How to transmit a signal to Arduino for 150m?

Question

Arduino

Hey! I sawed down a laser-trigger here a couple of years ago at the finish line of a cycling competition. A simple one, on a laser pointer and a photoresistor connected to the Arduino Uno, which, in turn, transmitted its values ​​​​to Processing, where they were "processed" and, when the threshold level was lowered (the laser was blocked), the time value was fixed. At the same time, the start times were synchronized and there were no problems.
But then we decided to upgrade and make a magnetic gate at the start with a random (several seconds) start time. When the gate is opened, the green traffic light lights up at the same time. Accordingly, the task arose to transfer the start time to the finish system.
Tell me how to organize the signal transmission easier and more reliably?
Distance from start to finish is 150m. You can say direct visibility - the sea buckthorn bush can grow))

Answer 1

Radio channel, modules on or any bulk.