EMI canceling / shielded landing pad?

[WildDoktor]

I'd like to launch/land my M2P from the top of my truck cab (or the hood, or the bed), but whenever I power it up on any of those spots I get a compass error. If I just move it off the truck, the error goes away. I've also found on one construction site that the ground itself had so much interference that I got a compass error.

Is there such thing as a heavy (so I don't need to weight it down with rocks), "shielded" landing pad? I've searched but not found anything yet. Not really worried about keeping it compact; plenty of space in the truck to just keep it in there and haul it around.

Hmmm...if I threw a rubber floor mat on the roof, would that work? (I don't have any rubber floor mats, just carpet, or I would have tried that by now.)

Thoughts? Thanks!

 

[msinger]

How about holding it up in the air and launching from your hand?

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[WildDoktor]

How about holding it up in the air and launching from your hand?

I'm not a big fan of hand launching/landing, I'd rather have a pad that won't fly away, and will eliminate interference.

 

[Felix le Chat]

Any object that has live electrical circuits will produce magnetic fields and a car or truck has multiple live circuits.

There are options to minimize EM interference (twisted pairs/grounded foil sheathing encasing them) but this only works for the object housing the compass... the drone... DJI is well aware of the problem, but doesn't fit shielding to any of its cheaper (consumer-class) products.

Seeing as the launch pad is the car: shielding in the drone wouldn't do anything. Even if you put something directly under the drone, you have still got the rest of the car roof surrounding the 'insulator' which is equally magnetic.

People who own boats have wrestled with this problem since the invention of the compass... and still scratch their heads trying to compensate for deflection (which is the only thing you can do).

The simplest, quickest and cheapest solutions are to: a) move away from the car and launch, or: b) move away from the car and launch from your hand.

 

[Bad Santa]

Set the compass before putting the drone on the truck.

 

[Meta4]

Set the compass before putting the drone on the truck.

Set the compass??
Your drone's compass is already "set" and never needs recalibrating.

 

[tstr14]

I made a landing pad out of a piece of 2'x2' ABS plastic sheeting. I drilled holes in the corners and use a couple of galvanized steel tent spikes (just a long nail with a plastic piece on the head) to hold it in place.

 

[MS Coast]

I'd like to launch/land my M2P from the top of my truck cab (or the hood, or the bed), but whenever I power it up on any of those spots I get a compass error. If I just move it off the truck, the error goes away. I've also found on one construction site that the ground itself had so much interference that I got a compass error.

Is there such thing as a heavy (so I don't need to weight it down with rocks), "shielded" landing pad? I've searched but not found anything yet. Not really worried about keeping it compact; plenty of space in the truck to just keep it in there and haul it around.

Hmmm...if I threw a rubber floor mat on the roof, would that work? (I don't have any rubber floor mats, just carpet, or I would have tried that by now.)

Thoughts? Thanks!

Power up the drone while holding it in your hand away from the truck. Confirm the compass orientation is correct and place the drone on top of the truck. It's the startup that matters.

 

[KB9Radio]

You can't power it up near steel surfaces or surfaces that contain steel such as concrete which usually contains rebar or wire. If you have a truck with an aluminum body you would probably be ok. The only place I've found to launch from is a landing pad right on the ground. I've never got a compass error doing that. I don't know of a pad that would block the magnetic/iron interaction.
You definitely don't want a compass error, it will quickly send you in a direction you don't want to go.

 

[Vic Moss]

If you want to use a landing pad anyway, don't use the hood or cab of your truck. You're asking for trouble doing that anyway if you end up having an auto RTH.

 

[Bad Santa]

Power up the drone while holding it in your hand away from the truck. Confirm the compass orientation is correct and place the drone on top of the truck. It's the startup that matters.

I don't think he understands that is how it works.

"Your drone's compass is already "set" and never needs recalibrating."

Mine has asked to be calibrated a couple times.

 

[HoozierDroneDaddy]

I understand your apprehension to hand catching. However, the magnetic interference is a problem when starting up and launching your drone. So you could hand launch away from the vehicle, then when returning you could still land on the vehicle or truck bed. The return to home point would be from where you did launch, so the RTH would not land on your truck bed, you would have to manually land it there.

 

[WildDoktor]

Thanks all! Great discussion.

I do like the idea of powering up the drone outside the truck and waiting for gps lock, then placing it on the roof / hood / bed. As @KB9Radio mentioned, I've had interference issues from both concrete pads and gravel parking lots, so holding it while powering up should totally work in this situations as well.

For that matter, at that point I suppose I *could* just hand-launch it...as I've been reading thru this thread it occurs to me that I'm more "ok" with hand launching it than I am with hand-catching it. And as was also mentioned, I've not had any interference issues when landing it, and I have actually landed it both on the roof and in the bed with no issues.

So looks like I'm going to try hand launching it and then landing it on / in the truck and see how that goes. I'm still going to get a heavy mat to land on so I don't scratch up my truck, but it won't have to be a "shielded" mat.

 

[Capt KO]

Cardboard box usually works in a pinch but some trucks are like huge magnets and mess the compass for several feet. My '06 Tundra is one of them.

 

[Meta4]

Mine has asked to be calibrated a couple times.

It hasn't
Your compass is working just fine and has warned you that you've put the drone somewhere that there's a problem with magnetic interference.
When that happens, recalibrating the compass can't possibly solve the problem that your compass is warning you about.
The correct action is to switch off, move the drone away from the problem and start again somewhere else.
You really don't need to be recalibrating your drone's compass.

 

[DISC]

Real snippets of info in these columns - didn’t realise it was only a startup issue. Many Thanks guys!

 

[Bad Santa]

It hasn't
Your compass is working just fine and has warned you that you've put the drone somewhere that there's a problem with magnetic interference.
When that happens, recalibrating the compass can't possibly solve the problem that your compass is warning you about.
The correct action is to switch off, move the drone away from the problem and start again somewhere else.
You really don't need to be recalibrating your drone's compass.

Really? I wasn't within 20 feet of a structure and nowhere near any rebarred concrete.
Meh, I didn't crash. That was enough.

 

[Meta4]

Really? I wasn't within 20 feet of a structure and nowhere near any rebarred concrete.

Really ... your compass was warning you about something, whether you could see it or not.

Meh, I didn't crash. That was enough.

Your compass never needs recalibrating.

It sounds like you might benefit from a refresher on the drone's compass, and what calibration actually does.
Read the first post in this thread for some important factual information

A short explanation of compass function, calibration and errors.

Jun 9, 2020

BACKGROUND

The aircraft compass is often misunderstood, both in terms of function and purpose, but it is important to understand what the compass measures, why, and what happens to that information.

At the most basic level the purpose of the compass is to measure the earth’s magnetic field in order to find magnetic north relative to the aircraft heading. At any point near the earth the magnetic field is a single-valued vector quantity described by field strength and direction, and the compass comprises a 3-axis magnetometer aligned with the principal axes of the aircraft (x, y, z)...

• sar104
• Replies: 128
• Forum: Crash & Flyaway Assistance

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[Bad Santa]

As if I don't know what a compass does....

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[Meta4]

As if I don't know what a compass does....

Your response back in post #5 indicates that you have a very poor understanding of compass calibration does.
The video you just posted has more misinformation.

I'll suggest again that you need to read the first post in the thread I linked to get a proper understanding of what compass calibration actually does and when it might be required (almost never).