Teenager beats speeding ticket with GPS

[stroker1]

* from Yahoo -News *

A teenager has successfully defended himself against a speeding ticket by convincing the court that his GPS was more accurate than a police radar gun.

Shaun Malone, 18, was issued a speeding ticket after a police radar gun tracked him as going 62 mph in a 45 mph zone. However, he appealed the ticket because his GPS, which was installed by his parents to monitor his driving, showed he was driving within the speed limit.

The court originally ruled against the ticket, as a court expert said GPS was not accurate enough to give a precise reading. But after examining the particular system, installed by Rocky Mountain Tracking, he decided it would be suitable.

"This case has caught the attention of the nation, and it will set a precedent on how police departments use speed traps in the face of an increased GPS presence," says Brad Borst, president of Rocky Mountain Tracking, and who is also a former Police Officer.

"The accuracy and reliability of GPS has helped bring this important issue into the limelight."

The device measures real-time speed every 30 seconds and can also be configured to send out an email message to the owners if the car reaches speeds of 70 mph or over.

[stroker1]

Just out of interest, i always justify my speed with cruise control set at the speed shown on my Tomtom

Would anyone else agree that this is good practice? As far as i'm concerned, the GPS signal shows your true and accurate speed - ANYONE?

John.

[Tomo1971]

I would agree. The GPS will be slightly out as you go up or down hill and of course will depend on how many satalites it is seeing at the time. Certainly more accurate than the speedo of the car.

I do the same, set the CC to the TomTom speed rather than the car speed display as most other people seem to do especially while going through SPECS systems etc.

Steve

[redbaron]

not sure how relevant a US piece of news is to us in the uk.

[westerdam2]

not sure how relevant a US piece of news is to us in the uk.

Agreed. I wouldn't like to put it to the test in a UK court! Besides, unless he had some sort of recording device fitted which would provide a note of precise speed and time of day, it is simply his word against the police radar evidence.

Not that I'm suggesting that the firm involved is also a winner with lots of free publicity

[Mrs Stig]

About three months ago, I was driving through a village where the villagers had a portable sign telling drivers how fast they were going. My speedo said 25mph and their sign said 33. They were writing down number plates, so I was a little disturbed. The Stig stopped and asked them what they were doing and they said they were reporting anyone going over 40mph. He pointed out that their sign may not have been accuarate and they said they had it callibrated each morning. Apparently the police were writing to the people they reported and warning them....... :thumbdwn:

Edited 20 July, 2008 by Mrs Stig
Stig quality control............

[VRStu]

If GPS is accurate enough for dropping bombs then I think I'll take my chances with it.

[Auric Goldfinger]

I would agree. The GPS will be slightly out as you go up or down hill and of course will depend on how many satalites it is seeing at the time. Steve

Don't think speed will be out due to the number of satellites. The minimum required [ 3 I think ] will be the same as 6. The more satellites it See's may give you a more accurate position, not speed I dout 3 satallites say's your doing 30mph, if your seeing 6 your doing 33mph.........I will stand corrected though.

[gadgetman]

Remember tho non military GPS has an allowed accuracy of +/- 5%.

Speedo also has a similar error margin. Would you risk that speedo is right and GPS actually wrong?

I've had mine tested, and I know my tomtom is 5mph slower than car speedo - which is 10% higher than limit.

[anewman]

I cannot see how going up and down a hill will affect a GPS speedo reading. A GPS lock is 3 dimensional. Therefore movement is calculated within a 3d plane, including altitude as a variable.

The thing I would disagree with here is the 30 second update - that may not be regular enough to say with any certainty that he was not speeding the second he went past the camera.

I remember a similar news story of someone putting together a GPS device to record speed and intentionally set off speed cameras trying to use the GPS records as a defence but failed.

[tippo1983]

not sure how relevant a US piece of news is to us in the uk.

with regards to the uk law, no relevance whatsoever.

[woodenspatulas]

with regards to the uk law, no relevance whatsoever.

ah but it none the less proves what we all know, speed cameras and other police devices can be wrong!

the only way to prove someone was speeding imoa is by a correctly calibrated poilce car following the speeding car for over 1 mile.

even speed cameras can fail, i remember seeing someone had painted over the white lines, so if the camera went off there was no lines to prove the car was going to fast

[anewman]

I go back on what I said. I must have remembered incorrectly or this is a different case entirely. But this is a UK story.

Here for all to read BBC NEWS | England | Wear | Inventor wins speed camera battle

Inventor wins speed camera battle

Dr Phillip Tann

Dr Tann claims his system is more accurate than mobile cameras

A scientist escaped a charge of speeding at 42mph, after claiming a device he invented showed him travelling 12mph slower.

[michaelp]

Just out of interest, i always justify my speed with cruise control set at the speed shown on my Tomtom

Would anyone else agree that this is good practice? As far as i'm concerned, the GPS signal shows your true and accurate speed - ANYONE?

John.

I agree, after 100's of thousands of km in varying conditions, the GPS indicated speed has never produced a speeding ticket and I travel on the indicated limits. This is especially helpful if I mess with my tire sizes to verify actual ground speed instead of indicated speed via the speedometer.

[mannyo]

I cannot see how going up and down a hill will affect a GPS speedo reading. A GPS lock is 3 dimensional. Therefore movement is calculated within a 3d plane, including altitude as a variable.

Yes a GPS lock is 3D, but in order to achieve that the GPS reciever must have a lock on at least 4 satellites in the correct location in the sky. If the receiver is getting less than this, or the satellites it can see are not positioned correctly then the fix will only be 2D, eg. X&Y. This is quiet apparent on my columbus which displays on its GPS stats wether the fix is a 2D or 3D one, in town it tends to be 2D only as the building tend to block satellites, it can be the same in the countryside where trees line the road blocking good reception.

How accurate a GPS is regarding speed depends on this fix, and also how good and fast the software is at calculating the speed along with how the receiver deals with the decreased positional accurarcy of civillian GPS systems. Yes the millitary use the same sats but their receivers are more accurate and also cost a lot more. The error in civillian applications was a US requirement in granting permission to use a system which they own. Also it is possible for the US if they so wish to decrease the accuaracy further at the push of a button.

[simonsheil]

There is a misconception that GPS is accurate to 5%. The fact is that the signal wanders slightly which leads to an inaccuracy over a time span. However, at any one time a reading 10s after the previous one will give you the same position.

I'm preety sure military grade equipment accurate to 10m is more than sufficent to blow up most itmes. I know cruise missiles use it, however my understanding was the vast majority of precision weapons use laser guiding either from a plane or the ground.

To get round the movement of the signal wher high accuracy is needed either a GPS is set up on a known location and compared with the remote reading, or a GPS is set up and left to read for several hours to achieve a reasonable degree of accuracy to where it is.

[Calomax]

I cannot see how going up and down a hill will affect a GPS speedo reading. A GPS lock is 3 dimensional. Therefore movement is calculated within a 3d plane, including altitude as a variable.

The thing I would disagree with here is the 30 second update - that may not be regular enough to say with any certainty that he was not speeding the second he went past the camera.

I remember a similar news story of someone putting together a GPS device to record speed and intentionally set off speed cameras trying to use the GPS records as a defence but failed.

The question of the accuracy of GPS speed readings comes up quite often on PocketGPSWorld and other Sat Nav fora. The usual answer given is that they are accurate when driving straight and level.

[AlphaPapa]

About three months ago, I was driving through a village where the villagers had a portable sign telling drivers how fast they were going. My speedo said 25mph and their sign said 33. They were writing down number plates, so I was a little disturbed. The Stig stopped and asked them what they were doing and they said they were reporting anyone going over 40mph. He pointed out that their sign may not have been accuarate and they said they had it callibrated each morning. Apparently the police were writing to the people they reported and warning them....... :thumbdwn:

I have been a victim of this! It is a completely pointless waste of time, money and effort. I was caught doing 44 mph in a 30 in Camberley, Surrey about 4 months ago. I received a letter from the police informing me that on this occasion there would be no fine or points etc but if caught again i will be prosecuted. Only issue is.. i have never been to Camberly in my life neither has my car. On the time and date that i was supposedly caught my car was sat outside a house in Beverley, about 270 miles away.

So whats the point if the miserable old busy body cannot record the correct registration on his clip board?

[Aspman]

I believe the military used to scramble the GPS signal to make it less accurate for public use but I think they gave up on this and now allow the public full accuracy.

http://www.rbbi.com/news/2000/gps1.htm

Quite old news. Not sure how relevant it is.

[GentleGiant]

The Speed Warning signs I have seen are all well out of calibration, setting them off at between 20-25mph in a 30mph zone; one goes off as I pull away and turn right at traffic lights, at 15mph!!!

[Brimma]

They have some funny ideas in the good old US of A

[vrsadz]

gps 1 - 0 the law

[No Waiting]

If GPS is accurate enough for dropping bombs then I think I'll take my chances with it.

I some how suspect that the bomb dropping GPS systems are a bit more sophisticated than a £200 TomTom toy, or even the £1200 Columbus