Blue is the faster color!

[pawtracks]

Unfortunately the run was logged in my driveway

Obviously this is not true or accurate, need some advice or ideas about why.

This question goes out to all you GPS users.

If you use Garmin Mapsource & Google Earth, even better.

I have GPS on my FJR for nearly every ride.

I will record the track for future use, ride data, average speed, max speed, altitude, trip length, find my way back there someday, etc...

When I was viewing my route from Reno back to San Diego in Google Earth I (as I often do) right clicked on the track to see the trip summary (which looked like this)

Max speed of 181.6 (WTF!) :glare:

I looked through a few places where I knew I was going faster (~120-130ish) but couldn't find this 182 MPH mystery pace. Then I found it, a 266 ft track section leading to my driveway!

Does anyone else have experience with some GPS data errors?

Garmin, Google Earth?

Garmin 2730

Garmin Mapsource 6.11.1

Google Earth 4.0.1693 (Beta*)

*Beta should not be an issue, the GPS data is fed to Google Earth from Garmin Mapsource (and Mapsource showed the error first)

I have a very clear shot of the sky in this section of road so I am not thinking about loss of GPS signal or heavy tree, cloud cover, etc...

 

[Luke]

Did you do a wheelie at the same time?

 

[Rickster]

You'll note that speed was logged after a zero stop at 12:47:47 (log shows next entry at 12:47:54) and also shows the leg time of 1 second next to it (time stamp shows 7 seconds, but leg time shows 1 second). It also shows a distance traveled of 266 feet.

Speed is calculated based on the distance/time and the lag in updating your position (once per second), coupled with the errors in your true position as determined by the GPS unit (google "GPS error") sometimes causes logs like that.

Note that 266 feet in 1 second is: 266 FPS = 390 MPH

and 266 feet in 7 seconds is: 38 FPS = 55.7 MPH

 

[pawtracks]

You'll note that speed was logged after a zero stop at 12:47:47 (log shows next entry at 12:47:54) and also shows the leg time of 1 second next to it (time stamp shows 7 seconds, but leg time shows 1 second). It also shows a distance traveled of 266 feet.
Speed is calculated based on the distance/time and the lag in updating your position (once per second), coupled with the errors in your true position as determined by the GPS unit (google "GPS error") sometimes causes logs like that.

Note that 266 feet in 1 second is: 266 FPS = 390 MPH

and 266 feet in 7 seconds is: 38 FPS = 55.7 MPH

Thanks for the feedback

I don't take my GPS as the 100% gospel but it is usually pretty damn close, never been this far off before so I figured I would ask some others.

Right before the 182 mph track is a stop sign which I normally come to a full stop at. (Leo's like to hide in the bushes here & give failure to stop awards) At least he didn't catch my next blast up the hill!

This stretch of the road, hill, corner I am typically going 15-20 MPH like the data shows.

 

[kaitsdad]

Interesting how this happens. I work in El Segundo, CA, and noticed this display when I arrived home:

I had driven by what used to belong to Hughes Aircraft, known as the "Dolly Parton Building" - and for a block or two there my Garmin thought I was in Virginia somewhere - I figured it was due to massive amounts of radar emissions, or some such thing. (Man, my third eye hurts...)

 

[pawtracks]

I guess that seals it

'06's are faster...

and I thought my error was off a little!

 

[shokdimn]

Hey folks,

Haven’t got any idea what caused the GPS problem. But would suggest, in a friendly manner, rechecking those conversion numbers from FPS to MPH. Course maybe I made a mistake but, I come up with:

181.6 MPH = 266.34 FPS and

38 FPS = 25.99 MPH.

 

[Rickster]

Hey folks,

Haven’t got any idea what caused the GPS problem. But would suggest, in a friendly manner, rechecking those conversion numbers from FPS to MPH. Course maybe I made a mistake but, I come up with:

181.6 MPH = 266.34 FPS and

38 FPS = 25.99 MPH.

yeah -- you're right, guess i should have used a calculator.

The point, however, was that the log shows the distance traveled (266 feet), and lapsed time of 7 seconds, and leg time of 1 second (or something like that).

The error is probably sliding EPE/DOP, and the time log differences.