................................................................................................... 3 How long will the battery last? .................................................................................. 3 Can I shut off the WWVB signal? .............................................................................. 3 Is there a booster antenna to receive the WWVB signal in a difficult location? ............................................................................................................................ -
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. -
High Frequency (HF)
Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection 1990-06 High Frequency (HF) radio signal amplitude characteristics, HF receiver site performance criteria, and expanding the dynamic range of HF digital new energy receivers by strong signal elimination Lott, Gus K., Jr. Monterey, California: Naval Postgraduate School http://hdl.handle.net/10945/34806 NPS62-90-006 NAVAL POSTGRADUATE SCHOOL Monterey, ,California DISSERTATION HIGH FREQUENCY (HF) RADIO SIGNAL AMPLITUDE CHARACTERISTICS, HF RECEIVER SITE PERFORMANCE CRITERIA, and EXPANDING THE DYNAMIC RANGE OF HF DIGITAL NEW ENERGY RECEIVERS BY STRONG SIGNAL ELIMINATION by Gus K. lott, Jr. June 1990 Dissertation Supervisor: Stephen Jauregui !)1!tmlmtmOlt tlMm!rJ to tJ.s. eave"ilIE'il Jlcg6iielw olil, 10 piolecl ailicallecl",olog't dU'ie 18S8. Btl,s, refttteste fer litis dOCdiii6i,1 i'lust be ,ele"ed to Sapeihil6iiddiil, 80de «Me, "aial Postg;aduulG Sclleel, MOli'CIG" S,e, 98918 &988 SF 8o'iUiid'ids" PM::; 'zt6lI44,Spawd"d t4aoal \\'&u 'al a a,Sloi,1S eai"i,al'~. 'Nsslal.;gtePl. Be 29S&B &198 .isthe 9aleMBe leclu,sicaf ,.,FO'iciaKe" 6alite., ea,.idiO'. Statio", AlexB •• d.is, VA. !!!eN 8'4!. ,;M.41148 'fl'is dUcO,.Mill W'ilai.,s aliilical data wlrose expo,l is idst,icted by tli6 Arlil! Eurse" SSPItial "at FRIis ee, 1:I.9.e. gec. ii'S1 sl. seq.) 01 tlls Exr;01l ftle!lIi"isllatioli Act 0' 19i'9, as 1tI'I'I0"e!ee!, "Filill ell, W.S.€'I ,0,,,,, 1i!4Q1, III: IIlIiI. 'o'iolatioils of ltrese expo,lla;;s ale subject to 960616 an.iudl pSiiaities. -
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) -
Identification of Novel HPFH-Like Mutations by CRISPR Base Editing That Elevates the Expression of Fetal Hemoglobin
bioRxiv preprint doi: https://doi.org/10.1101/2020.06.30.178715; this version posted July 1, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Identification of novel HPFH-like mutations by CRISPR base editing that elevates the expression of fetal hemoglobin Nithin Sam Ravi1,3, Beeke Wienert4,8,9, Stacia K. Wyman4, Jonathan Vu4, Aswin Anand Pai2, Poonkuzhali Balasubramanian2, Yukio Nakamura7, Ryo Kurita10, Srujan Marepally1, Saravanabhavan Thangavel1, Shaji R. Velayudhan1,2, Alok Srivastava1,2, Mark A. DeWitt 4,5, Jacob E. Corn4,6, Kumarasamypet M. Mohankumar1* 1. Centre for Stem Cell Research (a unit of inStem, Bengaluru), Christian Medical College Campus, Bagayam, Vellore-632002, Tamil Nadu, India. 2. Department of Haematology, Christian Medical College Hospital, IDA Scudder Rd, Vellore-632002, Tamil Nadu, India. 3. Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram - 695 011, Kerala, India. 4. Innovative Genomics Institute, University of California Berkeley, Berkeley, California- 94704, USA. 5. Department of Microbiology, Immunology, and Molecular Genetics, University of California - Los Angeles, Los Angeles, California - 90095, USA. 6. Institute of Molecular Health Sciences, Department of Biology, ETH Zurich, Otto-Stern- Weg, Zurich - 8092, Switzerland. 7. Cell Engineering Division, RIKEN BioResource Center, Tsukuba, Ibaraki 305-0074, Japan. 8. Institute of Data Science and Biotechnology, Gladstone Institutes, San Francisco, California -94158, USA 9. School of Biotechnology and Biomolecular Sciences, University of New South Wales - 2052, Sydney, Australia. 10. Research and Development Department Central Blood Institute Blood Service Headquarters Japanese Red Cross Society, 2-1-67 Tatsumi, Tokyo, 135-8521, Japan *Corresponding Author: Dr. -
Correlation of Very Low and Low Frequency Signal Variations at Mid-Latitudes with Magnetic Activity and Outer-Zone Particles
Ann. Geophys., 32, 1455–1462, 2014 www.ann-geophys.net/32/1455/2014/ doi:10.5194/angeo-32-1455-2014 © Author(s) 2014. CC Attribution 3.0 License. Correlation of very low and low frequency signal variations at mid-latitudes with magnetic activity and outer-zone particles A. Rozhnoi1, M. Solovieva1, V. Fedun2, M. Hayakawa3, K. Schwingenschuh4, and B. Levin5 1Institute of Physics of the Earth, Russian Academy of Sciences, 10 B. Gruzinskaya, Moscow, 123995, Russia 2Space Systems Laboratory, Department of Automatic Control and Systems Engineering, University of Sheffield, Sheffield, S1 3JD, UK 3University of Electro-Communications, Advanced Wireless Communications Research Center, 1-5-1 Chofugaoka, Chofu Tokyo, 182-8585, Japan 4Space Research Institute, Austrian Academy of Sciences, 6 Schmiedlstraße, 8042, Graz, Austria 5Institute of marine geology and geophysics Far East Branch of Russian Academy of Sciences, 1B Nauki str., Yuzhno-Sakhalinsk, 693022, Russia Correspondence to: A. Rozhnoi ([email protected]) Received: 31 May 2014 – Revised: 28 October 2014 – Accepted: 31 October 2014 – Published: 4 December 2014 Abstract. The disturbances of very low and low frequency Hayakawa, 2008; Hayakawa et al., 2010; Hayakawa, 2011; signals in the lower mid-latitude ionosphere caused by mag- Biagi et al., 2004, 2007; Rozhnoi et al., 2004, 2009). This netic storms, proton bursts and relativistic electron fluxes band of electromagnetic waves is trapped between the lower are investigated on the basis of VLF–LF measurements ob- ionosphere and the surface of the Earth, and reflected from tained in the Far East and European networks. We have found the boundary between the upper atmosphere and lower iono- that magnetic storm (−150 < Dst < −100 nT) influence is sphere at altitudes of ≈ 70 km (daytime) and ≈ 90 km (night- not strong on variations of VLF–LF signals. -
Tigersharc Embedded Processor ADSP-TS101S
TigerSHARC Embedded Processor ADSP-TS101S FEATURES BENEFITS 300 MHz, 3.3 ns instruction cycle rate Provides high performance Static Superscalar DSP opera- 6M bits of internal—on-chip—SRAM memory tions, optimized for telecommunications infrastructure 19 mm × 19 mm (484-ball) CSP-BGA or 27 mm × 27 mm and other large, demanding multiprocessor DSP (625-ball) PBGA package applications Dual computation blocks—each containing an ALU, a multi- Performs exceptionally well on DSP algorithm and I/O bench- plier, a shifter, and a register file marks (see benchmarks in Table 1 and Table 2) Dual integer ALUs, providing data addressing and pointer Supports low overhead DMA transfers between internal manipulation memory, external memory, memory-mapped peripherals, Integrated I/O includes 14-channel DMA controller, external link ports, other DSPs (multiprocessor), and host port, 4 link ports, SDRAM controller, programmable flag processors pins, 2 timers, and timer expired pin for system integration Eases DSP programming through extremely flexible instruc- 1149.1 IEEE compliant JTAG test access port for on-chip tion set and high-level language-friendly DSP architecture emulation Enables scalable multiprocessing systems with low commu- On-chip arbitration for glueless multiprocessing with up to nications overhead 8 TigerSHARC processors on a bus COMPUTATIONAL BLOCKS PROGRAM SEQUENCER DATA ADDRESS GENERATION INTERNAL MEMORY 6 MEMORY MEMORY MEMORY JTAG PORT SHIFTER PC BTB IRQ INTEGER 32 32 INTEGER M0 M1 M2 JALU KALU ADDR 64K × 32 64K × 32 64K × 32 SDRAM CONTROLLER -
Identifying and Removing Tilt Noise from Low-Frequency (0.1
Bulletin of the Seismological Society of America, 90, 4, pp. 952–963, August 2000 Identifying and Removing Tilt Noise from Low-Frequency (Ͻ0.1 Hz) Seafloor Vertical Seismic Data by Wayne C. Crawford and Spahr C. Webb Abstract Low-frequency (Ͻ0.1 Hz) vertical-component seismic noise can be re- duced by 25 dB or more at seafloor seismic stations by subtracting the coherent signals derived from (1) horizontal seismic observations associated with tilt noise, and (2) pressure measurements related to infragravity waves. The reduction in ef- fective noise levels is largest for the poorest stations: sites with soft sediments, high currents, shallow water, or a poorly leveled seismometer. The importance of precise leveling is evident in our measurements: low-frequency background vertical seismic radians 4מ10 ן spectra measured on a seafloor seismometer leveled to within 1 (0.006 degrees) are up to 20 dB quieter than on a nearby seismometer leveled to radians (0.2 degrees). The noise on the less precisely leveled sensor 3מ10 ן within 3 increases with decreasing frequency and is correlated with ocean tides, indicating that it is caused by tilting due to seafloor currents flowing across the instrument. At low frequencies, this tilting generates a seismic signal by changing the gravitational attraction on the geophones as they rotate with respect to the earth’s gravitational field. The effect is much stronger on the horizontal components than on the vertical, allowing significant reduction in vertical-component noise by subtracting the coher- ent horizontal component noise. This technique reduces the low-frequency vertical noise on the less-precisely leveled seismometer to below the noise level on the pre- cisely leveled seismometer. -
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. -
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.