The radar panel will typically have three displays, from L to R, Target, Lock, Patrol.
Some members lock, some don't. At the time of being caught ask to see the lock speed, as already pointed out, the display will also show the patrol speed when you're speed was locked.
Given you know you were speeding, I would just pay the ticket.
I have seen quite a few different radar units in operation, they don't lie if calibrated. The patrol speed is taken from the patrol vehicle's speedometer.

A tip. Have you ever sped up as soon as you've passed a police car in the opposite direction? Many have rear facing radar as well. With the touch of a button on the remote control, they can switch to rear radar and in away mode as opposed to closing.