Speeding ticket wrongfully accused?

On tuesday a cop had pulled me over and said i was going 82 in a 65. There was only one problem with that, and that is that i was going around 71. This is my first time getting a ticket so I am all confussed about the situation especially trying to fight it. I FOR SURE know I was going 71. I had my gps on because i was comming home on the highway from a unfamiliar way. When he had passed i checked the speed on my spedometer and gps and they both read 71. I want to plead not guilty because I know for sure i didnt do it, im man enough to take responsibility and if there was the slightest chance of that I was doing that I would just pay the ticket. Noticing when the cop had passed on the other side of the highway, he was using moving radar, there were about 2 cars around myself and 1 also a dark color car similar to mine was comming up fast by me. When the cop had turned around in the median the other car that was speeding noticed it and slowed to 60. before the cop came he had pulled into the other lane and got infront of me, and well you know the rest. I have looked up that radar could be very inconsistant that many things can interfere but dont get me wrong it has to be good if they continue using it. I noticed there was a wide median that could have messed up with the angle of the radar thus increasing my speed but also the big thing I wanted to argue was that with his moving radar it does not tell you which exact car it had locked onto thus the cop is guessing which car he may have though and with surrounding cars is not 100% sure it was me. I would not be asking for help if I know I was going that fast. If anyone has any advice please let me know!!!