Phantom twitching at long distance

Dmitry Duka · Nov 29, 2015

Hello everyone,

Yesterday I had a flight with my Phantom 1 and I noticed that whenever I get quite a bit far away (> 400 meters I would say) the phantom twitches a little bit. It's easier to just look at it yourself -

That's GPS mode only

The twitching I'm talking about is at 4:58, 5:05 and 5:08 marks. The distance that the phantom was from me was about 550-600 meters. I didn't ever notice this issue while flying in close range, let's say closer than 200 meters.

I heard there are twitching issues with gimbals (I've got HS-2D), but I think it's quite clear that this is phantom twitching, not gymbal. I didn't shake my right stick at all, just steady push to move forward. I'm quite sure that it's not a wind gust too, because it also happened today, again at a distance of about 500 meters in a calm weather. So it never happens nearby, but sometimes happens far away.

My current theory is that phantom receiver loses control signal for a moment and just counts current pitch (in this case pitch, but it could be yaw or roll too, I guess) value as 0, but after a moment receives a correct value. I hope NAZA wouldn't zero out a throttle channel, in case it's not receving anything.

My gear info that might be relevant:
Phantom 1
HS-2D + Gopro 3+ Black
TS832 5.8G transmitter
miniOSD
DJI transmitter, I guess one of earlier revisions with throttle stick without a spring (so it stays wherever I left it)

Does anybody have any ideas why is that twitching happening and if I could fix it (apart from not flying longer than 300 meters from me)?

Thanks!

Pilot_FML · Nov 29, 2015

Definitely an odd sporadic behavior...

Does it occur on different batteries?

Almost looks like an intermittent change/loss in power.

Could also be some sort intermittent connection occurring... has any work been done on the quad recently?

Dmitry Duka · Nov 29, 2015

Thanks for your answer. I've got 3 new turnigy 2200mAh baterries and 2 stock dji with the same capacity. I didn't ever try flying that far on dji batteries (I've got them second hand, so they aren't fresh), so I can't be sure it's not battery, however I get quite strong impression that this is related to distance, not battery. Also on the video posted above, I don't think this twitching is related to sudden power loss, because judging by the sound and also height (osd), it didn't lower throttle, just corrected its attitude for unknown reason. I didn't do anything to the phantom myself (can't tell for the previous owner) lately, but at least everything looks to be in a good shape.

I think it would help me if somebody would tell how signal loss looks like - does it happen all at once (so it falls into failsafe and that's it) or it can go on and off sporadically until it doesn't receive anything and only then it falls to failsafe?

Pilot_FML · Nov 30, 2015

No way to accurately say what "intermittent" signal loss looks like. I doubt that's what your seeing because a signal loss would cause the flight controller to first try and maintain a level attitude and then begin the fail-safe routine. The momentary swerve to right (i.e. unusual motor speed change) means either the flight controller is at fault or that the flight controller can't sufficiently control a motor(s) well enough to maintain level flight.

Since the majority of electronic problems are caused by something mechanical (ie., loose connection, bad solder joint, corrosion at some connection, broken wire, shorted motor winding, etc.etc.), I'd suggest your time is best spent first ruling out these possibilities.

The cold operating temperature you were flying in complicates troubleshooting even more. The cold could by itself cause a connection to intermittently open up with resulting momentary loss of power to one (or more) motors.