I'm guessing that in a case of a family and a speeding ticket, being decided by a county traffic commissioner, that commissioner is going to rely on the radar gun.

Again, I'm just guessing, but I would bet it's going to take some federal criminal case, some real effort and data by the attorneys, and a judge with some clerks to put to work before somebody is willing to accept a new source of data that would overturn convention.

92BuickLeSabre

Speed is determined by distance over time. Even the best GPS systems have fluctuating accuracy. Go under a bridge or a tunnel and you have just thrown off your GPS's ability to accurately determine speed.

sguth925m

@ConstyXIV: yeah, thats what they WANT you to believe.

homerjay

if you have a nuvi (or possibly other models) it will show the maximum speed you've reached since it was last reset.. he shouldve shown that to the cop

andrewthemacfanboy

@homerjay:
I'm pretty sure GPS satellites are one-way and all the actual work is done on the ground

ConstyXIV

@ttran97:

that would qualify as the "right" device as data from GPS units is admissible in court as it is used in court trials for establishing timelines.

jayuup

Maybe the GPS doesn't store the data, but maybe the satellite does just like the Major League Baseball satellite. Break out your tinfoil hats.

/drunk
/humor

homerjay

actually with the right device, right data, you could make a very compelling argument based on reasonable doubt.

If the data is available (key issue) and can be shown to not be corrupted, a GPS unit can show location and timestamp on two points along the specific roadway. Airplane speed enforcement is nothing more than that...time stamp travel between two points.

The key would be to argue that the data is accurate and unspoiled. That would be the key issue that the city/county/state courts would have to argue. But if the state certifies GPS as a billing tool for taxis, rental by mile for rental trucks, ambulance bill by mile, or some other endeavour, this argument holds merit, at least it will in the eyes of the courts.

jayuup

I saw this story on the news a few weeks ago. They're not using a portable GPS. The dad installed one of those GPS things in the car that can track his son via internet with a laptop...and that thing stored the time/location/speed.

ttran97

Yeah, good luck with that.

strider_mt2k

You cannot be serious.

ruggels

Yea, he's right, the GPS is going to be more accurate, but it doesn't store that data, so it's still a matter of he said she said.

BurstAneurysm

Yeah stupid cops don't realize that over a certain distance the speed captured by the radar gun has the chance of becoming incredibly inaccurate. There is actually notices on the radar guns box about this, but because the radar gun doesn't poop out at the maximum distances, the cops think its still working accurately, and they give bad tickets. New radar guns should be updated with a "not-accurate" warning light, when cops use it on cars which are too far away.

AlanIn4D

jsut subpoena the source ocode for the radar gun the company wont relese it and thent he case can be dimissed because you are unable to analyze the code

Catharsis

@sguth925m: GPS gives a pretty damn accurate speed measurements. More accurate than your speedometer could possibly be unless you recalibrate it to your tire radius every time it changes by an inch with pressure.

illiniguy

You are kidding yourself if you dont think your GPs data is not stored.

Maybe not by the manufacture, or the device, or ON the device... a recent Forensic Files episode PROVES it is maintained and recorded data and it is stored for some time on a "3rd parties" server.

Deal with it - you are being followed.

Stacky Botrus

@Spaceman7 I should have tried that one in court.. but I really was speeding

tommo

@banmojo: Wow! Do I detect a little hostility there? Take a deep breath, and as you exhale, hum. "AAaaauummmmmmm...... "

OR, take a chill pill, Dude!

But, your message has some merit!

lunarstreaker

"F*** 'em, and their laws!"
Mmm, angry muzak make me wanna lift weights or hit people :^)

banmojo

(sorry, double) -And also, how many times has a poor sod been pulled over in his 1991 Hyundai for a 73mph uphill b/c teh dumb cop was measuring his lateral acceleration and not the straight line velocity?
I know at least 1 person who's brought the physics into court and beaten the ticket.

spaceman7

@sguth925m:If you start at point A and drive to point B, as long as you get a time and position reading at A and B it doesn't matter if most of the time was spent in a tunnel. You'll have the average speed between A and B.

Now, of course, if A and B are far apart you could fly through part and crawl the rest of the way, and so be speeding some of the time. But as long as A & B are in close proximity to the location where the ticket was issued, he has a good case.

MegaZone

Er; if a GPS unit is already more accurate than the speedo on Alex Roy's M5, I think its data will be quite sufficient, mkay?

spaceman7

Here in Australia there have already been a number of successful challenges to radar infringements using GPS data, the most recent one in July this year. Perhaps this chap could look Down Under for some precedents to support has case against his local authorities? :-)

OzDJ

@Stacky Botrus, feel free to fill us in on how on earth that's possible given unites such as the nuvi pictured simply receive information in their default configuration, and do not transmit. Thanks in advanced for your detailed explanation.

ruggels

GPS doesn't calculate instantaneous speed. It calculates speed between measurements. So the Radar may win because the GPS only calculates the average speed between points. The GPS would have to make calculations many times a minute to prove that the kid couldn't have been going the Radar detected speed.

Skeptic

I wonder how one would fare with one of these CarChips: [www.davisnet.com]

I have one, so I know that you can't easily/readily tamper with the data, and it logs your speed in 1-second increments, so it'd be pretty easy to prove you were or weren't going a certain speed at a certain time.

Of course, the downside of any such device is that it'll usually end up proving that you were speeding *somewhere* at *some point* on that trip, since it's virtually impossible for one to *always* be under the speed limit.

I can see it now.. "Okay, so you weren't doing 62 in the 45 zone -- but the data logger shows you were doing 85 *somewhere* on Thursday night. I'll write you up for that, since it's not legal anywhere to be doing 85..."

sodakar

@ConstyXIV: my previous comment was supposed to be in response to this comment. Woops.

lafond66

@sguth925m: Satellites basically just broadcast who they are, and the current time. Your GPS knows the geosynchronous locations of the satellites and uses that to triangulate it's position.

I feel like if you had the data, a GPS will be infinitely more accurate in judging speed than a radar gun. Laser would be more accurate, but still I think GPS is pretty spot on.

lafond66

@Skeptic: Most GPS units take a reading at least once per second.

Phlegmbert

@andrewthemacfanboy:
yeah, my garmin does that too. the problem is i strive to set the max speed as high as i can. it's only ~94 right now. i guess it would work if you reset it everytime you started driving...

weinus

There is another factor in this. The vertical direction on most GPS has horrible resolution. If there was any incline at all, the speed on the GPS could be totally useless. I don't think any commercial GPS would have good enough data to beat the radar gun.

rockboy04

Just pay the ticket! We all know he was speeding.

My question is, I can tell when a vehicle is going 62 in a 45 minus any radar gun.
And my eyes are bad from staring at a computer screen all the time.
The cop pointed and fired the radar gun at the kid because it looked like the kid was going 62 miles per hour.
And the cop does it for a living.
I only do it in games.

M. Schlabach

@ruggels:

Go to Court TV.. seach for episodes which relate to GPS or murders which occur accross muliple state lines.

Watch it.

It was EVEN a Garmin that was stated - you can see it clearly.

Deal with it poncho.

Stacky Botrus

I haven't read all the comments, but, how can you say the GPS doesn't store the information? You are so wrong - my GPS contains a track log that can easily be saved and looked at to find speed and locations at a certain time. Of course, you have to actually save the log off - but it can be done. I think this guy has a good chance of getting out of the ticket! Good luck!!

ksat

@BurstAneurysm:Wrong. There are some with data logging.

w00zzy

@rockboy04: He wasn't traveling up and down in a Wonkavator--he was traveling in a car, which is what GPS was designed for. They have very high resolution on NESW directions.

And even the resolution doesn't matter that much, only that it shows he was HERE at this time, and then he was HERE at this slightly later time. Calculate the distance between the two, and how long it took him to get between those points--and you have his speed. It's not that complicated people!

dragonphyre

@sguth925m: So not true... GPS measures where you were the last time it checked your position (1 second ago) and then it checks your position against where you are now.

Yes, the system averages out your speed, but it's not over miles and miles. It's over one or two datapoints. Much higher accuracy, and much more provable than a radar gun.

Of course you realize that if this case is won, the cops will want to install GPS units in every single car which will log everything you have ever done--and then use that against you.

dragonphyre

Some guy just won a similar case here in the UK using GPS data, here:

[news.bbc.co.uk]

Makes a lot of sense to me.....

mac_kix_windoze

Every new car has a record of your speed. The "Black Box" (Air Bag Sensor) is constantly recording as you drive. GM vehicles, once they sense a significant change in velocity it saves speed, percent of throttle, braking, engine RPM, and several other things like if you were wearing your seatbelt up to five seconds before the collision.

sguth925m

My opinion:

Cost of Paying Ticket < Cost of Fighting Ticket

... most of the time, depending on where you live.

EvilJ

@Skeptic - The GPS does indeed take an instantaneous velocity reading. It does this by measuring the doppler shift of the signals broadcast from the satellites. This is the same method the radar gun uses to measure your velocity. GPS uses both position and velocity data to estimate your acceleration and jerk (the derivative of acceleration) in order to predict your location even in the absence of data. It needs to do this in order to estimate the effects of errors due to satellites coming into and out of visibility as they pop over the horizon or are hidden behind bridges...

zer0energy

You can guess Onstar has a record of your speed; nothing says "voided warranty" like proving that you were "racing". Also, they sell parental units that log, upload to a website. Wanna bet his dad, the former sheriff, didn't put one in his car.

On a second point, how is it the police can use every bit of technology your tax dollars can buy against you, get a court order for the data collector, but have an issue with you logging and producing exculpatory data.

junyo

My GPS keeps the top speed I travel until I decide to erase it...the other day my top speed was 170 MPH in a Ford F250...how accurate is that? RADAR Accuracy is +/- 1 mph, same for the laser. In California you cannot introduce evidence of speed when it is measured with a clock, and that is exactly what a GPS does.

sguth925m

@dragonphyre: Re: Wonkavator. Best comment all day!

SpudMills

The data, if stored, is an easily editable text or XML file.

DeadWriter

@EvilJ: Factor in increased insurance rates, and fighting a ticket USUALLY makes sense.

Pixelantes Anonymous

I bet it was a [url="http://www.lightninggps.com/home/index.php"]GPS unit that stores the info[/url]

deedrit

Cost of fighting ticket < insurance cost of ticket

The state wins 97% of all traffic cases ... but only because 95% of all cited motorist plead guilty by signing the "guilty" line on the ticket and sending in their money.

Of the remaining 5% who fight, on average 3 out of every five win.

Ask for a continuance ( which makes the court date NOT the same date the cop sets aside each month for traffic court ), and your odds of winning by default ( cop doesn't show ) increase enormously.

kbarrett

Yeah, he (we ALL) should just save our money for a Wonkavator

jellobrains

So now when you have a unit, and a cop asks for the data off the unit to confirm you were speeding, (and therefore eliminate the ability to use gray areas to get out of a ticket) removing the right to a trail, we will be able to know who to blame.
The knife cuts both ways....

OldElvis

@sguth925m:

yeah, the time between entering & exiting the tunnel and the calculated distance based on the GPS cooordinates would serve as distance...

rthprog

(Cost of paying ticket < Cost of fighting ticket) < Satisfaction of creating legal precedence and rubbing it in the cop's face.

CapitalC

@rthprog: Which would give you an "average" speed through the tunnel, not "instantaneous." If the tunnel in a mile long and the GPS notes that it took you a minute to get through it the unit might say you were traveling 60mph. But if it "lost" you in the tunnel it doesn't know if you were going 110mph for the first .8 of a mile and then crawled out the last .2 of a mile.

This all reminds me of a Steven Wright line when he got pulled over by the cop.

"Do you know the speed limit is 60mph?"
"Yeah, but I wasn't going to be out that long..."

ninjamurf

@kbarrett: There is no "guilty" line on a ticket. Signing the ticket is merely a promise to appear in court. You can pay the fine that they may send you in the mail but the cop should even tell you as he's handing you the ticket to sign that, "this is not an admission of guilt it is merely a promise to appear."

And I've been doing some of the math and this doesn't make sense people. Good GPS units are only accurate to something like 3m (~10ft) and are usually just given within a range of 15m! If you are traveling at 60mph you are going ~90 feet per second. If your GPS takes a measurement every second you could be off by +/- 20 feet. This equates to an instantaneous velocity difference ranging between ~47-75 mph. How is this accurate?

ninjamurf

I work in marketing for Decatur Electronics, the company that made the radar gun.

The unit used is here (I think there's a link to the tech specs of the unit, too).

I'm not a technical expert, but radar reads instantaeously--the only processing is the unit processing the Doppler shift of the reflected signal.

Moreover, radar case law demands that the unit be a confirmation of officer's estimate. Somebody mentioned this earlier: these guys do this for a living (and have pretty well-trained eyes regarding speeding) and clock people they think are speeding for confirmation.

Hope that helps.

JakeDecatur

The big obstacle for many courts will be foundation to convince them the GPS data is accurate. It acutally may be necessary to have an engineer from Garmin, TomTom, etc. testify in court on how the machine was designed and works before it would be accepted. You would also have to show that the GPS data had not been manipulated by anyone. But once that happened sucessfully defeating the radar data, it would be a precedent that theoretically all users of the same GPS unit could use without any hassle.

doubleT

I am flat out amazed at how many people have misconceptions about what GPS devices are or are not capable of.

1) GPS devices CAN log data, but not all do
2) GPS devices CAN transmit data back to a server, but very few do
3) GPS devices CAN give an accurate speed measurement, but you must make sure that the samples are taken at short intervals (say 1-2 seconds apart) not once per minute
4) GPS devices require multiple satellites to be accurate and the more the better. Three is minimum to give you 3-dimensional location (yes, you get altitude too)
5) Typical GPS log data also contains detailed information about satellite signals, speed, confidence factor, etc.
6) Not all GPS logs have detailed info, some just have date, time, lat, lon and alt (no satellite data)

With the right GPS, and assuming it is configured properly, they will have no problem proving the actual speed he was travelling. The question is...will it matter?

srhall

I have been following this story intently because i know the police, and the area this was said to have taken place. The police in that area are known for eye-balling how fast you are going and then claiming their radar said you were going XX speed. Also the courts in Sonoma County will prob go with the kid anyway, they are pretty liberal there.

nanao