demod.rar_fsk demod_matlab fsk demod

clear; clc; symb = dec2bin(abs('i')) bitstr = symb; fs = 8000; bdur = 0.05; T = bdur; F1 = 2000; F0 = 1000; t = [0:1/fs:bdur-1/fs]'; S1 = sin(2*pi*F1*t); S0 = sin(2*pi*F0*t); sig0 = [] for i=1:length(bitstr) if bitstr(i)=='1' sig0 = [sig0;S1]; elseif bitstr(i)=='0' sig0 = [sig0;S0]; end end soundsc(sig0) figure,plot(sig0) %-------------------------------------------- %Adding 100Hz noise to sig. x = [0:1/fs:0.35-1/fs]'; ns = 0.1*sin(2*pi*100*x); figure,plot(x,ns) soundsc(ns) sig = sig0 + ns; figure,plot(sig) soundsc(sig) %-------------------------------------------- %Fourier sa sig (figure contains both 1000 & 2000 frequencies) Fs=8000; freq = [0:1400]'/1400*(Fs/2); SIG = fft(sig); figure, plot(freq,abs(SIG(1:1401))), grid %------------------------------------------- %extracting first bit sa sig from 1-400 b1=sig(1:400); figure,plot(b1) freq1 = [0:200]'/200*(Fs/2); B1 = fft(b1); figure, plot(freq1,abs(B1(1:201))), grid a1=[abs(B1)]'; %------------------------------------------- %extracting second bit sa sig from 401-800 b2=sig(401:800); figure,plot(b2) freq2 = [0:200]'/200*(Fs/2); B2 = fft(b2); figure, plot(freq2,abs(B2(1:201))), grid a2=[abs(B2)]'; %------------------------------------------- %extracting 3rd bit sa sig from 801-1200 b3=sig(801:1200); figure,plot(b3) freq3 = [0:200]'/200*(Fs/2); B3 = fft(b3); figure, plot(freq3,abs(B3(1:201))), grid a3=[abs(B3)]'; %------------------------------------------- %extracting 4th bit sa sig from 1201-1600 b4=sig(1201:1600); figure,plot(b4) freq4 = [0:200]'/200*(Fs/2); B4 = fft(b4); figure, plot(freq4,abs(B4(1:201))), grid a4=[abs(B4)]'; %------------------------------------------- %extracting 5th bit sa sig from 1601-2000 b5=sig(1601:2000); figure,plot(b5) freq5 = [0:200]'/200*(Fs/2); B5 = fft(b5); figure, plot(freq5,abs(B5(1:201))), grid a5=[abs(B5)]'; %------------------------------------------- %extracting 6th bit sa sig from 2001-2400 b6=sig(2001:2400); figure,plot(b6) freq6 = [0:200]'/200*(Fs/2); B6 = fft(b6); figure, plot(freq6,abs(B6(1:201))), grid a6=[abs(B6)]'; %------------------------------------------- %extracting 7th bit sa sig from 2401-2800 b7=sig(2401:2800); figure,plot(b7) freq7 = [0:200]'/200*(Fs/2); B7 = fft(b7); figure, plot(freq7,abs(B7(1:201))), grid a7=[abs(B7)]'; %------------------------------------------- % demodulation if a1(101)==200 A1=1; else A1=0; end if a2(101)==200 A2=1; else A2=0; end if a3(101)==200 A3=1; else A3=0; end if a4(101)==200 A4=1; else A4=0; end if a5(101)==200 A5=1; else A5=0; end if a6(101)==200 A6=1; else A6=0; end if a7(101)==200 A7=1; else A7=0; end binary = [A1 A2 A3 A4 A5 A6 A7]