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Vol: 53(67) No: 2 / June 2008 Signal Processing Issues in Networked Control Systems Radu-Emil Precup Department of Automation and Applied Informatics, “Politehnica” University of Timisoara, Faculty of Automation and Computers, Bd. V. Parvan 2, RO-300223 Timisoara, Romania, phone: +40-256-4023-29, e-mail: radu.precup@aut.upt.ro, web: http://www.aut.upt.ro/~rprecup Stefan Preitl Department of Automation and Applied Informatics, “Politehnica” University of Timisoara, Faculty of Automation and Computers, Bd. V. Parvan 2, RO-300223 Timisoara, Romania, e-mail: stefan.preitl@aut.upt.ro, web: http://www.aut.utp.ro/~spreitl Igor Škrjanc Laboratory of Modelling, Simulation and Control, University of Ljubljana, Faculty of Electrical Engineering, Tržaška 25, 1000 Ljubljana, Slovenia, phone: +386 (0)1 4768-311, e-mail: igor.skrjanc@fe.uni-lj.si, web: http://msc.fe.uni-lj.si/Staff.asp?person=7 Ion-Bogdan Ursache Department of Automation and Applied Informatics, “Politehnica” University of Timisoara, Faculty of Automation and Computers, Bd. V. Parvan 2, RO-300223 Timisoara, Romania, e-mail: bogdan.ursache@aut.upt.ro Petru Alexandru Clep Department of Automation and Applied Informatics, “Politehnica” University of Timisoara, Faculty of Automation and Computers, Bd. V. Parvan 2, RO-300223 Timisoara, Romania, e-mail: alexandru.clep@aut.upt.ro Claudia-Adina Dragos Department of Automation and Applied Informatics, “Politehnica” University of Timisoara, Faculty of Automation and Computers, Bd. V. Parvan 2, RO-300223 Timisoara, Romania, e-mail: claudia_dragos_83@yahoo.com Keywords: networked control systems, real-time experiments, Hilbert-Huang transform Abstract The paper deals with the treatment of some issues specific to the signal processing in the framework of networked control systems (NCSs). The time delay is important and therefore the numerical problems related to the transcendental form of the characteristic equation are tackled. The paper analyzes also the performance of the NCSs reviewing the previous research regarding the influence of the sampling rate, network delay and dropped packets on the control system performance. In this context the Hilbert-Huang transform is applied to smooth the signals and the rapidly variable time delay in the communication between the operator and remote sites. On example of controllers developed for NCSs is represented by the sliding mode controllers. 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