can anyone explain how a cop "locks" on to your car and paces you? like how many miles the cop has to follow before he's sure i'm speeding? how close? has to be behind me? b/c this cop said he paced me goign 78 in a 65 when i saw him merge onto the freeway from the ramp for and apparently paced me right after that when he was only on the freeway for less than 1/2 miles and started pacing me.