Hi,
May be you can try this
fs = 500e3; % sampling freq
N = length(y);
TimeWindowLength = N/fs; % Time axis range
deltaT = 1/fs;%distance between samples
x = 0:deltaT:deltaT*N;
plot(x,y);
I know this can be done with less steps... but this will give u an understanding
of the problem...
You can extend this further to get a FFT of the signal and plot it.
arun