Break this down

805hd · Mar 15, 2017

Was flying today at the park right by my house (plenty of interference). Calibrated on the asphalt and launched from it as well (normally use a piece of plywood). After I was up and flying I got a warning..

"Magnetic Filed Interference. Exit P-GPS Mode"

So I flew back, landed, picked a grassy open spot to recalibrate back up she went and all was fine.

Questions,

Was this caused by interference or a bad calibration?

Will RTH still work outside of GPS mode?

I've flown with no GPS lock before. But if this happened at great distance it could of got ugly.

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Thanks!

kndll · Mar 15, 2017

sometimes a simple power down and power back up will clear the interference , I get that from time to time for no real reason.

AeroMirage · Mar 15, 2017

hmmmm.... when in doubt..... reboot.
I have had trouble before with Inspire 1 not responding to camera gimbal commands.
Would Tilt but not pan. Rebooted... all was well.

805hd · Mar 15, 2017

Would return home have worked? Usually I'm a lot farther out when I go fly the fields.. What's proper procedure if this happened under conditions where signal might not be 100% (5-10000' away)?

This has got me a bit nervous to fly.. lol

Thanks!

jwmcgrath · Mar 15, 2017

805hd said:
Would return home have worked? Usually I'm a lot farther out when I go fly the fields.. What's proper procedure if this happened under conditions where signal might not be 100% (5-10000' away)?

This has got me a bit nervous to fly.. lol

Thanks!

I'm saying no.

Outside of GPS lock, it doesn't know where it is and it doesn't know where home is, let alone how to get there.

That said, I can't imagine why GPS lock wouldn't be reestablished with the bird being in the air. But I do understand the nervousness.

Meta4 · Mar 15, 2017

805hd said:
Was flying today at the park right by my house (plenty of interference). Calibrated on the asphalt and launched from it as well (normally use a piece of plywood). After I was up and flying I got a warning..
"Magnetic Field Interference. Exit P-GPS Mode"
So I flew back, landed, picked a grassy open spot to recalibrate back up she went and all was fine.

If you recalibrate the compass every flight you are leaving yourself open to this sort of thing (and worse).
There is no need to recalibrate the compass all the time.
Get a good compass calibration and just leave it.

805hd · Mar 15, 2017

Meta4 said:
If you recalibrate the compass every flight you are leaving yourself open to this sort of thing (and worse).
There is no need to recalibrate the compass all the time.
Get a good compass calibration and just leave it.

If I calibrate at area A and then drive to area B I wouldn't need to recalibrate?

I was under the impression you need to calibrate at a new spot but not again if you continue to fly there later or the next day kinda thing?

Meta4 · Mar 15, 2017

805hd said:
If I calibrate at area A and then drive to area B I wouldn't need to recalibrate?
I was under the impression you need to calibrate at a new spot but not again if you continue to fly there later or the next day kinda thing?

No ... just get a good compass calibration in a clean area and stick with it.
The whole calibrate every flight or every new location thing is a myth and the cause of lots of problems.

Read this for some background.
Compass Calibration, A Complete Primer

tevek · Mar 15, 2017

805hd said:
Agree but on healthy drones it shows GPS signal through the whole route.. that's why I ask. I was well withing line of sight this time but if this had happened a distance with the hammer down who knows what would of happened.

As Meta4 says, do the calibration the one time and unless you are prompted to do so, leave it alone. A bad compass calibration is probably going to conflict with the GPS given the amount of data being processed and that's probably why it dropped out of GPS mode. Happened to me just the once after I calibrated on top of a buried HV cable and I got the warning pretty well straight away, with no GPS I'd suspect your RTH is going to be in trouble.

805hd · Mar 15, 2017

Meta4 said:
No ... just get a good compass calibration in a clean area and stick with it.
The whole calibrate every flight or every new location thing is a myth and the cause of lots of problems.

Excellent news.. I'll be out in the fields in about a hour. Zero noise around me, should be a good spot.

Thanks

805hd · Mar 15, 2017

jwmcgrath said:
I'm saying no.

Outside of GPS lock, it doesn't know where it is and it doesn't know where home is, let alone how to get there.

That said, I can't imagine why GPS lock wouldn't be reestablished with the bird being in the air. But I do understand the nervousness.

Agree but on healthy drones it shows GPS signal through the whole route.. that's why I ask. I was well withing line of sight this time but if this had happened a distance with the hammer down who knows what would of happened lol.

Going to recal tonight out in the field. Should be the cleanest spot I've ever calibrated.

805hd · Mar 15, 2017

tevek said:
As Meta4 says, do the calibration the one time and unless you are prompted to do so, leave it alone. A bad compass calibration is probably going to conflict with the GPS given the amount of data being processed and that's probably why it dropped out of GPS mode. Happened to me just the once after I calibrated on top of a buried HV cable and I got the warning pretty well straight away, with no GPS I'd suspect your RTH is going to be in trouble.

Yes, this is all making sense. I calibrated in the middle of the street. Not the brightest idea. Who knows what's under there..

Thank you for the reply!

tevek · Mar 15, 2017

805hd said:
Yes, this is all making sense. I calibrated in the middle of the street. Not the brightest idea. Who knows what's under there..

Thank you for the reply!

No worries and good luck!

niteliter · Mar 15, 2017

As ODD as this may seem,I have discovered that most of my "Magnetic Field Interference" warnings were from the cell phone clipped to my belt,simply taking the phone off my belt and placing it in my truck took care of it,and as long as I keep my phone in the truck,I get no warnings anymore.When I do get one I look and and have a "DUH!" moment when I see the phone tagging along.
( this is my personal experience and may or may not apply to anyone else alive or dead) =

With The Birds · Mar 15, 2017

805hd said:
Agree but on healthy drones it shows GPS signal through the whole route.. that's why I ask. I was well withing line of sight this time but if this had happened a distance with the hammer down who knows what would of happened lol.

Going to recal tonight out in the field. Should be the cleanest spot I've ever calibrated.

Healthy drones is saying the AC had enough satellites visible and acquired to obtain a GPS lock and valid position information. The problem is when a compass issue is detected the AC will switch to ATTI mode as default. p-GPS requires valid compass and gps data.

The good I news is that if you have signal your position on the Mao will be valid and with the aid of the camera flying hime should be no issue.

Loose signal in this scenario and the AC will either friftbwith the breeze untill auto landing or, if RTH engages, fly to where it thinks the home point is and with a dodgy compass that may not be where you would hope.

Do not press the RTH button when your compass is playing up.

805hd · Mar 15, 2017

niteliter said:
As ODD as this may seem,I have discovered that most of my "Magnetic Field Interference" warnings were from the cell phone clipped to my belt,simply taking the phone off my belt and placing it in my truck took care of it,and as long as I keep my phone in the truck,I get no warnings anymore.When I do get one I look and and have a "DUH!" moment when I see the phone tagging along.
( this is my personal experience and may or may not apply to anyone else alive or dead) =

Mines always on airplane mode in my truck along with with my keys.. good practice.