dsp总结(mitra).ppt

DSP group Chap-3 Chapter 10 FIR Digital Filter Design Impulse response of ideal filters Lowpass digital filters Highpass digital filters Bandpass digital filter Bandstop digital filter FIR Filter Design Based on Windowed Fourier Series Convolution in frequency domain where DTFT Truncation in time domain DSP group 2007 chap10-ed1 1.84 ? /N 20.9dB 4?/(N+1) 13.3dB Rect. 11.12 ? / N 6.64 ? / N 6.22 ? /N Transition Bandwidth ?? 75.3dB 12 ? /N 58.1dB Blackman 54.5dB 8 ? /N 42.7dB Hamming 43.9dB 8 ? /N 31.5dB Hanning 4 ? /N 26.5dB Bartlett Minimum Stopband Attenuation Main-lobe width Relative Sidelobe Level Type of window 10.2.4 Fixed Window Functions ---- table 10.2 (1) Determine the suitable window by the minimum stopband attenuation (3) Compute impulse response of the desired filter (according to the IDTFT) with ?c (4) Obtain the designed FIR filter: (2) Determine the length of FIR by the transition width ?? (10.39’) N Kaiser window ? = N/2 Chap 11 DFT Algorithm Implementation Compute DFT directly: complex multiplications: N2 times complex additions: N(N-1) times. (1) ------complex conjugate symmetry (2) ------periodicity in n and k The symmetry and periodicity properties of WN k n : * Chap 2 Discrete-Time Signals and Systems Classification of Sequences Conjugate-symmetric sequence xcs[n] : xcs[n]= xcs*[?n] Conjugate-antisymmetric sequence xca[n] : xca[n]= ? xca*[?n] x[n]= xcs[n]+ xca[n] (2.19) x[n]= xev[n]+ xod[n] (2.21) If x[n] is real sequence, then Energy of sequence : Some basic sequence Unit sample sequence: Unit step sequence: Sinusoidal sequence: Exponential sequence: Representation of an arbitrary sequence Classification of Discrete-Time Systems Linear system ---- superposition always h