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Nexus 7 and Signal Loss and battery health

jimmy johnson

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Hi guys,

New pilot here, first drone and first post. I got a Mavic and I love it so far. I am using a Nexus 7 wifi and I have been putting it and the phone in my pocket into airplane mode. I found out about Airdata UAV and uploaded my flight logs there. My main issue that was revealed is that I have lots of signal loss according to the Signal Map. It's green when it's really close but after it gets a little distance it goes all red and purple. I've never actually lost the RC signal on the controller as far as I can tell but I'm getting tons of these errors on every flight on Airdata.

I have several days to exchange the drone if the drone is defective in some way (and not deal with DJI support) but how can I test that? If the mobile device can't keep up (it doesn't have enough storage for video cache), I could try with my LG G3 but I don't think it's an approved device. Unfortunately I don't have anything else to test at the moment and I own no IOS devices.

One other issue I saw is the original battery indicates minor deviations. I have a second battery that reports 0 deviations that I just used the first time yesterday, but the original one shows these minor deviations in the 40's each time on cell 1 so I'm wondering if this cell is going to go bad even though it's had about 3 flights so far.


airdata_signal_loss1.png


airdata_signal_loss2.png


airdata_signal_loss3.png

battery_deviation.png
 
I wouldn't pay huge attention to that part of the airdata warnings to be honest. I get a ton of them and always a solid signal and video feed.
The angle of transmitter to drone is very critical, make sure you use the radar to keep it pointing directly at the mavic and also angle the antennas so the flat edges are aimed directly at it, not the top lobes or angled.
I also suspect the mavic antennas are more toward the rear - i always get weaker signals on airdata when the drone is coming back towards me rather than flying away from me.
 
Well I am glad to hear I am not the only one. I had a good video feed and tried to point the flats of the antenna towards the drone and did airplane mode. Everything worked as expected although the Nexus 7 is a bit sluggish with DJI Go 4 and has very limited storage even aftet deleting tons of crap. I guess I will see if the LG g3 can take it which has cloudy g3 android 5.0. DJI Go 4 installed without issue and it has a faster processor and more memory so I will test it out.

I wouldn't pay huge attention to that part of the airdata warnings to be honest. I get a ton of them and always a solid signal and video feed.
The angle of transmitter to drone is very critical, make sure you use the radar to keep it pointing directly at the mavic and also angle the antennas so the flat edges are aimed directly at it, not the top lobes or angled.
I also suspect the mavic antennas are more toward the rear - i always get weaker signals on airdata when the drone is coming back towards me rather than flying away from me.
 
Ive got no issue running on my Nexus 7 2013 LTE. Not finding it sluggish at all FWIW.
 
Ive got no issue running on my Nexus 7 2013 LTE. Not finding it sluggish at all FWIW.

Well by sluggish the video looks good but I have to wait like a second for a menu to pop up. Video cache fills up everytime too. Did you turn this off or anything else that might improve performance of the app? I am running Kitkat on my Nexus 2013 since it was peppier than the stock Lollipop it came with.
 
Something else is wrong, you shouldn't be seeing almost constant red warnings less than 500 feet away.
there could be any number of explanations why that area is problematic though - so does it do it in other locations?
 
Mine is running 6.0.1 (Marshmallow, the final release before the device went out of support).
I used to have a 2G video cache turned on with no issues although i have turned it off recently purely as i dont feel the need for it to record low res video on the tablet itself.
I do kill some rogue apps before loading DJI go though now - trip advisor and a few other select apps suck a LOT of resources.
 
I'm running Marshmallow 6.0.1 with rarely any problems. I clear the DJI Cache everytime before I Fly also in Airplane mode with all apps closed. I use the nexus dedicated to the Mavic. Very clean install. I also run CCcleaner before every flight.
 
Something else is wrong, you shouldn't be seeing almost constant red warnings less than 500 feet away.
there could be any number of explanations why that area is problematic though - so does it do it in other locations?

Ive flown to about 6,500ft distance and on reviewing the data could see nothing but red and purple on that map. Yet the flights were totally normal, no drop in video and the signals were still showing as full. I dont put much faith in the accuracy of the airdata map (or at least, real world effects of what it classes as poor).
 
I have flown three locations so far. The last one had more orange and green but the distance was not far at all. I did get reds when it was directly over my head. Maybe flew 200 ft away and there were even more houses and stuff around. At this location in the picture it was in a park in a big rocky field. Nearest building was a library parking lot. I would expect less interference here than the other location.

Controls and video have been responsive but I did see interference warnings occasionally like in the notification picture.
 
My first flight also had purples and reds everywhere at a different park. But my devices were not in airplane mode and were tethered so I guessed it might be that. This flight was airplane mode in a deserted rocky field.

I will take it on another test flight in a farm today. Is it possible to do a more real world signal loss test? Maybe push it out real far and see if it RTH? How far would be a good test?

I have flown three locations so far. The last one had more orange and green but the distance was not far at all. I did get reds when it was directly over my head. Maybe flew 200 ft away and there were even more houses and stuff around. At this location in the picture it was in a park in a big rocky field. Nearest building was a library parking lot. I would expect less interference here than the other location.

Controls and video have been responsive but I did see interference warnings occasionally like in the notification picture.
 
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Directly overhead is going to produce a weaker signal unless you hold the RC completely parallel to the ground and allow the flat edge of the antennae to beam straight up.
 
Right, after the first flight I learned about that and I try to point the flats at the Mavic. If I truly have bad signal loss, at what distance do you think it will go before the controller drops it?

Also, what do you think about the battery deviation on the one cell on my original battery? The second battery had zero deviations.

Directly overhead is going to produce a weaker signal unless you hold the RC completely parallel to the ground and allow the flat edge of the antennae to beam straight up.
 
Personally i think you're over analysing the logs. Its an electronic piece of equipment, there will always been variability between individual samples and its a mistake to apply a one size fits all set of data points to them.
Ultimately, the drone is working, you've had no signal loss, the RC or app havent shown any weak or drop in signal (other than directly above which is normal), the battery deviation is low. So i'd say its working fine.
 
Copy, just want to make sure I have a good drone and this is all normal. Based on your post and others I've seen, it appears that some Android devices have this "signal loss" data for some reason.

Personally i think you're over analysing the logs. Its an electronic piece of equipment, there will always been variability between individual samples and its a mistake to apply a one size fits all set of data points to them.
Ultimately, the drone is working, you've had no signal loss, the RC or app havent shown any weak or drop in signal (other than directly above which is normal), the battery deviation is low. So i'd say its working fine.
 
I suspect its more the arbitrary bands airdata assigns the error rate rather than the android device or app.
Its easy to drown in data and forget the real world exists.
 
Thought I'd report in. I tested with the LG G3 and had much better results on the signal data on the first flight I did today. Mostly green and a little orange. On the second fight, I forgot to put it into airplane mode so both cellular and wifi were on and caused purple lines everywhere but it still caused no issues in flight. I pretty much get the "Strong interference" warnings on every flight, even the green ones so I don't know what that is all about.

I think it's a combination of wifi interference and processing power that may be the cause of these variations in this signal data. I flew the drone over 1800 ft away around a rural community and it did great with no signal loss. It was very nice. :)
 
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