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Fight Over $194 Speeding Ticket Costs $15,000 and Counting
An anonymous reader writes "Roger Rude, a retired Sonoma County sheriff's lieutenant, is still fighting a speeding ticket his step-son, Shaun Malone, received in 2007. Shaun Malone was allegedly going 62 mph in a 45-mph zone, according to a Petaluma police officer. To the officer's surprise, Malone was using a GPS tracking device which reported his speed to an online database every 30 seconds. At the time of stop, the GPS reported Malone's speed at 45 mph. Rude has been helping Malone fight the speeding ticket for over two years. The Petaluma Police Department has spent $15,000 in the prosecution of this case. The case is now in the hands of the Commissioner."
The judge was right to rule against the GPS. A sample rate of once every 30 seconds ISN'T accurate. It doesn't "prove" anything about his speed when he was clocked by the cops.
As you transition between satellites, GPS can shift your position suddenly. Atmospheric effects and satellite movement can cause drift over time. Within 1 second you don't see a lot of drift. Over 30 seconds, yeah... You'll see some.
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Then there are buildings, canyons, bridges, issues with radio-line-of-sight, reflected signals, etc. Multipath effects can be a problem.
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There's far more than I can go into here. Wiki GPS has a good description of all the issues.
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Most cars can accelerate to the speed limit within a few seconds. When driven by teenagers, it's closer to instantaneous. The real question is: How long was Malone sitting at that stoplight at Frates Road AFTER the zero-speed reading? Zero time, and he probably wasn't speeding. 10 seconds, and he probably was.