信号与系统奥本海姆原版PPT第六章教案.ppt

6 Time and frequency characterization of SS Problems: 6.5 6.23 6.27 * * * * * * * * * * * * * * * * * * * * * * * 6 Time and frequency characterization of SS 6.1 The Magnitude-phase Representation of the Fourier Transform For signal x(t) : 6. Time and Frequency Characterization of Signals and Systems * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS 6.2 The Magnitude-phase Representation of the Frequency Response of LTI System System characterization: Impulse response: Frequency response: * 6 Time and frequency characterization of SS 6.2.1 Linear and Nonlinear Phase Linear phase: Nonlinear phase: Example: Effect: Linear phase means non-distortion of signal transmission. * 6 Time and frequency characterization of SS ( Linear phase ) ( Nonlinear phase ) ( Original signal ) * 6 Time and frequency characterization of SS 6.2.2 Group Delay Definition: Example: Distortionless system: is flat. * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS 6.2.3 Log-Magnitude and Bod Plots Magnitude spectrum: Phase spectrum: * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS 6.3 Time-Domain Properties of Ideal Frequency- selective Filters Lowpass filter: (1) Continous time: (2) Discrete time: * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS 6.4 Time-Domain and Frequency-domain Aspects of Non-ideal Filters Basic parameter of lowpass filter: * 6 Time and frequency characterization of SS * 6 Time and frequency characterization of SS * 6 Time and frequency characterizatio