High interferance zones

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Oct 7, 2015
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#1
Hello all,

I some questions about high interferance areas.
There's a friend that needs a survey about a building in order to make a rehabilitation project.
When checking the area, I've noticed that there was a building from our eletricity company. Once I went there with my P3pro to make the survey, I couldn't configure the compass as there was always the message of high interferance.

My doubts about this are:
1- Can I balance the compass, get GPS coverage and "home point", in a relatively distant and safe place (where interferance is not a problem) and then fly up to this target area?
2- If I do so, is it safe to use the ATTI mode in this kind of works?

Thank you all for the help,
I've posted the map for you too see better this problem.
Have great and safe flights!
EXEMPLO.jpg
 

Meta4

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#2
1- Can I balance the compass, get GPS coverage and "home point", in a relatively distant and safe place (where interferance is not a problem) and then fly up to this target area?
2- If I do so, is it safe to use the ATTI mode in this kind of works?
1. Yes .. you never want to calibrate your compass in an area where the earth's normal magnetic field is distorted by a lot of iron or steel or electrical activity.
You will be fine using a good calibration from a clean site.
2. Yes but GPS will probably work just fine anyway.

Launch away from the building with electrical activity.
Fly slowly toward the closest point you will have to be for your survey and watch the Phantom to see if it flies straight.
If it starts to wander in a curve or spiral, just back away gently back to where it was safe.
If you run into a problem, try flying higher and see if that helps.
 
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#4
Yep, but if the compass becomes nuts, and the GPS follows the compass orientation, then I may have a problem. If I'm in ATTI mode, at least the GPS won't "control" the p3.. At least this is my basic point of view about this :)
 
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#5
Yep, but if the compass becomes nuts, and the GPS follows the compass orientation, then I may have a problem. If I'm in ATTI mode, at least the GPS won't "control" the p3.. At least this is my basic point of view about this :)
GPS doesn't follow the compass. GPS just tells you where you are relative to your Home Point.

Compass just provides what direction your heading relative to the front of the Phantom (which way your camera is pointing).

To get home (return to home) DJi wrote the feature so that the Phantom comes home facing home which means the compass needs to be accurate. They could have easily simplified it and made the RTH feature not use the compass by having the Phantom go home using GPS without it needing to face home before going home. I would argue that they should set it up that way as you shouldn't be using RTH unless there is an emergency and then you don't really care which way the Phantom is facing when it comes back. RTH would just use GPS and the barometer (height) to get from point A to point B. GPS could determine which motors to spin at what speeds to get home by continually calculating the relative GPS position from point A to point B. The craft would have to move in any direction initially but it could adjust from there.
 
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ianwood

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#6
Don't calibrate the compass there. Do it somewhere that is safe and free from man made influences. If GPS mode is not fully reliable, switching to ATTI mode is a good idea.
 
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#7
GPS doesn't follow the compass. GPS just tells you where you are relative to your Home Point.

Compass just provides what direction your heading relative to the front of the Phantom (which way your camera is pointing).

To get home (return to home) DJi wrote the feature so that the Phantom comes home facing home which means the compass needs to be accurate. They could have easily simplified it and made the RTH feature not use the compass by having the Phantom go home using GPS without it needing to face home before going home. I would argue that they should set it up that way as you shouldn't be using RTH unless there is an emergency and then you don't really care which way the Phantom is facing when it comes back. RTH would just use GPS and the barometer (height) to get from point A to point B. GPS could determine which motors to spin at what speeds to get home by continually calculating the relative GPS position from point A to point B. The craft would have to move in any direction initially but it could adjust from there.

:O
Really?! ****, it means that I have some kind of problem with compass interferance, I better not press RTH, or it will most probably go in the wrong direction! Thanks for that information, didn't know it worked like that.

So, to resume, if I have anykind of panic during this flight in this area, never trust on GPS, compass and RTH. My only option is to change to ATTI mode and get out of that area "manually". Once I'm out, I may turn on P mode again and check for GPS coverage.
 

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