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H2R July 26 & 27
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H2R July 26 & 27
6/28/10 1:20 PM
Jeff,

Spent this past weekend at Harris Hill Road. I captured much better data this time (fewer gaps). I was running the latest version of Trackmaster, put the phone in Airplane mode, then used ATK to kill all apps except ATK & Trackmaster.

However, I think you have a bug in how you sort through the data for Top Speed. There are erronously very high (180 to 200 mph) top speeds given for a lap when true top speed is about 110 mph. I noticed that almost all these erronously very high top speeds are associated with a very large acceleration, then followed by a large negative acceleration. See the attached file.

The lap times and average speeds seem dead on.

Device is HTC Eris using internal gps. Mounted in horizontal mode to the right and above center of steering wheel - directly above right hand when at 3 o'clock on the wheel.

Thanks for the great program!

Alan
Attachments: Jun262010334PM20100628_145235.xls (218.0k)
RE: H2R July 26 & 27
6/28/10 1:29 PM as a reply to Alan James Wolfe.
Can you also attached the data in Google Earth format?

Jeff
RE: H2R July 26 & 27
6/28/10 3:08 PM as a reply to Jeff Trackaroo.
Jeff Trackaroo:
Can you also attached the data in Google Earth format?

Jeff


Here 'ya go.
Attachments: Jun262010334PM20100628_145108_kmz.zip (62.5k)
RE: H2R July 26 & 27
6/28/10 3:26 PM as a reply to Alan James Wolfe.
If you look at the data in Google Earth, you'll see the internal phone GPS isn't doing a very good job and has pretty poor accuracy. That would explain the high top speeds. Some phones have better GPS accuracy than others. The older phones like the Eris, Hero, & Moment seem to have less reliable GPS. In these situations, I'd recommend mounting the phone in a location that gets a better view of the sky to improve signal - up high and near the windshield. I'd also recommend using an external bluetooth GPS with Trackmaster. But unfortunately the Droid Eris does not support that.

Jeff
RE: H2R July 26 & 27
6/30/10 1:53 PM as a reply to Jeff Trackaroo.
Yes, I understand the performance of the Eris internal GPS. I've played around with GPS Status and the best error I see is 6 ft using 11 of 12 visible satellites. That's with open sky. I've also validated that the current mounting position in the car is the best orientation and position. It gives an average error of about 19 ft using 7to9 of 9to10 visible satellites.

I was hoping there might be something you could do through data smoothing.

Otherwise I am stuck with current performance till HTC fixes their bluetooth stack or I upgrade in 14 months.

And again, $7 for a lap timer is a great deal.

Alan

p.s. ***** Moved to Suggestions Forum *******