1 Electronics Telecommunication and Computer Dept. ISEL-IPL, R. Conselheiro Emídio Navarro, 1959-007 Lisboa, Portugal
2 CTS-UNINOVA, Quinta da Torre, Monte da Caparica, 2829-516, Caparica, Portugal
3 DEE-FCT-UNL, Quinta da Torre, Monte da Caparica, 2829-516, Caparica, Portugal
Tel.: + 351218317000
* E-mail: plouro@deetc.isel.ipl.pt