Are you required to sign a speeding ticket to make it valid?
No. Your signing doesn't mean you agree to what the ticket says, simply that you acknowledge getting the ticket. ("I didn't get any ticket, your Honor." ;) If you don't sign, you can be waiting until another cop comes to witness, or taken somewhere to where there is another cop to witness, or even nothing, because you are probably on camera anyway. Not signing doesn't gain you anything except a pis sed off cop who may start looking for your car a lot more. Good Luck!!
Lol, if you're asking if not signing one means you dont get a ticket, I dont think so...