# Plotting Power Spectrum Density in Matlab

1. Sep 3, 2011

### yongs90

1. The problem statement, all variables and given/known data
I have an autocorrelation function given by
R($\tau$) = $J_0$(2$\pi$$f_d$$\tau$)

I have already plotted it in Matlab using the following commands
ts=0.0000001;
fs=1/ts;
fd=100;

tau=0:0.0000001:0.05;
R=besselj(0,2*pi*fd.*tau);

How do I plot its PSD in Matlab and the plotted picture looks like this:
http://www.mypicx.com/09032011/Temp/

2. Relevant equations

3. The attempt at a solution
When I use the command pwelch(R), it just won't yield the picture.
http://www.mypicx.com/09032011/blabla/

I will obtain something different. How do I scale it so that I will resemble the picture given. thanks

Last edited: Sep 3, 2011