DJI air unit stopped recording in mid flight - Low signal

[Diver]

Hi all,
I have an iFlight DC5 with DJI air unit on it.
Yesterday I went to fly in acro mode for the first time. I had two problems .
1. Sudenly the air unit's DVR stopped recording in mid flight on all packs I use.
I don't know if this is relevant , but it happened after power loops .
The goggle's DVR was working with no problem
2. The signal indicator for the video was low , even in short distances (100 meters) in open space . I had set the output power to 700mw .
Is this normal ?
If it helps , I'm uploading the srt file from goggle's sd card .
Any ideas ?
Thanks in advance

 

[TVQ]

The video on your attachment flooks great from takeoff to landing, enjoyed watching you chasing off the birds by the way. Didn’t appear there was any loss of signal or image quality issues. Was this clip from the card in the Air Unit?’ Is it possible one of the antennas came loose?

 

[Diver]

It's from the goggles DVR . The one in air unit is kind of corrupt but watchable . It stops after the power loop Any idea about that ?
Antennas visualy look fine but I can't check the extension cable from the air unit to the back of the drone . I have to disassemble the frame and I tried to avoid it for now . The video looks good but if you check the srt file , you'll see that the signal is variable even in a very close distance .

 

[thetechnobear]

the video file on the air unit will be unaffected by video transmission issues, as it just records directly from the camera.

did you get any errors in the goggles? (slow sdcard error is a common one!)

what type of sdcard are you using, you need to use a decent quality brand, rated with high write speed. something like a sandisk extreme.
note: the airunit is recording at high resolution that the googles, so that means needs a faster card.
(though i use sandisk extreme in both air unit and goggles)


I guess, if it occurs after a powerloop could be power related , but Id check the sdcard first.

signal indicator, ignore it...
look at the bitrate its a better indicator, that should stay at 50mb (or whatever you have set it too) at least to 500m in clear line of sight.... I get that at 25mW , let alone 700mW
if you check my youtube channel (thetechnobear) you can see me testing antennas, which'll give you an idea of what to expect. ( I go out to 1km, on 25mw)

 

[Diver]

This is the card inside air unit

I saw something in the right side but it lasted for a few seconds and didn't catch it , sorry .

I have upload the osd data as subtitles on the video. Can you check it please to see the signal ?
I'll also upload the video from air unit's dvr and post the link .

I'll check your channel tomorrow.
Thanks



Edit : Here is the video from the air unit that fails after the power loop.

 

[thetechnobear]

I saw something in the right side but it lasted for a few seconds and didn't catch it , sorry .

k, thats going to be SD card slow... its a known and seemingly random issue, we all get it from time to time.

AIR UNIT SD Card slow

Hi Guys! Need help. I'm having an issue on SLOW SD CARD on Air unit. I'm using Sandisk Extreme PRO 64GB.I did a format in the airunit but still having the SD CARD SLOW every single flight. I'm running 700mw. I saw the recommended Sandisk is extreme (without pro). Should I upgrade the SD? I have...

forum.dji.com

I'd say I get it something like 1 in 4 or 5 flights... whats odd, is restarting recording midflight does not help.
but I can have it fail in one flight, land, change batteries - and it works fine on the next flight.

unfortunately, we arent really seeing dji do any development on the air unit side any more, so I think its unlikely it'll ever be fixed - ho hum.
I think many dont care too much since google dvr works, and many then add something like a go-pro for better inflight footage.

 

[Diver]

Thanks , next time , I'll pay more attention to read the message .
But isn't it strange that in all packs , the recording stopped after the power loop ?
If it is a power problem , you think a step down converter from the battery to air unit will help ?
About the video I watch on your channel with the range test , something must be very wrong with mine , isn't it ?
Is there any simple way (with a multimeter ) , without disassemble the frame , to see if the signal reach the connectors of the antennas ?

 

[thetechnobear]

sdcard - all i can say is for me, the sdcard slow error, happens pretty randomly...
perhaps, if yours is always after a heavy power draw, for you its power related... but hard to know.
perhaps try loops early on in flight when your battery still has lots of juice...
also what power rating does your battery have? I use 120C , but most say above 100C is fine.

you cant really test the antennas, without some kind of power meter.
a couple of things to becareful of....

a) air unit connectors
because there is a lip on the top of the air unit, in some configurations its very easy for the mmcx connectors to 'pop out' or not to be properly located.
Ive actually cut out a little bit of this lip, to stop it pushing against the connectors.
(I only recently did this, but its worth checking for)
I don't know if this is relevant for your drone, as depends how you antennas are mounted.

b) air unit overheating
if you power up the quad, and leave it on the ground for too long ( * ) - the air unit will overheat.
you can tell this happening - if you do NOT get 'unlocked' as you take off.
you could also test this by **temporarily** turning off auto temperature control in goggles.

( * ) basically I try to keep it under a minute or so....usually less, but my first flight, Im waiting for the gps lock.(so that may be a tiny bit more)
the unlocked means (afaik) ... the air unit is in low power mode whilst not armed, to try to prevent itself from overheating.
when you arm, and take off it knows the air flow will keep it cool - so it unlocks full power mode.
however, if the air unit is too warm already - it wont unlock and so will stay in low power mode.

 

[Diver]

Thanks , I'll check it on Sunday and I'll tell you the results.

But another problem has appeared . I asked iFlight's tech support for help with my problems and they suggest to flash the FC with the firmware . I did it but after that when I type "diff all" I have a warning and an error.
# diff all
###WARNING: NO CUSTOM DEFAULTS FOUND###
# version
# Betaflight / STM32F7X2 (S7X2) 4.2.9 Apr 27 2021 / 19:34:29 (e097f4ab7) MSP API: 1.43
###ERROR: diff: NO CONFIG FOUND###

I have contact iFlight's service , but I don't expect an answer before Monday.
Other than that , the quad looks like it is working ok , at least on the ground.
Is it safe to fly on Sunday or do I need to resolve these messages first ?
And If yes , how ?
Thanks in advance