# Matlab decimate time axis

#### sharkDawg

Joined May 21, 2008
10
Hi guys, my problem is that i want to show my original signal and decimated signal on the same plot but am not sure how to do this as the sampling rates are different. Any ideas? I am currently plotting them separately.

Rich (BB code):
nsamp = 512;    %signal duration, 64ms
fs1 = 8000;     %samp frequency
N = 2;          %decimation factor
fs2 = fs1/2;    %target samp frequency
fc = 3500;      %cutoff frequency
n = 40;         %filter order
x1 = 0;

% generate the required signal
for fa = 600:600:3600

x1 = x1 + sin(2.*pi.*(0:nsamp-1).*fa/fs1);

end

%filter
Wn = fc/fs1;
b=fir1(n, Wn);
x1_fltrd = filter(b,1,x1);

% decimate
x2 = x1_fltrd(1:N:end);

%plot
figure(1);
time_axis = ((0:nsamp-1)*0.064);
plot(time_axis, x1);                        %   Plot original sine wave

figure(2);
time_axis1 = ((0:nsamp-257)*0.064);
plot(time_axis1, x2,'r');