Dirk Piester

Dirk Piester
Physikalisch-Technische Bundesanstalt | PTB · Department 4.4 Time and Frequency

Dr.-Ing., Diplom Physics
Time and frequency metrology: time keeping, time and frequency dissemination, synchronization

About

132
Publications
23,271
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Introduction
Dirk Piester received his diploma degree in physics and Dr.-Ing. degree from the Technische Universität Braunschweig. Since 2002, he has been with the Time Dissemination Group of PTB where he is in charge of PTB’s time services. His main research interest is the comparison of remote atomic clocks and time scales via telecommunication and navigation satellites as well as optical fibers. In this framework two fellowships (in 2007 and 2010) were granted by the Japan Society for the Promotion of Science (JSPS). He chaired the Consultative Committee for Time and Frequency Working Group on Two-Way Satellite Time and Frequency Transfer from 2009 to 2015 and he is engaged in technical assessments for Germany’s national accreditation body DAkkS.
Additional affiliations
July 2002 - present
Physikalisch-Technische Bundesanstalt
April 1999 - June 2002
Technische Universität Braunschweig
Education
April 1999 - June 2002
Technische Universität Braunschweig
Field of study
  • Semiconductor Technology
October 1993 - March 1999

Publications

Publications (132)
Article
Full-text available
In the global network of institutions engaged with the realization of International Atomic Time (TAI), atomic clocks and time scales are compared by means of the Global Positioning System (GPS) and by employing telecommunication satellites for two-way satellite time and frequency transfer (TWSTFT). The frequencies of the state-of-the-art primary ca...
Technical Report
Two-way satellite time and frequency transfer (TWSTFT) has been developed into a widely used technique of time and frequency transfer between laboratories that contribute, with their atomic clocks and, in some cases, with their primary frequency standards, to the realization of International Atomic Time (Temps Atomique International, TAI). The TWST...
Article
Any mobile telecommunications network requires syntonization among its various elements. The need to exploit the available radio spectrum efficiently and providing new kinds of services render frequency syntonization insufficient. Phase and time-of-day synchronization will be necessary in the future. Thus, network operators are searching for effici...
Article
We carried out a 26-day comparison of five simultaneously operated optical clocks and six atomic fountain clocks located at INRIM, LNE-SYRTE, NPL and PTB by using two satellite-based frequency comparison techniques: broadband Two-Way Satellite Time and Frequency Transfer (TWSTFT) and Global Positioning System Precise Point Positioning (GPS PPP). Wi...
Article
Laboratory sources for standard frequency and time that receive external time signals to control their built‐in oscillators are widely used wherever accurate and stable frequency and time, optionally with universal synchronization, are required. We propose a method to obtain traceability of such signals to Coordinated Universal Time (UTC) and parti...
Conference Paper
Frequency counters are widely used in industry laboratories to facilitate routine frequency measurement and calibration services. Such services require evidence of traceability to internationally recognized standards if an accreditation is sought. And it is the responsibility of the operator to demonstrate his ability and practices to comply with r...
Conference Paper
Packet delay asymmetry and jitter are known to be major factors limiting the time accuracy in network-based synchronization protocols. One aim of the UTIME project was to better understand the network asymmetry and jitter problem and to try improving the current limitations. To this purpose two network links have been established in Germany. Link A...
Conference Paper
This paper presents a complete study and characterization of a two-way satellite time and frequency transfer link between two remote earth stations equipped with analog modems and software-defined radio receivers driven by atomic clocks. Techniques based on code-phase and carrier-phase measurements were developed to compute time and frequency devia...
Article
Full-text available
A correction to this paper has been published: https://doi.org/10.1007/s10291-021-01146-7
Conference Paper
TWSTFT has been one of the most popular techniques used for comparison of remote atomic clocks. It typically employs the code-phase of a signal modulated by a pseudorandom noise (PN) code sent and received by microwave link via a geostationary telecommunications satellite [1]. The National Institute of Information and Communications Technology (NIC...
Article
Full-text available
The realization of Coordinated Universal Time, one of the tasks of the International Bureau of Weights and Measures, relies on a network of international time links which currently is organized in a star-like scheme that links all contributing laboratories. GPS signal reception is the technique most widely employed by the laboratories. The PTB curr...
Conference Paper
By law PTB is entrusted with realization and dissemination of legal time for Germany, which is defined as UTC(PTB) plus one or two hours. During the last 24 months, including December 2019, UTC(PTB) did not deviate from Coordinated Universal Time UTC by more than 3.2 ns. The services of dissemination can be grouped in “traditional”, “IT-based”, and...
Article
Seit vielen Jahren nimmt die Bedeutung des Internets bzw. des World Wide Web (WWW, Web) stetig zu. Damit geht die Erwartung vieler Menschen einher, alle für sie relevanten Informationen im Web zu finden. Der Browser und seine unterstützenden Technologien entwickeln sich zum universellen Instrument auf dem Weg in die Wissensgesellschaft. Daher liegt...
Preprint
Full-text available
We carried out a 26-day comparison of five simultaneously operated optical clocks and six atomic fountain clocks located at INRIM, LNE-SYRTE, NPL and PTB by using two satellite-based frequency comparison techniques: broadband Two-Way Satellite Time and Frequency Transfer (TWSTFT) and Global Positioning System Precise Point Positioning (GPS PPP). Wi...
Conference Paper
The use of disciplined oscillators offers a straight forward tool to establish traceability of the measurands frequency and time to national standards and ultimately to Coordinated Universal Time (UTC). Traceability means that a complete and unbroken chain of calibrations exists from the measurement device to the respective standard, and that each...
Article
Two-way satellite time and frequency transfer (TWSTFT) is a primary technique for the generation of coordinated universal time (UTC). At present, more than 12 timing laboratories around the world use SAtellite Time and Ranging Equipment (SATRE) modems in TWSTFT operations and contribute data for the realization of UTC. The advantages of TWSTFT are...
Conference Paper
Laboratory sources for standard frequency, one pulse-per-second (1pps) ticks, and time-of-day information which receive external time signals to control their built-in oscillators are widely used wherever accurate and stable frequency and time optionally with universal synchronization are required. Nowadays, such devices mostly apply the signals re...
Conference Paper
The comparison of distant clocks has always been an important part of time metrology. It is important in science in general as well as in everyday applications. Signals from the satellites of the Global Positioning System (GPS) started to be used for the purpose in the early 1980s. This is of course ongoing, and the Time and Frequency Department of...
Article
We report on the evaluation of the performance of optical time transfer links connecting a facility of Deutsche Telekom in Bremen with the Physikalisch-Technische Bundesanstalt in Braunschweig. In the current configuration three links have been established, two via a hub in Hannover and one using an independent alternate route. They are equipped wi...
Article
Full-text available
Two-way satellite time and frequency transfer (TWSTFT) is a primary technique for the generation of coordinated universal time (UTC). About 20 timing laboratories around the world continuously operate TWSTFT using satellite time and ranging equipment (SATRE19) modems for remote time and frequency comparisons in this context. The precision of the SA...
Conference Paper
Optical time transfer between PTB and Deutsche Telekom started in 2015. Since December 2016 it has been upgraded to a permanent installation connecting PTB and Deutsche Telekom facilities in Hannover and Bremen. In this paper we report on the evaluation of the performance of this installation and describe future perspectives.
Article
Zusammenfassung Die Rückführung eines als Frequenznormal betriebenen disziplinierten Oszillators (DO) auf gesetzliche Einheiten im Rahmen von Akkreditierungen nach DIN EN ISO/IEC 17025 wird beschrieben. Der Fokus liegt dabei auf der für die Rückführung wichtigen Anbindung von in Kalibrierlaboren betriebenen DOs über die Zeitsignale von GPS, Galileo...
Conference Paper
Full-text available
PTB’s time services accessible to the common public comprise the operation of Network Time Protocol (NTP) servers, a telephone time service and the standard frequency and time dissemination by the low frequency transmitter DCF77. New achievements in such services have been gained by improving the timing infrastructure for connecting external facili...
Conference Paper
Full-text available
Two-Way Satellite Time and Frequency Transfer (TWSTFT or TW for short) is one of the primary techniques for the realization of Coordinated Universal Time (UTC), which is computed by the International Bureau of Weights and Measures (BIPM). TWSTFT is carried out continuously by about 20 timing laboratories around the world. One limiting factor of the...
Conference Paper
We report on the upgrade of a fiber optic network for time and frequency transfer between PTB in Braunschweig and the test center of Deutsche Telekom in Bremen, Germany. The network provides 10 MHz and 1 PPS signals at remote locations intended for the supervision of the mobile telecommunication network of Deutsche Telekom. Here we present the resu...
Conference Paper
We report on the initial use of Galileo signals in the Time and Frequency Department of Physikalisch-Technische Bundeanstalt (PTB). To this end PTB operated five GNSS receivers capable of receiving Galileo Open Service signals with calibrated signal delays for the two frequencies E1 and E5a.
Conference Paper
We report on a new means for obtaining time information via long-wave signals, provided by Europäische Funkrundsteuerung GmbH (EFR) via three transmitters located at Mainflingen, Germany (129.1 KHz), Burg, Germany (139.0 kHz), and Lakihegy, Hungary (135.6 kHz), respectively. The signals are received and continuously monitored by Physikalisch-Techni...
Article
A robust and reliable synchronization network, able to distribute signals traceable to a recognized standard, is crucial for the operation of future 5G telecommunication networks. In this article we present the results of time transfer using optical fibers. The main goal is to test the long-term capability of ELSTAB technology (developed by AGH) to...
Conference Paper
Full-text available
The recent activities in the field of time and frequency dissemination and applications at PTB resulted in improved quality and a wider reach of the offered services. The basis of these activities remains PTB’s local realization of Coordinated Universal Time UTC(PTB). PTB’s time services comprise the operation of NTP time servers, a telephone time...
Conference Paper
Full-text available
The International Bureau of Weights and Measures and the Consultative Committee for Time and Frequency Working Group on Two-Way Satellite Time and Frequency Transfer (TWSTFT) have stimulated a pilot study on using software defined radio (SDR) receivers for TWSTFT in the framework of the realization of Coordinated Universal Time. The SDR receivers b...
Conference Paper
Full-text available
Deutsche Telekom together with AGH and PTB @ ITSF 2016 Optical Time Transfer (OTT): PoC Results and Next Steps Proof of Concept results with Optical Time Transfer, Electronically Stabilized (ELSTAB) method acc. to AGH University Krakow, Poland at Deutsche Telekom network at Germany are shown.
Conference Paper
This paper describes the carrier-phase two-way satellite time and frequency transfer experiment performed between the metrology institutes PTB (Braunschweig) and LNESYRTE/OP (Paris) using ground stations equipped with dedicated modem equipment developed by NICT. The frequency instability of the PTB-OP link reached 4x10-16 at 1 day, a performance of...
Conference Paper
Two-Way Satellite Time and Frequency Transfer (TWSTFT or TW) is one of the primary time transfer techniques for UTC generation. In this framework the Triangle Closure Calibration (TCC) method has been used to calibrate links between certain laboratories whose links to the pivot lab are directly calibrated. TCC is based upon requiring the closure of...
Conference Paper
The operation of a mobile telecom network relies directly on the synchronization of thousands of base stations that must be robust and operate reliably 24 hours a day. Nowadays networks using advanced Long Time Evolution (LTE) standard need not only frequency syntonization, but also time synchronization that should ideally be traceable to UTC. In t...
Conference Paper
We performed a carrier-phase two-way satellite frequency transfer (TWCP) experiment between LNE-SYRTE and PTB for several days in September 2015. Different hardware configurations were analyzed at the LNE-SYRTE earth station and a suitable configuration was identified by placing up- and down-converters indoors. Additionally atomic fountain frequenc...
Conference Paper
Full-text available
Two-Way Satellite Time and Frequency Transfer (TWSTFT) links were first introduced to Coordinated Universal Time (UTC) generation in 1999. These TWSTFT links were calibrated by alignment with the corresponding GPS time links, of which the nominal uncertainty was 5 ns. In the past decade, the primary calibration technique for TWSTFT link calibration...
Conference Paper
During 2014 (June 5th to August 17th), a campaign intended for the calibration of the time transfer links at the nanosecond uncertainty level established via Two-Way Satellite Time and Frequency Transfer (TWSTFT) between the Galileo Precise Timing Facilities PTF1 and PTF2, and five UTC(k) laboratories associated to the Galileo Full Operational Capa...
Presentation
Nowadays, atomic clocks are widely used in areas where precise time and frequency are essential. Examples are telecommunication (network synchronization), satellite navigation (GPS), and astronomy (VLBI). One aspect in time and frequency metrology is the realization of the scale interval of the second as defined in the international system of units...
Article
Full-text available
Wo kommt die Weltzeit her? Welche Rolle spielen die Atomuhren der Physikalisch-Technischen Bundesanstalt dabei? Wie wird in Deutschland die Zeit gemacht und wie wird sie verbreitet? Diese Fragen werden im Folgenden erörtert.
Conference Paper
Full-text available
The recent activities in the field of time and frequency dissemination and applications at PTB were directed towards an improvement in quality and reliability of the offered services. As a foundation of its work, PTB has substantially improved the quality of its local realization of Coordinated Universal Time UTC(PTB). Since February 2010 UTC(PTB)...
Conference Paper
To continue and improve the earlier studies by different authors [1-4], in 2011 the BIPM launched a pilot study on the accurate calibration for the UTC time links [5]. The goal is to unify the UTC time link calibration uncertainties ≤ 2 ns. This is attainable with the ‘one for all’ METODE scheme and a dedicatedly designed travelling calibrator (Std...
Conference Paper
A remote comparison campaign of Caesium fountain clocks from four National Metrology Institutes in Europe and Asia was carried out in May 2013. Six fountains at Physikalisch-Technische Bundesanstalt (PTB) Germany, Scientific Research Institute of Physical-Technical and Radio Technical Measurements (VNIIFTRI-SU) Russia, National Physical Laboratory...
Conference Paper
Two strontium lattice clocks, one in Japan and the other in Germany were directly compared by a two-way satellite frequency transfer technique that utilizes the carrier phase of the transmitted signal. The comparison has resulted in a fractional difference of 1.1(1.6)×10-15, directly confirming the frequency agreement on an intercontinental scale.
Article
Full-text available
We have demonstrated a direct frequency comparison between two $^{87}{\rm Sr}$ lattice clocks operated in intercontinentally separated laboratories in real time. Two-way satellite time and frequency transfer technique based on the carrier phase was employed for a direct comparison with a baseline of 9 000 km between Japan and Germany. A clock compa...
Article
In this paper we report that carrier-phase two-way satellite time and frequency transfer (TWSTFT) was successfully demonstrated over a very long baseline of 9,000 km, established between the National Institute of Information and Communications Technology (NICT) and the Physikalisch-Technische Bundesanstalt (PTB). We verified that the carrier-phase...
Article
The recent activities in the field of time and frequency dissemination and applications at PTB were directed towards an improvement in quality and reliability of the offered services. As a foundation of its work, PTB has substantially improved the quality of its local realization of Coordinated Universal Time UTC(PTB). Since February 2010 UTC(PTB)...
Conference Paper
Full-text available
A new collaborative European project “International timescales with optical clocks” (ITOC) aims to tackle the key challenges that must be addressed prior to a redefinition of the SI second. A coordinated programme of comparisons will be carried out between European optical clocks developed in five different laboratories, enabling their performance...
Conference Paper
In November 2012 the time transfer links between Physikalisch-Technische Bundesanstalt (PTB), Observatoire de Paris (OP/LNE-SYRTE), Swiss Federal Institute of Metrology (METAS), and TimeTech GmbH were calibrated using TimeTech's mobile TWSTFT calibration station for the first time.
Conference Paper
We describe experiments with the AGH-designed fiber optic system for time and frequency dissemination, based on an active stabilization of the fiber delay. The measurements were performed at the Physikalisch-Technische Bundesanstalt, Braunschweig, over a field-deployed optical fiber loop going from PTB to the Magnesium clock laboratory in the Leibn...
Article
The Atomic Clock Ensemble in Space (ACES) will be a future ESA experiment which utilizes ultra-stable clocks on-board the International Space Station (ISS). This mission is expected to perform tests of fundamental physics (relativity, possible drift of fundamental constants with time) and at the same time allows to compare the ACES time reference w...
Conference Paper
Full-text available
The relative calibration of the GPS time link between European Organization for Nuclear Research (CERN) and Gran Sasso National Laboratory (LNGS), performed in 2011, is reviewed. “Relative” means that traveling equipment was used to calibrate the delay of the link as a whole, but no information on absolute delays of individual components was gained...
Article
Full-text available
We demonstrate the capability of accurate time transfer using optical fibers over long distances utilizing a dark fiber and hardware which is usually employed in two-way satellite time and frequency transfer (TWSTFT). Our time transfer through optical fiber (TTTOF) system is a variant of the standard TWSTFT by employing an optical fiber in the tran...
Article
The Physikalisch-Technische Bundesanstalt (PTB) has substantially improved the quality of its local time scale UTC(PTB), which is the national realization of the international time reference Coordinated Universal Time (UTC). It serves as the basis for PTB's time services, for local clock comparisons and for international time comparisons. Since Feb...
Conference Paper
Full-text available
Since 2010 ROA has supported the coordination of the EURAMET Technical Committee for Time and Frequency (TC-TF) Project 1156, GPSCALEU, a reaction from EURAMET TC-TF to Recommendation 2 of CCTF 2009: to study the characterization of GNSS equipment in use for establishing the time links between institutes contributing with their clocks to TAI. Start...
Conference Paper
Full-text available
Two-Way Satellite Time and Frequency Transfer (TWSTFT) using geostationary telecommunication satellites has become an important technique for comparing remote timescales. There is a need for periodic calibration of the signal delays along the links which are part of the network for the realization of the International Atomic Time (TAI). In order to...
Conference Paper
Full-text available
For over fifty years the Physikalisch-Technische Bundesanstalt (PTB) has disseminated time signals and standard frequency by means of the low-frequency transmitter DCF77. In addition, since the 1970s legal time for Germany has been broadcast using coded time information by way of amplitude modulated second markers. This service, especially, has bec...
Conference Paper
GNSS-based time transfer is the prevalent technique used in the generation of Coordinated Universal Time (UTC); in September 2011, 56 links out of the total of 67 were GNSS-only. These links are realized by combining the data from a single GNSS receiver in each of the time laboratories involved. Some modern receivers have shown only sub-nanosecond...
Conference Paper
The Physikalisch-Technische Bundesanstalt (PTB) has substantially improved the quality of its local time scale UTC(PTB), which serves as the national realization of the international time reference Coordinated Universal Time (UTC). Since February 2010 UTC(PTB) has been realized using an active hydrogen maser (AHM) steered in frequency via a phase m...
Conference Paper
The time transfer link between NIM and PTB was for the first time calibrated using a travelling GPS receiver developed by NIM. The calibration uncertainty was estimated to about 2 ns. The result obtained could be compared to the result derived from differential calibrations made by BIPM in previous years. Both results agree well within 1 ns.
Conference Paper
The Physikalisch-Technische Bundesanstalt (PTB) realizes its atomic time scale UTC(PTB) as approximation to the international time reference UTC. It serves as the basis for PTB's time services, for the local clock comparisons and for international time comparisons. Since February 2010 UTC(PTB) has been realized using an active hydrogen maser steere...
Conference Paper
Two-way satellite time and frequency transfer between Asia and Europe has been performed for many years first by a two-transponder and later by a one-transponder configuration on the IS-4 and the AM-2 satellites, respectively. A diurnal phase instability was observed in links established through IS-4, while such instability has not been observed wh...
Conference Paper
Two-way satellite time and frequency transfer connecting Asia with Europe continued for four years using Intelsat-4. Six institutes in Asia and two in Europe participated in this network. Frequency instabilities of some links reached first half of \(10^{-15}\) at an averaging time of 1 day, which enables us the meaningful direct comparison between...
Conference Paper
Full-text available
Two self-developed GPS receivers of NIM (National Institute of Metrology), which are based on a Javad E_GGD receiver and a NovAtel OEMV3 receiver, respectively, have been installed and operated at PTB (Physikalisch-Technische Bundesanstalt) for a time transfer link calibration between both institutes. During the operation of the traveling receivers...
Conference Paper
Full-text available
Two-Way Satellite Time and Frequency Transfer (TW for short) is one of the primary techniques for UTC (Coordinated Universal Time) time transfer. One of its advantages is its ability of accurate calibration, reflected by its low achievable Type B uncertainty, uB(TW). Of the time links included in the calculation of UTC, the best uB(TW) is about 1 n...