Can flying near radio towers interfere with Mavic Pro?

[BudWalker]

I will conduct the test on my next outing.

If the test fails and I get this problem again, I guess I'll just have to fly the Mavic straight backwards and forwards without turning it from now on lol.

On a serious note I'm losing a lot of confidence in my Mavic.

Edit: Is is worth re-calibrating the compass and IMU?

Is is worth re-calibrating the compass and IMU

Yes, but let's wait until after you do your test so that we'll know if it helped. Just the IMU and then another test. Follow that with a compass calibration and another test. Otherwise we wouldn't know which calibration helped, if it did..

 

[BudWalker]

Keep that piece of advice that was given earlier by ac0j in mind adam3112 ... If you look at the Google map picture (your log files) and compare that to your take-off video, it appears that the arrow depicting the Mavic on the Google Earth map, is pointing about 20 degrees left of the direction your video shows the Mavic to be looking in. That may confirm some earlier analysis of the initial data. As part of your pre-takeoff check, once the Mavic tells you it has established GPS - expand the map view and check that the arrow on the map, is pointing the same way that the actual Mavic is on the ground in front of you.
I think you had some bad luck first-flight. My first flight ever went way wrong (not a DJI drone) and ended up 20 metres up a tree when I tested RTH - I still don't know where ti thought home was ... Took me a week to get it down! Fly safe & have fun.

I discounted this because 1) it's difficult to compare the video against the map heading indicator, and 2) the gimbal may not have been aligned with the X axis. Also, as I mentioned earlier, if Yaw were compromised due to a geomagnetic distortion, then there would be a Yaw/magYaw separation as the Mavic ascends out of the distortion.

Regardless, checking the map heading indicator against the actual heading is the single most effective way to prevent launch time fly aways.

 

[adam3112]

Keep that piece of advice that was given earlier by ac0j in mind adam3112 ... If you look at the Google map picture (your log files) and compare that to your take-off video, it appears that the arrow depicting the Mavic on the Google Earth map, is pointing about 20 degrees left of the direction your video shows the Mavic to be looking in. That may confirm some earlier analysis of the initial data. As part of your pre-takeoff check, once the Mavic tells you it has established GPS - expand the map view and check that the arrow on the map, is pointing the same way that the actual Mavic is on the ground in front of you.
I think you had some bad luck first-flight. My first flight ever went way wrong (not a DJI drone) and ended up 20 metres up a tree when I tested RTH - I still don't know where ti thought home was ... Took me a week to get it down! Fly safe & have fun.

You are right in that on close inspection it does appear the arrow for the mavic on the map is more off to the left than the video seems to show, of course at the time I didn’t notice it as the arrow is facing in the general direction that the Mavic was actually facing but I will definitely pay closer attention to this in the future to ensure arrow and mavic direction is more precise.

 

[sar104]

I discounted this because 1) it's difficult to compare the video against the map heading indicator, and 2) the gimbal may not have been aligned with the X axis. Also, as I mentioned earlier, if Yaw were compromised due to a geomagnetic distortion, then there would be a Yaw/magYaw separation as the Mavic ascends out of the distortion.

Regardless, checking the map heading indicator against the actual heading is the single most effective way to prevent launch time fly aways.

Agreed - there was definitely no magnetic issue at the takeoff point.

 

[Starz]

I don’t care who’s right, I’m buying everybody a beer!

 

[Randy]

Hi all,

Just before I explain, I just want to say that I replaced my faulty equipment mentioned in the other thread and got myself a brand new, sealed Mavic 1 Pro. My Mavic's IMU and Compass is calibrated and showing as normal in the settings. In fact everything is showing as normal. I had calibrated them yesterday when I took it out on a previous flight.

So today being my second flight, I took my Mavic up to a viewpoint which happens to be near a radio tower. I was about 200 Meters away from the tower but for some reason as soon as I took off and went forward (with 13 Satellites), I suddenly got Compass error and my Mavic was put in to atti mode, flung forward with the strong wind and missed the trees by Inches. I'm still amazed at how it missed. Watching it back on the video still makes my heart sink, these trees were easily 70-80 ft high and the drone was being pushed fast. I'll try and post a video of it.

So after this near nightmare, I came to a stop at the other side of the tree line in an open area, almost having a heart attack. I then got weak GPS signal. A few seconds later, GPS connectivity got restored with 18 satellites. I flew back and landed at the home point straight away.

I took off a second time and I got a message pop up on the app saying 'Strong Wireless Interference. Fly with caution.' Luckily it stayed in GPS mode for the duration of the flight and I got it back safely.

So my question is, is it likely the radio tower interfered with my Mavic today? I'm hoping there isn't an underlying problem.

Thanks.

The same thing happened to me shooting video of a steel bridge that was being torn apart, there’s lots of steel there and it’s going to mess with the compass every time in my experience. As long as I still have video feed it continue on business as usual.

 

[sar104]

The same thing happened to me shooting video of a steel bridge that was being torn apart, there’s lots of steel there and it’s going to mess with the compass every time in my experience. As long as I still have video feed it continue on business as usual.

There was no magnetic interference from the bridge in this case.

 

[Dave A]

I read the entire thread and I must say it was way more interesting than any documentary I've seen in a long time. I'm one of those guys who fly these drones, MPP, but doesn't really know what makes them work......or not work. These threads although very technical are important to me because little by little I start to understand what not to do and what to look out for in a flying environment.

As much as I enjoy these threads (no disrespect to those that have lost their drones) I hope to never be the focus of one. Nine months of flying so far with zero problems......fingers crossed.

 

[billfraser1]

I read the entire thread and I must say it was way more interesting than any documentary I've seen in a long time. I'm one of those guys who fly these drones, MPP, but doesn't really know what makes them work......or not work. These threads although very technical are important to me because little by little I start to understand what not to do and what to look out for in a flying environment.

As much as I enjoy these threads (no disrespect to those that have lost their drones) I hope to never be the focus of one. Nine months of flying so far with zero problems......fingers crossed.

I also would like to complement the various contributors to what has been a very informative and intriguing thread. I'm a retired engineer, but fairly new to drones. In a nutshell, knowledge is power, particularly when it comes to staying out of trouble. This thread contributed significantly to my knowledge. It was particularly gratifying to see so much of the discussion conducted with politeness and respect to the other contributors! Flames don't help! Much more of the same please!

 

[norfilm]

As a tv transmitter engineer I can tell you that your mavic suffered severe Radio Interference. Somewhere in this thread i saw you were in Reigate, in which case the white cylinder at the top of the tower is pumping out twelve kilowatts of TV power. An additional fifteen kilowatts of radio transmitters are on site. Although not on the Mavic's frequency that is a deeply unhealthy quantity of radiation. You're quite safe on the ground - 150 feet up its a different story. It's quite possible if you had been where the UAS was, you'd have been microwaved. Don't have a air navigation map of the area but it's probably marked as HIRTA (high intensity radio transmission area). Safe flying!

 

[adam3112]

Hi all, so I did the test earlier today which BudWalker suggested earlier in the thread. I carried it out in a different location and no issues with the Mavic throughout and stayed in GPS mode. Here's the flight record. I'll upload the DAT file on a separate post as this site doesn't like me attaching multiple files. Is there anything Budwalker and Sar104 you can pick out from them which seem unusual? Thanks for all your help.

 

[adam3112]

I'm not sure which dat file it is, but here's both parts from today attached.

 

[FoxhallGH]

I never at any point said you were wrong, just that the only visible hazard was the tower. I was there so I should know. You keep saying this issue is because I took off from reinforced concrete or steel, all I’m saying is I took off from a muddy, grassy gravelly footpath and those things were not to be seen on the ground or anywhere in my takeoff vicinity.

On some parts of that footpath your foot could easily sink 12 inches in mud, so any concrete or steel present in that spot is going to be quite deep in the ground.

Just a thought about something you said in an earlier post @adam3112 ... Looking at the Google Earth sat-maps of the site, you can't see any overhead power cables going into the transmitter site. However, the "grassy, gravelly footpath" - where "your foot could easily sink 12 inches in mud" - and where your Mavic was sitting on top of when it took off - looks rather straight with a gentle curve off into the tree-line heading directly toward the transmitter site ... Now - again - just a theory, but I wonder if that 'foot-path' could actually be a trenching scar, where a major underground power cable has been laid into the site? I'd think that with all of the transmitters and power needs of that site, you'd need to have quite a hefty armoured 3-phase mains power cable coming into that antenna building somewhere. Your statement (above) reminded me that when you dig a trench for a cable or pipe, it is often filled in without being compressed back to the original density of the earth, and it can mean that the ground is softer, and gets muddier in the wetter months along the line of the trench. You'd need a metal detector to prove it - but - that's another theory as to what could be there ...

 

[norfilm]

A drone flying at the height of the antenna would be in a field strength of many volts per metre. The link transmitter for a drone is +20 dBm, or 0.1 watts at 2.4 gHz, the total output of the radio tower is of the order of 26000 watts. The intermodulation products from the different transmitters will totally swamp the UAS link. (The clue is the 'interference' warning).The underground mains cable is a possibility, I grant you, but flying anywhere near the antennas could actually damage the electronics on board the UAS.

 

[Dragon2650]

Ask Ken Heron! Flying too close to radio towers with a drone

 

[sar104]

As a tv transmitter engineer I can tell you that your mavic suffered severe Radio Interference. Somewhere in this thread i saw you were in Reigate, in which case the white cylinder at the top of the tower is pumping out twelve kilowatts of TV power. An additional fifteen kilowatts of radio transmitters are on site. Although not on the Mavic's frequency that is a deeply unhealthy quantity of radiation. You're quite safe on the ground - 150 feet up its a different story. It's quite possible if you had been where the UAS was, you'd have been microwaved. Don't have a air navigation map of the area but it's probably marked as HIRTA (high intensity radio transmission area). Safe flying!

That's fascinating, but radio interference was not this issue here. The problem was a brief period of separation of compass and IMU yaw, most likely due, as @BudWalker pointed out, to an incorrect z-axis rate gyro gain value.

 

[norfilm]

That's fascinating, but radio interference was not this issue here. The problem was a brief period of separation of compass and IMU yaw, most likely due, as @BudWalker pointed out, to an incorrect z-axis rate gyro gain value.

I hate to disagree with sar 104. If he consults the British Civil Aviation Agency CAP722 (unmanned Aircraft System Operations in UK Airspace- Guidance) - no doubt the FAA has something very similar - on page 119 it states 'Radio Frequency (RF) interference. Pilots must take into account of the possible reduction in operating range in an urban environment due to the heavy use of communications equipment............along with the general RF saturation level. The correct name for radio waves is Electro MAGNETIC radiation. Not for nothing do they tell you to keep your phone away when doing a compass calibration. Not because of magnets, because of radiation. At risk of boring everyone, a strong RF field affects everything. Wiring acts as an antenna and gets into IMU, control receiver, motor ESC's, GPS, even the control circuits within the battery. As a transmitter engineer, my advice is GIVE TOWERS A WIDE BERTH - I do!

 

[sar104]

I hate to disagree with sar 104. If he consults the British Civil Aviation Agency CAP722 (unmanned Aircraft System Operations in UK Airspace- Guidance) - no doubt the FAA has something very similar - on page 119 it states 'Radio Frequency (RF) interference. Pilots must take into account of the possible reduction in operating range in an urban environment due to the heavy use of communications equipment............along with the general RF saturation level. The correct name for radio waves is Electro MAGNETIC radiation. Not for nothing do they tell you to keep your phone away when doing a compass calibration. Not because of magnets, because of radiation. At risk of boring everyone, a strong RF field affects everything. Wiring acts as an antenna and gets into IMU, control receiver, motor ESC's, GPS, even the control circuits within the battery. As a transmitter engineer, my advice is GIVE TOWERS A WIDE BERTH - I do!

Feel free to disagree but you may have missed the point of my post. I was not arguing that high-power transmissions cannot interfere with aircraft communications or electronics, I was pointing out that the problem, in this case, was a very transient yaw separation on the first yaw maneuver after takeoff. It didn't persist or return, and there is no evidence to suggest that it was anything other than an initial rate gyro gain error.

If there really had been EM interference with the aircraft electronics then I would have expected to see problems throughout the flight, not just at takeoff.

 

[dekip]

Thanks Meta4 for this and everyone else for their help. I can only presume then that there is something under the ground in that field I was in, perhaps relating to the fort not too far away which my Mavic didn’t like?

Will have to recalibrate the Mavic when I next take it out to be sure it hasn’t thrown the compass and IMU out of place.

I believe I have experienced this when I took off near a lrge flood wall (No doubt full of rebar) and a public street. Made it to about 40 ft AGL and it went crazy. I hit Sport mode and fought it like a bucking bronco back to the ground. It was the scariest and only time I have seen,

 

[Inspirephil]

Hi all,

Just before I explain, I just want to say that I replaced my faulty equipment mentioned in the other thread and got myself a brand new, sealed Mavic 1 Pro. My Mavic's IMU and Compass is calibrated and showing as normal in the settings. In fact everything is showing as normal. I had calibrated them yesterday when I took it out on a previous flight.

So today being my second flight, I took my Mavic up to a viewpoint which happens to be near a radio tower. I was about 200 Meters away from the tower but for some reason as soon as I took off and went forward (with 13 Satellites), I suddenly got Compass error and my Mavic was put in to atti mode, flung forward with the strong wind and missed the trees by Inches. I'm still amazed at how it missed. Watching it back on the video still makes my heart sink, these trees were easily 70-80 ft high and the drone was being pushed fast. I'll try and post a video of it.

So after this near nightmare, I came to a stop at the other side of the tree line in an open area, almost having a heart attack. I then got weak GPS signal. A few seconds later, GPS connectivity got restored with 18 satellites. I flew back and landed at the home point straight away.

I took off a second time and I got a message pop up on the app saying 'Strong Wireless Interference. Fly with caution.' Luckily it stayed in GPS mode for the duration of the flight and I got it back safely.

So my question is, is it likely the radio tower interfered with my Mavic today? I'm hoping there isn't an underlying problem.

Thanks.

Any type of interference (wireless, radio, electrical) will play havoc with your drone. I live fairly close to some power lines and I always get the warnings about that every time. Sometimes it messes up my flight and sometimes it doesn’t. Go figure?