Please select Into the mobile phone version | Continue to access the computer ver.
Compass error & signal loss in flight
2050 23 2016-6-23
Uploading and Loding Picture ...(0/1)
o(^-^)o
Ste_Photo
lvl.3
Flight distance : 384449 ft
United Kingdom
Offline

Hi everyone, I am hoping someone can help or give advice based on what I experienced yesterday.

I got a new P3S 2 days ago and yesterday had the opportunity to fly it at a park. I just wanted to get a feel for the basics and try out RTH etc and therefore set it to beginner mode. I tried to calibrate the compass and kept getting errors so tried several times in slightly different locations until it appeared to work. Had the safe to fly (GPS) green notification in the app so took off, went to an altitude of about 60 feet about 32 feet away, hovered and turned. At this point I got a compass error, I thought no problem I've still got control but then got a no signal alert. There was nothing I could do, I hit the RTH button in the app, it said something like RTH failed and off it went out of sight. I was worried because it wasn't flying very high and it was heading towards a building site, what a horrible feeling, I then started to run in the hope I'd see it. Luckily RTH kicked in and it returned to the park at some speed and landed.

Now I accept I may have done something wrong, maybe compass calibration for example but I'd like to learn from this experience to ensure it never happens again. However I don't know what I could have done about the loss of signal as it was close range, no obstructions, no radio interference and in an open area. The firmware is up to date, IMU had been calibrated all looked ready to go. If it was at a lower altitude it would have crashed and this bothers me, the last thing I want to do is injure someone or damage someones property. I've really lost confidence and worried about it happening again. I am thinking it may be better to not use the beginner mode and fly higher so that it can't hit anything and then rely on RTH should it lose signal.

I've uploded the video to youtube: it's not exciting but shows what happened. The signal loss happens about  2m30s.

Thanks for any input, it will be appreciated :-)

2016-6-23
Use props
labroides
Captain
Flight distance : 9991457 ft
Australia
Offline

Was your compass error around 3 minutes in the video?
The building site is all reinforced concrete which means it's half steel and your Phantom is quite close.
The earth's normal magnetic field there is distorted be all that steel and your compass was telling you that the magnetic field it was sensing was different from what it was calibrated for.
2016-6-23
Use props
Matt-and-Riley
First Officer
Flight distance : 324442 ft
United Kingdom
Offline

Wow, that was very close to being another anti-drone headline in the tabloids. You are surrounded by all sorts of wifi, mobile masts and other interference. There could be all sorts of drains, pipes and cables under that Park. Guess this is a good example of why not to fly over congested areas, the Caa will be after you. First thing I would do is get some insurance from bmfa.org,  at least youll be covered for injuries and damage. Things can go wrong very quickly and you're very lucky to get away with it this time.

My underwear would need washing after that
2016-6-23
Use props
Geebax
Captain
Australia
Offline

I also noted there were lots of building around you, including a high rise residential building. The Phantom shares it's radio frequency with the WiFi systems being used in those buildings, and WiFi uses the exact same Frequency-hopping system the Phantom uses. That means they try to find a free channel among the 8 channels available, if a channel is already occupied, it automatically switches to the next until such time as it either finds a free channel, or finds all of them are in use, and it then declares 'signal loss' and you lose control.

The answer? Get out of town. Get away from all those WiFi systems and try again.
2016-6-23
Use props
Cessna172
Second Officer
United States
Offline

Your Phantom was moving with the wind.If you had been ANY lower....or ANY of those buildings ANY taller.......



RTH....when it works......It's a beautiful thing  :-)
2016-6-23
Use props
04red6
Second Officer
Flight distance : 5484997 ft
United States
Offline

labroides@yahoo Posted at 2016-6-23 19:26
Was your compass error around 3 minutes in the video?
The building site is all reinforced concrete w ...

lol
That is a highly unlikely. The compass is not that sensitive. We do not have to fly miles away from any metal.  
2016-6-23
Use props
04red6
Second Officer
Flight distance : 5484997 ft
United States
Offline

Cessna172 Posted at 2016-6-23 19:57
Your Phantom was moving with the wind.If you had been ANY lower....or ANY of those buildings ANY tal ...

Bingo, It seems to have switched out of GPS mode and then the wind took it. It is floating away in the same direction the trees are blowing.
2016-6-23
Use props
labroides
Captain
Flight distance : 9991457 ft
Australia
Offline

04red6 Posted at 2016-6-24 10:56
lol
That is a highly unlikely. The compass is not that sensitive. We do not have to fly miles away ...

Try flying in close to a construction site sometime yourself sometime.
You might find out how sensitive your compass is.
Do you have an alternative explanation for what caused the compass error?
2016-6-23
Use props
DJI-Paladin
DJI team
Flight distance : 2408 ft

Hong Kong
Offline

Hello Ste_Photo, you can follow some useful advice above. In my opinion, it is recommended to choose a place free of wifi and steel to fly. 飞行环境.JPG
2016-6-23
Use props
Ste_Photo
lvl.3
Flight distance : 384449 ft
United Kingdom
Offline

Thank you for all your comments. I naively assumed I'd be ok in beginner mode, flying low to get a feel for the controls. Also wanted to see how RTH worked from just beyond 20 metres, guess I found out but not the way I was expecting :-) I was prepared for a wi-fi disconnect which would only affect the video/app feed and knew I could initiate RTH via the s2 switch but didn't expect full controller loss at such close range. I knew which way it was facing but pulling back on the stick did nothing. I've flown a little Hubsan X4 (a toy in comparison) in the same park a touch higher but obviously there's no compass or GPS to think about just 100% manual flying.

'labroides' the compass error was about 2m30s in the video just as it was rotating then almost immediately it lost the controller signal too.

If anyone from the Manchester area reads this please let me know where you fly. There are plenty of fields not too far away but most is farmers land and don't fancy being chased by an angry farmer :-)

'Matt-and-Riley' thanks and I'll look into getting insured.

Anyway lesson learned, won't be doing that again and hopefully the video and this post will prevent others making the same mistake.
2016-6-24
Use props
rliamharpurb
lvl.2

United Kingdom
Offline

Ste I would advise recalibration on an area devoid of any interference like a farmers field, put the RC down and take all metal objects such as keys and phones off your person,

You could also try installing the 32 channel hack as this will give your quad and RC more channels to use in the likely event of interference

I have also had issues after calibrating my compass in my house and back yard but since I've been out to the countryside and recalibrate it, it has been fine

Until you get more confident I'd suggest flying higher and in a bigger space to get a feel for the controls and how the craft responds in different wind conditions

Also to give you an example on my p4 if I fly in a residential area similar to where you are in the video I get a lot of video drops and my range is drastically decreased, if I head into the countryside the furthest I have been is 2300m or so and still had full signal on everything,

Also to build trust with RTH I suggest going to a big field and flying around 50m away and 20m high providing there are no obstacles and turning off your controller to see how the craft performs when it does fully loose signal, this will build your trust in the craft greatly and is something that I done when I first got mine, just bear in mind you need to make sure your RTH values are set correctly ie your RTH altitude and what the craft is set to do when you loose signal

Liam
2016-6-24
Use props
Ste_Photo
lvl.3
Flight distance : 384449 ft
United Kingdom
Offline

rliamharpurb Posted at 2016-6-24 10:12
Ste I would advise recalibration on an area devoid of any interference like a farmers field, put the ...

Thanks Liam

I didn't know about the channel hack, will look into that. Thanks for your advise, appreciate it.

My mission is to find a very large open area but struggling as most is farming land with limited access.

Ste
2016-6-24
Use props
rliamharpurb
lvl.2

United Kingdom
Offline

Hi again

You could always ask the farmer and obviously tell him you won't be paying any attention to any of his or hers buildings,

The channel hack is as simple as plugging your tablet into your computer and dropping a file into the app, I can't select a custom channel but on auto it seems to use the other channels

Failing a farmer giving you permission which I am not sure if you do or don't need you could just park in a gateway or lay by and fly over the area this is what a lot of people tend to do

Liam
2016-6-24
Use props
Ste_Photo
lvl.3
Flight distance : 384449 ft
United Kingdom
Offline

rliamharpurb Posted at 2016-6-24 14:06
Hi again

You could always ask the farmer and obviously tell him you won't be paying any attention t ...

I've got the P3 Standard, from what I've found I don't think it applies to this model.

Been looking on google earth and found a great location about 20 minutes drive away, lots of large fields and one has public right of way.

Thanks again...
2016-6-24
Use props
rliamharpurb
lvl.2

United Kingdom
Offline

No problem happy flying!
2016-6-24
Use props
soneerr
lvl.1

Netherlands
Offline

Got the same problems here, I highly doubt that the P3 compass is that sensitive. We all paid much money for the hardware. And DJI is a company with a high name. They can't expect us to fly only in wide open fields of 30 miles with nothing on it. That is just not realistic. People may be using it for commercial-ends like shooting a clip etc. This may require shots in the city or something. Don't tell me it is only made for flying in the 'open fields'.
2016-6-25
Use props
04red6
Second Officer
Flight distance : 5484997 ft
Offline

labroides@yahoo Posted at 2016-6-24 14:23
Try flying in close to a construction site sometime yourself sometime.
You might find out how sensi ...

Okay, I do it all the time. I have for years. Look on you tube, there are plenty of videos with people flying around buildings, construction, power plants, hydro electric damns. Take your pick. All have tons of steel in them.
Maybe he set his quad in top of something that has a magnet in it. I just found out that my Nvidia shield K1 has 5 pretty strong magnets in the frame.
It could have been a number of factors. But I can assure you just because he was flying within 500ft of building construction, that was causing the compass error.
2016-6-25
Use props
04red6
Second Officer
Flight distance : 5484997 ft
Offline

04red6 Posted at 2016-6-26 08:05
Okay, I do it all the time. I have for years. Look on you tube, there are plenty of videos with pe ...

... Was not causing the error.
2016-6-25
Use props
labroides
Captain
Flight distance : 9991457 ft
Australia
Offline

04red6 Posted at 2016-6-26 10:05
Okay, I do it all the time. I have for years. Look on you tube, there are plenty of videos with pe ...

500 feet won't do anything ... you don't have to convince me of that.
But flying close to lots of steel reinforcing like I saw in his video can.
I have had to fly in construction sites and experienced the spiraling toilet bowl effect.
If you are close enough to enough steel, that's what happens.
Who said anything about 500 feet !!
2016-6-25
Use props
Ste_Photo
lvl.3
Flight distance : 384449 ft
United Kingdom
Offline

I went to the countryside yesterday and had the same issue (same as the city park incident) at short distance, compass error then signal loss, RTH kicked in. Flew for 20 minutes had a few more compass errors then landed when the battery was low. Checked the flight log in the phone and it's only logged 1 minute of the flight, is that normal?

Changed the battery and flew again had one signal loss, cancelled RTH went over 300 ft high and seemed much better. It changed to ATTI mode about 5 times but only for a few seconds. This time the whole flight was logged on the phone app. Also the compass calibration worked first time unlike at the park so not sure what's causing the inflight errors.

So the first flight wasn't so good but the second flight much better. I feel more confident now and don't panic when I see an error which can only be a good thing

Still concerned the compass is so sensitive and having lost the control signal at close range is also worrying. When both happen at once you're really screwed.
2016-6-26
Use props
droneflyers.com
First Officer
Flight distance : 60709 ft
  • >>>
United States
Offline

04red6 Posted at 2016-6-25 20:05
Okay, I do it all the time. I have for years. Look on you tube, there are plenty of videos with pe ...

True- BUT, keep in mind the Standard is by far the lowest cost model of this type and doesn't have the signal strength, dual GPS and other such features.

The Phantom 4 has dual compass and IMU for this specific reason.

So, to some degree, you do get what you pay for - we can't expect a budget bird to have the reliability of one that is 2 or 3X the price.
2016-6-26
Use props
Chris512
lvl.1

United States
Offline

Ste_Photo Posted at 2016-6-27 01:06
I went to the countryside yesterday and had the same issue (same as the city park incident) at short ...

Ste_Photo, keep in mind that these turn-key drones are being flown in environments where, traditionally, no experienced RC pilot would fly.  They are using microwave frequency radios and interference is common from everything from cell phone microwave transmitters to GMRS repeaters.  And the interference does not have to be on the frequency/band you are using - it can be several harmonics away on a different band.

Losing compass calibration, GPS and control signal like you did on your first flight is indicative of EMI/RFI problems.  The aircraft lost navigation and control signals, switched itself to attitude mode and drifted with the wind until it regained navigation and was able to RTH.  Always be careful of flying around these things in an RFI-rich environment.  As I said, traditionally, no experienced RC pilot would fly where many people are flying these drones today.  You cannot always depend on the aircraft's autonomous features to compensate.  GPS differential correction signals are lost occasionally even in full-size manned aircraft Nav units due to geomagnetic disturbance.  But the GPS receiver in the Phantom is not as sophisticated (or expensive) as certified aviation units that can fly without differential correction until signal is regained.
2016-6-26
Use props
droneflyers.com
First Officer
Flight distance : 60709 ft
  • >>>
United States
Offline

Ste_Photo Posted at 2016-6-26 13:06
I went to the countryside yesterday and had the same issue (same as the city park incident) at short ...

If you are having constant compass errors - even in more rural areas, chances are there is something wrong with the compass, etc.

If this continues, you should return it. There have been some range (low range) reports with the P3S - usually requiring the bird to be swapped or serviced.

But constant compass errors are not normal. Obviously try the usual - reinstall the app, maybe reinstall or upgrade the firmware and recal the compass.

But, basically, you should almost never get compass errors. I have flown 4 different Phantom models and it has been a rarity over the years....so return it under warranty if this continues.
2016-6-26
Use props
Ste_Photo
lvl.3
Flight distance : 384449 ft
United Kingdom
Offline

Hi, it's me again Thanks for the additional info and replies. Even though the dji app didn't show my first flight in the rural location I did manage to find it with a file manager and it's complete. I checked the log of the first and second flight using phantom log viewer which shows a few compass and yaw errors. I also uploaded to Healthy drones and that shows the changes to atti mode but says the compass is good.

Here's a link to the first flight: http://healthydrones.com/main?share=WaCAMi

and the second flight: http://healthydrones.com/main?share=juVVtk

In the second flight I initiated atti mode myself about 5 times for practise everything else was automatic. Just looking at the Healthy Drones logs it looks more like lack of visible satellites rather than a compass error but Phantom log viewer at phantomhelp.com would suggest a compass issue, sorry can't share their data. Maybe it's nothing but thought I'd mention it.

2016-6-27
Use props
Advanced
You need to log in before you can reply Login | Register now

Credit Rules