lista 6-7

clear all;
close all;
%ładowanie sygnału
load('s1.mat');
load('s2.mat');
%parametry sygna;lu
fp=2000;
N=length(s1);

t=[0:1:N-1]/fp;

figure(1)
subplot(2,2,1);
plot(t, s1);
subplot(2,2,2);
plot(t,s2);
%całkowanie ilości binów do analizy
Nf=N;
%liczba binow nie zaleznych do obserwacji czykli od 0 do fp/2
N21=Nf/2+1
%generacja skali na osi f
f=linspace(0,fp/2,N21);
%widmo amplitudowe
w1=abs(fft(s1,Nf));
w2=abs(fft(s2,Nf));

subplot(223)
stem(f,w1(1:N21));
xlabel('czestotliwosc [Hz]');
ylabel('modół wimda')

subplot(224)
stem(f,w2(1:N21));
xlabel('czestotliwosc [Hz]');
ylabel('modół wimda')
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function [Xk] = test_DFT(xn,Nf)
%TEST_DFT Summary of this function goes here
%WY: Xk-widmo zespolone o ilosci Nf binow
%   Detailed explanation goes here
Wn=exp(-j*2*pi/Nf);%fazor podstawowy
%inicjalizacja
F= zeros(Nf,Nf);
%macierze przekształcanie F- funckje bazowe
for k=0 : Nf-1
    for n=0 : Nf-1
        F(k+1, n+1) = Wn^(k*n);
    end;
end;
Xk= xn*F;

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%teraz tak k = 1 oznaczenie takie robim że wN=e^(-j2*pi/n) a zatem jak te n
%się zmienają no teraz tak k=1 idziemy po N w wykładniku 1 -----1 W^1------
%W^(n-1) można zobaczyć że fazor jest
clear all;
close all;
N=1000;
fp=1000;
t=(0:N-1)/fp;
x=sin(2*pi*100*t);

figure(1)
subplot(311)
plot(t,x);
xlabel('czas[s]')
ylabel('x(t)')

Nf=N;
%liczba binow nie zaleznych do obserwacji czykli od 0 do fp/2
N21=Nf/2+1
%generacja skali na osi f
f=linspace(0,fp/2,N21);
w1=abs(fft(x,Nf));
w2=abs(test_DFT(x,Nf));

subplot(312)
stem(f,w1(1:N21));
subplot(313);
stem(f,w2(1:N21));
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
close all;
clear all;

[x,fs]=audioread("mbi04czep.wav");
N=length(x);
t=[0:1:N-1]/fs;
figure(1)
subplot(221)
plot(t,x)


N21=N/2+1;
f=linspace(0,fs/2,N21);
w=abs(fft(x,N));
subplot(222)
plot(f,w(1:N21));

dr=2;
y=decimate(x,dr);
Ny=length(y);
fpy=fs/dr;

ty= 0:1/fpy:(Ny-1)/fpy;

subplot(223);
plot(ty,y)


fl=linspace(0,fpy/2,Ny/2+1);
wy=abs(fft(y,Ny));
subplot(224)
plot(fl,wy(1:Ny/2+1));
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

clear all; close all;
% ----------------  generowanie sinusa
fpx = 10000;
Nx = 10000;
tx = 0:1/fpx:(Nx-1)/fpx;
f0 = 1400;
f1=2800;
x = sin (2*pi*f0*tx)+sin(2*pi*f1*tx);

subplot (221);
plot (tx,x);
xlabel ('czas[s]');
ylabel ('sygnal przed decymacja');

Nf = 2^11;
N21 = Nf/2 + 1;
wx = abs(fft(x,Nf));
fx = linspace(0, fpx/2, N21);
subplot (222);
plot (fx, wx(1:N21));
xlabel ('czest[Hz]');
ylabel ('modul widma');

% ------------------------------------------------------------------
%%      decymacja w petli
%       Tutaj nalezy dopisac kod
% ------------------------------------------------------------------
dr = 2; % 4, 5, 10

fpy =fpx/dr;
Ny = floor(Nx/dr)
y=zeros(1,Ny);
   for i=1:Ny
     y(i) = x((i-1)*dr+1);

   end



%%
ty = 0:1/fpy:(Ny-1)/fpy;

subplot (223);
plot (ty,y);
xlabel ('czas[s]');
ylabel ('sygnal po decymacji');

wy = abs(fft(y,Nf));
fy = linspace(0, fpy/2, N21);
subplot (224);
plot (fy, wy(1:N21));
xlabel ('czestotliwosc [Hz]');
ylabel ('modul widma'); ylim([0 1000])

set (gcf,'Position',[50 50 800 700]);
%print -depsc ProbkAlias1