High magnetic interference

roblevine · Feb 15, 2018

So...I've been asked to shoot something downtown, among the skyscrapers. Not going really high - shooting a building that is lower. BUT - took my Mavic down there today to scope out the GPS situation...no GPS down there, but also - in one spot I got a "high magnetic interference". It was just on one corner - when I moved off the corner (I was just carrying the Mavic) the warning went away.

So - what happens if you're flying and you run into high magnetic interference? Do you lose control? I'll prolly be flying in Atti mode there.

NickU · Feb 15, 2018

It'll throw up the compass error message on screen and most likely one with gps errors too, then drop into ATTI mode if you're in sport or p-gps mode.

If you're already in atti, then I doubt you'll experience any other side effects (other than whingey warning messages

)

Make sure to stay VLOS and don't hit RTH - prob best to set hover in place instead of go home.

If you're lucky, the magnetic anomaly might just get ground based and you'll not get any issues up in the air.

roblevine · Feb 15, 2018

Thanks. So in Atti GPS & compass are ignored?

NickU · Feb 15, 2018

Pretty much, yes. The compass and gps readings are still taken and used to show your track, range & heading with respect to take off point (if the aircraft can obtain the readings), but you're the one doing the flying and in control.

As I said, beware using return to home point as it uses compass and gps to work out how to go home!

roblevine · Feb 15, 2018

NickU said:
Pretty much, yes. The compass and gps readings are still taken and used to show your track, range & heading with respect to take off point (if the aircraft can obtain the readings), but you're the one doing the flying and in control.

As I said, beware using return to home point as it uses compass and gps to work out how to go home!

I thought there was a way to say what happened if signal lost? Since I can't get GPS there seems like Return To Home should be disable-able? Otherwise it might remember its last one?

NickU · Feb 15, 2018

You should be able to set the RTH option in Dji Go. You need to check settings for remote controller signal lost (main controller->advanced settings) and also the one for smart RTH with low battery (in battery settings).

roblevine · Feb 15, 2018

NickU said:
You should be able to set the RTH option in Dji Go. You need to check settings for remote controller signal lost (main controller->advanced settings) and also the one for smart RTH with low battery (in battery settings).

Thanks for your help NickU

roblevine · Feb 19, 2018

After action: Given the dangers of this location downtown, I opted to use my Mavic Pro Platinum for a test shoot. That spot was like the Bermuda Triangle of drones. I was able to takeoff and fly a few missions; but on like the fourth flight I lost data link at one point for a second and a half and the drone drifted 10 ft in three seconds - nearly crashing into a building but for quick action on my part. I called it a day after that. At various points there was magnetic interference, loss of GPS signal, loss of data signal (at one point) and high wireless interference.

eldorado · Feb 20, 2018

roblevine said:
...fourth flight I lost data link at one point for a second and a half and the drone drifted 10 ft in three seconds - nearly crashing into a building but for quick action on my part.

Whew. Great save.
Could you clarify data link issue. Do you mean you lost video?

I assume you had control link working in order to execute "quick action". Could you share what you did to save the flight?

roblevine · Feb 20, 2018

eldorado said:
Whew. Great save.
Could you clarify data link issue. Do you mean you lost video?

I assume you had control link working in order to execute "quick action". Could you share what you did to save the flight?

Ok I misinterpreted a bit - turns out I lost GPS - not data link - that was from another flight. I was flying with Litchi - here's the Airdata report + video of the incident. Control lost at six second mark of the video.

UPDATE: I put in the GPS map - bird had no idea where it was.

FalconCam · Feb 21, 2018

Blimey that was close!

eldorado · Feb 22, 2018

roblevine said:
Ok I misinterpreted a bit - turns out I lost GPS - not data link - that was from another flight. I was flying with Litchi - here's the Airdata report + video of the incident. Control lost at six second mark of the video.

UPDATE: I put in the GPS map - bird had no idea where it was.

YIKES!
GPS Shadow below tall buildings!
Probably best to stay in ATTI however Mavic does't allow you to set that so not the best machine in that location as you mention.
Really tricky site for an Inspire.
Wind around buildings can suddenly change and too close to a cement wall like that and the bird can stick to the wall or rotor right into it.
In AirData you can look at their CSV output and review the GPS by the milisecond. I have seen GPS fail for fractions of a second and the sudden in/out of positioning data causes the bird to jump about unexpectedly as it regains/looses signal. Worth a look IMHO
Check out this link:
World Map of Live Satellite Positions - In-The-Sky.org
It can help calculate the shadow over time.
Very wise idea to carry the bird around the site to measure signals before flying!

roblevine · Feb 22, 2018

eldorado said:
YIKES!
GPS Shadow below tall buildings!
Probably best to stay in ATTI however Mavic does't allow you to set that so not the best machine in that location as you mention.
Really tricky site for an Inspire.
Wind around buildings can suddenly change and too close to a cement wall like that and the bird can stick to the wall or rotor right into it.
In AirData you can look at their CSV output and review the GPS by the milisecond. I have seen GPS fail for fractions of a second and the sudden in/out of positioning data causes the bird to jump about unexpectedly as it regains/looses signal. Worth a look IMHO
Check out this link:
World Map of Live Satellite Positions - In-The-Sky.org
It can help calculate the shadow over time.
Very wise idea to carry the bird around the site to measure signals before flying!

Thanks for the link!