Educational Virtual Instrumentation Application for System Identification

The PC based virtual instrumentation is a dynamic and attractive alternative to the classic instrumentation. Its main advantages are: flexibility and adaptability, low cost, wide development of extension PC boards with measurements features, attractive representation of measurement results, in different forms, on the PC´s monitor. The paper presents a system identification application with PC based (virtual) instrumentation. The virtual system is made of an external board, connected to the PC via the USB interface and a software tool, Agilent VEE (Visual Engineering Environment). The presented virtual system can work as a voltmeter, ammeter, signal generator, digital oscilloscope and power supply. The main contribution of the paper is the extension of the application domain of the virtual instrumentation system to system identification. The identification method consists of applying to the system input a binary pseudorandom signal (BPRS) and determining the impulse response of the system as being well approximated by the cross-correlation function between the input signal and the answer of the system. The application is intended for educational purposes but can be used in other areas too