I need help solving a mystery.  A new quad that I built has Crossfire and a DJI Air Unit.  It does not have GPS.  I've made just a few flights with the quad.  When I remove the SD card from the Air Unit and mount it on my computer, lo and behold the video files have correct date & timestamps--almost.  The times are about an hour later than the actual time, but that could be a daylight savings time issue.

The question is: how does the Air Unit know the date and time?  There is nothing in the settings to configure it.

At first I thought maybe Crossfire was getting the date/time from the radio and sending it to the quad.  But then I checked the radio and found that its date and time weren't even set correctly.  That's because I recently replaced the RTC battery in the radio and forgot to set the date/time afterwards.

Any ideas?

I wonder if the unit has a radio receiver to pick up the broadcast atomic time?

(03-Jan-2021, 08:20 PM)voodoo614 Wrote: I wonder if the unit has a radio receiver to pick up the broadcast atomic time?

I guess that's possible, but you'd think they'd advertise it as a feature.  Another possibility might be that either the Air Unit or the goggles have a battery backed-up RTC that gets set when you connect it up to the DJI Assistant on your computer.

It's weird.

When I get a chance, I'll connect both the Air Unit and the goggles up to DJI Assistant.  Then I'll check whether the 1-hour offset has vanished.  I think the last time I had them connected was when DST was still in effect.  I'll let you know what happens.

I believe the Air Unit synchronises it's date/time from the computer as you said.

(03-Jan-2021, 08:58 PM)SnowLeopardFPV Wrote: I believe the Air Unit synchronises it's date/time from the computer as you said.

I did a couple of experiments, and it looks like it's the goggles that keep track of the date/time.

First I briefly connected the Air Unit to DJI Assistant, and then recorded some video.  The timestamp was still ahead by slightly more than one hour.

Then I briefly connected the goggles to DJI Assistant, and again recorded some video.  This time the timestamp, even on the Air Unit, was exactly in sync with the local time.  So, mystery solved.

It does make sense for weight reasons to put the battery backup in the goggles.

That makes more sense. I think the goggles might use the time for things other than just the video files and as they have transmit capabilities it is logical for them so send the time over the air to the Air Unit. Then only the goggles need to have the correct time synchronised to them once which will then be relayed to each of your quads as you use them rather than you having to connect umpteen quads up to the DJI Assistant just to re-synchronize the time in each of them.