GPS vs Speedometer
Nov 25, 2008, 5:24 pm
#16
Join Date: Jun 2004
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Here's a study of GPS units on bicycles:
http://www.ncbi.nlm.nih.gov/pubmed/15519597
In there, the accuracy is typically within 0.1-0.4 m/s, or less than 1 mph.
With a WAAS-enabled GPS receiver, you can know your position with <1m error in most cases. If you update position every second, the maximum error is 2m in 2 seconds, or about 2mph. With a few seconds of averaging, that error will decrease.
Nov 26, 2008, 9:17 am
#18
Join Date: Jul 2007
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Many people change to a different size tires/wheels combination either as new or as replacement. I am using a set of alternate OEM size on my car that is larger than what came on the car by 4 percent but never bothered to recalibrate the speedo. So the speedo is under reporting the actual speed.
On the other hand, the GPS reports the true speed.
On the other hand, the GPS reports the true speed.