Carleton Engineering SCE Faculty A. Adler Courses ELG7173 Rayleigh Scattering |

## Rayleigh ScatteringRayleigh scattering origniates in the random positioning of small, isotropic inhomogeneities. Because of the random positioning, the phase of the ultrasound signals may add constructively or destructively, or somewhere in-between. It can be shown that such a system has a SNR of 1.91.In order to simulate this effect, we create the following Matlab/Octave code. function sig=usound(Nscat); t=linspace(0,2*pi,200); t(1)=[]; sig= zeros(size(t)); for i=1:Nscat; sig= sig+sin(t + 2*pi*rand); end endfunction for Nscat= [1,2,3,5,10,30,100,300,1000]; s= zeros(1,10000); for n=1:10000; s(n)= mean(abs(usound(Nscat))); end disp([ Nscat, mean(s), std(s), mean(s)/std(s)]); end ## Output
## Comments:- The SNR at Nscat=1 should be ∞. The reason that it isn't is because we are integrating over a discrete approximation to the sin.
- Note how quickly the approximation is close to SNR=1.91. Even with Nscat=2, the value is very close.
- I know that there are much more efficient ways to do this. This is supposed to be a quick simulation to illustrate the effect.
Last Updated: $Date: 2004-03-23 14:05:22 -0500 (Tue, 23 Mar 2004) $ |