I was going SB on 408 doing about 80 and I look over and see a state trooper looking back at me. He then pulls me over and says I was going 90. I have a radar detector which didn't go off and I didn't see him anywhere on the side of the road so I'm sure he didn't radar me. On the ticket it says "Pace Clock or Pack Clock" something like that, so I'm wondering if this means he got my speed by driving next to me. If this is the case then I plan on taking it to court for a few reasons being: He had to be going faster than me to catch up to me, how do we know his speedometer isn't off, there is no way I was doing 90 because I looked at my speedometer and there was traffic around no allowing me to go that fast, and how would I be doing EXACTLY 90 mph because that sounds like an estimate. Any input would be greatly appreciated as to what "Pace clock" means, if anybody else has had this type of ticket, or if there is any other information I could use in court, thanks.