Is wire mesh within cement/asphalt really a concern for interference??

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Hey all!

Though I've never had any issues with interference specifically when taking off from any cement surface I do hear such stories. I do construction progression videos sometimes and always have this in the back of my mind. I never know where i may have to take off from. I do know to avoid parking decks/garages...THAT i do believe. lol....I've heard launching pads can cause issues(though ive never experienced), Ive heard to never take off from cement/pavement/asphalt. So what do you all think?...is it really a valid concern?
 

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Hey all!

Though I've never had any issues with interference specifically when taking off from any cement surface I do hear such stories. I do construction progression videos sometimes and always have this in the back of my mind. I never know where i may have to take off from. I do know to avoid parking decks/garages...THAT i do believe. lol....I've heard launching pads can cause issues(though ive never experienced), Ive heard to never take off from cement/pavement/asphalt. So what do you all think?...is it really a valid concern?
It's potentially a very real problem and many drones have been lost because of it.

Your drone uses a magnetic compass and gyro sensors for directional guidance.
The gyros need to be initialised on starting up the drone, so they can provide accurate direction data.
It takes its initialisation from the magnetic compass, but if the drone's compass was placed close enough to a steel object, the compass will be deflected and the initialisation of the gyros will be wrong.
Asphalt doesn't have reinforcing steel and would only rarely have something steel buried close under it.
I suspect steel rings in launch pads aren't a problem unless you launched from the edge of the pad as the steel is small and far from the compass.
I've only heard people asking about it and seen no reports of it causing trouble.

For more details see this post: Avoiding the rebar effect
 

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Ive heard to never take off from cement/pavement/asphalt
I've never heard of issues with pavement or asphalt, but cement can be an issue (and has proven to be countless times) if it contains rebar.

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Story time lol- I was getting some video of a brand new skate park that was all concrete. I wanted to get a little cinematic shot starting at the top of a ramp and taking off. I landed on the top of the ramp and then immediately it went nuts! I had totally forgot about all the rebar that was in there. I went and retrieved it rather than taking off from there just to be safe.

checking compass direction is part of a check list that I use before flights.
Stay safe y’all!
 
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I have a P4P and took off from a dock on a lake. It started going up, then without my input, full blast right toward a tree. Frantic stick movements got it back. Metal frames under the dock. Scary situation. Now I am very aware of where I take off.
 
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Note that the compass is at the bottom of the legs, so that it is very close to the take-off surface, probably less than 1/4 in. Anything buried within the take off surface close to the top is very close.
 

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Very real , There is a the Frozen pier that i cannot take off from as the magnetic interference is very strong.
I have this video " If i would have flow out a little further it would have been stuck and landed in the water.

The Drone was only able to go up but lost the ability to go forward..
The Magnetic interference warning was the first to pop up followed up by Calibration .

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For an everyday practice, try to take off from a natural ground where is very likely no metal material under the surface (unless you take of from a hidden treasure spot under LOL.
The principle is related to the magnetic deviation at the take off spot. When you switch the drone on, magnetic sensors are set according to this deviation correctly. But this means only for this spot. When the drone goes off the ground this calibration is no longer valid because the drone is now in earth magnetic field as it should be. But the compass is now falsely calibrated for this new situation. And the result is that the drone has no 'idea' where to go when you push the right stick. So it will go into different direction you want it to.
That's generally all what we should know about wrongly calibrated compass or compass error which is the most often cause for drones flyaway situations.
 
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I've never heard of issues with pavement or asphalt, but cement can be an issue (and has proven to be countless times) if it contains rebar.

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thanks for clarifying...thats the word i was looking for -REBAR. truthfully i can't say im even certain what the differences are between pavement and asphalt..lol.. i know cement. What are most parking lots made of?..the black stuff...asphalt? do those typically have any metal/steel within them? Would taking off from something like a rolling case to add height make any difference?
 
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Meta4

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thanks for clarifying...thats the word i was looking for -REBAR. truthfully i can't say im even certain what the differences are between pavement and asphalt..lol.. i know cement. What are most parking lots made of?..the black stuff...asphalt? do those typically have any metal/steel within them? Would taking off from something like a rolling case to add height make any difference?
It would be very rare for the black stuff to have any buried steel under it.
They don't put reinforcing steel in roadways etc.
Any structural concrete is going to be full of steel, so beware of the grey stuff.

If you can't avoid the concrete, lifting the drone a foot or two above the deck (on a case etc) would prevent the issue of having the compass sitting just an inch away from invisible reinforcing.
 
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For the Phantom it is safe and very handy if you use the original box of the P4P and take off from it. It's around 25 cm ant should be enough to be in safe place.
And what we didn't mention here are the all other metal stuff like fences and other metal structures. Be at least several meters apart.
 
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msinger

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What are most parking lots made of?..the black stuff...asphalt? do those typically have any metal/steel within them?
No. I've never run into issues when taking off from asphalt covered parking lots.
 
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I flew a Phantom 3 Advanced for 5 years and got accustomed to doing the little circular compass calibration dance. Anytime I flew from a different location it seemed to want to recalibrate. I recently upgraded to a Mavic Air 2 and it seems comfortable taking off almost anywhere. It has yet asked to be calibrated. My question is .... is the calibration sequence the same as it is for the P3A ?

And to add to this thread's conversation, I've had compass errors trying to take off from picnic tables in campgrounds due the metal tube construction of the base.
 
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PhantomWetSuits

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I flew a Phantom 3 Advanced for 5 years and got accustomed to doing the little circular compass calibration dance. Anytime I flew from a different location it seemed to want to recalibrate. I recently upgraded to a Mavic Air 2 and it seems comfortable taking off almost anywhere. It has yet asked to be calibrated. My question is .... is the calibration sequence the same as it is for the P3A ?

And to add to this thread's conversation, I've had compass errors trying to take off from picnic tables in campgrounds due the metal tube construction of the base.

The same with Picnic tables and the Air 2 has been flawless on taking off from all things thus far.
We have yet to take it to the Frozen Pier but its coming as its roped off do to the covid..

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Hey all!

Though I've never had any issues with interference specifically when taking off from any cement surface I do hear such stories. I do construction progression videos sometimes and always have this in the back of my mind. I never know where i may have to take off from. I do know to avoid parking decks/garages...THAT i do believe. lol....I've heard launching pads can cause issues(though ive never experienced), Ive heard to never take off from cement/pavement/asphalt. So what do you all think?...is it really a valid concern?
If it is, you'll get compass error prior to take off. This can be confirmed if you try to take off from a man-hole cover or the top of a car.

D
 

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If it is, you'll get compass error prior to take off. This can be confirmed if you try to take off from a man-hole cover or the top of a car.

D
The big catch is that you won't always be warned by the compass.
If the compass is deflected by a big steel object like a manhole cover, it recognises that it's dealing with something much more than the normal magnetic field of the earth.
But smaller steel items close to the compass might not trigger a warning although they have deflected the compass.
You can check for this before launching by comparing the way the drone is facing with the way the drone icon in the map window or radar display is facing.
If both are facing the same way, things are good.
But if for example the drone is pointing east and the drone icon is pointing south, there's a problem.
The solution is to power off, move the drone to a better spot and start again.
 
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I work in the construction field and have 300 + hours flying P4P’s and Mavic 2 Pro’s. I generally launch from the roof of my car that has a glass roof but still a lot of metal. The P4P is more sensitive to magnetic interference. They have gone rogue a couple of times when going airborne. The Mavic’s are fine. As for asphalt, especially if you are in a parking lot you may be picking up electrical wires for lot lights, ductile iron sewer lines, etc. obviously it’s best to avoid any metal to get true calibration but sometimes, at least for me it’s near impossible. For instance, next week I have a shoot of a recently completed parking deck that is likely to give me issues. I will post a pic or two to illustrate the area that is probably a magnetic nightmare for the drone.
 
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It's enough to go a few m away. I think that's easy. Car roof is really not a fine solution.
But if you are3 calibrating the compas, you must be in a completelly no metal area. In an open field is the best.
I would not calibrate the compas in the city.
 

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It's enough to go a few m away. I think that's easy. Car roof is really not a fine solution.
But if you are3 calibrating the compas, you must be in a completelly no metal area. In an open field is the best.
I would not calibrate the compas in the city.
There's no need to be recalibrating the compass of a Phantom.
If it was flying properly last week, it's going to fly perfectly this week, no matter where you are.
 
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