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Old 02-28-2008, 03:33 AM   #18 (permalink)
trebuchet03
MechE
 
Join Date: Dec 2007
Location: Bay Area
Posts: 1,151

The Miata - '01 Mazda MX-5 Miata
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Quote:
Originally Posted by reformed View Post
GPS signals aren't 100% accurate on these portable navs.. you aren't paying for the technology. If you've had them in your car, you can see when you are driving and you pass a street, and then look at your nav and you will see the street either before you or after you on the screen. Sometimes its pretty close, sometimes its way off. ...
Pinpointing location is far different than calculating speed on the GPS network IIRC the current standard for civilian GPS is 15 feet (compared to P(y) encrypted millitary which is somewhere in the tens of centimeters) - but if you're using WAAS, that drops down to 1-3 meters thanks to the GPS ground stations But that still doesn't change velocity accuracy from relative measurements. It does play a role in location accuracy - but this accuracy goes up as time at that location increases.

I too am just passing along my experience

Out of curiosity - what models do you install?
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