Go home without GPS?

[Erel2]

Flight logs: DJI Flight Log Viewer - PhantomHelp.com

While filming a peaceful demonstration the drone was jammed several times. It first lost GNSS satellites and then disconnected. I thought that in such case the drone will start landing and was a bit surprised to see that it successfully flew back home. Maybe it was flying based on the compass. There was no wind.
It happened several times.

What do the experts say about RTH without connection and satellites?

 

[Meta4]

Flight logs: DJI Flight Log Viewer - PhantomHelp.com

While filming a peaceful demonstration the drone was jammed several times. It first lost GNSS satellites and then disconnected. I thought that in such case the drone will start landing and was a bit surprised to see that it successfully flew back home. Maybe it was flying based on the compass.

GPS interference is a fact of life in your part of the world:

GPSJam GPS/GNSS Interference Map

Map showing possible GPS interference around 40.135, 36.283.

gpsjam.org

If the drone loses GPS, it's still controllable but cannot hold position.
If it loses GPS and control signal, it will land where it is.
It cannot use a compass alone to find its way back.

I looked at your data and at first glance it appears that GPS was lost.
At 9:41 the data shows GPS sat numbers dropping to zero for 30 seconds.
But when I look closer, the location data was constantly updating the whole tome.
That would be impossible without GPS.
The same thing happened again at 12:20 for 40 seconds, and at 19:09 for 40 seconds.
Each time the GPS interference was enough to upset the number of sats displayed, but not enough to stop GPS from working.

What do the experts say about RTH without connection and satellites?

If you really do lose GPS location data, automated RTH will not be possible.

 

[Erel2]

Thanks. It was a local jammer for sure. One of the protestors saw the guy who operated it.

I understand what you are saying and it is reasonable. On the other hand, it does look like a complete blocking of GPS. Theoreticaly the drone can fly based on the last location and the compass towards the home point. It is safer than auto-landing in an unknown location. Maybe it is an improvement of the Mavic 3.

 

[Meta4]

Thanks. It was a local jammer for sure. One of the protestors saw the guy who operated it.

How would that person be able to tell?
It's more likely due to Russian operations in Syria

I understand what you are saying and it is reasonable. On the other hand, it does look like a complete blocking of GPS.

No it doesn't.
The recorded data shows a new, updated location for every 1/10th of a second.
If the GPS signal is blocked, this could not happen.

Theoreticaly the drone can fly based on the last location and the compass towards the home point.

You could if you had a hand bearing compass and a map and knew your location, but your drone cannot because it doesn't work like that.

 

[Erel2]

How would that person be able to tell?

It happened at a very specific location and he saw the operator point the equipment towards the drone. Outside of this location the satellites reception was excellent (I'm familiar with the occasional wide area blockings).

The recorded data shows a new, updated location for every 1/10th of a second.
If the GPS signal is blocked, this could not happen.

I agree.
And it does look like the satellites counter is misleading in this case. Maybe they blocked only one of the GNSS networks.