GPS failure-what happens to Radar display?

[davideo0]

In the event of a failure of the GPS navigation system on the Phantom 4 pro, I understand that reversion to ATTI mode will follow, but can anyone confirm that this also means the loss of the useful Radar display.

The relative direction information provided by the Radar display is a very useful facility to have when at a distance and in ATTI mode. It occurred to me that providing one of the two compasses was working, perhaps the Radar display would still give useful directional information.

Can anyone who has suffered a GPS failure confirm what happens to the Radar display?

Would the situation change if the GPS failure was as a result of loss of both compasses?

Perhaps one of the technical gurus amongst you could enlighten me?

 

[Alan-G]

Try setting your bird up indoors,(No props) probably no GPS either. check results.
good luck.

 

[davideo0]

Try setting your bird up indoors,(No props) probably no GPS either. check results.
good luck.

When I get home, I will certainly try that but I know that I usually manage to get some satellites even indoors.
So others experience would be great to hear.

 

[GavinW]

The most satellites I've ever gotten indoors was 4, which simply isn't enough to fly. I believe you need 9 to fly?

 

[KevMo Photog]

In the event of a failure of the GPS navigation system on the Phantom 4 pro, I understand that reversion to ATTI mode will follow, but can anyone confirm that this also means the loss of the useful Radar display.

The relative direction information provided by the Radar display is a very useful facility to have when at a distance and in ATTI mode. It occurred to me that providing one of the two compasses was working, perhaps the Radar display would still give useful directional information.

Can anyone who has suffered a GPS failure confirm what happens to the Radar display?

Would the situation change if the GPS failure was as a result of loss of both compasses?

Perhaps one of the technical gurus amongst you could enlighten me?

Your asking if you still have your bird and the green line to home being recorded right? And I would say that no it is not being updated if you lose GPS. Never happened to me yet on a DJI bird. Been flying 3 of their birds for over a year now.

 

[davideo0]

Your asking if you still have your bird and the green line to home being recorded right? And I would say that no it is not being updated if you lose GPS. Never happened to me yet on a DJI bird. Been flying 3 of their birds for over a year now.

The most satellites I've ever gotten indoors was 4, which simply isn't enough to fly. I believe you need 9 to fly?

Thank you both for your input.
I finally managed to do what Alan-G suggested and set the bird up indoors. The satellite count varied from 0 to 6.
During the time when gps was not available the Radar display remained visible and the red aeroplane indicated the relative bearing correctly both with regard to R/C and the north indication. What I can't tell, since there had been no flight, was whether the yellow track line would remain after a real GPS failure and whether if so it would be useful to return, ATTI mode, to home.
So it does seem that the Radar display remains after a failure in some circumstances.
But I don't believe this test to be definitive.
It would be great if someone who has had this type of failure could confirm or deny the above.

 

[smiller]

If you are indoors the vision system will be used for horizontal positioning and IMU and barometric pressure will be used for vertical and it works quite well, you don't really need GPS.

 

[KevMo Photog]

If you are indoors the vision system will be used for horizontal positioning and IMU and barometric pressure will be used for vertical and it works quite well, you don't really need GPS.

He's talking about if it happens in flight so he can rely on that radar flight line still being there to return home by smiller.

 

[smiller]

He's talking about if it happens in flight so he can rely on that radar flight line still being there to return home by smiller.

Ah, sorry, guess I read through it too fast.

 

[kndll]

I believe the radar works off of the compass only , not gps , so as long as the compass doesn't fail the radar will still guide you home .

 

[N017RW]

Correct.
GPS cannot provide heading. That is the domain of the magnetometer.

Remember, Heading (the direction of forward) and Course (your 2-dimensional path above the Earth) are two distinct things.

This is due to your a/c operating in a fluid.

You can be pointed North but heading South due to wind, for example.

Same as a boat on the water... you can be pointed one way yet moving another.

 

[KevMo Photog]

Correct.
GPS cannot provide heading. That is the domain of the magnetometer.

Remember, Heading (the direction of forward) and Course (your 2-dimensional path above the Earth) are two distinct things.

This is due to your a/c operating in a fluid.

You can be pointed North but heading South due to wind, for example.

Same as a boat on the water... you can be pointed one way yet moving another.

So if GPS disconnects then the bird in our radar will still point in a correct direction but may be actually moving in another? I get that. So we should be able to point bird at green line and get back to us right? Without GPS? Or does the green line go away if GPS disconnects? So what is your protocol for you if your bird was to ever lose GPS and you were slightly out of sight I guess is the bottom line. I fly Atti quite often btw so no prob on that.

 

[kndll]

not sure about the green line , but use the radar , turn the aircraft on the radar so it's pointing at the center , you are standing in the center of the radar circle

 

[KevMo Photog]

not sure about the green line , but use the radar , turn the aircraft on the radar so it's pointing at the center , you are standing in the center of the radar circle

So would it possibly require zooming out farther on map to see the home circle if you were out far enough to be out of view of home point on map?

 

[kndll]

your original question is about gps failure , I don't think the map would be of any help if gps failed , but the radar would still work because it uses the compass

 

[davideo0]

I believe the radar works off of the compass only , not gps , so as long as the compass doesn't fail the radar will still guide you home .

Thanks kndll, hopefully then Radar will remain to assist with RTH.

 

[KevMo Photog]

your original question is about gps failure , I don't think the map would be of any help if gps failed , but the radar would still work because it uses the compass

Isn't the radar the same thing and is overlaid over your map?

 

[davideo0]

Correct.
GPS cannot provide heading. That is the domain of the magnetometer.

Remember, Heading (the direction of forward) and Course (your 2-dimensional path above the Earth) are two distinct things.

This is due to your a/c operating in a fluid.

You can be pointed North but heading South due to wind, for example.

Same as a boat on the water... you can be pointed one way yet moving another.

In other words, apply the triangle of velocities or, if you prefer, ALLOW FOR DRIFT!

 

[Meta4]

In the event of a failure of the GPS navigation system on the Phantom 4 pro, ....

How often do you anticipate losing GPS outdoors?
It's a hypothetical situation that you shouldn't encounter unless you fly into a canyon or under tree canopy or have an extremely rare hardware failure.

 

[kndll]

Isn't the radar the same thing and is overlaid over your map?

radar and map are separate , radar in lower left corner