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Radar Beats GPS In Court — Or Does It?

Posted by Soulskill on from the technology-deathmatch dept.

TechnologyResource writes "More than two years ago in California, a police officer wrote Shaun Malone a ticket for going 62mph in a 45-mph zone. Malone was ordered to pay a $190 fine, but his parents appealed the decision, saying data from a GPS tracking system they installed in his car to monitor his driving proved he was not speeding. What ensued was the longest court battle over a speeding ticket in Sonoma county history. The case also represented the first time anyone locally had tried to beat a ticket using GPS. The teen's GPS pegged the car at 45 mph in virtually the same location. At issue was the distance from the stoplight — site of the first GPS 'ping' that showed Malone stopped — to the second ping 30 seconds later, when he was going 45 mph. Last week, Commissioner Carla Bonilla ruled the GPS data confirmed the prosecution's contention that Malone had to have exceeded the speed limit and would have to pay the $190 fine. 'This case ensures that other law enforcement agencies throughout the state aren't going to have to fight a case like this where GPS is used to cast doubt on radar,' said Sgt. Ken Savano, who oversees the traffic division. However, Commissioner Bonilla noted the accuracy of the GPS system was not challenged by either side in the dispute, but rather they had different interpretations of the data. Bonilla ruled the GPS data confirmed the prosecution's contention that Malone had to have exceeded the speed limit."

8 of 369 comments (clear)

  1. Standard Calculus by misosoup7 · · Score: 5, Insightful

    If the average speed is 45 mph, and he was stopped at the end (ie speed 0), then at some point he was going above 45. Especially since you can't stop instantaneously. This is like calculus you learn in High School... If the Judge ruled the other way, the future of America would be even in deeper sh*t than it already is.

    1. Re:Standard Calculus by pyr02k1 · · Score: 5, Informative

      The problem of this calculus you mention wasnt the speed at the end, nor even the beginning. we're missing a piece of information to properly go through this. distance. it says at a stop light, he was 0, then the next ping was 45. but the problem becomes distance covered in that 30 seconds. tie in the math, etc. if it says 45 on the ping, thats worthless. we need to know how far he traveled in 35 seconds to get an average speed, and, for the sake of argument, his vehicles 0-60 speed as well to get the stats on how quickly he could have possibly gone up to 60, nearly where they "clocked" him. obviously, his average speeds worthless, and his speed 30 seconds after his initial of 0 is worthless. we need the distance traveled in that 30 seconds. And TFA says "virtually" the same location. For all we know, he spotted the cop, hit his brakes and was doing 45 when he was pinged. Distance is key ... notice how TFA forgets that wonderful detail. And, I'm sure as a teenager, with a GPS, he knew that if he hit 70, theyd get an email alert. Heck, he probably knew that if he wanted to, he could go 69, wait for a ping, if he had timed them right, speed up to 100 and brake to 69 again, all before the second ping... I guess the parents forgot that Teenager + Technology is generally > Parents + technology

    2. Re:Standard Calculus by tokul · · Score: 5, Informative

      My gps can tell me my speed at the exact moment

      No, it does not. GPS only tells you your average speed between two GPS pings. Ping 1 - you are at X, ping 2 - you are at Y, your current speed is how fast you must move in order to get from X to Y in time between ping1 and ping2.

  2. Sgt is an idiot by syousef · · Score: 5, Insightful

    'This case ensures that other law enforcement agencies throughout the state aren't going to have to fight a case like this where GPS is used to cast doubt on radar,' said Sgt. Ken Savano,

    Well if the summary is true (and I know it might not be), it actually means the opposite since the GPS data was considered at the trial. That means others may try to present their GPS data in future. It certainly doesn't mean that people can't try that defense. There was no precedent set that the GPS data was less reliable than the radar. It's just that the GPS data could be interpretted to be in agreement with the radar data. Also, this is only applicable to one kind of GPS unit under one very limited set of circumstances.

    In other words Sgt. Ken Savano is either misrepresenting the whole situation or is incompetent when it comes to the prosecution of speeding violations. Either way he's coming across as dim witted and it raises serious doubts for me about his ability to perform his duties as a police officer, since he can't seem to understand the law.

    --
    These posts express my own personal views, not those of my employer
    1. Re:Sgt is an idiot by black3d · · Score: 5, Interesting

      The judge who allowed the case to proceed in the first place is also an idiot. I see no good reason why the case wasn't thrown out immediately.

      I can't quite fathom why the court system allowed "So what if the radar said I was going 62 at that point in time. I was going at 45 at two other completely different points in time." as an argument.

      I can see how it happened though -
      1. Stupid, dishonest, ignorant kid goes home and tells his parents "No, I wasn't speeding".
      2. Parents get GPS data readout which shows he was going at 45 "around that time" in two different readings.
      3. Parents lack basic knowledge of trigonometry and can't translate the speed over the distance travelled between readings.
      4. Neither can the court. Case proceeds.

      Seriously though, in every case like this where the defendant (the kid) lies to the court, they should be charged with contempt. If you don't want to lie, take the 5th. It sickens me daily that the majority of our courts time is wasted with dickless wonders who are too scared to accept responsibility for their actions.

      --
      "The true measure of a person is how they act when they know they won't get caught." - DSRilk
    2. Re:Sgt is an idiot by Anonymous Coward · · Score: 5, Insightful

      I fail to see how this has anything to do with trigonometry.

  3. Re:Radar takes an average vs GPS point by Anonymous Coward · · Score: 5, Funny

    You can do that, but then you could also get nailed with careless or wreckless driving....

    Wreckless driving usually gets you in less trouble than the alternative...

    Reckless. </pedant>

  4. It uses Doppler shift by Alef · · Score: 5, Informative

    A GPS typically calculates velocity from Doppler shift of the D-band signal. This give higher accuracy since the position reading is somewhat unreliable. It also means you can (in principle) get the velocity information virtually instantaneously without having to sample two locations. However, in reality a lot of averaging and filtering is going on, and I think many receivers weighs in both position deltas and Doppler shift in the equations, so the reading is going to have at least some lag.

    (Reference)