just pay it
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You shouldnt have been speeding in the first place.
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Ask for a caibration report for the unit that caught your speed. This may cost a few buck but if the speed detector was not in calibration, it could give a false reading….but ask for it long before your court date, it may take time.
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I work with alot of calibrated tools…..

If you were going that fast, pay it, and consider it a lesson learned…

You're ignorant for speeding 31mph over the limit in the first place. I'm pleased you were caught..
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If the police officer radared you, then you only have one very slim chance of getting out of it. You'd have to prove that the radar was not properly calibrated, which means you'd have to hire a lawyer who will have to put in a discovery request for the maintenance records for that vehicle, and that right there is going to cost you a bundle. If the lawyer finds out the radar was properly calibrated, you're screwed and you're out that money you paid to the lawyer. If you luck out and the maintenance schedule wasn't followed, you'll now have to shell out more money to have the lawyer represent you in court, and I guarantee you it'll cost you a lot more to beat the ticket than to pay it.

Here's a lower-cost alternative: Request a hearing before the judge or magistrate. When you get there, admit your screw-up, explain yourself, and ask for leniency. If you have an otherwise clean driving record and your explanation is at least plausible, the judge/magistrate may cut you a break on the ticket.
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People like you get families killed by running them off the road. Pay the ticket. It looks like you didn't learn anything, but try to slow down.
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Pay it.
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Depends on what state you're in and how the officer measured the speed. Most departments keep their equipment certifications current. Some states, such as Florida, even require the officer to test the radar before and after their shift, to verify that the unit is working properly. And that's to say the officer used radar. There's also laser and vascar.

And as the other officer stated, radar is just a confirmation of what the officer observed. The officer observes the vehicle, estimates a speed, and uses the radar to confirm that estimation. I have never seen anyone get off of a radar or laser (even harder) ticket, so just own up to your mistakes and take the driving school if it's available. You have little chance convincing a judge or hearing officer that you wasn't speeding!
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I'm a FL police officer.