Are radar guns that the police use really all that accurate?

Question

I was traveling on a mountain highway recently when an LED display road sign lit up stating I was driving 55 mph, when I knew I was going 45mph. I was not stopped but this really surprised me.

ret_roach_cop, I knew that my actual speed was 45mph because I saw it on my speedometer an instant after seeing the LED sign light up.

homeward07, your lengthy answer is very pro law enforcement and I do not disagree. However, you have not addressed the discrepancy that I mentioned in my question.

Answer 1

Yes it is nearly hundred percent accurate, seriously it could be the meter in your car that is spoil which is not a surprise as car easily have malfunction. I have been working as a police for 6 years and have use the radar guns myself. I will not lie as I already resign.

Answer 2

those on the fringe of the line have a 9 mile margin of mistakes. also, many are believed to purposely upload some miles in preserving with hour as a way to make you decelerate, notwithstanding that's thoroughly unsubstantiated. notwithstanding, in case you had a 10 mile distinction, you want to take your automobile to get checked! The radar guns that police use of their autos are more advantageous precise certainly, and characteristic a 7 mile margin of mistakes. usually situations, the line signs and indicators are literally no longer measuring YOUR % once you bypass them, yet have become the speed of a automobile both beside or in the back of you.

Answer 3

The ones on the side of the road have a 9 mile margin of error. Also, many are believed to purposely add a few miles per hour in order to make you slow down, but that is completely unsubstantiated. However, if you had a 10 mile difference, you need to take your car to get checked! The radar guns that police use in their cars are more accurate indeed, and have a 7 mile margin of error.
Often times, the road signs are no longer measuring YOUR speed when you pass them, but are getting the speed of a car either beside or behind you.

Answer 4

Most jurisdictions use the RipCon 86 unit now. This is an instrument that needs no calibration, as it's empty inside.

The old guns were too heavy for full time use, and so, the new model is much more appropriate.

These guns save lives. Thousands of police officers, judges and clerks would be forced to find productive labor were it not for their effect upon society.

I feel no guilt whatsoever in sharing this with you, as if it saves a single life, my time has been worthwhile.

Speeding kills. Ticket fines save city, county, and state budgets. Folks, these exotic new Court complexes aren't cheap, nor are the bullet-proof security measures that protect us, (your servants), from the few mindless criminals who seek to harm us.
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Answer 5

With the radars that we use in our cars, they are calibrated every time before I go on duty. In reference to the speed trailers that you see on the side of the road, they are most commonly calibrated every time it gets placed at a new location. Every machine needs to be calibrated, no matter what model. In regards to your situation, I have seen many cars that have guages that might be off a little (off sized tires is the most common reason, dated car). It could be a multitude of things that could have caused it. More than likely, I would trust the sign more than the guage in the car.

Answer 6

They are if your the only target in their radar or ladar beamwidth. But oftentimes, there's multiple targets all going nearly the same speed in the same beamwidth in a pack of vehicles, and the radar or ladar gets confused. An obvious case is when your along side a tractor trailer truck going the same speed and your between the truck and the radar. Since the doppler radar target return from the truck is a hundred times bigger than the return from your car, it's highly unlikely that the radar can pick you out as a speeder.

Answer 7

It is to my understanding that the radar guns have to be calibrated, I do not know however at which times they do need calibration in order for them to be accurate enough. There was a show called "MythBusters" and they checked laser guns which fire a very small amount of I would guess laser power at every interval of a second and then they used a radar gun. I believe the laser gun won out in the ending of the myth. If I could explain it more to you, I would be here forever!!! Yet radar guns are quite accurate if they are calibrated enough times.

Answer 8

Those road side signs are not police radar, they are warning devices and are not normally certified or tested.

Police radar ( most don't use "guns" but use car mounted units") but yes they are very good to the 100th of a mph.
They are not only certified but they are tested using tuning forks at the start of every shift to be sure they are correct.

Answer 9

Those stand-alone radar stations are not very accurate because unlike the radar equipment in the police car, they are not regulary calibrated. Police don't use those stand alond stations to guage how fast you are going, otherwise they would have to be calibrated to the department's standards and that maintenance would have to be logged. Their purpose is mainly to serve as a reminder to drivers that they might be exceeding the speed limit.

If you are ticketed according to one of those stand-alone stations, you should contest the ticket in court where the officer would have to produce a log of when the machine was calibrated. Chances are, he won't be able to.

Answer 10

bobweb and Sgt G are both correct. To add to bobweb's answer, a good portion of teh initial 40 hour RADAR certification is spent training on determining which car shows up in your display. Also RADAR is just a backup, its the officer himself that determines how fast you are going and develops a tracking history. The RADAR just confirms his determination.