1. University of Liverpool, Jane Herdman Building, 4 Brownlow Street, Liverpool L69 3GP, United Kingdom, Jack.Woollam@liverpool.ac.uk, S.De-Angelis@liverpool.ac.uk
2. Geophysical Institute (GPI), Karlsruhe Institute of Technology, Hertzstraße 16, 76187 Karlsruhe, Germany, andreas.rietbrock@kit.edu
3. Department of Signal Theory, Telematics and Communications, University of Granada, Calle Periodista Daniel Saucedo Aranda, 18014 Granada, Spain, angelbueno@ugr.es