Uloha1_ANS_FEL

echo off
clc
clear all
close all
%generate sin_ with Gaussian noise
SNRdb = 3;
SNR = 0;
FS = 8000;
F = 1;
To = 0.25;
t = 0:1/FS:To-1/FS;
meanHelp = [];
powerHelp = [];
figure();
%----
sin_ = sin(2*pi*F*t); %clear sinus
gauss_ = randn(size(sin_));
Psin = mean(sin_.^2, 2);
Pnoise = mean(gauss_.^2, 2);
%normalization
SNR = 10^(-SNRdb/10);
gauss_ = gauss_ * sqrt(Psin) / sqrt(Pnoise)/SNR;
sin_gaus = sin_ + gauss_; %mixed sin with noise

countBlocks = 10;
lengthBlock = floor(length(sin_gaus)/countBlocks);

for i = 1:countBlocks
  j = (i-1)*lengthBlock + 1;
  k = j + lengthBlock - 1;
  vectHelp = sin_gaus(j:k);
  mean_ = mean(vectHelp);
  power = mean(vectHelp.^2);
  meanHelp = [meanHelp, mean_];
  powerHelp = [powerHelp, power];
end
meanHelp = ones(lengthBlock,1)  * meanHelp;
meanHelp = meanHelp(:)';
powerHelp = ones(lengthBlock,1)  * powerHelp;
powerHelp = powerHelp(:)';
%plot
subplot(2,1,1);
plot(t, sin_gaus, t, meanHelp, t, powerHelp);
xlabel('t[s]');
ylabel('|A|');
legend('sinus with noise', 'mean', 'power')
title('sinus 1Hz with Gaussian noise, SNR 3dB');

%generate oscillation sinus
Flow = 10;
FS = 8000;
Fhigh = 400;
To = 0.02;
t = 0:1/FS:To-1/FS;
%--------
k = (Fhigh-Flow)/To;
F = k*t+Flow; %vector of frequencies
sin_ = sin(2*pi*F.*t);
%plot
subplot(2,1,2);
plot(t,sin_);
xlabel('t[s]');
ylabel('|A|');
title('oscillation sinus');