Very new to this. Planning to use 2 beam-break lasers (IR transmitters & receivers) to determine speed of a ball.
What type of ball? Some assume it is a baseball.
How fast will it be moving?
What accuracy and precision do you need?
For example, if it is a baseball (3" diameter) and going 100 mph, it will take 1.7 mS to cross a point and 3.4 mS to travel 6" . (I know similar calculations were made above.)
IR detectors, such as the TSOP 4338 (
https://www.electro-tech-online.com/custompdfs/2012/11/tsop45.pdf) are fairly fast, but do take a finite time to respond. That response time is given in the datasheet as multiples of the base frequency (i.e., 38KHz). For the TSOP it is about 3 to 9 cycles (79 µS to 237 µS). How much jitter is there in the detection times? We don't know, but lets assume its 160 µS (0.16 mS). It is quite obvious when transmitting data that there is jitter.
That could be a 9% error from start and stop errors over the 6" travel distance. That's the difference between a major league and minor league player.
If it is a soccer ball, then that is a different story. Remember, though, that the ball will likely not pass the sensors exactly on its diameter every time.
Can you move the sensors further apart to give you more time so such errors are not such a significant part of the expected time (time of flight)?
John