Originally Posted by tennisplayer_85
As explained in the previous comment, moving the spot where the ball hits (lands on) the court horizontally almost doesn't have any effect on the speed.
Moving the ball 1 foot in the vertical direction does by 1.6 miles of error (see previous comment). So the 10 miles you talk about would mean moving the ball more than 6 feet from it's real landing location. In normal circumstances you should be able to guess the balls location within a foot of its real location (especially if its close to the lines).
I have tested it with real videos from the australian open where the professional radar gun shows the speed so i was able to compare. All the calculations i did where within 2,5 miles of the radar gun's speed except for 1 out of 10, I suggest you try it your self at a pro tournament.
R u in melbourne? If so we might be able to tie up some real world testing.
I have a Bushnell Speedster k-band & know a friend who's bought
the 2-digit huge LED radar thingy that you'd hang on the back fence.
Just need to find a court & someone with a strong reliable repeatable serve...