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conferenceseries.com
Volume 6, Issue 2 (Suppl) J Aeronaut Aerospace Eng
ISSN: 2168-9792 JAAE, an open access journal Satellite 2017
May 11-13, 2017
May 11-13, 2017 Barcelona, Spain
3rd International Conference and Exhibition on
Satellite & Space Missions
Optimal detection of changes in real-time data: Applications in satellites
Peter Johnson
University of Manchester, UK
Detecting changes in random processes as quickly and accurately as possible is important for many scenarios. Examples include:
detecting a plane using radar; identifying nuclear material at ports; reacting to breakages in atomic clocks on satellites and;
determining when is the best time to buy/sell stocks and shares. Using advanced applied probability, it is possible to provide an
optimal time to stop and declare that a change has occurred (optimal in the sense of minimizing the delay after the change) with a
fixed probability of error. This collaborative work looks at problems of this type applied to issues in detecting breakages in clocks on
board satellites. The sophisticated solutions of these optimal stopping problems show that the first hitting time of a test statistic to a
defined boundary is the quickest possible decision time for a given level of accuracy (see figure). This means that no other method
can outperform the algorithms used, which is a valuable asset in high performance systems. This research has two high profile satellite
applications: The New Horizons mission, and The Galileo Project. Most recently solutions of this type have been involved in helping
engineers from NASA detect an unusual change in the two on-board quartz clocks (which are replied upon to beam accurate data
back to earth) as its satellite passed Pluto. These methods are also helping resolve similar problems in detecting the breakages in
the atomic clocks used in the Galileo project; the first global navigation system primarily for civilian use is being developed by the
European Union. The accuracy of these clocks is critical to accurate positioning with a 100 nanosecond error meaning positioning
could be out by up to 30 meters on the ground.
Biography
Peter Johnson is currently pursuing his Post-doctorate studies at University of Manchester, Manchester. He has mainly worked with optimal stopping and free
boundary problems in the area of sequential analysis. However, he also has a keen interest in “HMM tracking algorithms, filtering theory and non-linear optimal
stopping problems”. His research area is Applied Probability.
Peter Johnson, J Aeronaut Aerospace Eng 2017, 6:2(Suppl)