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GO app lost connection in flight, would not reconnect - why?
2140 12 2017-8-4
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cameracollector
Second Officer
Flight distance : 807133 ft
Canada
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After a few dozen or so flights, for the first time I had an issue that really gave me a scare.  I was flying over a farm field the other day, getting some low proximity shots, in an area I have flown in before with no issues.  I flew about 600 meters out about 4' - 5' above ground level, stopped, did a 45 degree turn and another 600 or so meters out. At the time I was about 800 meters from home point. I was stopped and was just hovering when the GO app started warning about bad signal, I was behind a thin row of trees so I walked out to where I'd be LOS and also gave it some throttle to gain altitude because I wanted to get a few high still shots anyway.

Well, then the GO app just lost connection altogether, screen faded and it would not reconnect no matter what. I was in plain LOS by then but I could not see the P4 as it was too far away. I knew it was in the clear so I shut down the app and restarted it a couple of times, but it would not reconnect.  Starting to sweat a bit I hit the RTH button a couple of times, and started to prepare myself for a long walk as I could not hear it returning.  Well, after a (very long) minute or two I finally heard it and it was coming back. The app was still greyed out and disconnected, and the P4 just kept going past the home point so I tried the sticks and was able to stop it. if I let go of the sticks it wanted to keep going past me, but I could still control it so I brought it down. I had to be quite agressive with the sticks to bring it down too, it seemed to be flying quite erratically.  I believe at the time the app was also displaying an interference warning of some sort too, but I was concentrating on just getting it on the ground to notice exactly what it said.   

I powered it down, cycled the power on my S2 tablet, started the app again and powered up the P4 - everything was back to normal. Did a couple of short flights to use up the rest of the battery with no other incidents.

Never had this happen before - I've had the app crash a time or two in mid flight, but usually just stop and hover, restart the app and it reconnects. As an aside, since I put the tablet in airplane mode I've also not had the app crash again.

Now I'm scared to fly to far away after that, but I'm wondering if there was radio interference in that particular area. There are some oil pump jacks and well sites in the area and I'm wondering if one of them was transmitting on the same frequency or something.

I was hoping the camera kept recording, but I stopped recording just as I hit the area where it lost contact - also when the bird came back the camera/gimbal was hanging at an angle like it wasn't even powered on, which I thought was a little strange.

Would there be any logs that would show what might have happened?  I'm real curious as to what may have caused this.

My app is at 4.0.5 and the RC is 1.8.0.  Not sure what the P4 firmware is but probably the last one before the update everyone is complaining about having to log in all the time.


2017-8-4
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Geebax
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Australia
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'Starting to sweat a bit I hit the RTH button a couple of times, and started to prepare myself for a long walk as I could not hear it returning.'

Not a good idea to 'hit the RTH button a couple of times', because one press engages RTH, and the next press cancels it. Best thing if you cannot see the aircraft is to switch off the RC unit, which will engage RTH, wait a few minutes and when you hear the aircraft, switch it back on again and prepare to take control.

Regarding the logs, go to Phatomhelp and follow the insteuctions to upload your flight data, then come back here and post a link to the results: http://www.phantomhelp.com/LogViewer/Upload/
2017-8-4
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DJI Thor
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Flight distance : 13602 ft
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If you could still control the RC in this case, then it was the connection between RC and app failed. Had you noticed about the prompt of the app when it disconnected to your RC? Some cases like transmission signal lost, RC signal weak, poor contact between RC and mobile device etc. would contribute app's disconnection. Please try to relaunch the app or extract the connecting cable and plug it in quickly if it is during flight to see if it could regain the connection. You can also try to reinstall the app, don't forget to backup important files and records first.
2017-8-5
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cameracollector
Second Officer
Flight distance : 807133 ft
Canada
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I got an RC signal weak error just before the disconnect, so I gave it some altitude immediately to improve the LOS but it didn't work. Also stopped the app several times and unplugged the USB cable like you suggested, but neither worked.

I'd reinstall the app but I don't want the newest version that forces me to log on & that everyone is complaining about.
2017-8-6
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Dobmatt
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Flight distance : 1831050 ft
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cameracollector Posted at 2017-8-6 08:54
I got an RC signal weak error just before the disconnect, so I gave it some altitude immediately to improve the LOS but it didn't work. Also stopped the app several times and unplugged the USB cable like you suggested, but neither worked.

I'd reinstall the app but I don't want the newest version that forces me to log on & that everyone is complaining about.

If you set RTH accordingly when connection is lost or Go app is not responding, than she will, no matter what. No panic, no sweat, just push and hold RTH button for few seconds and wait ... It's almost like a cow coming back at twilight from pasture ...
2017-8-6
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cameracollector
Second Officer
Flight distance : 807133 ft
Canada
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Geebax Posted at 2017-8-4 22:32
'Starting to sweat a bit I hit the RTH button a couple of times, and started to prepare myself for a long walk as I could not hear it returning.'

Not a good idea to 'hit the RTH button a couple of times', because one press engages RTH, and the next press cancels it. Best thing if you cannot see the aircraft is to switch off the RC unit, which will engage RTH, wait a few minutes and when you hear the aircraft, switch it back on again and prepare to take control.

uploaded the flight log, results are here: http://www.phantomhelp.com/LogViewer/YYVTUR3FT9OJTGN5E6CX/

the log ends where I lost connection, it does not include the RTH flight. I see a few "downlink restored" messages which is from when the trouble first started I assume.
2017-8-8
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Punchbuggy
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Flight distance : 483166 ft
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Dobmatt Posted at 2017-8-6 10:38
If you set RTH accordingly when connection is lost or Go app is not responding, than she will, no matter what. No panic, no sweat, just push and hold RTH button for few seconds and wait ... It's almost like a cow coming back at twilight from pasture ...

Hi Dobmatt. I have to say that's not true. Sure, in almost all such cases loss of contact will result in the set action kicking in, but I've experienced myself an identical scenario as described.

While still in LOS, connection was interrupted and it just hovered, even though 'lost connection' was set for RTH. My first thought was that I'd just walk the few hundred metres to where it was (and about 40m off the ground), and wait for it to auto-land on low battery. But then after about 30 sec it decided to respond to a manual RTH, and started to return. I took control and landed it, and then took it up again. I have only experienced that once with my P4 in all the time I've flown it. It's initially quite scary when something doesn't work to spec. BTW, the P4 was running the beta then - v2.00.012 - and my P4P was flying around in the same area (on it's latest firmware) and didn't have an equivalent episode.

Otherwise, the limp gimbal condition described is an issue reported by many, but after power cycling the craft typically doesn't reoccur. On the upside for the op, both issues appear to be rare.
2017-8-8
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Geebax
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Australia
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Punchbuggy Posted at 2017-8-8 18:22
Hi Dobmatt. I have to say that's not true. Sure, in almost all such cases loss of contact will result in the set action kicking in, but I've experienced myself an identical scenario as described.

While still in LOS, connection was interrupted and it just hovered, even though 'lost connection' was set for RTH. My first thought was that I'd just walk the few hundred metres to where it was (and about 40m off the ground), and wait for it to auto-land on low battery. But then after about 30 sec it decided to respond to a manual RTH, and started to return. I took control and landed it, and then took it up again. I have only experienced that once with my P4 in all the time I've flown it. It's initially quite scary when something doesn't work to spec. BTW, the P4 was running the beta then - v2.00.012 - and my P4P was flying around in the same area (on it's latest firmware) and didn't have an equivalent episode.

'While still in LOS, connection was interrupted and it just hovered, even though 'lost connection' was set for RTH. My first thought was that I'd just walk the few hundred metres to where it was (and about 40m off the ground), and wait for it to auto-land on low battery. But then after about 30 sec it decided to respond to a manual RTH, and started to return.'

That is correct behaviour on the part of the aircraft. When it lost connection with you, it was probably loss of the return link, not loss of the control link, so it simply hovered in the one spot waiting for you to tell it what to do. Hence the reason it responded to an RTH command.
2017-8-8
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Punchbuggy
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Geebax Posted at 2017-8-8 21:53
'While still in LOS, connection was interrupted and it just hovered, even though 'lost connection' was set for RTH. My first thought was that I'd just walk the few hundred metres to where it was (and about 40m off the ground), and wait for it to auto-land on low battery. But then after about 30 sec it decided to respond to a manual RTH, and started to return.'

That is correct behaviour on the part of the aircraft. When it lost connection with you, it was probably loss of the return link, not loss of the control link, so it simply hovered in the one spot waiting for you to tell it what to do. Hence the reason it responded to an RTH command.

OK, G. But it's all still via 2.4Ghz. I'm surprised to hear that one direction of the same signal path can be momentarily affected, but not the other. Unless you're suggesting that the transmitter on the P4 itself decided to momentarily stop working?
2017-8-8
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Geebax
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Australia
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Punchbuggy Posted at 2017-8-8 23:12
OK, G. But it's all still via 2.4Ghz. I'm surprised to hear that one direction of the same signal path can be momentarily affected, but not the other. Unless you're suggesting that the transmitter on the P4 itself decided to momentarily stop working?

No, not at all. But it is not one direction of the same signal path, it is two completely different transmission channels. And because of this, it is quite normal for one channel to drop out while the other is still working. And for some reason, it is normally the return video channel that gives out before the contol channel. Radio propagation is a very complex subject, but suffice to say that two seperate radio transmission systems next to each other do not always behave the same way. A few centimetres difference of position can mean full strength on one channel and none on the other.
2017-8-9
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Punchbuggy
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Geebax Posted at 2017-8-9 02:12
No, not at all. But it is not one direction of the same signal path, it is two completely different transmission channels. And because of this, it is quite normal for one channel to drop out while the other is still working. And for some reason, it is normally the return video channel that gives out before the contol channel. Radio propagation is a very complex subject, but suffice to say that two seperate radio transmission systems next to each other do not always behave the same way. A few centimetres difference of position can mean full strength on one channel and none on the other.

OK, cool. Thanks for explaining, G.
2017-8-9
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Labroides
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if I let go of the sticks it wanted to keep going past me, but I could still control it so I brought it down. I had to be quite agressive with the sticks to bring it down too, it seemed to be flying quite erratically.
Your Phantom was attempting to RTH and you were fighting it.
If you had cancelled the RTH by touching the RTH button, you would have had full control with no problems.
A little practice with initiating RTH, cancelling and resuming control would be a good think to get a better idea of how it works.
And try switching off the controller too to see how that initiates RTH.
It looks like you have plenty of open space to work with.
2017-8-9
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cameracollector
Second Officer
Flight distance : 807133 ft
Canada
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So I took the P4 out for another flight last night, and when I powered up the radio, tablet & aircraft, the GO 4 app came up but would not connect, no matter what it seemed. I restarted the GO app several times, even restarted the Samsung tablet but still no connection. Then I shutdown the radio and P4, closed the app again and powered everything up - again it came up disconnected, but this time after a few minutes it finally connected.  I flew the battery out, going out about 800 meters a couple of times with no issues, even flew down some railroad tracks behind tree covers and no lost connection.

This is strange behavior, with the last two flights having connection issues.  This time when the app would not connect to the P4 (it did say it was connected to the radio) I noticed I still had control of the aircraft, and the gimbal wasn't hanging loose.

I'm a little nervous about this, not wanting another disconnect when the P4 is a long ways away or out of sight.  I put in a ticket to DJI about it and their recommendation, as expected was update the app - which I'm reluctant to do because of all the issues I've been reading about.  I may just have to do it though..
2017-8-15
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