I been driving around campus and sometimes the police puts a speed sign. Every time I drive it does not reads my speed, I'm not 100% sure because I have not been able to try it without cars passing by either on the opposite way or behind me. Just once for like for 30 sec. I was by myself after a car passed it and it said "You speed is 0" but I was really close to it. Also if a have a car kind of far behind me I would drive about 25+ (speed limit 20) but it would still read the car behind me (reading would be 18 - 22).
What do you guys think? Does it filter out my speed because it is not strong enough?