1 Introduction
2 Background
2.1 The origins of UTC
2.2 Organizations with responsibilities related to UTC
2.2.1 International Telecommunication Union
2.2.2 BIPM, CIPM and CGPM
2.2.3 IERS
2.3 Other organizations associated with time scales and related
standards
2.3.1 IAU
2.3.2 IUGG
2.3.3 IGS
2.3.4 URSI
2.3.5 International Civil Aviation Organization (ICAO)
2.3.6 International Maritime Organization (IMO)
2.3.7 World Meteorological Organization (WMO)
2.3.8 International Committee on GNSS (IGS)
2.3.9 International Organization for Standardization
(ISO)
3 Description of current and potential future reference time scales
3.1 Description of current time scales including reference time
scale
3.1.1 Solar time
3.1.2 Ephemeris time
3.1.3 Atomic time
3.1.4 International Atomic Time
3.1.5 Coordinate time scales
3.1.6 Coordinated Universal Time
3.2 Motivation
for changing the leap-second procedure
3.3 Description of potential future reference time scales
4 Systems for dissemination of time signals
4.1 Introduction
4.2 Radiocommunication services
4.2.1 VLF broadcasts
4.2.2 LF broadcasts
4.2.3 HF broadcasts
4.2.4 Television broadcasts
4.2.5 Global navigation systems (broadcast)
4.2.6 Augmentation systems for global navigation systems
and regional navigation systems (broadcast)
4.2.7 Meteorological-satellite
4.2.8 Communications satellites (two-way mode)
4.3 Other dissemination systems
4.3.1 Telephone time dissemination services
4.3.2 Internet-based time dissemination services
4.3.3 Optical fibre-based time dissemination services
5 Use of UTC in radiocommunication services, technology, science and other
applications
5.1 Radiocommunication services
5.1.1 Radionavigation-satellite services
5.1.2 Radio astronomy service
5.1.3 Mobile-satellite service
5.1.4 Fixed-satellite service
5.1.5 Broadcasting-satellite service
5.1.6 Mobile service (MS)
5.1.7 Maritime mobile service, including global maritime
distress and safety service (GMDSS), aeronautical mobile service and
radiodetermination service
5.1.8 Digital systems
5.1.9 Time-stamping service
5.1.10 Financial services
5.1.11 Maritime navigation
5.2 Time metrology and traceability
5.3 Astronomy
5.4 Geodesy
5.5 Radio sciences
5.6 Meteorology
5.7 IT and Industry 4.0
6 Impact of a possible change of UTC to a continuous time scale in
radiocommunication services, technology, science and other applications
6.1 Impact on radionavigation-satellite service
6.1.1 Advantages and disadvantages of using the current
UTC
6.1.2 Advantages and disadvantages of using a possible
continuous UTC
6.1.3 Measures and time period required for
radionavigation-satellite service to implement changes of UTC
6.2 Impact on mobile-satellite service, fixed-satellite service and
broadcasting-satellite service
6.2.1 Advantages and disadvantages of using the current
UTC
6.2.2 Advantages and disadvantages of using a possible
continuous UTC
6.2.3 Measures and time period required for
mobile-satellite service, fixed-satellite service and broadcasting-satellite
service to implement changes of UTC
6.3 Impact on the mobile service
6.3.1 Advantages and disadvantages of using the current
UTC
6.3.2 Advantages and disadvantages of using a possible
continuous UTC
6.3.3 Measures and time period required for mobile
service to implement changes of UTC
6.4 Impact on the radio astronomy service
6.4.1 Advantages and disadvantages of using the current
UTC
6.4.2 Advantages and disadvantages of using a possible
continuous UTC
6.4.3 Measures and time period required for radio
astronomy service to implement changes of UTC
6.5 Impact on the maritime mobile service, including global
maritime distress and safety service (GMDSS), aeronautical mobile service and
radiodetermination service
6.5.1 Advantages and disadvantages of using the current
UTC
6.5.2 Advantages and disadvantages of using a possible
continuous UTC
6.5.3 Measures and time period required for maritime
mobile service to implement changes of UTC
6.6 Impact on Maritime navigation
6.6.1 Advantages and disadvantages of using the current
UTC
6.6.2 Advantages and disadvantages of using a possible
continuous UTC
6.6.3 Measures and time period required for maritime
navigation to implement changes of UTC
6.7 Impact on Astronomy
6.7.1 Advantages and disadvantages of using the current
UTC
6.7.2 Advantages and disadvantages of using a possible
continuous UTC
6.7.3 Measures and time period required for Astronomy to
implement changes of UTC
6.8 Impact on Geodesy
6.8.1 Advantages and disadvantages of using the current
UTC
6.8.2 Advantages and disadvantages of using a possible
continuous UTC
6.8.3 Measures and time period required for Geodesy to
implement changes of UTC
6.9 Impact on radio sciences
6.9.1 Advantages and disadvantages of using the current
UTC
6.9.2 Advantages and disadvantages of using a possible
continuous UTC
6.9.3 Measures and time period required for radio
sciences to implement changes of UTC
6.10 Impact on Time metrology and traceability
6.11 Impact on IT and Industry 4.0
6.12 Impact on digital systems
6.12.1 Solutions to address the occurrence of a leap
second in digital representations
6.12.2 Summary of the impact on digital systems
6.13 Impact on the time-stamping service
6.13.1 Advantages and disadvantages of using the current
UTC
6.13.2 Advantages and disadvantages of using a possible
continuous UTC
6.13.3 Measures and time period required for
time-stamping service to implement changes of UTC
6.14 Impact on financial services
6.14.1 Advantages and disadvantages of using the current
UTC
6.14.2 Advantages and disadvantages of using a possible
continuous UTC
6.14.3 Measures and time period required for financial
services to implement changes of UTC
6.15 Impact of a continuous international reference for time on the
IERS and EOP users
6.15.1 Impact of a continuous international reference for
time on the IERS
6.15.2 Impact of a continuous international reference for
Time on EOP Users
6.16 Impact on other applications
7 Conclusion / Summary of relevant issues considered in this Report
8 References