GPS out data problem - iFly Owners Q&A

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GPS out data problem

9/9/2014 9:30 AM

Walter

Joined: 7/8/2009

Posts: 2778

Re: GPS out data problem

To be sure I understand: You get the same results regardless of the True / Magnetic North setting?

Walter Boyd
President, Adventure Pilot

9/9/2014 10:26 AM

Walter

Joined: 7/8/2009

Posts: 2778

Re: GPS out data problem

Ignore my prior post, I found the problem. The RMC sentence includes a Magnetic Variation parameter that is being populated incorrectly in your area. Most of the country works perfectly, which is why I didn't catch it sooner. It might be a problem with our magnetic variation model (calculating that number is more difficult than you might think, it's not linear and it changes over time). Anyway, now that we can see the problem, we can fix it. I'll try to get this in the next release.

Thanks for your help finding this!
Walter

Walter Boyd
President, Adventure Pilot

9/9/2014 11:47 AM

les patron

Joined: 5/4/2011

Posts: 215

Re: GPS out data problem Modified By les patron on 9/9/2014 11:49:30 AM

Walter
Last Saturday I was having a 10 degree problem that varied depending on the direction I was flying.
This was on the 720 with .39b, and the magnetic north setting.
I was flying in the NY Westchester / Conn. area.
Could this be the same issue?
Les

9/11/2014 8:56 AM

Walter

Joined: 7/8/2009

Posts: 2778

Re: GPS out data problem

Yes it could be the same thing, and it's been fixed. If you're on the beta team you can download that version now. Otherwise this will be in production next week. The Magnetic Variation part of the GPRMC sentence was being populated incorrectly if it was a "West" declination. So the bug was most noticable in the North-East part of the country, which has a steep West magnetic declination.

-Walter

Walter Boyd
President, Adventure Pilot