Hey guys, in those days i have had a problem with litchi that concern the return to home.
When i try to return to home with my Phantom 4 pro with litchi in waypoint mode, with the RC button ( i don't know any other method to rth in waypoints mode, if you know other methos, please tell me) the drone goes "crazy": It starts to raise up and then starts to fly in the right direction but suddenly stops "violently" ( the drone shake), then again It starts to raise up again (to higher altitude) and starts again to fly and to stop violently. I have to take the commands personally or It Will continue to reach higher altitude. What problem It could be? Is there a solution? Please help me. Thank you.

PS: another Little question (i use an iPad). When i fly i have to shut down the iPad GPS or this is not a problem? Thank you

Are you moving the function switch on your RC off of the "F" mode and onto "Atti" or "P" mode. That has to happen to first exit a waypoint mission. I don't know why else it would be have that way.

One possible explanation might be that obstacle avoidance is detecting and trying to fly over an obstacle.
Was the RTH path toward a low, bright sun?

You can leave the iPad GPS on or turn it off, it won't make any difference.

I hear often about GPS in phones and pads, should it be on? Should it be off? Let us put paid to this confusion and examine some facts.

Your iPhone or iPad does not have a satellite finding GPS system. Lets look at some simple facts and see how your pad or telephone works out its location.

Every iPad ever made has both WiFi and Bluetooth, two wireless technologies for connecting to nearby devices (in the case of Bluetooth) and the internet (in the case of WiFi). The only additional option is to add a cellular module, originally called 3G and now called LTE for the latest models. This cellular option allows the iPad to connect to the internet anywhere your cell phone works.

In addition to the cellular radio, the 3G/LTE models of the iPad also have a built-in location receiver. Apple calls this “assisted GPS,” which is probably where the confusion comes in. By assisted GPS, Apple means that the GPS receiver in the iPad can use nearby cell towers (fixed antennae stations) to provide a faster position lock (what engineers call “time to first fix”). Instead of starting up cold and searching for satellites, which can take up to a few minutes in some cases, the iPad knows right where to look. With a hot start like this, your iPad can find its location in just seconds.

The DJI aircraft (ac) is responsible for finding satellites and determining an accurate GPS position.  The ac sends its position at 0.1 second intervals to the controller where it is used to set the home point, to calculate such things as distance and speed and navigate a predetermined plan if required. The “flight log” is used to store this and much more information about the flight. The ac knows where it is and what it is doing better than most pilots. That is how the ac can still find its way home even if you “Semtex” your controller, phone and pad during a flight.

Your pad or mobile telephone can be used in any mode you wish. It is advisable to put phones into “flight” mode to stop interrupts from incoming calls, messages, emails etc. A pad with cellular capability or connected to a WIFI during flight will have the advantage of supplying a map during the flight but will not compromise ac navigation. If you want a map but have no cellular capability you can cache this at home with WIFI available. An alternative in the field is to use your cellular phone as a “hot spot”.

Dockater Posted at 2017-11-16 18:14
I hear often about GPS in phones and pads, should it be on? Should it be off? Let us put paid to this confusion and examine some facts.

Your iPhone or iPad does not have a satellite finding GPS system. Lets look at some simple facts and see how your pad or telephone works out its location.

Your iPhone or iPad does not have a satellite finding GPS system. Lets look at some simple facts

Here are some real facts
iPhones do have a GPS receiver.
Wifi only ipads don't have GPS but cellular iPads do have GPS.

Does the same issue appear if changed to DJI GO 4?

Labroides Posted at 2017-11-16 16:29
One possible explanation might be that obstacle avoidance is detecting and trying to fly over an obstacle.
Was the RTH path toward a low, bright sun?

It seems you are correct. When i used dji go 4 to try the rth the sensors told that the drone was seeing obstacles. But how Can the sun make the drone thinks there are obstacles?

DJI Susan Posted at 2017-11-16 20:11
Does the same issue appear if changed to DJI GO 4?

Yes. But i don't know why It happens

andrea–passa Posted at 2017-11-17 00:22
It seems you are correct. When i used dji go 4 to try the rth the sensors told that the drone was seeing obstacles. But how Can the sun make the drone thinks there are obstacles?

The OA system can be fooled by the sun and think it is the obstacle.

Labroides Posted at 2017-11-16 19:33
Your iPhone or iPad does not have a satellite finding GPS system. Lets look at some simple facts

Here are some real facts

Ok some more facts:

I WAS WRONG, and apologize for that.

Since the iPhone 3S, iPhones have a satellite based GPS and so do iPads with a cellular module. They also have and use an A-GPS capability, which lets the GPS receiver determine its basic current location much faster than normal. Even if there is no cellular telephone reception it is still possible the use the GPS capability with the appropriate software.

It remains true to say that the GPS capability of the phone or pad does not have to be switched on or off when using DJI products. Or correct me someone please.

andrea–passa Posted at 2017-11-17 00:24
Yes. But i don't know why It happens

The OA will not work well when flying toward the sunshine. Please change the aircraft direction if the similar issue occurs.

DJI Susan Posted at 2017-11-21 03:41
The OA will not work well when flying toward the sunshine. Please change the aircraft direction if the similar issue occurs.

Just for the information, it does not need to be directed toward the sun, i have seen all sort of directions even with the sun above where the craft did a complete stop due to the light. GuessP4P is more sensitive due to the extra sensors.
Here a few shots where it did nothing but show up on the rardar, sometimes it would go to a complete stop until moved slightly in another direction, distance on the rardar change with angle of the light.

Labroides Posted at 2017-11-17 00:34
The OA system can be fooled by the sun and think it is the obstacle.

Yup this has happened to me many times, just turn the quad away from the sun and it flies normal agin