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Rebar interference? Low altitude flight stability fixed!
1619 6 2015-2-26
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PureSQNut
Second Officer

United States
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So after several failed tech calls to DJI with a simple reply from them of "send it in" I started looking deeper into several of the issues that I was having that continued to steer torward either repeated IMU calibration issues and/or Compass Calibration issues and the reports of how much effect metal and external interference has had on the Inspire during this process.

I decided to contact a friend of mine who owns a test lab that is A2LA Acredited test facility that specalizes in testing of EMI/EMC cewrtification testing and explained all of the issues I was having  as well as showed him several of the forums to read the info and complaints that people had been to see if it could be anything more than "a defective bird".

So we started testing at his facility and it was really baffling as every calibration was on the money, and flights were flawless (except the DJI app stopped working multiple times each flight 'android platform'.."). We put the Inspire into his test chamber and started introducing certain types of materials and other types of material and electrical interference into the equation and found the biggest culpruit to issues was metal (as has been stated over and over by DJI and on this and other forums), Magnets, and broadcast RF, (went with what has already been said, right?!

So we went back to my house and started looking at surrounding areas around where I fly out of anad had done the calibrations and no metal, no transmitters, no antennas, no metal buildingsm no repeaters, no cell phone towers, nothing........    ....  Then we looked down and realized we were on a large concrete slab. We grabbed a metal detector and found the slab to be filled with tons of metal (re-bar). We then proceeded to test the Inspire on an update sitting on the flat concrete and found a rather concentrated level of interference being created between the inspire and the surface below it. So we built a wood table (no screws all dove tail jointed) that allowed the Inspire to sit 40" above the concrete substrait. We then proceeded to re-calibrate the IMU on the platform and retested for RF or interference and the levels were sifnificantly lower.

So my question is can Re-Bar in concrete cause this kind of issue and cause adverse effects in calibration. Since I have started using this podium method keeping the Inspire off of the concrete my flight stability issues have literally resolved themselves (didnt fix the app shutting down several times per flight or the ongoing range issues im having or having to  calibrate the compass more than once sometimes as I change locaitons) but its a lot more stable and I have had ZERO issues of it feeling like it is flying away from me.

Here is a video of me doing some low level flying (3-4 ft) that I have tried to do multiple times at this same location (local baseball complex thats shut down for the winter) and never been able to do as before the Inspire would wobble on altitude and sometimes veer left and right. This time, I couldnt ask for a better flight and I have repeated this flight several times now with no issues. Now yes this isnt at my house but what have I done differently. I stopped calibratig it on the sidewalk and started calibrating it only on the asphalt of the street or on any other hard level surface that isnt concrete. Not saying concrete is the problem but im wondering if the re-bar in the concrete could cause these issues?

Thoughts?  or is this all just by coincience?

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2015-2-26
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GB44
Captain
Flight distance : 343848 ft
United Kingdom
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Just checked out your video, looks like your getting some jello or something going on across the middle of the picture every so many seconds !!

2015-2-26
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PureSQNut
Second Officer

United States
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yeah im still trying to figure that out and why.   that video was more for the flight stability issues.  Video has not been my friend. lol  learning more as I go. Not sure if its my editor or my bird.
2015-2-26
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jhogge
lvl.3

United States
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I don't know if the rebar is the issue but your testing seems to indicate that it cannot be ruled out.

If you cannot rule it out, you have to consider it a possible factor.
2015-2-26
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PureSQNut
Second Officer

United States
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jhogge Posted at 2015-2-27 08:09
I don't know if the rebar is the issue but your testing seems to indicate that it cannot be ruled ou ...

Its odd, and its strange, but its got opportunity to the cause.  

When I was at CES I stopped by the DJI booth in South hall and they were flying the Inspire in their netted demo area and there was two guys showing off the dual control function f the inspire. One of them had mentioned that the metal in the concrete floor was casing an issue for something, cant remember what it was that it was messing with but I remember that catching me by surprise. I'm wondering if it was related to this.
2015-2-26
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kevinlutch
lvl.1

Canada
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Excellent information,  thank you.
2015-2-26
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thanakarnchai.y
Second Officer
Flight distance : 364347 ft
Thailand
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When we take off  from  roof  deck(High Rise  Building) or canopy  will be prepare  table and never get yellow LED  PH.2 also
2015-2-26
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