MP Signal Lost - and Recovered by Controller Power Cycle

[Gryphon962]

Well I knew it was only a matter of time before I'd be posting about some incident, but fortunately this one ended well.

I'm at my usual flying site, using Litchi, making sure I understand how Focus mode works. After a quick fly around, over the HP I set the MP heading where I want it, engage Focus, select 'Aircraft Heading' as the option, and push right stick forward to send it out on that course while retaining focus on a palm tree off to left of track that I had set as the POI.

All went fine for 20 secs or so then I get 'Signal Lost' on the Litchi app, but the RC still says 'Joystick'. MP has stopped and is hovering about 100 yards away from me and the HP. So ok, no panic, its not going anywhere, and the HP is set, and visible in the map view. I try to control the MP as the RC still says Joystick, but it doesnt move.

First question: my setup for loss of signal is RTH, but it just sat in hover. So it seems both the MP and the RC think the link is there, but Litchi thinks not. And the MP doesnt respond to controls. Any idea what is going on at this point?

My subsequent actions were as follows:

1. Close Litchi, reopen. No change.
2. Power down the RC, power it on, reconnect the phone with Litchi - NOW it tells me its returning home on both - and I can see the MP climbing up to execute a RTH.
3. End of problem.

So I power everything down and restart it all, including new battery. For rest of session I have no problems at all.

(When the forum lets me I will ) attach the Litchi csvs for the flight up to the 'signal loss' and the recovery after the loss. I cant see anything in the first indicating a problem until it suddenly ends in mid air.

The second log starts in mid air, in RTH mode, and apart from a lag until some telemetry comes through (battery) its all fine.

Second question: anyone have any idea what lost connection to what, and did I do the right things?

First part of flight

Second part of flight

(for some reason I cant attach the Litchi csv files... what should I upload instead?)

 

[brett8883]

Well I knew it was only a matter of time before I'd be posting about some incident, but fortunately this one ended well.

I'm at my usual flying site, using Litchi, making sure I understand how Focus mode works. After a quick fly around, over the HP I set the MP heading where I want it, engage Focus, select 'Aircraft Heading' as the option, and push right stick forward to send it out on that course while retaining focus on a palm tree off to left of track that I had set as the POI.

All went fine for 20 secs or so then I get 'Signal Lost' on the Litchi app, but the RC still says 'Joystick'. MP has stopped and is hovering about 100 yards away from me and the HP. So ok, no panic, its not going anywhere, and the HP is set, and visible in the map view. I try to control the MP as the RC still says Joystick, but it doesnt move.

First question: my setup for loss of signal is RTH, but it just sat in hover. So it seems both the MP and the RC think the link is there, but Litchi thinks not. And the MP doesnt respond to controls. Any idea what is going on at this point?

My subsequent actions were as follows:

1. Close Litchi, reopen. No change.
2. Power down the RC, power it on, reconnect the phone with Litchi - NOW it tells me its returning home on both - and I can see the MP climbing up to execute a RTH.
3. End of problem.

So I power everything down and restart it all, including new battery. For rest of session I have no problems at all.

(When the forum lets me I will ) attach the Litchi csvs for the flight up to the 'signal loss' and the recovery after the loss. I cant see anything in the first indicating a problem until it suddenly ends in mid air.

The second log starts in mid air, in RTH mode, and apart from a lag until some telemetry comes through (battery) its all fine.

Second question: anyone have any idea what lost connection to what, and did I do the right things?

First part of flight

Second part of flight

(for some reason I cant attach the Litchi csv files... what should I upload instead?)

Without having gone through the log throughly I can tell you there is kinda a known bug that if the drone is in joystick mode and the device is suddenly discontented the drone can sometimes remain in joystick mode. In this situation you would want to switch to sport mode to regain manual control you could have also hit the RTH on the remote.

Power cycling did the trick here because it knocks it out of joystick mode and into RTH but with sport mode you don’t lose connection so I’d prefer that or your good old friend the panic button aka RTH.

If you ever have an issue with anything first thing to try is switch to sport mode then if that doesn’t work RTH.

It sounds like to me the app disconnected so I’d maybe check try a different cable or make sure it’s fully pulled in.

 

[Gryphon962]

...

If you ever have an issue with anything first thing to try is switch to sport mode then if that doesn’t work RTH.

It sounds like to me the app disconnected so I’d maybe check try a different cable or make sure it’s fully pulled in.

Good advice; I didn't think of going to Sport mode, wish I had given that a try. I recall pressing 'Pause' but that had no effect. I didnt try RTH manually.

The interesting thing about this one is the app was saying Signal Lost rather than Disconnected, while the RC was saying 'Joystick'. Puzzling...

I've also realized that the Litchi csv doesn't seem to include the info you'd get in a DAT file, so there is no list of events going on inside the operating system, which might have been useful in this case. Does anyone know how to get DAT like info out of Litchi?

 

[Gryphon962]

AND...today it happened again, 799 secs into a flight today. Fortunately it was in hover about 50 feet away. Again, the app said 'signal lost', but RC looked fine, so this time I went to S immediately and had full control. So I flew it back to my HP and did some experiments to try and find the issue:

• Restarting Litchi changed nothing
• Disconnecting phone, closing Litchi, and then reconnecting and restarting Litchi also did nothing
• I had to restart the RC to get Litchi to reconnect to the drone

I changed battery, rebooted everything, and flew a final flight with no issues.

The csv from Litchi is posted here and says 'Downlink lost' in the last row at time 799.

Using DJI Assistant 2, I pulled the logs off the drone itself, used Extract DJI and CSVView, and as far as I can tell, the drone's log shows a complete sortie with no signal loss. I am having trouble posting the csv from the drone - what should I set the sample rate to in DatCon to enable me to upload it (the full file is 300MB)...?

The full event log from the drone's DAT shows nothing happening at or around the 799 second point (it shows me going to S mode at 808 seconds). Puzzled...

 

[brett8883]

AND...today it happened again, 799 secs into a flight today. Fortunately it was in hover about 50 feet away. Again, the app said 'signal lost', but RC looked fine, so this time I went to S immediately and had full control. So I flew it back to my HP and did some experiments to try and find the issue:

• Restarting Litchi changed nothing
• Disconnecting phone, closing Litchi, and then reconnecting and restarting Litchi also did nothing
• I had to restart the RC to get Litchi to reconnect to the drone

I changed battery, rebooted everything, and flew a final flight with no issues.

The csv from Litchi is posted here and says 'Downlink lost' in the last row at time 799.

Using DJI Assistant 2, I pulled the logs off the drone itself, used Extract DJI and CSVView, and as far as I can tell, the drone's log shows a complete sortie with no signal loss. I am having trouble posting the csv from the drone - what should I set the sample rate to in DatCon to enable me to upload it (the full file is 300MB)...?

The full event log from the drone's DAT shows nothing happening at or around the 799 second point (it shows me going to S mode at 808 seconds). Puzzled...

Glad the S mode suggesting worked well! You can upload the dat file by posting it in a google drive or Dropbox folder thing and then sharing the link.

You can also upload it to DJI Flight Log Viewer | Phantom Help

And then share the link to the page with the analysis by posting the link directly into the forum.

From what you said though it sounds like a common case of the device losing connection with the remote. Try a new cable.

 

[Gryphon962]

I almost agree; but the app is giving 'Signal Lost' not 'Disconnected' - which is odd when the drone is 50 feet away, and the RC seems to be connected still.

If I disco and reconnect the phone (as I did a bit later in the flight) you get 'App Lost' events in the logbut that didnt happen at 799 secs (the signal loss).

Aircraft DAT file is here

Litchi csv is here

 

[Gryphon962]

Update: I think that the two occasions where I've had this 'signal lost' error have been the only 2 occasions where I have flown with Litchi without turning Airplane mode on.

So I guess I better be religious about turning Airplane mode on, and see if it ever happens again........

 

[brett8883]

Update: I think that the two occasions where I've had this 'signal lost' error have been the only 2 occasions where I have flown with Litchi without turning Airplane mode on.

So I guess I better be religious about turning Airplane mode on, and see if it ever happens again........

What device are you using?

 

[Gryphon962]

What device are you using?

Nokia 6.1. Has AndroidOne, so no bloatware, 3GB RAM, and a Snapdragon 630 processor. Its not a flapship phone by any means, but its better than all the tablets I've looked at replacing it with.

 

[royster]

I tell you I had expierenced the issues you have summarized.
When I switched to a tablet that came highly recommended, the Acer Iconia, an 8" tablet that was on for 100 odd dollars, all my issues are in the past.
Seems it must be the Iconia with the Med Tek processor. Was it a coincidence that I have had not a single drop out, or loss of signal since using the Acer? I don't know but, for the last 7-8 months, Litchi has been my go to App & I have not had one single issue.