[ChrisH]

Assuming the measured length is 1 meter, there is a simple calibration that can be performed to check the speed tester. Simply hold it so the ball can drop through it vertically. Hold the ball close to the first sensor and drop it through. The ball speed should read 2.2 m/s.

Don't belive me? do the math! Hint d=(at^2)/2. If anybody needs more than that post here and I'll walk you through it. I figured this out for our own tester.

ChrisH