speedo vs. gps
Posting Guru
Joined: Aug 2004
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From: Upstate, NY
Most of the newer units will track up to 15 satellites while actively using signal from anywhere from 2 to 5. You need at least 3 for a nominal 3D signal and for altitude to be available while is generally accepted that 4 or more are needed to reduce horizontal errors.
http://www.gpsnuts.com/myGPS/GPS/Technical/ed.htm
http://www.gpsnuts.com/myGPS/GPS/Technical/ed.htm
Tuned
Joined: Feb 2007
Posts: 490
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I have a Magellan GPS in my patrol car, and the patrol car has a certified speedometer. They are either both dead on or they are both out of whack by the exact same amount, as they are in total agreement.
Now that I see this post I think I'll put it the GPS in my truck and see what kind of accuracy the Ford non-certified speedometer has.
Now that I see this post I think I'll put it the GPS in my truck and see what kind of accuracy the Ford non-certified speedometer has.
Senior User
Joined: Apr 2006
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From: Burt N.Y.
I work for a GM dealer and when we get a complaint of an inacurate speedometer reading. Usually somone trying to get out of a ticket. The recomended procedure is to use a hand held GPS unit to verify speed. Plus or minus 4% is ok.
Senior User
Joined: Apr 2006
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From: Texas
Originally Posted by PowerStrokeHD
It may have less to do with your GPS units and more to do with what Ford considers "accurate" for a speedometer. It very common to find a 2-3% variance from actual, usually with the speedo running on the fast side. This is true of any Ford vehicle on the road.
Ford does set the tires RPM (revolutions per mile) at the factory based on the tire size ordered, so tire size is already taken in account by Ford.
Ford does set the tires RPM (revolutions per mile) at the factory based on the tire size ordered, so tire size is already taken in account by Ford.
"I read on the internet" that in Germany it's against the law for a manufacture to set their speedometers to show actual or less than true speed, by law they MUST show faster than you're going.
Tuned
Joined: Feb 2007
Posts: 490
Likes: 3
Originally Posted by jwd1475
I work for a GM dealer and when we get a complaint of an inacurate speedometer reading. Usually somone trying to get out of a ticket. The recomended procedure is to use a hand held GPS unit to verify speed. Plus or minus 4% is ok.
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