Author Topic: Discrepancies between projections on iPhone and Etrex legend Hcx  (Read 1649 times)

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deepdowndawn

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Hey everyone,
I'm currently working on my second hide and running into a little problem. The hide involves a projection. I took coordinate readings with my gpsr in the field and used my iPhone to calculate the bearing and distance between the two. (both GCtools and IGCT apps).
When i got home, I thought I'd double check the projection on my gps unit by putting in the bearing and distance, and the coordinates it gives are slightly off (about 9 m).
I'm not sure why it's giving me different results. I've made sure the gps unit is set to true north. I'm assuming the iPhone does the same.
Any idea why they aren't giving the same results? Which one should I go with?
thanks for the help

deepdowndawn

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Re: Discrepancies between projections on iPhone and Etrex legend Hcx
« Reply #1 on: November 12, 2011, 18:04:40 »
woops...so sorry guys...i posted too soon...projected from the wrong wp. all is good. sigh!

bluelamb03

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Re: Discrepancies between projections on iPhone and Etrex legend Hcx
« Reply #2 on: November 13, 2011, 12:47:48 »
There are many ways to 'project' from a waypoint. A common desktop applet called FizzyCalc, http://www.fizzymagic.net/Geocaching/FizzyCalc/, gives you three ways to make the projection.

For short distances the differences aren't very great but there is a local cache by Dan-the-Hutt, his PGW - Big X, http://coord.info/GCV6DJ, where you'll get different answers depending on which GPSr you're using. Every manufacturer does things a little differently....

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