08-15-2017, 12:10 PM
(08-15-2017, 08:25 AM)timc Wrote: Do you know how overheight detection works? Because I don't. I may be naive, but I assume it is not easily spoofed.
Yes, a few pages ago I posted some photos close-up of the one installed at the North end.
There are 3 pairs of through-beam photosensors - standard industry stuff. One is a transmitter, one is a receiver. If something blocks the beam, the state of the sensor changes (depending if it's Light-ON or Dark-ON).
The sensors itself are very easily spoofed. Put your hand in front of the ones down low at waist height. You'll block it - I guarantee it. The robustness of the system that others are discussing comes from stuff like debounce timers and so on to give it some level of stability against false triggers.