I'm not sure exactly what kind of radar/laser is used by the La. state police, but they all have a hand held button and a "standby" mode on their unit,when in this mode, it emits no signal, but the unit is on and ready to go. When they're parked "running radar", they "pace" the oncoming cars and if needed, hit the button and they have an instant mph reading on you, your detector will go off, but it's too late.....
BTW: In good ole La.,word is if you have a radar detector, you get NO warning, you automatically get a ticket and it WILL NOT be "fixed"... I guess it pi$$es off the cops when you have one on the dash...
BTW: I don't have one, I just stay within 5 mph of the posted limit and the cops never give me a second look.....so far.....
David