My Mavic has suddenly gotten “weak GPS signal” while flying this week. Is this normal? Flight log pics included.

[ScubaBob]

Very interesting!

I’ll test this tomorrow. If I can’t launch on a sidewalk. Where do you suggest I launch? Grass seems to be too high usually to launch. Where do you like to launch from?

Sidewalks have rebar (round solid steel bars) to strengthen the concrete and hold it together. For a typical 4" thick sidewalk the rebar is about 2" from the surface. I keep a 2 foot square piece of 1/4" plywood (easily available from Home Depot or Lowes) with me so that I can take-off on sand, grass, etc. plus it gives the drone a good contrasting image to capture for recording home. You can paint the plywood (or masonite) a bright orange or put an identifying pattern on it, too. You can also use the fold-up windshield screens for your car as a take-off and landing pad. AutoZone sells ones that are 18" x 24" +/- and fold up into an 8" x 1" circle so they are easy to carry.

 

[mlash]

Very interesting!

I’ll test this tomorrow. If I can’t launch on a sidewalk. Where do you suggest I launch? Grass seems to be too high usually to launch. Where do you like to launch from?

Hand launch if necessary! If you don't know how then practice until you become good at it. It will save you a lot of grief in the future!

 

[Billyboy72]

Very interesting!

I’ll test this tomorrow. If I can’t launch on a sidewalk. Where do you suggest I launch? Grass seems to be too high usually to launch. Where do you like to launch from?

Grass but use a landing pad or a large piece of cardboard. Def stay away from sidewalks, steel, bridges etc.

 

[rodolpholemos]

If the drone loses GPS signal mid air, what difference the launch surface could make?? If the drone couldn't lock enough satellites on the launch area or you have compass errors on that spot, then the cause could be metal nearby. For example: when I try to launch my Mavic Air from the roof of my car, it always shows compass error...

 

[BD0G]

That yawing (rotating) that is occurring would bother the heck out of me when I want to shoot multiple AEB shots at different exposures. It would more than likely cause "ghosting" in the sequence of shots as the image being photographed would not remain in the center.
You want zero rotation in a hover or based on wind conditions as little as possible.
Interested to hear what DJI replies with.
Please post thier findings.

 

[Point Zero]

After reading through this thread I would think your best course of action is to send the drone back to DJI telling them that this particular drone is not working correctly, send them the video and flight logs and ask to have it repaired or replaced. You have a right to enjoy your purchase and if its not working as advertised then replace or refund. Yeah its going to suck not having your drone for a week or so but after that you will be having the fun and enjoyment that comes from owning a high quality drone.

I have had magnetic interference on take off (M2P) at least 10 times in the last two weeks and never has this resulted in any strange behaviour or signal loss that you have encountered. Based on that I would say send it back and get it checked out asap.

I hope you get this issue sorted out dude.

 

[CactusJackSlade]

Right, its very serious too just because it can drift away and damage property or something. This has happened far too much on just my practice runs so I am terrified to take it out to a client's place of business. I am hoping between this forum and DJI support, we will get this sorted out. I kinda hope its a bad drone and i get it replaced.

Thus a good reason to practice flying without GPS... it can and WILL happen on occasion, especially around buildings/congested cities etc, and when that happens a pilot should be able to control the aircraft, regardless. Practice, practice practice!

 

[Dingo]

You may want to download the free app" UAV forecast" , click the help icon bottom right and read about KP index and GPS elevation mask. It will explain why you could start off with plenty of satellites but then loose some to the point where GPS is lost.

 

[Meta4]

You may want to download the free app" UAV forecast" , click the help icon bottom right and read about KP index and GPS elevation mask. It will explain why you could start off with plenty of satellites but then loose some to the point where GPS is lost.

Neither of those is of any use.
The effect of the KP index on drone flying is a myth. No detrimental effects have ever been observed.
No matter where you are in the world you will always have enough satellites.
The only way you wouldn't would be if you fly in an area where terrain or cover blocks a substantial part of the sky.

 

[Meta4]

One correction, concrete surfaces ARE NOT half steel. Lighter weight surfaces have a wire mesh (usually a 4"x4" nesh), while heavy duty surfaces will have steel reinforcing bars (size will vary with the load design, but usually they are 10" to 12" OC), but they are NOT half steel. It appears to me the compasses in our units are very sensitive, and even a placement of several inches one side to another will affect the initialization of the compass. I agree it is the best to avoid it altogether, but it does make sense where someone may have launched from a driveway, and later get an error.

Obviously it's not 50% steel and 50% concrete but the amount of steel is substantial and it's very easy to place your compass right above a decent chunk of steel.
The images I posted in post #47 show examples of how much steel can be under the concrete and how variable it is..

 

[SYC12]

Idk it’s very frustrating.

No you don’t have to. Just don’t launch from the concrete sidewalk.

 

[BanditsRoost]

Interesting! It seems very weird to me that most normal surfaces can cause you to lose gps and crash. That doesn’t sound right to me. I assume 95% of drone users launch from sidewalks or other concrete. I wish there was a way to confirm if it was causing the magnetic interference or if I should exchange for a new one.

I am also pretty positive that my sidewalk leading up to my house is not reinforced. Maybe it can be interference from my house being a few feet away on launch? Idk it’s very frustrating.

In my area most all sidewalks are reinforced. If you really want to know purchase any toy or inexpensive metal detector and check.
Toy detectors ----$40
Crashed Drone----- big$
Good advice from many experenced pilots---- FREE

 

[JimZ]

No

Mine is reinforced, I watched them do it...must just depend on the area

 

[Gerry Mander]

After skipping several pages of this thread, people are still talking about reinforced 'sidewalks'. I had an identical event as described 2 weeks ago with my Mavic Air One. Top of a barren mountain - no man made objects for miles. Launched off a flat grass area. 18 - 20 satellites, aircraft signalled ' weak light, downward sensors not working' (sun was shining). then 'weak GPS signal', followed by 'ATTI' mode (still 20 satellites visible), then drone done its own thing , dropped height 140 feet, horizontal speed indicated 67mph. Stopped, then I magaed to 'connect' with it again and got it home. No metal for many miles. I checked the sensor calibrations after, and al was 'excellent' except the IMU Accelerometer which was 'good', but not excellent, so calibrated the IMU. Very strange as I have had over 200 trouble free flights. Going to pop the top cover off it and see if there are any loose connections to IMU / Compass. Any other suggestions which do not include 'steel' most welcome , thanks

 

[LakeWorthB]

After skipping several pages of this thread, people are still talking about reinforced 'sidewalks'. I had an identical event as described 2 weeks ago with my Mavic Air One. Top of a barren mountain - no man made objects for miles. Launched off a flat grass area. 18 - 20 satellites, aircraft signalled ' weak light, downward sensors not working' (sun was shining). then 'weak GPS signal', followed by 'ATTI' mode (still 20 satellites visible), then drone done its own thing , dropped height 140 feet, horizontal speed indicated 67mph. Stopped, then I magaed to 'connect' with it again and got it home. No metal for many miles. I checked the sensor calibrations after, and al was 'excellent' except the IMU Accelerometer which was 'good', but not excellent, so calibrated the IMU. Very strange as I have had over 200 trouble free flights. Going to pop the top cover off it and see if there are any loose connections to IMU / Compass. Any other suggestions which do not include 'steel' most welcome , thanks

You should take a look at the logs, and see if you see anything.

 

[Gerry Mander]

You should take a look at the logs, and see if you see anything.

Hi - A few have already looked at the log, and cant explain why it went hay-wire. Nothing definitive from anyone, but suggestions such as IMU calibration / or even failure...Bad wiring connections within drone to IMU? Ive had over 200 trouble free flights. I have re calibrated the IMU (for 1st time ever), but not flown it yet, since the incident. hopefully someone can have a look at this link...

 

[Meta4]

Any other suggestions which do not include 'steel' most welcome , thanks

Don't worry about it.
What you observed was just a false alarm that's been showing up since the app update to 1.2.2.

 

[Gerry Mander]

Don't worry about it.
What you observed was just a false alarm that's been showing up since the app update to 1.2.2.

Serious?, the drone dropped 140feet, and was doing its own thing for 30+ seconds. If it wasn't so high up, it would have been a gonner. This similar problem seems to be 4+ years old and happened to many many people, and I've yet to come across a reason or a fix..

 

[Meta4]

Serious?,

Sorry ... I didn't notice that you had the original Air and thought you were describing the current common false alarm affecting the Air 2 on the DJI Fly app.

I had a look at your data and am unsure of the cause of the drop.
There is an unexplained error message that just says Other (8).
Perhaps @slup would like a challenge with this.