Help with Airdata

[Raghid]

Hi All,

I was flying at a beach while on a holiday and I almost lost my drone as signal was lost half way through the flight and RTH kicked in. The drone was heading straight into a hill on the way back. I know I should have adjusted my RTH height limit to above 30. I was very lucky that I gained the signal back less about 1 meter before the disaster and somehow canceled the RTH and flew the drone back to safety.
Can someone help with analyzing what went wrong there and what might have cause the loss in the signal

Airdata UAV - Flight Data Analysis for Drones

Thanks in Advance,

Raghid

 

[Mark The Droner]

It would be easier to alalyze if you'd upload your log here and paste the link: DJI Flight Log Viewer

site credit: msinger

 

[LarBear360]

The airdata info is rarely helpful to the data experts who read these posts. Nevertheless, I don't know if there is anything in the DJI flight log that would explain signal loss; only that it happened. Hoping someone could explain the minor signal errors.

 

[sar104]

Hi All,

I was flying at a beach while on a holiday and I almost lost my drone as signal was lost half way through the flight and RTH kicked in. The drone was heading straight into a hill on the way back. I know I should have adjusted my RTH height limit to above 30. I was very lucky that I gained the signal back less about 1 meter before the disaster and somehow canceled the RTH and flew the drone back to safety.
Can someone help with analyzing what went wrong there and what might have cause the loss in the signal

Airdata UAV - Flight Data Analysis for Drones

Thanks in Advance,

Raghid

The fact that the drone would have hit the hill heading back to you is a rather clear indication that the hill came between you and the drone as it descended behind it from 264 ft to 111 ft - hence the signal loss. That also appears to be the case from the limited information that you chose to share from AirData. If you want a definitive answer then you need to enable user download of the csv and kml files from AirData.

 

[Raghid]

The fact that the drone would have hit the hill heading back to you is a rather clear indication that the hill came between you and the drone as it descended behind it from 264 ft to 111 ft - hence the signal loss. That also appears to be the case from the limited information that you chose to share from AirData. If you want a definitive answer then you need to enable user download of the csv and kml files from AirData.

Thanks for your quick reply and my apologies as this was the first time I share a report through airdata. Never used it before.
Please try the below new link:

Airdata UAV - Flight Data Analysis for Drones

Thanks

 

[Raghid]

It would be easier to alalyze if you'd upload your log here and paste the link: DJI Flight Log Viewer

site credit: msinger

Please see below:
DJI Flight Log Viewer - PhantomHelp.com

Thanks in Advance

 

[sar104]

Thanks for your quick reply and my apologies as this was the first time I share a report through airdata. Never used it before.
Please try the below new link:

Airdata UAV - Flight Data Analysis for Drones

Thanks

For some reason that log starts in the middle of the flight, at around 244 ft AGL. Apart from that, assuming that you were controlling from the location where it finished the flight, the answer is that you simply flew it behind the hill, which is always going to cause signal issues.

 

[LarBear360]

Thanks for your quick reply and my apologies as this was the first time I share a report through airdata. Never used it before.
Please try the below new link:

Airdata UAV - Flight Data Analysis for Drones

Thanks

From the airdata image, it appears your home point is off-shore. Or is it just a thing with the tides? Were you located at the home point?

Just a wild guess, but you launched from a boat which started to drift into the shoreline at which time the hill came between you and the drone?

 

[sar104]

From the airdata image, it appears your home point is off-shore. Or is it just a thing with the tides? Were you located at the home point?

Just a wild guess, but you launched from a boat which started to drift into the shoreline at which time the hill came between you and the drone?

The home point is not only offshore, it's 244 ft in the air. I'm guessing that the location of the controller was where the aircraft landed. The following image shows the viewshed from the point where signal was lost. If that's the case then it's not surprising that it disconnected.

 

[sar104]

Here's a better view perhaps:

 

[LarBear360]

The home point is not only offshore, it's 244 ft in the air. I'm guessing that the location of the controller was where the aircraft landed. The following image shows the viewshed from the point where signal was lost. If that's the case then it's not surprising that it disconnected.

View attachment 93633

Yup. Never seen that before. The first entry log on airdata has it 244 feet in the air and 288 feet from home 30 seconds into the flight. Signal lost as it appears to go around the bend.

 

[sar104]

Just to make this completely clear:

Downlink was lost first, but then that results in no uplink data until downlink returns. So uplink went down (so to speak) somewhere between 266 s and 282 s.

 

[sar104]

Yup. Never seen that before. The first entry log on airdata has it 244 feet in the air and 288 feet from home 30 seconds into the flight. Signal lost as it appears to go around the bend.

This flight appears to have been manual under Litchi, so it's possible that it launched with DJI Go - hence the partial log and the strange home point.

 

[Raghid]

Thanks everyone for your valuable input. Looks like i have a lot to learn. i have actually launched the drone from where it landed. I was using the litchi app. Few minutes into the flight the app crashed and closed itself so i opened it again and everything was normal tell i lost the signal and rth kicked in. Not sure if thats the reason for the new home point!

 

[sar104]

Thanks everyone for your valuable input. Looks like i have a lot to learn. i have actually launched the drone from where it landed. I was using the litchi app. Few minutes into the flight the app crashed and closed itself so i opened it again and everything was normal tell i lost the signal and rth kicked in. Not sure if thats the reason for the new home point!

Right - so the main lesson here is that you will lose signal if you put solid earth (hills) or even large buildings between the aircraft and the controller. This is essentially line of sight communications at these frequencies.

 

[sar104]

Thanks everyone for your valuable input. Looks like i have a lot to learn. i have actually launched the drone from where it landed. I was using the litchi app. Few minutes into the flight the app crashed and closed itself so i opened it again and everything was normal tell i lost the signal and rth kicked in. Not sure if thats the reason for the new home point!

The home point issue is interesting, because the aircraft's home point was clearly not the location recorded in the Litchi log - when it entered RTH it set a heading of 240° direct for the takeoff location on the shore rather than heading for the Litchi-recorded home point. Also the Litchi log does not include a home point recorded notification, so the app seems to have simply assumed that the first logged location was the home point. That would appear to be a Litchi bug.

 

[Raghid]

Right - so the main lesson here is that you will lose signal if you put solid earth (hills) or even large buildings between the aircraft and the controller. This is essentially line of sight communications at these frequencies.

Lesson learnt. Thanks

 

[Avocet]

Although unlikely, it is also possible that the OP accidently changed the HP mid flight, especially after an app crash. Don't ask me how i know this! :

 

[sar104]

Although unlikely, it is also possible that the OP accidently changed the HP mid flight, especially after an app crash. Don't ask me how i know this! :

But that clearly did not happen, since when it started RTH it headed for the original takeoff point.

 

[slugger]

Hi All,

I was flying at a beach while on a holiday and I almost lost my drone as signal was lost half way through the flight and RTH kicked in. The drone was heading straight into a hill on the way back. I know I should have adjusted my RTH height limit to above 30. I was very lucky that I gained the signal back less about 1 meter before the disaster and somehow canceled the RTH and flew the drone back to safety.
Can someone help with analyzing what went wrong there and what might have cause the loss in the signal

Airdata UAV - Flight Data Analysis for Drones

Thanks in Advance,

Raghid