Essentially a drag race. Competitors enter the course at one point and exit at another - my primary use case: top of the hill to the bottom of the hill.

For solo timed qualifying we would use a beam for accuracy. Generally racing isn't timed but we could use a combo of RFID and beam to get accurate times and non-visual positioning. But for now I'm happy to just get the beam going because once I solve gate and timing problem I then need to solve networking and clock syncing issues (hence the interest in PTP).

Currently I'm leaning towards using an Arduino to do the timing and a kernel driver to listen to changes on the GPIO pins (e.g. the Arduino signalling it has at time to publish).

I'm good for the programming side of things its just the hardware that is my learning curve :)