ca_HARTS
Northern CA
Full Member
Joined: 05/17/2004
View Profile
 Offline
|
Well it has been a while but the court commissioner ruled that radar wins this time around. Attached is the link to the article:
www.pressdemocrat.com/article/20091104/ARTICLES/911049901/1350
Tom
Tom
|
rgatijnet1
Florida
Senior Member
Joined: 06/22/2009
View Profile
Good Sam RV Club
|
Not too surprising. I monitor altitude with our GPS when we are driving in the mountains. There are many times when the satellite signal is interrupted and our altitude and speed remains constant when it is obvious that we are ascending or descending a hill. On both our Garmin and TomTom GPS units, the readout stays at the last signal and does not go to zero. It changes only when a new signal is received to update the info. After a long period of time with no signal, it does report that the signal is lost, but usually, when the signal is just temporarily interrupted, there is no indication on either the speed, direction of travel, or altitude, on the GPS unit.
If he was on an open, unobstructed section of road, his GPS unit was probably accurate altho a lot can happen between 30 second updates between the GPS and the home PC.
|
SAR Tracker
USA
Senior Member
Joined: 05/29/2003
View Profile
Offline
|
ca_HARTS wrote:Well it has been a while but the court commissioner ruled that radar wins this time around. Attached is the link to the article:
Link to Story
Tom
fixed it for ya...
Rusty & Cheryl & Serendipity (dog & Chief Security Officer)
2000 F150 4x4 5.4L/3.55 (117k miles and goin' STRONG!)
2008 Weekend Warrior FB2100
"Common sense is in spite of, not the result of, education" - Victor Hugo (1802-1885)
|
mdprince
Santa Clarita, CA
Senior Member
Joined: 11/13/2004
View Profile
Offline
|
Also on a faster type car or truck, you can accelerate very fast and the GPS data will lag a bit. You could easily be going 90 for a few seconds before the display updates.
It was an interesting case, and I'm a big fan of GPS, but the LEO radar trumps just about everything !!!
2006 Revolution LE 40E
2004 Jeep Rubicon Toad/Brake Buddy or
20' Toy Trailer/Quads 'n Dirt Bikes
|
Daveinet
il
Senior Member
Joined: 10/29/2003
View Profile
Offline
|
Actually the case is not a very good one. The GPS reading was never challenged. I'm very surprised the parents contested it. The software they were using only records data every 30 seconds. In fact, when they compared the readings, based on the location of the car from one reading to the next, the kid had to have been speeding in order to have made it from one location to the next in 30 seconds. The GPS actually confirmed the kid was guilty. The "hook" of the title suggests that this case has legal ramifications on futures cases, but technically it means nothing.
I think to have a real case based on GPS, one would have to have much higher resolution data. This would give several readings of both location and speed vs time. I would think several points of data confirming location, one would be hard pressed to prove otherwise. GPS's can have glitches in data, but it would be unlikely that it would have multiple points of data that showed a consistent speed based on location that were all wrong. The other thing is that one would have to compare it to a certified standard immediately following the ticket, to certify its accuracy. GPS is valid and does stand up in court. The reason I know this is that I have received a ticket. On the ticket it stated the OFFICER used a GPS to clock my speed, so it is considered a legally valid method of speed measurement.
An even better set up would be a data monitor that uses both GPS data and OBDII output. There are devices that do both.
Dave
FMCA F298817
'83 Revcon Prince 31' FWD
502 w/Howell/Edelbrock MPFI, Thorley's & Magnaflows,
Koni FSD, Class A built for gear heads 
??????
Revconeers Forum
There is nothing compassionate about taking someone elses money and giving to the poor.
|
|
|
JohnnyT
Goshen New York
Moderator
Joined: 07/15/2003
View Profile
Good Sam RV Club
|
Moved from class A forum
|
BULLETLS1
Guatemala, C.A. (NOT Dakotas, Wyoming, Iowa...)
Senior Member
Joined: 11/29/2008
View Profile
Offline
|
try this, with your hand held GPS,
while going highway speed put the gps in front of you, arm extended full forward, then with a movement of your arm move the gps in a linear fashion towards your chest then towards your back, all of these in close to one second....
speed DOES change, and sometimes takes a while to recover back to where it was, even thou the rig speed is constant....
I was a super fan of GPS when it first came public... maybe because of a novelty high tech "toy", now I doubt all the new tech that will come as in "free flight"....
I I HAVE A DATE WITH ETERNITY, AND I DON´T WANT TO BE LATE!
|
tatest
Oklahoma
Senior Member
Joined: 05/14/2005
View Profile
Offline
|
I've had satellite data glitches push a general-purpose handheld up to several hundred MPH while it is stationary. You don't usually see something like this in an automotive GPS because it is making "fuzzier" position measurements at longer intervals, and software will screen out numbers that are absurd for the intended use.
Speed enforcement radar is calibrated for that purpose, following guidelines set over the years by the courts. There is no case history for navigational GPS as a legally recognized speed measurement tool, and with the current state of technology (the US DoD navigation system) it is unlikely that GPS will be accepted for that purpose. The system is prone to instantaneous blunders, which are corrected statistically over the long term.
Tom Test
Itasca Spirit 29B
2001 Ranger Edge
|
Matthew_B
The boonies near Dallas, Oregon
Senior Member
Joined: 08/18/2005
View Profile
Offline
|
rgatijnet1 wrote:Not too surprising. I monitor altitude with our GPS when we are driving in the mountains. There are many times when the satellite signal is interrupted and our altitude and speed remains constant when it is obvious that we are ascending or descending a hill. On both our Garmin and TomTom GPS units, the readout stays at the last signal and does not go to zero. It changes only when a new signal is received to update the info. After a long period of time with no signal, it does report that the signal is lost, but usually, when the signal is just temporarily interrupted, there is no indication on either the speed, direction of travel, or altitude, on the GPS unit.
If he was on an open, unobstructed section of road, his GPS unit was probably accurate altho a lot can happen between 30 second updates between the GPS and the home PC.
The presumption of continuing at the current speed is done to try and get a re-lock as fast as possible. Notice how long it takes to find lock when powering it up stationary in the exact location you powered it down compared to when you power off a unit, move and then power it up in motion. The former is a LOT faster because the unit knows where it is to start the calculations to get the exact time. By assuming that you're keeping doing what you were doing before it gets a lock quicker.
Now what is lacking in many user interfaces is the immediate indication that there is no longer a lock.
|
Matthew_B
The boonies near Dallas, Oregon
Senior Member
Joined: 08/18/2005
View Profile
Offline
|
tatest wrote:There is no case history for navigational GPS as a legally recognized speed measurement tool, and with the current state of technology (the US DoD navigation system) it is unlikely that GPS will be accepted for that purpose. The system is prone to instantaneous blunders, which are corrected statistically over the long term.
Things change a LOT after 2013. At that point the new system will be online and will be considered accurate enough for guiding an airplane onto a runway or a ship through a narrow passageway.
I have no idea how long it will take for personal GPS units to show up, but when they do GPS will get FAR better.
|
|
|
