GPS Data Used To Disprove Radar Gun In Speeding Trial
from the not-so-fast dept
Over the past couple months, we've pointed to the misuses of technology to enforce traffic laws, particularly red light cameras which often end up causing more accidents or allow municipalities to decrease the yellow light time and increase ticket revenue. Last fall we noted the case of a teenager who was challenging another technological traffic enforcement: radar guns -- and he was using a different technology to do so: his GPS system. Now, the 18-year old driver has successfully contested that speeding ticket which he was issued for allegedly traveling 62 mph in a 45 mph zone.Luckily for the teen, his car had an advanced GPS system which not only provided directions but measured velocity to "within 1 mph." After receiving a trial and bringing a GPS expert to testify to the accuracy of the device, the $190 ticket has been dismissed. What is not clear is why the police officer's radar gun output was more than 1/3 inflated (though this is hardly an isolated incident). Also, as a number of people have pointed out, similar GPS data, if widespread, could also come to serve as critical evidence in convicting traffic law violators instead of providing a check on state authority.
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Filed Under: gps, radar guns, speeding tickets
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GPS accuracy
I have "while sitting at my computer with GPS hooked up" made a few trips to far away places... I once made a trip 'while sleeping' to Antarctica and back in less than 30 min.
When I woke up and looked at my computer screen, I thought DAMN I'm good. A trip to the South Pole and back while I was asleep. Can you get any better than that?
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Re: GPS accuracy
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Re: Re: GPS accuracy
The only questionable measurement while not moving is "direction", since direction measurement requires movement, it is not possible to return a value when the speed is zero.
If you have a GPS that "freaks out after a while" you might want to have it repaired.
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Re: GPS accuracy
The way the satellites are positioned and orbiting, 5-7 are technically "visible" at most locations, however due to the very low broadcast power and small antennas on hand-held units, often only 4 or 5 are picked up.
If it drops to 2, which is the case in a house, building, underground, etc, then it can only isolate your position to either of TWO intersections of arcs, which would be why it would go from wherever it was to Antarctica.
Next time, don't be such an obtuse dolt and expect a 1" antenna to pick up signals from satellites orbiting at 12,500 or so miles away while inside your house.
Car based GPS assumes you are on a road, and uses that fact as another variable to determine location, eliminating a good bit of error, and while on the dash of a car, likely picking up 6+ signals, the accuracy of speed estimations is more like 1/10th of a MP/H or less, and doesn't suffer from multi-path distortion like radar/lidar does.
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Re: GPS accuracy
I couldn't leave fast enough.
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Radar Accuracy
I used to regularly have lunch with an officer and he'd bring a portable radar unit sometimes. We'd routinely clock dumpsters and trees at anywhere from 50 to 300 miles per hour, and most cars exiting the drive-thru of the burger joint were clocked in at 45 MPH or so when they were moving at a walking pace.
Seems that the cops should use the units that MLB has for clocking pitches.
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Re: Radar Accuracy
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But the data from the high end GPS units such as those in law enforcement fleets can be certified within 1%. Luckily for the teen, his car had an advanced GPS system which not only provided directions but measured velocity to "within 1 mph." Sounds like a $2000.00 GPS unit to me.
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Re: "tuning" RADAR
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Re: "tuning" RADAR
Except the maximum speed at which the fork is moving will depend on the amplitude of the oscillation, not just the frequency. And there's no easy way to ensure the amplitude is constant.
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Re: Re: "tuning" RADAR
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Re: Re:
If you were to try composing a proper sentence while belittling other poster's comments, the casual reader just might think you are knowledgeable on the subject matter.
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Re: Re: "tuning" RADAR
hmmmmm... tuning is a type of calibration.
Granted saying "calibration is tuning" is not an equally true statement. How ever because of the similarities you can not blame some one for minor error in semantics.
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Re: Re: Re: "tuning" RADAR
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Re: Re: Re: Re: "tuning" RADAR
Lighting yourself on fire while eating animal crackers is also not a type of calibration. And because I'm responding to a poster chastising another for switching the terms tuning and calibration I fail to see the point of your comment.
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I worked for a small police department in upstate NY. In the five years that I worked there, not one officer checked his unit prior to the beginning of his or her patrol. The vehicles were checked for damage, but the radar units were not. Even the supposed traffic units, the low profile wonders that would generate more income for the town did this.
What I especially liked was the fact that one of my friends is a radiohead, has more antennas coming off the roof of his vehicle than a porcupine. He was stopped by an officer, citing the fact that he was speeding. When my friend started questioning the officers radar unit and its calibration, the officer quickly backed off, and let him go. It didn't help that my friend also had a radar unit sitting in his windshield at the time. And yes, he is licensed for it, since radar is essentially a radio that transmits and receives its own broadcasts.
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I worked for a small police department in upstate NY. In the five years that I worked there, not one officer checked his unit prior to the beginning of his or her patrol. The vehicles were checked for damage, but the radar units were not. Even the supposed traffic units, the low profile wonders that would generate more income for the town did this.
What I especially liked was the fact that one of my friends is a radiohead, has more antennas coming off the roof of his vehicle than a porcupine. He was stopped by an officer, citing the fact that he was speeding. When my friend started questioning the officers radar unit and its calibration, the officer quickly backed off, and let him go. It didn't help that my friend also had a radar unit sitting in his windshield at the time. And yes, he is licensed for it, since radar is essentially a radio that transmits and receives its own broadcasts.
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She rang a local radio station which took the car to the local race course and got a professional driver to push the car to see the max speed they could get and it was about 85kmph.
A few month later after about everyone who had been issued a fine for speeding on that strip of road appealed they tested the guns and found they were wrong more often then not.
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FYI
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This costs both time and money.
How many hundreds of innocent people chose to pay rather than go through that hassle - or because they did not have an advanced GPS system.
Hopefully, this wont end here - a class action suit would be appropriate if negligence can be proved on the part of the municipality.
That is the only way they will be motivated to change.
According to this blog - they do not even know why the Officer was receiving the wrong info - nor is there any indication that they will look into any other cases involving that Officer or that technology they are using
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GPS Data Used To Disprove Radar Gun In Speeding Trial
When I went to court for the citation before pleading I asked the Judge If recalibration was required between traffic stops, he replied that this was the case. I then asked if it was possible to recalibrate the gun between stops and issue 3 citations within 3 minute, my being the third citation by the officer wielding the radar gun within this time period, He stated it was not. My case and the case of the second person cited in the speed trap were dropped.
He then called the officer,who was in court for an unrelated matter. to the bench and had the bailiff clear the court. Once outside everyone could here the Judge berating the officer.
I was actually speeding slightly doing 30 mph in a 25 mph zone the citation was for 45 mph. An officer in a neighboring municipality I was friends with told me of the re calibrations mandated between stops saving me from having to pay an erroneously inflated fine - 5 mph versus 20 mph over the limit.
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Re: GPS Data Used To Disprove Radar Gun In Speeding Trial
Note that recalibration is a very different thing from a quick calibration check (which officers can do).
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Re: Re: GPS Data Used To Disprove Radar Gun In Speeding Trial
A discerning reader, then, might assume that a quick check was the actual requirement.
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Re: Re: Re: GPS Data Used To Disprove Radar Gun In Speeding Trial
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The cost?
Wouldn't it have been cheaper just to pay the ticket?
Then again, this is what too many police agencies count on: people will simply pay the fine because it's cheaper and easier than fighting in court.
Are the radar guns accurate? Who knows, since no one's challenging them.
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Re:
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He was lucky.
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Re:
I wish. I had an inaccurate speedometer, got a ticket, got it repaired, then went to court with the repair receipt. The judge said "That's no excuse. The law doesn't even require you to have a speedometer. Guilty". The same thing has happened to other people I've known and the court has never dismissed their tickets because of faulty speedometers.
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GPS data
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Tracking - not navigation
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gps tracking
1) Clocking the wrong vehicle when there is more than one vehicle or in a passing situation.
2) Stationary or Mobile radar. Stationary is much more accurate because the radar is not having to calculate the police car speed.
3) Catching and identifying the right vehicle that was speeding. This can be especially difficult while running stationary radar because of the delay of pulling out into traffic to chase after the suspect vehicle.
4) Radar calibration, which should occur at least once per year. This should not be confused with an officer checking calibration with tuning forks. The calibration should be checked before and after each ticket is issued, but at a minimum, at the beginning and end of the officer's shift.
5) Hills and turns in the road can easily affect radar readings. Radar should not be run around hills and turns. I have seen radar indicate (for a few seconds) speeds of several hundred miles per hour when it was obvious the vehicle was only traveling at a speed of maybe 50 - 75 MPH.
6) A/C or heater fan can interfere with radar readings.
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Re: gps tracking
2- Not true. They are equally accurate. Not sure where you got this tidbit from.
3- This is a training issue, identification of suspects is a fundamental element of police training.
4- Most states require certification for the device and the tuning forks every 6 months, and yes, the device should be tested with the calibration checks before and after each stop.
5- Hills affect the RADAR only when the target vehicle is behind the hill crest and a reading is not possible. Turns do not affect the RADAR except in the case of cosine angel effect, which is to the benefit of the driver, not the officer.
6- True..to some extent, but this is dealt with in two ways a) Training the officer to recognize ghost readings (which is a fairly easy thing to do) and b0 equip the vehicle with a proper dash mount for the device to shield the antenna from the fan openings in the dash
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Radar guns and speeding ticket
Recently, as I traveled down a desolate hyway in Arizona, I put my cruize control on 65 like always as that is the speed limit and, my car does not favor doing anything over that, it shakes and shimmies and is comfy doing 65.
Suddenly, I saw red flashing lights behind me and thought "I beter pull over, this cop is probably going after the big rig about 10 car lengths ahead of me, hauling but.
Not so, the cop was red lighting me and for what?
Speeding, specifically 81 in a 65 MPH zone.
Is it possible his radar gun was picking up the truck?
My car is so short, approximately 35-40 inches tall from the ground.
I am going to court tomorrow, just wanted to see if anyone has a comment
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Re: Radar guns and speeding ticket
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Re: Radar guns and speeding ticket
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Speeding Ticket
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Re: Speeding Ticket
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Inaccuracy of RADAR
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GPS is not always accurate
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More than GPS - Fighting the Corrupt System
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