How does the ALP determine distance (parking sensor mode)?

[RedRocket]

Why don't they change it to measure distance by round trip time instead of IR intensity, to eliminate falses from shiny surfaces?

Apply some logic here,it's b/c at the speed of light a couple of feet separation distance is an infinitesimally small amount of time duration to calculate & display w/o using a Cray computer processing power inside your AL-P CPU.