154 lines
4.2 KiB
Matlab
154 lines
4.2 KiB
Matlab
classdef Filter
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%FILTER Summary of this class goes here
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% Detailed explanation goes here
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properties
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H
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filterType
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f_cutoff
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signal_length
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filtdegree
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passband_ripple
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stopband_ripple
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fsamp
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end
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methods
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function obj = Filter(options)
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%FILTER Construct an instance of this class
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% Detailed explanation goes here
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arguments
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options.filterType = 1;
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options.f_cutoff = 0;
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options.fsamp = 0;
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options.filtdegree = 3;
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options.passband_ripple = 0.5;
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options.stopband_ripple = 0.5;
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end
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obj.filterType = options.filterType;
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obj.f_cutoff = options.f_cutoff;
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obj.filtdegree = options.filtdegree;
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obj.passband_ripple = options.passband_ripple;
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obj.stopband_ripple = options.stopband_ripple;
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obj.fsamp = options.fsamp;
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end
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function signalclass_out = process(obj,signalclass_in)
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% actual processing of the signal
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signalclass_in.signal = obj.process_(signalclass_in.signal);
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% append to logbook
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filterdesc = [num2str(obj.filtdegree),'. order ',char(obj.filterType),' filter with f_cutoff at ', num2str(obj.f_cutoff*1e-9), ' GHz.'];
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signalclass_in = signalclass_in.logbookentry(filterdesc);
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% write to output
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signalclass_out = signalclass_in;
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end
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function yout = process_(obj,xin)
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obj.signal_length = length(xin);
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obj.H = obj.buildFilter(obj.filterType);
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yout = obj.applyFilter(xin);
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end
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function y_filtered = applyFilter(obj,xin)
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y_filtered = ifft(obj.H.*fft(xin));
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end
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function H = buildFilter(obj,filterType)
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rp = obj.passband_ripple; %passband ripple
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rs = obj.stopband_ripple; %stopband ripple
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switch filterType
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case 1
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% Bessel filter, impulse invariant transformed
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[B, A] = besself(obj.filtdegree, 2*pi*obj.f_cutoff);
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[B ,A] = impinvar(B,A,obj.fsamp);
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case 2
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% Bessel filter, impulse bilinear transformed
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[Z, P, K] = besself(obj.filtdegree, 2*pi*obj.f_cutoff);
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[Z ,P, K] = bilinear(Z,P,K,obj.fsamp);
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[B ,A] = zp2tf(Z ,P ,K);
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case 3
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% Butterworth filter
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if obj.lowpass == 1 %lowpass
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[B, A] = butter(obj.filtdegree, obj.f_cutoff/(obj.fsamp/2),'low');
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else % highpass
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[B, A] = butter(obj.filtdegree, obj.f_cutoff/(obj.fsamp/2),'high');
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end
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case 4
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% Chebyshev 1 filter
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[B, A] = cheby1(obj.filtdegree,rp, obj.f_cutoff/(obj.fsamp/2));
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case 5
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% Chebyshev 2 filter
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[B, A] = cheby2(obj.filtdegree,rs, obj.f_cutoff/(obj.fsamp/2));
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case 6
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% Elliptic filter
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[B, A] = ellip(obj.filtdegree,rp,rs,obj.f_cutoff/(obj.fsamp/2));
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case 7
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% Hamming filter
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g=(obj.filtdegree-1)/2;
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wc=obj.f_cutoff/(obj.fsamp/2);
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B = wc*sinc(wc*(-g:g)).*hamming(obj.filtdegree)';
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A=1;
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case 8
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% Raised Cosine filter
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B = firrcos(obj.filtdegree,obj.f_cutoff,para.df,obj.fsamp);
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A=1;
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case 9
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% Sinc filter
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g=(obj.filtdegree-1)/2;
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wc=obj.f_cutoff/(obj.fsamp/2);
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B = wc*sinc(wc*(-g:g));
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A=1;
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end
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H = freqz(B, A, obj.signal_length,'whole');
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end
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end
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end
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