I have had a couple of times now the GO app crash in mid flight, both times the aircraft was close by and I just let it hover while I restarted the app, which started up ok and connected to the P4 where it left off. When it crashes it just says the app has stopped and needs to be restarted. However this is very disconcerting - what if the P4 wasn't close by and i couldn't see it, etc.?  My tablet is one of the newer Samsung Galaxy S2 9.5" and I bought it solely for flying the P4 so there is little else on it besides stock apps and the GO app. How can I ensure this doesn't happen again and has anyone else had this issue? thanks in advance..

There is a theory that these intermittent device crashes are caused by the RF signal bleeding into and causing havoc with the sensitive parts of the mobile device rather than the crashes being some kind of memory problem.  Some have tried placing RF blocking copper tape along the back of the devices in hopes of keeping out the bulk of the RF, being sure to keep the wifi antenna clear.  I did it to mine but haven't really used it enough to determine if the problem is solved.  Haven't had a crash since though.  It's been about a month.  

Mark The Droner Posted at 2017-7-4 08:36
There is a theory that these intermittent device crashes are caused by the RF signal bleeding into and causing havoc with the sensitive parts of the mobile device rather than the crashes being some kind of memory problem.  Some have tried placing RF blocking copper tape along the back of the devices in hopes of keeping out the bulk of the RF, being sure to keep the wifi antenna clear.  I did it to mine but haven't really used it enough to determine if the problem is solved.  Haven't had a crash since though.  It's been about a month.

is the devices wifi actually being used while connected to the radio via USB too?

if not, then the wifi and BT could be disabled while using it for flying.

When we say "crashed", I think we mean the app itself crashed and had to be reloaded or the device locked up completely and had to be rebooted.

Yes, it's possible the mobile device could refuse the connection with the RC because it's found another wifi it prefers.  So then you have to force it to go to the RC wifi by manually disconnecting from the other wifi and manually connecting to the RC wifi.  This happens to me sometimes when I fly out of wifi range.  But this wifi business isn't related to the P4 series since the P4 uses lightbridge.

I had one incident where there was two apps on my tablet, one of the upgrades installed a whole new app and the old version was separate, the new app could not connect to the aircraft for some reason, but if I manually closed it and opened up the old app it was fine. When I deleted both apps and redid the install I was ok.

Unless I am mistaken, I should be able to turn off the radio on the tablet completely with the P4, because like you said the P4 uses lightbridge  - correct?

And if the tablets radio is turned off, that should rule out RF interference in the app crash..

I use a Galaxy S2 8" with my P4.   I leave the tablet permanently in Aiplane mode, ie Wifi OFF.   The DJI Go 4 App crashes occasionallt, at random, in mid-flight, but taking the restart option always works (so far). Releasing the sticks means that the bird hovers serenely in place until the App restarts where it left off - generally less than ten seconds.   This has happened at up to a kilometer away, and recovers without dramas.  So long as there is line of sight for the radio signal between the drone and the RC, it should be OK.

The theory about RF bleed into the mobile device is unlikely to be prevented by copper foil. The USB cable connecting the RC to the device can make a wonderful pickup antenna and thus a path for the RF "feedback" to travel down.

If it is RF issues then looping the USB cable through some ferrite rings like the FPV'ers do may help then.

cameracollector Posted at 2017-7-4 19:30
If it is RF issues then looping the USB cable through some ferrite rings like the FPV'ers do may help then.

Ferrite rings, beads and collars can certainly be effective at HF frequencies (30Mhz and below) but whether they could be equally effective at 2.4 Ghz and above I wouldn't like to say.

Blériot53 Posted at 2017-7-5 12:07
Ferrite rings, beads and collars can certainly be effective at HF frequencies (30Mhz and below) but whether they could be equally effective at 2.4 Ghz and above I wouldn't like to say.

FPV guys use them at the > 2.4 Ghz all the time, they also use shielded cat6 cable for their connections too.

Blériot53 Posted at 2017-7-4 13:36
I use a Galaxy S2 8" with my P4.   I leave the tablet permanently in Aiplane mode, ie Wifi OFF.   The DJI Go 4 App crashes occasionallt, at random, in mid-flight, but taking the restart option always works (so far). Releasing the sticks means that the bird hovers serenely in place until the App restarts where it left off - generally less than ten seconds.   This has happened at up to a kilometer away, and recovers without dramas.  So long as there is line of sight for the radio signal between the drone and the RC, it should be OK.

Thanks for the advise. I've had the same problem with my Sony Z5c, app usually stop after 3-5 minutes. Today I put it in Airplanemode and flew for 20 minutes straight without any crash.

JanF Posted at 2017-7-30 06:11
Thanks for the advise. I've had the same problem with my Sony Z5c, app usually stop after 3-5 minutes. Today I put it in Airplanemode and flew for 20 minutes straight without any crash.

That's good news!   An improvement, no doubt?  I'm grounded today by heavy rain and winds.
Shall have to be patient for a while