You can fight the ticket. Consider the Basic Speed Law CA VC 22350 and 22351 and getting an Engineering and Traffic Survey. Depending on the survey and the location, there are technical defenses which may apply such as whether the police had a right to use radar at that location – “speed trap” VC 40802(b) as well as malfunctions and inaccuracies of the radar equipment and other defenses.
You can fight this ticket. I assume that it was a 22350 VC that you were cited for. I handle many tickets in Vnetura. Call me with any questions.