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StuartW
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That is a very fair point
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Tim Dawson
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GPS providers on Android are not supposed to apply geoid correction, so SkyDemon does that in order to give an AMSL altitude reading. Typically if a mock GPS app is already correcting it (they never should, really) then this will yield an altitude that is wrong, to the tune of the geoid undulation in your area. I can't explain the fact that your app appears to produce a correct result when you enable it, perhaps their wording is poor. You should be able to test it yourself to establish whether the output is correct though.
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StuartW
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+xGPS providers on Android are not supposed to apply geoid correction, so SkyDemon does that in order to give an AMSL altitude reading. Typically if a mock GPS app is already correcting it (they never should, really) then this will yield an altitude that is wrong, to the tune of the geoid undulation in your area. I can't explain the fact that your app appears to produce a correct result when you enable it, perhaps their wording is poor. You should be able to test it yourself to establish whether the output is correct though. Could you help me understand something - is this correction positive or negative from GPS altitude? I ask this as the value in SkyDemon without provider correction enabled ends up as a minus figure, suggesting the SD is applying a negative correction?
You suggest
perhaps their wording is poor
I've used two different apps - you think BOTH have worded their option to correction (tick yes or no) poor?
The bottom line here is that I just want to understand that the system I'll be using is showing something close to the correct information, and that I haven't missed something, or configured something incorrectly.
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Tim Dawson
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It could be positive or negative depending upon where you are in the world. It's the correction between ellipsoid altitude and geoid altitude, which is done by applying an geoid undulation figure. If you're interested in how it works there is probably access to a geoid undulation model out there on the internet.
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StuartW
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+xIt could be positive or negative depending upon where you are in the world. It's the correction between ellipsoid altitude and geoid altitude, which is done by applying an geoid undulation figure. If you're interested in how it works there is probably access to a geoid undulation model out there on the internet. Tim, thank you, although the issue still remains (or maybe not)
Is there really nothing else you can offer to help a new user get to the bottom of what may or may not be a problem?
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Tim Dawson
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I am pretty sure a solution was offered on the first page. To clarify, there is no SkyDemon setting; you need to play with the options in your mock GPS provider in order to find what works for your setup.
I know this is a mess, it's because Android doesn't natively support Bluetooth GPS. We wish it did, but it doesn't, and the workaround using mock GPS has these pitfalls.
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StuartW
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+xI am pretty sure a solution was offered on the first page. To clarify, there is no SkyDemon setting; you need to play with the options in your mock GPS provider in order to find what works for your setup.
I know this is a mess, it's because Android doesn't natively support Bluetooth GPS. We wish it did, but it doesn't, and the workaround using mock GPS has these pitfalls. I've gone back and read the whole of the first page and don't see a solution offered at all.
I'm obviously not going to get any help here, and as email support from SD was non-existent, I think it's time to give up on this and move on.
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Tim Dawson
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Can you let me know when you emailed support? I will find out what happened to your email. We always respond to support enquiries.
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Tim Dawson
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Having discussed this with my colleague, it appears she engaged you by email and discussed exactly the same issue. It seems we both told you the same thing in answer to your question. It's a shame we can't help you any further, but whatever you feel is going on, is something to do with your setup and not to do with SkyDemon.
Saying email support from SkyDemon was non-existent is simply not accurate.
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177
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Can you make GPS correction optionable? I tried to fly in X-Plane this week and Skydemon gives wrong altitude (-150ft for LKPD). I get the same altitude reading in "Fly is Fun" (my backup air nav app) if correction is ON. As soon as I turn it OFF it becomes okay.
Here's a screenshot:
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