Originally posted by woketman
B1, is the error constant over speed ranges? In other words, if the dude has a Walmart GPS unit, can he simply go for a ride in a car with a known to be accurate speedometer, check the GPS at a given speed, and then infer that accuracy upon the 350 mph reading?
No you cannot infer that your GPS unit is accurate by comparing readings at random times with your car.....Your car, (if on a long trip) is usually moving in a semi straight line thus making it easy to calculate from where it is at point a to where it will be at point b, (cheap GPS units dont update as fast or as much as the more costly one), thus giving you good readings at THAT TIME. Add some power reductions, speed ups, curves, go up and down some hills and see if your readings are just as good. As far as the 350mph reading goes....I doubt that plane was goin in a straight line long enough to verify the speed...and as ET said, the initial acceleration from the bungee was proably the reading he got. First the plane is at point A at a standstill...next time the GPS recieves a good signal its holy cow...way out at point B...he MUST have been goin X fast. I dont think so.
Luis