Monitoring method with function of correlation-based system identification

A monitoring method with a function of correlation-based system identification applicable for a digitally controlled DC-DC converter system is revealed. The monitoring method includes a plurality of steps. After the system is operated in a steady state, input a pseudo random binary sequence signal into the system via a pseudo random binary sequence generator and store the pseudo random binary sequence signal and an output signal of a path to be monitored in a memory unit. Then perform a correlation analysis of data stored in the memory unit by a correlation analysis module and output an impulse response. Next obtain a frequency response of the impulse response by a discrete-time Fourier transform module. Finally, smooth the frequency response by an adaptive sliding window