[gdo]

they are quite good I could go a good distance, I'll try to test the range, but with the building, I could get it through 3 walls ~8in. thick, but these are interior walls. the construction of the building could affect transmissions. a taller building would have thicker walls and would have metal interfering with the transmission, I hope that this project turns out for you well

P.S. why did you start considering vex robotics, it wouldn't be my first choice for a police robot

EDIT: it could have interference if anyone is on that frequency, I've only had that problem when you have the wrong crystal, but as someone already stated if you have all 9 crystals you should be fine to avoid interference