False Radar

[imouttahere]

Not sure where to post this but I'll try here first. We were stopped by a radar police unit that said we were doing 72 mph. We have a Ford 550 with a 38' Mobile Suites. We came over the top of a hill and started down the other side. The speedometer registered 58 at the top as we started down. I braked to reduce the speed to the 55 mph speed limit. I noticed the cop down at the bottom of the hill. I kept the speedometer pegged at 55 the whole way down the hill. As we passed the cop he lit up the lights & pulled us over. Said we were doing 72 at the top of the hill and slowed down to 69. Imagine how frustrating it is when you know you were doing the limit & get pulled over. We confirmed afterwards with a gps unit that traveling at 55 mph we were actually doing 55.

A few miles down the road, there was some construction and they had one of those mobile radar units that light up & tell you what your speed is. As we approached at 53 mph, it flashed 55 & immediately changed to 72 mph & stayed at that speed indication as we passed it. Again we checked the gps & it also indicated we were doing 53.

The question I have is what the heck is causing the false radar indications? I have no radar detector and the only other thing I can think of is the tire pressure monitor that is wireless. We also have two iphones.

Something is causing the radar to indicate that we are doing about 14 to 15 mph faster than we really are. I can't keep getting a ticket at every radar trap in the country. HELP MR. WIZARD