One other thing.
If the numbers in your example screenshot are actually from the app, it looks to me like you are calculating the average speed between when the ball leaves the racquet and when it hits the ground, rather than estimating the initial speed of the ball when it leaves the racquet. Is that true?
If so, you should keep in mind that pro radar guns don't measure average speed-- they measure speed coming off the racquet (as mentioned further up in the thread). So your app will read considerably slower than a pro gun.
Last edited by Avles; 11-30-2012 at 09:51 PM.