Time and Frequency Transmission Facilities
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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. -
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. -
Role of the IERS in the Leap Second Brian Luzum Chair, IERS Directing Board Outline
Role of the IERS in the leap second Brian Luzum Chair, IERS Directing Board Outline • What is the IERS? • Clock time (UTC) • Earth rotation angle (UT1) • Leap Seconds • Measures and Predictions of Earth rotation • How are Earth rotation data used? • How the IERS provides for its customers • Future considerations • Summary What is the IERS? • The International Earth Rotation and Reference Systems Service (IERS) provides the following to the international scientific communities: • International Celestial Reference System (ICRS) and its realization the International Celestial Reference Frame (ICRF) • International Terrestrial Reference System (ITRS) and its realization the International Terrestrial Reference Frame (ITRF) • Earth orientation parameters that 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 • Due to the nature of the data, there are many operational users Brief history of the IERS • The International Earth Rotation Service (IERS) was created in 1987 • Responsible to the International Astronomical Union (IAU) and the International Union of Geodesy and Geophysics (IUGG) • IERS began operations on 1 January 1988 • IERS changed its name to International Earth Rotation and Reference Systems Service to better represent its responsibilities • Earth orientation relies directly on having accurate, well-defined reference systems Structure -
UA509: DCF77 Radio Clock DCF77 Radio Clock UA509 with 2 Serial Interfaces, Pulses Per Minute and Per Second, and a 2.5Mm LED Display
Meinberg Radio Clocks Auf der Landwehr 22 31812 Bad Pyrmont, Germany Phone: +49 (5281) 9309-0 Fax: +49 (5281) 9309-30 http://www.meinberg.de [email protected] UA509: DCF77 Radio Clock DCF77 Radio Clock UA509 with 2 serial interfaces, pulses per minute and per second, and a 2.5mm LED Display. Key Features - Direct conversion Quadrature Receiver - Pulses per second and per minute - 20mA input/output circuits - 2,5mm LED-display - 2 RS232 interfaces - Receiver status LEDs - Buffered hardware clock - Flash-EPROM with bootstrap loader rev 2006.0615.1425 Page 1/3 ua509 Description The hardware of UA509 is a 100mm x 160mm microprocessor board. The 20mm wide front panel contains an 8-digit LED display (2.5mm), three LED indicators and a time/date switch. The receiver is connected to the external ferrite antenna AI01 that is included in the sope of supply by the 5 meter 50 ohm coaxial cable (other lengths available). The radio controlled clock UA509 has been designed for applications where two independent serial interfaces are needed. The UA509 contains a flash EPROM with bootstrap loader that allows to upload a new firmware via the serial interface without removal of the clock. Characteristics Type of receiver Narrowband DCF77 quadrature receiver with automatic gain control, bandwidth: approx. 20Hz Display 8 digit 7-segment LED display (2.5mm) for time or date (switch-selectable) optional: 20HP (100mm) wide front panel with 10mm height 7-segment LED display Status info Modulation and field strength visualized by LEDs Free running state visualized by LED after switching to free running quartz clock mode Synchronization time 2-3 minutes after correct DCF77 signal reception Accuracy free run Accuracy of the quartz base after min. -
2201 24-Hour Room Temperature Controller REV13
s 2201 24-hour room temperature controller REV13.. Heating applications • Mains-independent, battery-operated room temperature controller featuring user-friendly operation, easy-to-read display and large numbers • Self-learning two-position controller with PID response (patented) • Operating mode selection: - Automatic mode with two heating phases - Automatic mode with one heating phase - Continuous comfort mode - Continuous energy saving mode - Frost protection • Automatic modes with time switch program • Heating zone control Use Room temperature control in: • Single-family and vacation homes. • Apartments and offices. • Individual rooms and professional office facilities. • Commercially used spaces. Control for the following equipment: • Magnetic valves of an instantaneous water heater. • Magnetic valves of an atmospheric gas burner. • Forced draught gas and oil burners. • Electrothermal actuators. • Circulating pumps in heating systems. • Electric direct heating. • Fans of electric storage heaters. • Zone valves (normally open and normally closed). CE1N2201en 24.04.2008 Building Technologies Function • PID control with self-learning or selectable switching cycle time • 2-point control • 24-hour time switch • Remote control • Preselected 24-hour operating modes • Override function • Party mode • Frost protection mode • Information level to check settings • Reset function • Sensor calibration • Minimum limitation of setpoint • Synchronization to radio time signal from Frankfurt, Germany (REV13DC) Type summary 24-hour room temperature controller REV13 24-hour room temperature controller with receiver for time signal from Frankfurt, Germany (DCF77) REV13DC Ordering Please indicate the type number as per the "Type summary" when ordering. Delivery The controller is supplied with batteries. Mechanical design Plastic casing with an easy-to-read display and large numbers, easily accessible operating elements, and removable base. -
Clock Synchronization Clock Synchronization Part 2, Chapter 5
Clock Synchronization Clock Synchronization Part 2, Chapter 5 Roger Wattenhofer ETH Zurich – Distributed Computing – www.disco.ethz.ch 5/1 5/2 Overview TexPoint fonts used in EMF. Motivation Read the TexPoint manual before you delete this box.: AAAA A • Logical Time (“happened-before”) • Motivation • Determine the order of events in a distributed system • Real World Clock Sources, Hardware and Applications • Synchronize resources • Clock Synchronization in Distributed Systems • Theory of Clock Synchronization • Physical Time • Protocol: PulseSync • Timestamp events (email, sensor data, file access times etc.) • Synchronize audio and video streams • Measure signal propagation delays (Localization) • Wireless (TDMA, duty cycling) • Digital control systems (ESP, airplane autopilot etc.) 5/3 5/4 Properties of Clock Synchronization Algorithms World Time (UTC) • External vs. internal synchronization • Atomic Clock – External sync: Nodes synchronize with an external clock source (UTC) – UTC: Coordinated Universal Time – Internal sync: Nodes synchronize to a common time – SI definition 1s := 9192631770 oscillation cycles of the caesium-133 atom – to a leader, to an averaged time, ... – Clocks excite these atoms to oscillate and count the cycles – Almost no drift (about 1s in 10 Million years) • One-shot vs. continuous synchronization – Getting smaller and more energy efficient! – Periodic synchronization required to compensate clock drift • Online vs. offline time information – Offline: Can reconstruct time of an event when needed • Global vs. -
Concern on UTC Leap Second Schedule Announcements
Concern on UTC Leap Second Schedule Announcements Karl Kovach 15 Aug 19 © 2019 The Aerospace Corporation UTC & Leap Seconds • International Earth Rotation Service (IERS) – The “keeper’ of UTC • The ‘decider’ of UTC leap seconds • U.S. Naval Observatory (USNO) – Contributes to IERS for UTC • Follows IERS for UTC leap seconds • U.S. Department of Defense (DoD) – Follows USNO for UTC & UTC leap seconds • Global Positioning System (GPS) – Should be following USNO for UTC & UTC leap seconds 2 UTC Leap Second Announcements • IERS announces the UTC leap second schedule – USNO forwards the IERS announcements • DoD uses the IERS leap second announcements – GPS should simply follow along… 3 IERS “Bulletin C” Announcements Paris, 6 July 2016 – Bulletin C 52 4 IERS “Bulletin C” Announcements Paris, 9 January 2017 – Bulletin C 53 5 IERS “Bulletin C” Announcements Paris, 06 July 2017 – Bulletin C 54 6 IERS “Bulletin C” Announcements Paris, 09 January 2018 – Bulletin C 55 7 IERS “Bulletin C” Announcements Paris, 05 July 2018 – Bulletin C 56 8 IERS “Bulletin C” Announcements Paris, 07 January 2019 – Bulletin C 57 9 IERS “Bulletin C” Announcements Paris, 04 July 2019 – Bulletin C 58 10 UTC Leap Second Announcements • IERS announces the UTC leap second schedule – USNO forwards the IERS announcements • DoD uses the IERS leap second announcements – GPS should simply follow along… • GPS also announces a UTC leap second schedule – Should be the same schedule as IERS & USNO 11 GPS Leap Second Announcement WNLSF DN ΔtLSF 12 GPS Leap Second Announcement Leap -
Leap Second Application Anomaly
PRESS RELEASE Leap Second Application Anomaly Affected products The following models will not properly apply the leap second coming 31 December 201 6. Model 1 084A/B/C Model 1 093A/B/C Model 1 1 33A Model 1 088A/B Model 1 094B Model 1 092A/B/C Model 1 095B/C What is a leap second? A leap second is the second added to or subtracted from the UTC time reference when the difference between UTC and UT1 approaches 0.9 seconds. By adding an additional second to the time count, clocks are effectively stopped for that second to give Earth the opportunity to catch up with atomic time. What does this mean, UTC, UT1 , et cetera? There are many time references in use. There is time based on atoms. There is time based on the Earth's rotation. Then there is time that we civilians use. • International Atomic Time (TAI). TAI is a statistical atomic time scale based on a large number of clocks operating at standards laboratories around the world with the unit interval of the SI second. • Universal Time (UT1 ). UT1 is also known as Astronomical Time and is the non-uniform time based on the Earth’s rotation. • Coordinated Universal Time (UTC) is a widely used standard for international timekeeping of civil time and differs from TAI by the total number of leap seconds. • Global Positioning System (GPS) Time is the atomic time scale implemented by the atomic clocks in the GPS ground control stations and the GPS satellites themselves. GPS time was zero at 0h 6 January 1 980 and does not include leap seconds. -
2203 Weekday / Weekend Room Temperature Controller REV17
s 2203 Weekday / weekend room temperature controller REV17.. Heating applications • Mains-independent, battery-operated room temperature controller featuring user-friendly operation, easy-to-read display and large numbers • Self-learning two-position controller with PID response (patented) • Operating mode selection: - 7-day (weekday / weekend) automatic mode. with max. 3 heating phases - Continuous comfort mode - Continuous energy saving mode - Frost protection - Exception day (24 hour operation) with max. 3 heating phases • A separate temperature setpoint can be entered in automatic mode and for the exception day for each heating phase • To control a heating zone Use Room temperature control in: • Single-family and vacation homes • Apartments and offices • Individual rooms and professional office facilities • Commercially used spaces Control for the following equipment: • Magnetic valves of an instantaneous water heater • Magnetic valves of an atmospheric gas burner • Forced draught gas and oil burners • Electrothermal actuators • Circulating pumps in heating systems • Electric direct heating • Fans of electric storage heaters • Zone valves (normally open or normally closed) CE1N2203en 24.04.2008 Building Technologies Function • PID control with self-learning or selectable switching cycle time • 2-point control • 7-day time switch • Remote control • Preselected 24-hour operating modes • Override function • Holiday mode • Party mode • Frost protection mode • Information level to check settings • Reset function • Sensor calibration • Minimum limitation of setpoint • Periodic pump run Protection against valve seizure • Synchronization to radio time signal from Frankfurt, Germany (REV17DC) Type summary Room temperature controller with 7-day (weekday/weekend) time switch REV17 Room temperature controller with 7-day (weekday/weekend) time switch and receiver for time signal from Frankfurt, Germany (DCF77) REV17DC Ordering Please indicate the type number as per the "Type summary" when ordering. -
Best Practices for Leap Second Event Occurring on 30 June 2015
26 May 2015 Best Practices for Leap Second Event Occurring on 30 June 2015 Sponsored by the National Cybersecurity and Communications Integration Center in coordination with the United States Naval Observatory, National Institute of Standards and Technology, the USCG Navigation Center, and the National Coordination Office for Space-Based Positioning, Navigation and Timing. This product is intended to assist federal, state, local, and private sector organizations with preparations for the 30-June 2015 Leap Second event. Entities using precision time should be mindful that no leap second adjustment has occurred on a non- holiday weekday in the past decade. Of the three leap seconds implemented since 2000, two have been scheduled on 31 December and the most recent was on Sunday, 1 July 2012. Please report operational challenges you experience to the following organizations: GPS -- United States Coast Guard Navigation Center (NAVCEN), via the NAVCEN Website, http://www.navcen.uscg.gov/ under "Report a GPS Problem" Network Timing Protocols (NTP) -- Michael Lombardi at NIST, Boulder, Colorado at 303-497- 3212, or [email protected]. ============================================= 1. Leap Second Introduction The Coordinated Universal Time (UTC) time standard, based on atomic clocks, is widely used for international timekeeping and as the reference for time in most countries. UTC is the basis of legal time for most of the world. UTC must be adjusted at irregular intervals to maintain its correlation to mean solar time due to irregularities in the Earth’s rotation. These adjustments, called leap seconds, are pre-determined. The next leap second will occur on 30 June 2015 at 23:59:59 UTC. -
DLC32 / DATAREG 32C Data Logger
DLC32 / DATAREG 32C Data logger User Manual Doc.-No: E122211209022 Baer Industrie-Elektronik GmbH Rathsbergstr. 23 D-90411 Nürnberg Phone: +49 (0)911 970590 Fax: +49 (0)911 9705950 Internet: www.baer-gmbh.com COPYRIGHT Copyright © 2009 BÄR Industrie-Elektronik GmbH All rights, including those originating from translation, (re)-printing and copying of this document or parts thereof are reserved. No part of this manual may be copied or distributed by electronic, mechanic, photographic or indeed any other means without prior written consent of BÄR Industrie-Elektronik GmbH. All names of products or companies contained in this document may be trademarks or trade names of their respective owners. Note Based on its policies, BÄR Industrie-Elektronik GmbH develops and improves their products on an ongoing basis. In consequence, BÄR Industrie-Elektronik GmbH preserve the right to modify and improve the software product described in this document. Specifications and other information contained in this document can change without prior notice. This document does not cover all functions in all possible detail or variations that may be encountered during installation, maintenance and usage of the software. Under no circumstances whatsoever will BÄR Industrie-Elektronik GmbH accept any liability for mistakes in this document or for any sub sequential damage arising from installation or usage of the software. BÄR Industrie-Elektronik GmbH preserves the right to modify or withdraw this document at any time without prior announcement. BÄR Industrie-Elektronik GmbH does not accept any responsibility or liability for the installation, usage, maintenance or support of third party products. Printed in Germany Table of Contents 1 General Information............................................................................................. -
LSI for Radio Clocks
LSI for Radio Clocks Takayuki Kondo Katsuya Maruyama Tsunao Oike Radio clocks sustain accurate time at all times, as The broadcasting of time information is conducted in they are equipped with functions for receiving low Japan by the National Institute of Information and frequency signals (the standard-time and frequency- Communications Technology, an incorprated signal emission) that carry time information and administrative agency, with the standard frequency automatically correct time and calendars. Products fitted transmitting offices established at two locations including with a radio clock function are on the increase, since the Ohtakado-yama standard frequency station in Fukushima broadcast range of the standard frequency was extended Prefecture (1997) and Hagane-yama standard frequency to cover all Japan in 2001, which resulted in radio clocks station in Saga Prefecture (2001). Each transmitting getting into the limelight. station covers a radius of 1,200km and the two Conventional radio clocks were used as ordinary transmitting stations combined cover almost the entire clocks (table clocks, watches, wall clocks, etc.) but with area of Japan (Figure 2). Further, mutual interference is the recent improvement of LSIs for radio receiver and avoided with different frequencies assigned, 40KHz from antennas combined with a reduction in power Ohtakado-yama station (Fukushima-Pref.) and 60KHz consumption, raised sensitivity and miniaturization, from Hagane-yama station (Saga-Pref.). application of the device in various products is anticipated, such as consumer appliances, mobile devices and home electric appliances. This paper will provide a general summary of the “ML6191”, a real-time clock LSI with an automatic time correction function that is a combination of the RF for the Approx.