g_fir.m

digital signal processing常用工具箱

% G_FIR: GUI module for FIR filter design
%
% Usage: g_fir
%
% Version: 1.0
%
% Description: 
%              This graphical user interface module is used
%              to interactively investigate the design of FIR 
%              digital filters. The design methods include 
%              windowed (rectangular, Hanning, Hamming, 
%              Blackman), frequency-sampled, least-squares, 
%              and optimal equiripple.  The filter types 
%              include lowpass, highpass, bandpass, bandstop, 
%              and general.  All filters are linear-phase 
%              filters.
% Edit window:
%              F_0     = lower cutoff frequency
%              F_1     = upper cutoff frequency
%              B       = transition bandwidth
%              delta_p = passband ripple
%              delta_s = stopband attenuation
% Type window:
%              Lowpass filter
%              Highpass filter
%              Bandpass filter
%              Bandstop filter 
%              User-defined filter
% View window:
%              Magnitude response
%              Phase response
%              Impulse response
%              Pole-zero plot
%              Window
% Checkboxes:
%              dB display
% Slider bar:
%              FIR filter order: m
% Menu bar:
%              Method option
%              Save option: x,y,a,b,fs 
%              Caliper option
%              Print option
%              Help option 
% See also: 
%              F_DSP G_SAMPLE G_RECONSTRUCT G_SYSTEM 
%              G_SPECTRA G_CORRELATE G_FILTERS G_MULTIRATE
%              G_IIR G_ADAPT

% Programming notes:

% Check MATLAB Version

if (f_oldmat)
   return
end

% Initialize

clc
clear all
pv = 1;                    % plot view
fs = 2000;                 % sampling frequency
F_0 = 300;                 % lower cutoff frequency
F_1 = 600;                 % upper cutoff frequency
B = 50;                    % transition bandwidth
delta_p = 0.05;            % passband ripple (linear)
delta_s = 0.1;             % stopband ripple (linear)
A_p =-20*log10(1-delta_p); % passband ripple (dB)
A_s =-20*log10(delta_s);   % stopband ripple (dB)
m = 40;                    % filter order
m_min = 2;                 % minimum filter order
m_max = 256;               % maximum filter order
dB = 0;                    % linear plots (1 = log)
fs_min = 1;                % minimum sampling frequency
fs_max = 44100;            % maximum sampling frequency 
method = 5;                % filter design method
win = 1;                   % window type (0 to 3)
xm = 3;                    % fitler type
xm_old = xm;               % previous xm
a = 1;                     % denominator
b = [1 1];                 % numerator
white = [1 1 1];
M = 1000;
x = f_randu(M,1,-1,1);
y = filter(b,a,x);

% Strings                          
                          
userinput  = 'u_fir1';           % default M-file function specifying desired amplitude response
useroutput = 'u_fir1.mat';       % default MAT-file for saving data 
inputstr   = ['[b,a,m,fs,x,y,userinput,xm,xm_old] = '...
              'f_getfir (xm,xm_old,fs,F_0,F_1,B,delta_p,delta_s,m,method,win,userinput,b,a,x,y,hc_type); '];
plotstr    = 'f_plotfir (pv,han,fs,hc_dB,a,b,xm,method,win,F_0,F_1,B,delta_p,delta_s,userinput,fsize); ';
barstr     = 'f_showslider (hc_m,han,m,'''',1); ';
g_module = 'g_fir';
drawstr  = 'f_drawfilt (han(1),colors,fsize); ';

% Create figure window with tiled axes
 
[hf_1,han,pos,colors,fsize] = f_guifigure (g_module);

% Add menu options

hm_fir = f_firmenu (inputstr,plotstr,method,'Method');
hm_save = f_savemenu (useroutput,'','Save data');
f_calmenu (plotstr)
f_printmenu (han,drawstr)
f_helpmenu ('f_tipsfir',g_module)
f_exitmenu

% Draw block diagram

eval(drawstr)

% Edit boxes

axes (han(2))
cback =  [inputstr plotstr];
hc_F0 = f_editbox (F_0,0,fs/2,pos(2,:),3,1,1,colors(2,:),white,cback,'Lower cutoff frequency',fsize);
hc_F1 = f_editbox (F_1,F_0,fs/2,pos(2,:),3,2,1,colors(2,:),white,cback,'Upper cutoff frequency',fsize);
hc_B  = f_editbox (B,0,B,pos(2,:),3,3,1,colors(2,:),white,cback,'Transition bandwidth',fsize);
hc_fs = f_editbox (fs,fs_min,fs_max,pos(2,:),3,1,2,colors(1,:),white,cback,'Sampling frequency',fsize);

cback5b = ['if dB == 0, '...
           ' eval(get(hc_delta_p,''String'')),delta_p = f_clip(delta_p,0,1);'...
           ' A_p = -20*log10(1 - delta_p);'...
           'else, '...
           ' eval(get(hc_delta_p,''String'')),A_p = f_clip(A_p,0,A_p);'...
           ' delta_p = 1 - 10^(-A_p/20);'...
           'end; '];
hc_delta_p = f_editbox (delta_p,0,1,pos(2,:),3,2,2,colors(2,:),...
                        white,[cback5b inputstr plotstr],'Passband ripple',fsize);

cback6b = ['if dB == 0, '...
           ' eval(get(hc_delta_s,''String'')),delta_s = f_clip(delta_s,0,1);'...
           ' A_s = -20*log10(delta_s);'...
           'else, '...
           ' eval(get(hc_delta_s,''String'')),A_s = f_clip(A_s,0,A_s);'...
           ' delta_s = 10^(-A_s/20);'...
           'end; '];
hc_delta_s = f_editbox (delta_s,0,1,pos(2,:),3,3,2,colors(2,:),...
                        white,[cback6b inputstr plotstr],'Stopband attenuation',fsize);

% Select filter type

nt = 5;
labels = {'Lowpass','Highpass','Bandpass','Bandstop','User-defined'};
cstr = ['if method == 6, '...
        '   method = 5; '...
        'end, '...
        'for i = 0 : 6, '...
        '   if i == method, '...
        '       set(hm_fir(i+2),''Checked'',''on''), '...
        '   else, '...
        '       set(hm_fir(i+2),''Checked'',''off''), '...
        '   end, '... 
        'end, '...
        ];

tipstrs = {'Lowpass filter','Highpass filter','Bandpass filter','Bandstop filter','Load a,b,fs'};
cback = {[inputstr barstr plotstr],...
         [inputstr barstr plotstr],...
         [inputstr barstr plotstr],...
         [inputstr barstr plotstr],...
         [inputstr barstr plotstr]};
 [hc_type,userinput] = f_typebuttons (pos(3,:),nt,xm,labels,colors(1,:),white,cback,userinput,tipstrs,nt,fsize);

% Select view

nv = 5;
labels = {'Magnitude response','Phase response','Impulse response','Pole-zero plot','Window'};
cback = {plotstr,plotstr,plotstr,plotstr,plotstr};
fcolors = {colors(2,:),colors(2,:),colors(2,:),colors(2,:),colors(2,:)};
tipstrs = {'Plot A(f)','Plot phi(f)','Plot h(k)','Plot pole-zero pattern','Plot window w(k)'};
hc_view = f_viewbuttons (pos(4,:),nv,pv,labels,fcolors,white,cback,tipstrs,nv+1,fsize);

% Check boxes

cbackdB = ['dB = get (hc_dB,''Value''); '...
           'if dB,'...  
           ' set(hc_dB,''Value'',1),'...
           ' eval(get(hc_delta_p,''String'')),'...
           ' eval(get(hc_delta_s,''String'')),'...
           ' A_p = -20*log10(1 - delta_p);'...
           ' A_s = -20*log10(delta_s);'...
           ' set(hc_delta_p,''String'',[''A_p = '',mat2str(A_p,3),'';'']),'...
           ' set(hc_delta_s,''String'',[''A_s = '',mat2str(A_s,3),'';'']),'...
           'else,'...
           ' set(hc_dB,''Value'',0),'...
           ' eval(get(hc_delta_p,''String'')),'...
           ' eval(get(hc_delta_s,''String'')),'...
           ' set(hc_dB,''Value'',0),'...
           ' delta_p = 1 - 10^(-A_p/20);'...
           ' delta_s = 10^(-A_s/20);'...
           ' set(hc_delta_p,''String'',[''delta_p = '',mat2str(delta_p,3),'';'']),'...
           ' set(hc_delta_s,''String'',[''delta_s = '',mat2str(delta_s,3),'';'']),'...
           'end; '];
hc_dB = f_checkbox (dB,pos(4,:),nv+1,1,nv+1,1,'dB display',colors(3,:),...
                     white,[cbackdB inputstr plotstr],'Toggle dB display',fsize);

% Filter order slider

dv = 1;
tipstr = 'Adjust FIR filter order m';
cback = [inputstr barstr plotstr];
hc_m = f_slider (m,m_min,m_max,pos(5,:),colors(2,:),'y',cback,tipstr,dv,'',fsize);

% Compute initial filter

eval (inputstr);

% Create plot

eval (plotstr)