Re: Speed trap
"so someone clearly didn't calibrate them properly."
In which case you should be griping about it. There are a couple of speed signs around here that used to go off at 26mph until complaints were made.
It's also worth noting that when multiple vehicles are in a radar beam you'll get heterodyne effects (retruns for both vehicle speeds AND their additive speeds AND the difference speeds as returns either side of the primary speeds AND if there's a static reflective surface you'll get odd returns from that too (especially corrugated fencing).
On top of that, the radar frontal area of most post-1985 cars is so small that the return from the back end of a truck 1 mile down the road will be "louder" than the return from such a car less than 300 yards away (almost all vehicles have larger rear radar returns than frontal ones).
That's why the UK police rely extensively on portable lasers to keep only the target illuminated and why speed cameras have to take two photos against calibrated road markings to prove the vehicle being photographed really is the one that was speeding.
Biting the hand that feeds IT
