Will the drone fly out of range or just stop

[PatR]

You are perfectly correct. As mentioned, you have to initially take off with GPS active and disable whilst in flight but then it will RTH no problem. Telemetry is also recorded (including position) with GPS disabled.

Your description is telling you that GPS was not completely severed. Although switched off it has to still be running in the background. Telemetry is not tied to GPS functionality. If actual flight telemetry is being recorded there is still a radio link maintained with the aircraft. When link is lost, aircraft telemetry stops. There's nothing available to record.

If both the C2 link and GPS are lost at the aircraft there is absolutely nothing that can be done to bring the aircraft back. Best you can hope for is for the aircraft to stop, hover, and drift with the wind until the battery runs down. Military grade stuff is no different in such a scenario. This is a condition where "fail safe" programming becomes important. Systems that can employ programming to achieve a specific flight profile or reduce throttle to a controlled descent speed when link and GPS are lost can be extremely beneficial for multirotors. A command to hover and drift until link is regained or hover and drift awaiting a pre-set battery level to be reached and then land can save the day. Without the C2 link there is no way for the aircraft to return home even if GPS is regained. The original Home position was lost with the GPS failure.

 

[samsflite]

If actual flight telemetry is being recorded there is still a radio link maintained with the aircraft. When link is lost, aircraft telemetry stops..

I disagree with this, Telemetry seems to be completely separate from Control Link. This is why there are three antennae, one for control, one for video (which can become redundant 5.8GHz control), and one for telemetry. I seem to remember having seen instances on here where the telemetry section of people's ST16 diplays have gone blank but they've retained control of the aircraft. Correct me if I'm wrong however!

 

[PatR]

If we lose both the 5.8 and 2.4 links we lose the ability to transfer flight data. I'm not going to say you're wrong, but I do not believe it possible to exchange data without a radio link. It's the road the telemetry runs on.

 

[Steve Carr]

The H480 will do this so long as the flight started with GPS active so that the H 'knows' where the ST 16 is/was at the time of take off. The H480 will then return to the last known position of the ST16 even if GPS is inactive at the time the control signal is lost.

Interesting. After seeing your comment I did a search and found the reference here on post #17 from @samsflite. Anyone passed a UK Flight Assessment with Typhoon H?

To be clear, I consider Home when the mode switch is changed, and RTH as the failsafe mode when the control signal is lost. So in the referenced thread, RTH works but Home does not.

It is certainly a topic worthy of further testing and verification. I would think that if the H is on the ground and has acquired GPS and then it's turned off, the position of the ST16 would already be known.

 

[Rubik]

Interesting. After seeing your comment I did a search and found the reference here on post #17 from @samsflite. Anyone passed a UK Flight Assessment with Typhoon H?

To be clear, I consider Home when the mode switch is changed, and RTH as the failsafe mode when the control signal is lost. So in the referenced thread, RTH works but Home does not.

It is certainly a topic worthy of further testing and verification. I would think that if the H is on the ground and has acquired GPS and then it's turned off, the position of the ST16 would already be known.

When the TH and ST16 are started, the default is GPS ON, even if you turned GPS turned OFF for the previous flight. Therefore, if GPS is turned off or even if the controller shuts down (dead ST16 battery), the TH should know the position of the controller and be able to fly home autonomously.

However, if GPS is turned OFF during a flight and the controller is then shut down (who in their right mind would do this), when the ST16 reboots, GPS will still be OFF according to the screen. I tested this much on the ground. In a flight, I think the TH will still fly home autonomously. I'm not going to test this in the air.

If the ST16 is ON but switches out of flight control mode (this happened to me once when it lost control contact with the TH), does the HOME switch still work? Or do we just wait the 10+/- seconds until the TH figures out that it has no other control and initiates autonomous RTH? In my incident, it returned to my position at RTH altitude and hovered until I got back into flight control mode and landed manually. If I had not regained manual control, I assume it would have landed itself when the onboard battery was low enough.

I don't see a scenario where the TH would not fly home autonomously (except TH malfunction or loose battery). Agreed, interesting topic.

 

[JulesTEO]

Actually the telemetry just skips logging whenever there's no communication, (for those unfamiliar with the telemetry logs, they are logged insanely fast; first image shows how at close range there are more than 20 logs per second!) but they get less frequent the less communication there is with the aircraft. (no communication, no entry logged)

2nd graphic is the actual telemetry from the day I lost RC with the H. Originally I thought the H had started heading home Before receiving my command, but my memories were wrong: it was just a very brief moment the groundstation and the aircraft lost contact. It was shortly after the 4 seconds of lost RC (and video) that I flipped the fly mode to Home.
The H remained heading home even after having 2 much longer periods of silence (10 seconds each, even though it was already getting closer)

Note: this happened when I was still flying with an older firmware without the dual band control. I'm also adding another image from a recent flight (yesterday) where you can see how different the Telemetry logs the dual band system.

(I' dont know what to make of the different IMU status, looks like they're related to lost RC but I'm not sure)

It still confuses me a bit to see those absolute zeros instead of any other value. This second image doesn't show RC lost though, it was a normal eventless flight, but it seems the dual control is constantly switching seamlessly between 2.4ghz and 5.8ghz, even if the aircraft is right infront of me I will get zeroes recorded on the RSSI column.

Greetings!

 

[Steve Carr]

@JulesTEO that is a nice graphic.

 

[Dilly Joat]

JulesTEO - Thank you for that explanation. I had been wondering about the number of RSSI entries of 0 when everything else appears normal. If the H is only recording the 2.4Ghz then this would explain it but why would it switch frequencies so much?

 

[THoff]

I suspect that the log is not actually showing a switching in the RC frequency, and that it is merely showing interleaved telemetry information for the two bands, distinguished by the presence of the RSSI for 2.4GHz and its absence for 5GHz.