EEET 0770 Digital Filter Design Digital Filters Design





















































- Slides: 53
EEET 0770 Digital Filter Design ���������� Digital Filters Design Chapter 4 Finite Impulse Response Filter Design Asst. Prof. Dr. Peerapol Yuvapoositanon, Ph. D, DIC Department of Electronic Engineering and Graduate School of Electrical Engineering Centre of Electronic Mahanakorn Systems and University of Technology Digital Signal Processing 1
EEET 0770 Digital Filter Design ขอดของ FIR • มความเสถยร (stable) • สามารถออกแบบใหผลตอบสนองทางเฟส เปนเชงเสน (Linear phase) ไดงาย Centre of Electronic Systems and Digital Signal Processing 2
EEET 0770 Digital Filter Design เฟสทเปนเชงเสน (linear phase) ������ a=������� FIR ��������� �� Centre of Electronic Systems and Digital Signal Processing 3
EEET 0770 Digital Filter Design ��������� �� • ���������� h(n) 0 1 N ������ 2 3 4 ������ (symmetric) N ������ 0 1 2 3 4 5 N ������ 0 1 2 3 4 ���������� 0 1 N ������ (Antisymmetric) Centre of Electronic Systems and 2 3 4 5 Digital Signal Processing 4
EEET 0770 Digital Filter Design Low pass filter (LPF ) Band pass filter (BPF) Centre of Electronic Systems and Digital Signal Processing High pass filter (HPF) Band stop filter (BSF) 7
EEET 0770 Digital Filter Design ผลตอบสนองอมพลสของตวกรองตำผาน LPF Centre of Electronic Systems and Digital Signal Processing 8
EEET 0770 Digital Filter Design ��������� ���� ��� d(n) �������� d(n) noncausal ( �������) ������ ��� (approximation) Centre of Electronic Systems and Digital Signal Processing 9
EEET 0770 Digital Filter Design ��������� =����� (Cut-off frequency) Centre of Electronic Systems and Digital Signal Processing 10
ผลตอบสนองอมพลสของตวกรองต ำผาน ทมการ เลอน M ลำดบ EEET 0770 Digital Filter Design Centre of Electronic Systems and Digital Signal Processing 11
EEET 0770 Digital Filter Design �������� = n n n ������� h(n) ����������� w(n) ���� N = ������ (order) ����� M=(N-1)/2 Centre of Electronic Systems and Digital Signal Processing 13
EEET 0770 Digital Filter Design �������� = �������� Centre of Electronic Systems and Digital Signal Processing 14
EEET 0770 Digital Filter Design ����������� ----- ��������������� ��� 1������ 2��������� Centre of Electronic Systems and Digital Signal Processing 15
EEET 0770 Digital Filter Design ขอกำหนดในการออกแบบตวกรอง (Filter specification) ������� �� ������� Centre of Electronic Systems and Digital Signal Processing 16
EEET 0770 Digital Filter Design ��������� (Main lobe) ������� (sidelobe) ��������� Centre of Electronic Systems and Digital Signal Processing 17
EEET 0770 Digital Filter Design �������� �� As 8. 9% 21 ������ 0. 63%44 ����� �� (Hannin g) 0. 22%53 ����� �� Centre of Electronic Systems and (Hamming) Digital Signal Processing 1 18
EEET 0770 Digital Filter Design ���� 1 (��� ) ���������� ����������� 7. 2 ������������ ������� 44. 44 ����� Centre of Electronic Systems and Digital Signal Processing 21
EEET 0770 Digital Filter Design ���� 1 (��� ) Centre of Electronic Systems and Digital Signal Processing 22
EEET 0770 Digital Filter Design ��������� Centre of Electronic Systems and Digital Signal Processing 500 Hz ex_7_1. eps 23
EEET 0770 Digital Filter Design ผลตอบสนองอมพลส Centre of Electronic Systems and Digital Signal Processing h(n) ของตวกรอง ex_7_2. eps 24
EEET 0770 Digital Filter Design �������� -21 d. B Centre of Electronic Systems and Digital Signal Processing 25
EEET 0770 Digital Filter Design ������� -44 d. B Centre of Electronic Systems and Digital Signal Processing 26
EEET 0770 Digital Filter Design �������� -74 d. B Centre of Electronic Systems and Digital Signal Processing 27
EEET 0770 Digital Filter Design (DFD) Module 2 3 1 Centre of Electronic Systems and Digital Signal Processing 28
EEET 0770 Digital Filter Design Lab. VIEW program Centre of Electronic Systems and Digital Signal Processing 29
EEET 0770 Digital Filter Design Lab. VIEW program Centre of Electronic Systems and Digital Signal Processing 30
EEET 0770 Digital Filter Design High. Pass Centre of Electronic Systems and Digital Signal Processing 31
EEET 0770 Digital Filter Design Bandpass Centre of Electronic Systems and Digital Signal Processing 32
EEET 0770 Digital Filter Design Bandstop Centre of Electronic Systems and Digital Signal Processing 33
EEET 0770 Digital Filter Design Hanning Centre of Electronic Systems and Digital Signal Processing 34
EEET 0770 Digital Filter Design Hamming Centre of Electronic Systems and Digital Signal Processing 35
EEET 0770 Digital Filter Design Blackman-Harris Centre of Electronic Systems and Digital Signal Processing 36
EEET 0770 Digital Filter Design ������ 2 ����������� 2 k. Hz ������������ Centre of Electronic Systems and Digital Signal Processing 37
EEET 0770 Digital Filter Design . 1�������� ������� ��� ����������� ������������� Centre of Electronic Systems and Digital Signal Processing 38
EEET 0770 Digital Filter Design �������� (0. 02%( ������ 7. 2 ���������� ��������� 300 � Centre of Electronic Systems and Digital Signal Processing 41
EEET 0770 Digital Filter Design %window. m technique demonstrating of the window design fc=500; fs=2000; N=41; M=(N-1)/2; wc=2*pi*fc/fs; n=0: N-1; %%%%%%% we can add a smallest number % 'eps' to avoid dividing by zero d=sin(wc*(n-M+eps)). /(n-M+eps)/pi; %%%% uncomment lines below for different windows w=ones(1, N); % Rectangular % w=. 5 -. 5*cos(2*pi*n. /(N-1)); %Hanning % w=. 42 -. 5*cos(2*pi*n. /(N-1))+. 08*cos(4*pi*n. /(N-1)); %blackman h=d. *w; figure(1); subplot(111); freqres(h, 1, fs, 'db') figure(2); subplot(111); stem(h) grid on xlabel('n') ylabel('h(n)') Centre of Electronic Systems and Digital Signal Processing 42
EEET 0770 Digital Filter Design การออกแบบ FIR เทคนกการสมความถ (Frequency Sampling Techniques) ������������������� 7 ������������ 1 Centre of Electronic Systems and Digital Signal Processing 43
EEET 0770 Digital Filter Design ������������������ “FIR: Frequency Sampling” �� DSP 7: ������������ h(n) ������������� Centre of Electronic Systems and Digital Signal Processing 44
EEET 0770 Digital Filter Design ��������� ������ ���������� ��� Centre of Electronic Systems and Digital Signal Processing 45
EEET 0770 Digital Filter Design เลอก N เปนเลขค ครอบคลม 1 0 1 2 3 Centre of Electronic Systems and Digital Signal Processing 10 20 46
EEET 0770 Digital Filter Design ����������� FIR �������� 2 k. Hz ������ (fs) 10 k. Hz ������� ���������� = �������� = Centre of Electronic Systems and Digital Signal Processing 47
EEET 0770 Digital Filter Design ��������� 1 Centre of Electronic Systems and Digital Signal Processing 48
EEET 0770 Digital Filter Design ���� 21 ��� ex_8_8. eps Centre of Electronic Systems and Digital Signal Processing 49
EEET 0770 Digital Filter Design ��������� 61 ��� ����������� = �������� = Centre of Electronic Systems and Digital Signal Processing 50
EEET 0770 Digital Filter Design ���� 61 ���������� 21 ��� ex_8_9. eps Centre of Electronic Systems and Digital Signal Processing 51
EEET 0770 Digital Filter Design %freq_sampl. m demonstrating low-pass design for FIR % fs=10000; % ������ 10 k. Hz wc= 0. 4*pi; % ��������� N=21; % ����������� Mp= ceil(wc*N/(2*pi)); %�. �. ���������� 0<w<pi Mpp=Mp-1; %�. �. ���������� pi<w<2 pi Ms= N-Mp-Mpp; %�. �. ���������� 0<w<pi H=[ones(1, Mp) zeros(1, Ms) ones(1, Mpp)]; %������� k=0: 1: N-1; % ��N ������� H=H. *exp(-j*pi*(N-1)*k/N); % ������� =���� *��� h=real(ifft(H)); %��������� figure(1) freqres(h, 1, fs) Centre of Electronic Systems and Digital Signal Processing 52