This spin echo simulation in matlab. Blue is magnetic filed, red is spins. This is NMR effect. first applied signal that rotate spins at 90 degrees then after pause at 180 degrees. Spins are not coherent because of fluctuations. after some time spins coherent back for a while and increasing of mean spin appear this called spin echo.
Download apps, toolboxes, and other File Exchange content using Add-On Explorer in MATLAB.