Please note this course is only available for private cohorts. Please contact NPL Training if you would like more information on enrolling a cohort.

The second is the SI unit used to measure time. As well as enabling us to tell the time of the day, accurate timekeeping is key to satellite navigation systems, underpins the functioning of the internet and facilitates highly accurate timestamping for transactions in financial trading.

Ancient civilisations used sundials and obelisks to tell the time, which was imprecise, and restricted in cloudy weather or at night. These methods of timekeeping were based on the daily rotation of the Earth around its own axis. However, this period of rotation is not regular enough to serve as a definition for modern-day applications.

Atomic clocks, which keep time using transition energies in atoms, revolutionised timekeeping. The National Physical Laboratory (NPL) developed the first operational caesium-beam atomic clock in 1955. This clock was so accurate that it would only gain or lose one second in 300 years, but modern atomic clocks can be as much as a million times more accurate than this.

The Second and Time and Frequency Metrology course is part of NPL’s Fundamentals of Metrology training programme. This programme is comprised of seven standalone modules, each corresponding to one of the seven SI base units. The module is delivered via a series of pre-recorded video lectures and includes a scheduled live group Q&A session with metrology experts from NPL. Please note this course is only available for private cohorts. Please contact NPL Training if you would like more information on enrolling a cohort.

This course includes the following topics:

• Time scales and time dissemination services.
• Characterisation of clocks and oscillators.
• Principles of atomic clocks.
• Compact atomic clocks: design and engineering.
• Femtosecond optical frequency combs.
• Optical frequency comparison and dissemination using optical fibre links.
• The future of timekeeping.

Learners who successfully complete the course will receive an NPL Certificate of Completion.

Module Prerequisites
To lay the foundations for this module, all learners are provided with access to two half-day NPL e-learning courses: Introduction to Measurement and Metrology and Introduction to Measurement Uncertainty. Learners should complete both of these courses before starting this module.