phantom 4+ weak gps signal

[kevinmoody]

Just received the unit back from DJI. Now every time I fly it says "weak GPS signal" Tried in the city and out in the country . Out in the country it showed 16 satellites - in the city 11. All updates have been performed. Firmware is up to date. Calibration completed. Any help?

 

[Meta4]

Just received the unit back from DJI. Now every time I fly it says "weak GPS signal" Tried in the city and out in the country . Out in the country it showed 16 satellites - in the city 11. All updates have been performed. Firmware is up to date. Calibration completed. Any help?

I don't think I've ever seen any Phantom report weak GPS signal for the Phantom.
The only times I've seen Weak GPS signal, it was referring to the tablet rather than the Phantom and the indication of 16 sats on your display would support this.
Is there something blocking satellite reception for the display unit?
If not, that suggests there may be a problem with the display unit's GPS or its connections.

 

[kevinmoody]

In the mountains of Oklahoma on a mountain top in a clear cut area flying at 100'. No interference from any trees or vehicles.

 

[Meta4]

In the mountains of Oklahoma on a mountain top in a clear cut area flying at 100'. No interference from any trees or vehicles.

I put that last sentence there if that was the case.

 

[P4P hannuz]

I have exactly the same problem with a brand new p4p. I did not notice it lost GPS first flight, yet, familar to the Mavic, I did find it rather instable / drifting in flight. The flight log showed no GPS. I did not pay any further attention to it till today.

Today I did my second flight and I did notice the weak signal message. With the controller coming with the LCD screen there no mobile device, yet, the mobile device signal was said to by weak in terms of GPS. To resolve the issue I calibrated the IMU and compas, upgraded to v1.005 and calibrated again. No solution, on take off and hover, although saying GPS present (green bar) she still drifts. And on RTH she is meters off, so I need manual adjustment all the time.

Does this sound familar? Anyone having the same experience using the built-in LCD controller? If so, any resolution?

 

[Meta4]

I did notice the weak signal message. With the controller coming with the LCD screen there no mobile device, yet, the mobile device signal was said to by weak in terms of GPS. To resolve the issue I calibrated the IMU and compas, upgraded to v1.005 and calibrated again. No solution, on take off and hover, although saying GPS present (green bar) she still drifts. And on RTH she is meters off, so I need manual adjustment all the time

GPS is normally trouble free.
You need to work out whether the issue is related to the GPS receiver in your Phantom or in the screen unit.
Calibrating the compass and IMU won't have any effect on GPS issues.

 

[P4P hannuz]

Thanks for the reply.

I agree, IMU and compass won't affect GPS issues. Yet, as I understand inertial guidance, inertial guidance and compass together should be suffcient to get her at least close to home. Unless, that data isn't tracked /processed. Yet, I'm not confident enough to give it a field test. Might turnout as a total loss.

I would guess that the issue is in the controller as the message refers to the mobile device. Yet, how to work that out? Any suggestions?

I see three options, yet, how to intepret the result/validate the findings?
- 1. Compare landing spots by GPS home by aircraft or by controller. Yet, which one is correct?
- 2. Set GPS home by aircraft and shutdown the controller. Next compare landing spot to the ones obtained from option 1.
-3. Indoor I have no GPS. So, aircraft outside and controller indoors. Set GPS home to aircraft and go.

Yet, as before, I'm not confident enough to give either option a go. Any other suggestions?

 

[Meta4]

I agree, IMU and compass won't affect GPS issues. Yet, as I understand inertial guidance, inertial guidance and compass together should be suffcient to get her at least close to home. Unless, that data isn't tracked /processed. Yet, I'm not confident enough to give it a field test. Might turnout as a total loss.?

Without GPS, the Phantom is not capable of RTH.
It needs GPS to know where it is and compare that with the stored homepoint to work out how to return to there.

But that is all about GPS on the Phantom.
GPS in the controller is of no use except for follow-me flight and resetting the home point to the current location of the controller (used when flying from a moving boat or car etc).

I would guess that the issue is in the controller as the message refers to the mobile device. Yet, how to work that out? Any suggestions?

The only time I've seen a message about a Weak GPS Signal, it was referring to the GPS signal for the tablet - and "weak" really meant No Signal
Is there a reason that your controller would have had poor GPS conditions?
Were you under a roof or tree cover, close to a building that blocked the sky etc?
I don't know if it's possible to disable GPS in the P4pro+ screen but it is in a normal Android tablet. - That would also give the message.

I see three options, yet, how to intepret the result/validate the findings?
- 1. Compare landing spots by GPS home by aircraft or by controller. Yet, which one is correct?
- 2. Set GPS home by aircraft and shutdown the controller. Next compare landing spot to the ones obtained from option 1.
-3. Indoor I have no GPS. So, aircraft outside and controller indoors. Set GPS home to aircraft and go.

If your screen display tells you that the Phantom has sats and you are in Green - P-GPS mode, everything should be fine to fly.

You mentioned unstable flight and RTH location being a little off.
Was the Phantom continuing to drift and unable to hold position?
Or was it holding but wandering slightly?

RTH location is not usually precisely the same as launch point.
It's common for GPS to have an error of 1-2 metres and sometimes a little more.
How much error did you observe?

 

[P4P hannuz]

Without GPS, the Phantom is not capable of RTH.
It needs GPS to know where it is and compare that with the stored homepoint to work out how to return to there.

But that is all about GPS on the Phantom.
GPS in the controller is of no use except for follow-me flight and resetting the home point to the current location of the controller (used when flying from a moving boat or car etc).

Thx, clear

The only time I've seen a message about a Weak GPS Signal, it was referring to the GPS signal for the tablet - and "weak" really meant No Signal
Is there a reason that your controller would have had poor GPS conditions?
Were you under a roof or tree cover, close to a building that blocked the sky etc?
I don't know if it's possible to disable GPS in the P4pro+ screen but it is in a normal Android tablet. - That would also give the message.

Unbelievable, but by default the location provision in the built-in controller is set to off. That may explain a lot. Its raining now so I'll have to wait and see whats the impact. The built-in smart device controller is running Android 5.1.1. Updating is controlled by DJI.

I was in a wide open field with no buildings even remote.

If your screen display tells you that the Phantom has sats and you are in Green - P-GPS mode, everything should be fine to fly.

Will give it a shot when dry. Sat count is and remains low though. 6 - 11/12. Insufficient if you ask me to be accurate all the time. Yet, it may very well be due to the rain at present.

You mentioned unstable flight and RTH location being a little off.
Was the Phantom continuing to drift and unable to hold position?
Or was it holding but wandering slightly?

Both, drifting and wandering. Very likely to wind variations.

RTH location is not usually precisely the same as launch point.
It's common for GPS to have an error of 1-2 metres and sometimes a little more.
How much error did you observe?

Off by at least 6 meters, 18 yards.

Thx for getting back to me. I'm moving forward

 

[Meta4]

Sat count is and remains low though. 6 - 11/12. Insufficient if you ask me to be accurate all the time. Yet, it may very well be due to the rain at present.

You would have to have a substantial fraction of the sky blocked to have insufficient sats for safe flying.
If you have the horizon obscured by trees, buildings or hills the GPS count on the ground may be low but this would improve as your Phantom climbs.
Rain has no effect upon GPS.

Off by at least 6 meters, 18 yards.

Although it would be very uncommon that could still be within the variable error of GPS.
There's no need to let RTH do the landing.
You can cancel any time and resume control if you have control signal.
But try a few more times to see where it wants to land.
GPS either works or it doesn't - you don't get it half working.
If you want fancy, hi-tech landing accuracy, the P4 pro also has a feature called Precision Landing that uses optical technology to land within centimetres of the launch point (when the ground and light conditions allow).
You can read about this in the manual and enable it in the app settings.

 

[P4P hannuz]

Alright, first all thx for all the help. Appreciate it! My problem is solved.

Indeed, the number of sats increased on increasing height as it should. Further, hover was stable and smooth, and as it should be landing was excellent. All is now very, very similar to the Mavic.

Conclusion, by default the p4p LCD controller comes with location off. The message weak GPS is, hence, very misleading. One looks for the solution at the wrong places.Thx for pointing that out.

Finding the location on setting is a hassle, worse I can not find it anymore. Hope this helps others in their quest.

Happy flying everyone. Cheers hannuz