Hi All,

During a recent flight of our S900+A2 we experienced some loss of control. It appears to be related to low control signal strength, possibly due to interference. The machine was only approx. 25m away during the event.

Initially we thought the machine had gone into failsafe and attempts were made to regain control by changing the flight mode. We didn't notice the LED indicate failsafe and the landing gear didn't lower. This all happened pretty quickly, the camera operator noticed a low signal in RED of value 8 on the LB OSD and attempts were made to reposition the antennas for better reception. Full control was eventually regained and the machine was landed without incident.

I've review the iOSD logs and it appears that control signal was lost on a few occasions. The attached shows the elevator input and U input (flight mode). The first arrow shows when the problem started. The machine was being flown forward and at the time of the issue, it was about to be flown backwards. The control signal in from the Lightbridge appears to hold the last command for a period of time before it and the A2 enter a failsafe situation.

Can someone please confirm that the flat line inputs are actually the Lightbridge holding the last received value?

Thanks.

Bit of an update, I did some tests on the bench. I removed the 3.5mm cable from the trainer port on the transmitted and also powered off the Lightbridge ground unit. It appears that the Lightbridge does hold the last input until the control link has resumed.

The A2 did go into failsafe as expected after 3 seconds.

Correct, The A2 handles the failsafe.

DJI-BladeStrike Posted at 2015-9-30 01:29
Correct, The A2 handles the failsafe.

Thanks BladeStrike. Just needed to confirm the behaviour experienced during the intermittent control loss. There were a few hairy moments while it was all going on.

Cheers.

Further to the above issue, we've continued to experience low control signal with our Lightbridge recently.

White paddle antennas mount on legs.
Ground unit is mount on a tripod.
Both TXs have 2.4 disabled.

At the time of low signal, the machine has been within 50-100m of the ground unit and not in the "null" of the antennas. Video signal at the time is fine and doesn't drop out.

We haven't checked the signal diagnostics at the time but have done while the machine is in the garage. Antenna 1 on the ground unit always shows significantly lower signal strength than Antenna 2.

Wifi disabled on GH4 and Samsung TabS tablet.

We've had a fair share of issues with video with the lightbridge. Started having pixelation etc. We've changed out

the HDMI to HD-AV cable and also the cable from the Z15 slipring to GCU. Things are better but somewhat inconsistent.
Any ideas?
Thanks.