f=1000;
Fs=48000; %48kHz
L=2000; %wartosc do testowania
T=1/Fs; %odleglosc miedzy probkami

t=[1:L-1]*T; %wektor kolejnych chwil czasowych
X=1*sin(2*pi*f*t);
Y=fft(X);
P2 = abs(Y/L);
P1 = P2(1:L/2+1);
P1(2:end-1) = 2*P1(2:end-1);
f = Fs*(0:(L/2))/L;
title('Single-Sided Amplitude Spectrum of X(t)')
xlabel('f (Hz)')
ylabel('|P1(f)|')
subplot(2,1,1);
plot(X)
subplot(2,1,2);
plot(f,P1)