You DO KNOW that these and all detectors ONLY work when the radar/laser is in armed mode,,,,,,,, if the cop is chilling and not pulling the radar trigger you dont know he's there, as soon as he pulls the trigger your detector goes nuts but he has YOUR SPEED.......... now he leaves it roam mode, yes you will pick up his signal way before his range..... and yes I'm talking from experience.
Radar is harder to prove in court UNLESS your the only vehicle, lazer is different, 100% accurate in everyway, apart from rain.