FSK for speed up network-code

int_m(i+1)=int_m(i)+m(i)*ts;
end
[M,m,df1]=fftseq(m,ts,df); %Fourier transform
M=M/fs; %scaling
f=(0:df1:df1*(length(m)-1))-fs/2; %frequency vector
u=cos(2*pi*fc*t+2*pi*kf*int_m); %modulated fsk signal
[U,u,df1]=fftseq(u,ts,df); %Fourier transform
U=U/fs; %scaling
pause %Press any key to see a plot of the message & fsk signal in time
domain
subplot(2,1,1)
plot(t,m(1:length(t)),'g')
axis([0 0.6 -2 2])
xlabel('Time(sec)') %xlabel heading of message signal
ylabel('Amplitude') %ylabel heading of message signal
title('Message signal')
subplot(2,1,2)