Originally Posted by JackB1
I don't understand how this can be accurate? Because you approximate the spot you are serving from and you also approximate the spot the ball hits on the court. Also, where you stand isn't where you contact the ball. Some guys hit the ball 2 feet inside the baseline and some guys hit it from behind the baseline.
The calculations are based on formulas from http://www.donthireddy.us/tennis/speed.html
. That website has a calculator that calculates the speed for you. All you need is the frame rate of your camera and the number of frames it takes from the time the ball leaves the racket and the time it hits the ground.
The app basically does the same thing, but makes inputting data much easier.
I have used the app many times now for me and my friends, and believe that it is reasonably accurate although I have never compared it to a radar gun.