In this simulation, you have two representations of wave motion to work with. One shows a movie of the wave traveling along a string - you can think of this representation as a sequence of photographs. The second representation is a plot of the displacement as a function of time for two points on the string (you can select which two points to use). Using only these two representations, you can determine the values of many different parameters that describe the wave.
For more info : http://weelookang.blogspot.sg/2011/04/ejs-open-source-wave-representations.html