1. Department of Multimedia and Information-Communication Technologies, Faculty of Electrical Engineering and Information Technology, University of Žilina, Univerzitná 8215/1, 010 26 Žilina, Slovakia
2. Electronic and Electrical Engineering Department, University of Strathclyde, 204 George Street, Glasgow G1 1XW, UK
3. Institute of Aurel Stodola, Faculty of Electrical Engineering and Information Technology, University of Žilina, Komenského 843, 031 01 Liptovský Mikuláš, Slovakia