176 lines
5.0 KiB
Matlab
176 lines
5.0 KiB
Matlab
classdef Filter
|
|
%FILTER Summary of this class goes here
|
|
% Detailed explanation goes here
|
|
|
|
properties
|
|
H
|
|
filterType
|
|
f_cutoff
|
|
lowpass
|
|
|
|
signal_length
|
|
filtdegree
|
|
passband_ripple
|
|
stopband_ripple
|
|
fsamp
|
|
|
|
w
|
|
end
|
|
|
|
methods
|
|
function obj = Filter(options)
|
|
%FILTER Construct an instance of this class
|
|
% Detailed explanation goes here
|
|
arguments
|
|
options.filterType filtertypes = filtertypes.bessel_inp ;
|
|
options.f_cutoff = 0;
|
|
options.fsamp = 0;
|
|
options.filtdegree = 3;
|
|
options.passband_ripple = 0.5;
|
|
options.stopband_ripple = 0.5;
|
|
options.lowpass = 1;
|
|
end
|
|
|
|
|
|
fn = fieldnames(options);
|
|
for n = 1:numel(fn)
|
|
obj.(fn{n}) = options.(fn{n});
|
|
end
|
|
|
|
|
|
end
|
|
|
|
function signalclass_out = process(obj,signalclass_in)
|
|
|
|
% actual processing of the signal
|
|
signalclass_in.signal = obj.process_(signalclass_in.signal);
|
|
|
|
% append to logbook
|
|
filterdesc = [num2str(obj.filtdegree),'. order ',char(obj.filterType),' filter with f_cutoff at ', num2str(obj.f_cutoff*1e-9), ' GHz.'];
|
|
signalclass_in = signalclass_in.logbookentry(filterdesc);
|
|
|
|
% write to output
|
|
signalclass_out = signalclass_in;
|
|
|
|
end
|
|
|
|
function yout = process_(obj,xin)
|
|
|
|
obj.signal_length = length(xin);
|
|
|
|
[obj.H,obj.w] = obj.buildFilter(obj.filterType);
|
|
|
|
yout = obj.applyFilter(xin);
|
|
|
|
end
|
|
|
|
function y_filtered = applyFilter(obj,xin)
|
|
|
|
y_filtered = ifft(obj.H.*fft(xin));
|
|
|
|
end
|
|
|
|
function [H,w] = buildFilter(obj,filterType)
|
|
w = [];
|
|
rp = obj.passband_ripple; %passband ripple
|
|
rs = obj.stopband_ripple; %stopband ripple
|
|
|
|
switch filterType
|
|
case 1
|
|
|
|
% Bessel filter, impulse invariant transformed
|
|
|
|
[B, A] = besself(obj.filtdegree, 2*pi*obj.f_cutoff);
|
|
[B ,A] = impinvar(B,A,obj.fsamp);
|
|
|
|
case 2
|
|
|
|
% Bessel filter, impulse bilinear transformed
|
|
|
|
[Z, P, K] = besself(obj.filtdegree, 2*pi*obj.f_cutoff);
|
|
[Z ,P, K] = bilinear(Z,P,K,obj.fsamp);
|
|
[B ,A] = zp2tf(Z ,P ,K);
|
|
|
|
case 3
|
|
|
|
% Butterworth filter
|
|
if obj.lowpass == 1 %lowpass
|
|
[B, A] = butter(obj.filtdegree, obj.f_cutoff/(obj.fsamp/2),'low');
|
|
else % highpass
|
|
[B, A] = butter(obj.filtdegree, obj.f_cutoff/(obj.fsamp/2),'high');
|
|
end
|
|
|
|
case 4
|
|
|
|
% Chebyshev 1 filter
|
|
|
|
[B, A] = cheby1(obj.filtdegree,rp, obj.f_cutoff/(obj.fsamp/2));
|
|
|
|
case 5
|
|
|
|
% Chebyshev 2 filter
|
|
|
|
[B, A] = cheby2(obj.filtdegree,rs, obj.f_cutoff/(obj.fsamp/2));
|
|
|
|
case 6
|
|
|
|
% Elliptic filter
|
|
|
|
[B, A] = ellip(obj.filtdegree,rp,rs,obj.f_cutoff/(obj.fsamp/2));
|
|
|
|
case 7
|
|
|
|
% Hamming filter
|
|
|
|
g=(obj.filtdegree-1)/2;
|
|
wc=obj.f_cutoff/(obj.fsamp/2);
|
|
B = wc*sinc(wc*(-g:g)).*hamming(obj.filtdegree)';
|
|
A=1;
|
|
|
|
case 8
|
|
|
|
% Raised Cosine filter
|
|
|
|
B = firrcos(obj.filtdegree,obj.f_cutoff,para.df,obj.fsamp);
|
|
A=1;
|
|
|
|
case 9
|
|
|
|
% Sinc filter
|
|
|
|
g=(obj.filtdegree-1)/2;
|
|
wc=obj.f_cutoff/(obj.fsamp/2);
|
|
B = wc*sinc(wc*(-g:g));
|
|
A=1;
|
|
|
|
case 10
|
|
|
|
% Gaussian Filter
|
|
%check if order ist multiple of 1/2
|
|
blocklen=obj.signal_length;
|
|
|
|
faxis=linspace(-obj.fsamp/2,obj.fsamp/2,blocklen+1)';%generates arow vector faxis of blocklen+1 points linearly spaced between and including -para.fs/2 and para.fs/2
|
|
faxis=ifftshift(faxis(1:end-1));
|
|
|
|
H=exp(-((faxis)/(obj.f_cutoff*2)).^(2*obj.filtdegree)*log(2)*2^(2*obj.filtdegree-1));
|
|
end
|
|
|
|
% Build Filter from coefficients
|
|
if filterType ~= 10
|
|
[H,w] = freqz(B, A, obj.signal_length,'whole');
|
|
|
|
end
|
|
|
|
end
|
|
|
|
|
|
function show(obj)
|
|
obj.signal_length = 1024;
|
|
[H,w] = obj.buildFilter(obj.filterType);
|
|
plot(w,20*log10(abs(H)))
|
|
%freqz(H);
|
|
end
|
|
end
|
|
end
|
|
|