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John Davis

John Davis

Principal scientist

John is the Science Area Leader for the National Time Scale Group. He joined NPL in 1986 after completing a PhD in ammonia masers at Keele University.

John initially worked on the development of an optically pumped caesium clock. He then moved to working on satellite time transfer methods, using television signals, GNSS and two-way methods using communication satellites. This involved collaborative work with other National Measurement Institutes, along with UK industry, including the collaborative development of a timing GNSS receiver.

John has worked on the developments on Kalman-filter-based clock ensembles, steering algorithms and clock predictors, in particular the modelling of clocks and measurement noise.

Much of John’s later work has been on a range of collaborations with other National Measurement Institutes, and organisations in the UK with interests in time and frequency. This has included work on the Galileo reference time scale, time scale aspects of GNSS vulnerability, and the design of time scales for the Square Kilometre Array radio telescope.

John’s work is currently focused on the development of a distributed time scale within the National Timing Centre programme.  

Areas of interest

  • Development of clock and time scale algorithms including ensemble and steering algorithms
  • Kalman filters, clock and time transfer models
  • GNSS systems
  • Time and frequency transfer and dissemination techniques
  • Design and development of robust time scales

Key publications

Email John Davis